Laborejo/engine/api.py

#! /usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Copyright 2022, Nils Hilbricht, Germany ( https://www.hilbricht.net )

This file is part of the Laborejo Software Suite ( https://www.laborejo.org ),

Laborejo2 is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

import logging; logger = logging.getLogger(__name__); logger.info("import")

#Python Standard Library
import sys
import random
random.seed()
from typing import Iterable, Callable, Tuple

#Template Modules
from template.calfbox import cbox
import template.engine.api #we need direct access to the module to inject data in the provided structures. but we also need the functions directly. next line:
from template.engine.api import *
from template.engine.duration import DM, DB, DL, D1, D2, D4, D8, D16, D32, D64, D128, D256, D512, D1024, D_DEFAULT, D_STACCATO, D_TENUTO, D_TIE
import template.engine.pitch as pitchmath
from template.helper import flatList, EndlessGenerator

#Our Modules
from . import items
from . import lilypond
from .tempotrack import TempoItem, TempoTrack
from .ccsubtrack import GraphItem, GraphTrackCC
from .track import Track

apiModuleSelfReference = sys.modules[__name__]

#New callbacks
class ClientCallbacks(Callbacks): #inherits from the templates api callbacks
    def __init__(self):
        super().__init__()

        self.setCursor = []
        self.setSelection = []

        self.tracksChanged = []
        self.tracksChangedIncludingHidden = []
        self.updateTrack = []
        self.updateBlockTrack = []

        #self.playbackStart = []
        #self.playbackStop = []
        self._cachedTickIndex = -1

        self.updateGraphTrackCC = []
        self.graphCCTracksChanged = []
        self.updateGraphBlockTrack = []

        self.updateTempoTrack = []
        self.updateTempoTrackBlocks = []
        self.updateTempoTrackMeta = []
        self.tempoScalingChanged = []

        self.prevailingBaseDurationChanged = []

        #self.recordingStreamNoteOn = []
        #self.recordingStreamNoteOff = []
        #self.recordingStreamClear = []

    def _dataChanged(self):
        """Only called from within the callbacks.
        This is about data the user cares about. In other words this is the indicator if you need
        to save again.

        The data changed when notes are inserted, track names are changed, a CC value is added etc.
        but not when the cursor moves, the metronome is generated or the playback tick advances.
        """
        session.nsmClient.announceSaveStatus(False)
        self._historyChanged()

    def _setCursor(self, destroySelection = True):
        """set a new cursor position.
        Only do destroySelection = False if you really modify the
        selection. If in doubt: destroy it. """
        if destroySelection or session.history.doNotRegisterRightNow or session.history.duringRedo:
            session.data.cursorWhenSelectionStarted = None

        if self.setCursor:
            ex = session.data.cursorExport()
            for func in self.setCursor:
                func(ex)

        """Exports a tuple of cursors. This is to indicate a GUI to
        draw a selection rectangle or so. Not for processing. Because:
        The exported top left item is included in the selection.
        The exported bottom right item is NOT in the selection.
        But for a GUI it looks like the rectangle goes to the current
        cursor position, which appears to be left of the current item."""
        ex = session.data.selectionExport()
        for func in self.setSelection:
            func(ex)

    def _updateChangedTracks(self):
        """Determines which tracks have changed in the step before
        this callback and calls an update for those"""
        changedTracks, currentItem = session.data.currentContentLinkAndItsBlocksInAllTracks()
        for track in changedTracks:
            self._updateTrack(id(track))
            if session.data.currentMetronomeTrack is track:
                setMetronome(track.asMetronomeData, label=track.name) #template api

    def  _updateTrack(self, trId):
        """The most important function. Create a static representation of the music data which
        can be used by a GUI to draw notes.
        track.staticRepresentation also creates the internal midi representation for cbox. """
        if self.updateTrack:
            ex = session.data.trackById(trId).staticRepresentation()
            for func in self.updateTrack:
                func(trId, ex)
            self._updateBlockTrack(trId)

    def _updateBlockTrack(self, trId):
        if self.updateBlockTrack:
            ex = session.data.trackById(trId).staticBlocksRepresentation()
            for func in self.updateBlockTrack:
                func(trId, ex)

        self._updateTempoTrack() #The last Tempo Block reacts to changing score sizes.
        self._dataChanged()

    def _updateGraphTrackCC(self, trId, cc):
        """No cursor, so it always needs a graphTrack Id.
        Also handles a GraphBlock overview callback,
        for extra block view or background colors."""
        track = session.data.trackById(trId)
        if cc in track.ccGraphTracks:
            graphTracksThatNeedUpdate = track.ccGraphTracks[cc].otherTracksWithOurLinkedContent()

            for gTr in graphTracksThatNeedUpdate:
                trId = id(gTr.parentTrack)
                ex = gTr.staticRepresentation()

                for func in self.updateGraphTrackCC:
                    func(trId, cc, ex)

                ex = gTr.staticGraphBlocksRepresentation()
                for func in self.updateGraphBlockTrack:
                    func(trId, cc, ex)

    def _updateSingleTrackAllCC(self, trId):
        """Used on CC-Channels change. No own callback list."""
        for cc, graphTrackCC in session.data.trackById(trId).ccGraphTracks.items():
            ex = graphTrackCC.staticRepresentation()
            for func in self.updateGraphTrackCC:
                func(trId, cc, ex)

    def _graphCCTracksChanged(self, trId):
        """CC graphs of a track deleted or added.
        Does not need to react to block or item changes, even (not) block duration changes
        which change the tracks overall duration!"""
        #TODO: moved?
        if self.graphCCTracksChanged:
            ex = list(session.data.trackById(trId).ccGraphTracks.keys())  # list of ints from 0 to 127
            for func in self.graphCCTracksChanged:
                func(trId, ex)
        self._dataChanged()

    def _tracksChanged(self):
        """Track deleted, added or moved. Or toggled double/non-double, visible, eudible etc.
        This callback is relatively cheap because it does not generate
        any item data."""
        #TODO: does NOT call template.api._numberOfTracksChanged
        session.data.updateJackMetadataSorting()
        ex = session.data.listOfStaticTrackRepresentations()

        if self.tracksChanged:
            for func in self.tracksChanged:
                func(ex)

        if self.tracksChangedIncludingHidden:
            exHidden  = session.data.listOfStaticHiddenTrackRepresentations()
            for func in reversed(self.tracksChangedIncludingHidden):
                func(ex + exHidden)
        self._dataChanged()

        session.data.metronome.label = session.data.currentMetronomeTrack.name #not the expensive redundant data generation
        self._metronomeChanged() #because the track name is sent here.

    def _updateTempoTrack(self):
        """Sends the block update as well.
        staticRepresentations also updates midi.

        Of course the order is: track meta, then blocks first, then items.
        This must not change! The GUI depends on it."""

        if self.updateTempoTrackMeta:
            ex = session.data.tempoTrack.staticTrackRepresentation() #only track metadata, no block information. parses all items.
            for func in self.updateTempoTrackMeta:
                func(ex)

        if self.updateTempoTrackBlocks:
            ex = session.data.tempoTrack.staticGraphBlocksRepresentation() #block boundaries and meta data. Does not parse items therefore cheap to call.
            for func in self.updateTempoTrackBlocks:
                func(ex)

        if self.updateTempoTrack:
            ex = session.data.tempoTrack.staticRepresentation() #export all items. performance-expensive.
            for func in self.updateTempoTrack:
                func(ex)

        #TODO: We need blocks before items, but also blocks after items. This is a cheap call though.
        if self.updateTempoTrackBlocks:
            ex = session.data.tempoTrack.staticGraphBlocksRepresentation() #yes, we need to regenerate that. That is the problem. #TODO.
            for func in self.updateTempoTrackBlocks:
                func(ex)

        self._dataChanged()
        #since the exported cursor also has a tempo entry it needs updating as well
        #TODO: but this also leads to centerOn cursor in the gui after every mouse click in the conductor.
        #self._setCursor(destroySelection = False)

    def _tempoScalingChanged(self, newValue):
        for func in self.tempoScalingChanged:
            func(newValue)

    def _playbackStart(self):
        for func in self.playbackStart:
            func()

    def _playbackStop(self):
        for func in self.playbackStop:
            func()


    def _prevailingBaseDurationChanged(self, newPrevailingBaseDuration):
        for func in self.prevailingBaseDurationChanged:
            func(newPrevailingBaseDuration)

    def _historyChanged(self):
        """sends two lists of strings.
        the first is the undoHistory, the last added item is [-1]. We can show that to a user to
        indicate what the next undo will do.

        the second is redoHistory, same as undo: [-1] shows the next redo action."""
        undoHistory, redoHistory = session.history.asList()
        for func in self.historyChanged:
            func(undoHistory, redoHistory)

    def _recordingStreamNoteOn(self, liveChord):
        """One dict at a time"""
        trId = id(session.data.currentTrack())
        for func in self.recordingStreamNoteOn:
            func(trId, liveChord)

    def _recordingStreamNoteOff(self, liveChord):
        """One dict at a time"""
        trId = id(session.data.currentTrack())
        for func in self.recordingStreamNoteOff:
            func(trId, liveChord)

    def _recordingStreamClear(self):
        for func in self.recordingStreamClear:
            func()

#Inject our derived Callbacks into the parent module
template.engine.api.callbacks = ClientCallbacks()
from template.engine.api import callbacks


_templateStartEngine = startEngine
def startEngine(nsmClient, additionalData:dict={}):
    _templateStartEngine(nsmClient)

    #Send initial Data etc.
    session.data.tempoMap.isTransportMaster = True #always true for Laborejo.
    callbacks._tracksChanged()  # This creates the frontend/GUI tracks with access through track ids. From now on we can send the GUI a trId and it knows which track needs change.

    for track in session.data.hiddenTracks: #After loading a file some tracks could be hidden. We want midi for them as well.
        track.staticRepresentation()  #that generates the calfbox data as a side effect. discard the other data.


    #because we do a simplicifaction in _updateGraphTrackCC that calls all tracks for one CC (for content links) we need to build the structure first, only during file load.
    for trId in session.data.listOfTrackIds():
        callbacks._graphCCTracksChanged(trId) #create structure: all CC graphs, accessed by CC number (0-127)

    for trId in session.data.listOfTrackIds():
        callbacks._updateTrack(trId) #create content: music items
        callbacks._updateTempoTrack() # does everything at once
        #done above. Special situation at file load. callbacks._graphCCTracksChanged(trId) #create structure: all CC graphs, accessed by CC number (0-127)
        for cc in session.data.trackById(trId).listOfCCsInThisTrack():
            callbacks._updateGraphTrackCC(trId, cc) #create content: CC points. user points and interpolated points.

    if session.data.currentMetronomeTrack.asMetronomeData:
        setMetronome(session.data.currentMetronomeTrack.asMetronomeData, label=session.data.currentMetronomeTrack.name) #track.asMetronomeData is generated in staticRepresentation  #template api. has callbacks
    callbacks._setCursor()

    if session.data.metaData["title"]:
        cbox.JackIO.Metadata.client_set_property("http://jackaudio.org/metadata/pretty-name", session.data.metaData["title"])

    global laborejoEngineStarted #makes for a convenient check. stepMidiInput uses it, which needs to know that the gui already started the api.
    laborejoEngineStarted = True

#General and abstract Commands

def getMetadata():
    """Do not confuse with template/config METADATA. This is Lilypond title, composer etc."""
    return session.data.metaData

def setMetadata(data):
    titleBefore = bool(session.data.metaData["title"])
    session.data.metaData = data
    if session.data.metaData["title"]:
        cbox.JackIO.Metadata.client_set_property("http://jackaudio.org/metadata/pretty-name", session.data.metaData["title"])
    elif titleBefore:
        cbox.JackIO.Metadata.client_remove_property("http://jackaudio.org/metadata/pretty-name")


def playFromCursor():
    playFrom(ticks=session.data.cursorExport()["tickindex"])

def playFromBlockStart():
    tr = session.data.currentTrack()
    ticks = 0
    for idx, bl in enumerate(tr.blocks):
        if idx == tr.state.blockindex:
            playFrom(ticks)
            return
        else:
            ticks += bl.duration()
    else:
        raise RuntimeError("reached end of blocks without matchin  current block index")


def getMidiInputNameAndUuid()->(str, int): #tuple name:str, uuid
    """Override template function. We access the stepMidi directly.
    Used by the quick midi input widget

    Return name and cboxMidiPortUid.
    name is Client:Port JACK format

    If not return None, None
    """
    from engine.midiinput.stepmidiinput import stepMidiInput  #singleton instance #avoid circular dependency. stepMidiInput import api
    if stepMidiInput.ready: #startup delay
        return stepMidiInput.fullName(), stepMidiInput.cboxMidiPortUid
    else:
        return None, None

topLevelFunction = None
def simpleCommand(function, autoStepLeft = True, forceReturnToItem = None):
    """
    simpleCommand demands that the cursor is on the item you want to
    change. That means for scripting and working with selections
    that you can't simply iterate over block.data, which is a list.
    Well you can, but then you don't get the context data which is in
    track.state.

    Recursive commands are not allowed"""
    global topLevelFunction  #todo: replace with a python-context
    if not topLevelFunction:
        topLevelFunction = function

    if autoStepLeft and session.data.currentTrack().state.isAppending():
        session.data.currentTrack().left()
        function() #<-------- The action
        session.data.currentTrack().right()
    else:
        function() #<-------- The action

    if forceReturnToItem:
        curBlock, curItem = forceReturnToItem
        session.data.currentTrack().toItemInBlock(curItem, curBlock) #even works with appending positions (None)

    if function == topLevelFunction:
        callbacks._updateChangedTracks() #works with the current item @ cursor.
        callbacks._setCursor()
        topLevelFunction = None

def insertItem(item):
    orderBeforeInsert = session.data.getBlockAndItemOrder()
    moveFunction = _createLambdaMoveToForCurrentPosition()
    if session.data.currentTrack().insert(item):
        def registeredUndoFunction():
            moveFunction()
            _changeBlockAndItemOrder(orderBeforeInsert)
        session.history.register(registeredUndoFunction, descriptionString=f"Insert {item}")
        simpleCommand(nothing, autoStepLeft = False) #for callbacks
        callbacks._historyChanged()

def insertItemAtTickindex(item, tickindex):
    #session.data.currentTrack().goToTickindex

    """
    Das ist eine conversion in der session. keine api befehle benutzen.
    hier weiter machen. Der Cursor muss in Ruhe gelassen werden. Oder aber ich resette ohne callback? das erscheint mir erstmal simpler.
    Ich brauch aber eine Funktion goToTickindex im Track die Pausen erstellt wenn man da nicht hinkommt.  Jetzt wünsch ich mir ich hätte die Noten nicht in ner liste sondern in einem dict mit tickindex. welp...
    vielleicht brauch ich eine komplette parallelwelt. das midi modul sollte auf jeden fall nicht die keysig suchen müssen. kontext wird in der api hergestellt, nicht im midi
    """

def _createLambdaMoveToForCurrentPosition():
    """for undo only"""
    def moveTo(trackIndex, blockIndex, localCursorIndexInBlock, pitchindex):
        try:
            session.data.goTo(trackIndex, blockIndex, localCursorIndexInBlock)
            session.data.cursor.pitchindex = pitchindex
        except: #the worst that can happen is wrong movement.
            pass
    trackIndex, blockIndex, localCursorIndexInBlock = session.data.where()
    moveFunction = lambda trIdx=trackIndex, blIdx=blockIndex, curIdx=localCursorIndexInBlock, pitchIdx=session.data.cursor.pitchindex: moveTo(trIdx, blIdx, curIdx, pitchIdx)
    return moveFunction


def _createLambdaRecreateSelection():
    """Not for undo.
    Call it when you still have a selection, right after you do the
    processing.

    This is to keep a selection that changed the item positions but you want to support a new
    call to the function immediately. For example the reorder notes by shuffling function.
    The user will most likely hit that several times in a row to find something nice.

    A valid selection implies that the cursor is on one end
    of the selection. It doesn't matter which one but for the
    sake of consistency and convenience we make sure that we end up with
    the cursor on the bottomRight position.
    It is entirely possible that the selection changed
    the duration and the dimensions. The bottom right item might not
    be on the same tickindex nor does it need to exist anymore.
    Only the topLeft position is guaranteed to exist and have the same
    tickindex. The item on that position however may not be there
    anymore.
    """
    def recreateSelection(moveToFunction, topLeftCursor, bottomRightCursor):
        session.data.cursorWhenSelectionStarted = None #take care of the current selection
        moveToFunction()
        session.data.goTo(topLeftCursor["trackIndex"], topLeftCursor["blockindex"], topLeftCursor["localCursorIndex"])
        session.data.setSelectionBeginning()
        session.data.goTo(bottomRightCursor["trackIndex"], bottomRightCursor["blockindex"], bottomRightCursor["localCursorIndex"])

    assert session.data.cursorWhenSelectionStarted #only call this when you still have a selection
    createSelectionFunction = lambda moveTo=_createLambdaMoveToForCurrentPosition(), tL=session.data.cursor.exportObject(session.data.currentTrack().state), bR=session.data.cursorWhenSelectionStarted, : recreateSelection(moveTo, tL, bR)
    return createSelectionFunction #When this function gets called we are back in the position that the newly generated data is selected, ready to to the complementary processing.


def _updateCallbackForListOfTrackIDs(listOfChangedTrackIds):
    for trackId in listOfChangedTrackIds:
        callbacks._updateTrack(trackId)

def _updateCallbackAllTracks():
    _updateCallbackForListOfTrackIDs(session.data.listOfTrackIds())

updateCallbackAllTracks = _updateCallbackAllTracks

def _changeBlockAndItemOrder(dictWithTrackIDsAndDataLists):
    """A helper function for deleteSelection, paste and other...
    This makes it possible to undo/redo properly. It registers
    itself with complementary data as undo/redo."""
    orderBeforeInsert = session.data.getBlockAndItemOrder() #save the current version as old version. as long as we keep this data around, e.g. in the undo stack, the items will not be truly deleted
    moveFunction = _createLambdaMoveToForCurrentPosition() #the goTo function for the cursor is not exactly in the right place. It may end up on the "other" side of a selection. Which is close enough.
    def registeredUndoFunction():
        moveFunction()
        _changeBlockAndItemOrder(orderBeforeInsert)
    session.history.register(registeredUndoFunction, descriptionString="change order")

    #Replace old data with new parameter-data.
    listOfTrackIDs = session.data.putBlockAndItemOrder(dictWithTrackIDsAndDataLists)

    #Make changes visible in the GUI
    _updateCallbackForListOfTrackIDs(listOfTrackIDs)
    callbacks._setCursor()

def cutObjects():
    copyObjects()
    _deleteSelection()

def _deleteSelection(backspaceParamForCompatibilityIgnoreThis = None): #this is so special it gets its own command and is not part of the single delete() command.
    orderBeforeDelete = session.data.getBlockAndItemOrder()
    moveFunction = _createLambdaMoveToForCurrentPosition()

    listOfChangedTrackIDs = session.data.deleteSelection()

    if listOfChangedTrackIDs: #delete succeeded.
        def registeredUndoFunction():
            moveFunction()
            _changeBlockAndItemOrder(orderBeforeDelete)
        session.history.register(registeredUndoFunction, descriptionString="delete selection")

        #Make changes visible in the GUI and midi
        for trackId in listOfChangedTrackIDs:
            callbacks._updateTrack(trackId)
        callbacks._setCursor()

def copyObjects(): #ctrl+c
    session.data.copyObjects()
    #The score doesn't change at all. No callback.
    #no undo.

def pasteObjects(customBuffer=None, updateCursor=True, overwriteSelection=True): #ctrl+v
    """api.duplicate overrides default paste behaviour by providing its own copyBuffer
    and not destroying the selection/keep the cursor at its origin position
    """
    dataBefore = session.data.getBlockAndItemOrder()
    moveFunction = _createLambdaMoveToForCurrentPosition()
    listOfChangedTrackIDs = session.data.pasteObjects(customBuffer, overwriteSelection)
    if listOfChangedTrackIDs: #paste succeeded.
        def registeredUndoFunction():
            moveFunction()
            _changeBlockAndItemOrder(dataBefore)
        session.history.register(registeredUndoFunction, descriptionString="paste")

        #Make changes visible in the GUI
        for trackId in listOfChangedTrackIDs:
            callbacks._updateTrack(trackId)

        if updateCursor:
            callbacks._setCursor()

def pasteObjectsTransposedReal(root:int=None, toPitch:int=None, adjustToKeySignKeySignature=False):
    """Uses the global/session clipboard buffer but pastes a transposed version, starting on the
    pitch cursor position, that is adjusted to the current keysignature.

    The notes are transformed into a custom buffer. We use standard paste for everything else.

    If root or toPitch for the transposition interval are None they will derive their pitch from
    the first pitch in the copy buffer and the cursor position, respectively.
    """

    if not session.data.copyObjectsBuffer:
        return #guard


    copyBuffer = session.data.getIndenpendetCopyObjectsBuffer()
    #Determine the first of the two pitches for our transposition interval
    if root is None or not type(root) is int:
        #First iteration only until the very first note, which we use to calculate the interval
        for track in copyBuffer:
            for item in track:
                if type(item) is items.Chord:
                    root = item.notelist[0].pitch #ordered by ascending pitch
                    break
                else: #inner loop finished without break. No chord? in the first track.
                    logging.warning("Found copy buffer without note in the first track. This is worth an investigation.")
                    continue #jump to the start and don't execute the outer loop break
            break #outer loop. We only get here if the inner loop did break as well.

        #Final Sanity Check. I don't think selections without chords are even allowed...
        if root is None:
            logging.error("pasteObjectsTransposedModal without notes in the copy buffer! (but not empty)")
            return

    if toPitch is None:
        toPitch = getCursorPitch()

    keysig = session.data.currentTrack().state.keySignature()
    #Edit the copy buffer in place. We don't modify the list, just the contents.
    for track in copyBuffer:
        for item in track:
            if type(item) is items.Chord:
                item.intervalAutomatic(root, toPitch)
                if adjustToKeySignature:
                    item.adjustToKeySignature([keysig,]) #keysig must be in a list because it is a chord. If it is just len==1 the transpose function will deal with it correctly.

    pasteObjects(customBuffer=copyBuffer) #normal paste except our special buffer


def pasteObjectsTransposedModal(root:int=None, toPitch:int=None):
    pasteObjectsTransposedReal(root, toPitch, adjustToKeySignature=True)


def duplicate(): #ctrl+d
    """Duplicate a single object and put it right of the original. The cursor moves with it
    to enable follow up insertion.

    Duplicate the entire selection and put the copy right of the last selected note.
    The cursor moves to selection start. deal with it.

    Basically a special case of copy and paste that does not touch the clipboard."""
    if session.data.cursorWhenSelectionStarted:
        customBuffer = session.data.copyObjects(writeInSessionBuffer = False)
        if customBuffer: #success
            session.data.goToSelectionStart()
            pos = session.data.where() #where even keeps the local position if a content linked block inserts items before our position
            pasteObjects(customBuffer = customBuffer, updateCursor = False, overwriteSelection = False)           #handles undo
            session.data.goTo(*pos)
            callbacks._setCursor(destroySelection=False)
    else:
        item = session.data.currentItem()
        if item:
            insertItem(item.copy())
        callbacks._setCursor()
#Score
def transposeScore(rootPitch, targetPitch):
    """Based on automatic transpose. The interval is caculated from two pitches.
    There is also tranpose. But no transposeTrack, this is just select track and transpose."""
    session.data.transposeScore(rootPitch, targetPitch)
    session.history.register(lambda r=rootPitch,t=targetPitch: transposeScore(t,r), descriptionString="transpose score")
    callbacks._historyChanged()
    _updateCallbackAllTracks()

def useCurrentTrackAsMetronome():
    """This is called once after loading/creating a session in startEngine"""
    session.data.currentMetronomeTrack = session.data.currentTrack()
    setMetronome(session.data.currentMetronomeTrack.asMetronomeData, label=session.data.currentMetronomeTrack.name) #template api. has callbacks

#Tracks
def insertTrack(atIndex, trackObject):
    moveFunction = _createLambdaMoveToForCurrentPosition()
    newTrackId = id(trackObject)
    session.data.insertTrack(atIndex, trackObject) #side-effect: changes the active track to the new track which can be used in the next step:
    def registeredUndoFunction():
        moveFunction()
        deleteTrack(newTrackId)
    session.history.register(registeredUndoFunction, descriptionString = "insert track")
    callbacks._tracksChanged()
    callbacks._updateTrack(newTrackId)
    callbacks._setCursor()

def newEmptyTrack():
    """Append an empty track and switch to the new track"""
    newIndex = len(session.data.tracks)
    newTrack = Track(session.data)

    if newIndex > 0:
        newTrack.initialKeySignature = session.data.tracks[0].initialKeySignature.copy()
        newTrack.initialMetricalInstruction = session.data.tracks[0].initialMetricalInstruction.copy()
        newTrack.upbeatInTicks = session.data.tracks[0].upbeatInTicks #just an int

    insertTrack(newIndex, newTrack) #handles callbacks and undo
    return (id(newTrack))

def deleteTrack(trId):
    """Can not delete hidden tracks because these don't implement undo.
    A hidden track is already considered "deleted" by the program.
    Therefore you can only delete visible tracks."""
    trackObject = session.data.trackById(trId)
    assert trackObject not in session.data.hiddenTracks #enforce docstring.
    trackIndex = session.data.tracks.index(trackObject)
    didDelete = session.data.deleteTrack(trackObject) #may or may not change the trackindex. In any case, logically the cursor is now in a different track.
    if didDelete: #score.deleteTrack does not delete the last remaining track
        def registeredUndoFunction():
            trackObject.sequencerInterface.recreateThroughUndo()
            insertTrack(trackIndex, trackObject)
        session.history.register(registeredUndoFunction, descriptionString = "delete track")
        callbacks._tracksChanged()
        callbacks._setCursor()
        if trackObject is session.data.currentMetronomeTrack:
            useCurrentTrackAsMetronome() #we already have a new current one

def deleteCurrentTrack():
    deleteTrack(id(session.data.currentTrack()))

def hideTrack(trId):
    """For the callbacks this looks like a delete. But there is no undo.
    The track still emits playback.

    hide and unhide track register in the history. deleteItem depends on the item to be in a visible
    track so it may possible to insert an item, hide the track and then undo which would try to
    delete an item in a hidden track. Therefore hide and unhide register.
     """
    trackObject = session.data.trackById(trId)
    result = session.data.hideTrack(trackObject)
    if result: #not the only track
        session.history.register(lambda trId=trId: unhideTrack(trId), descriptionString = "hide track")
    callbacks._tracksChanged() #even if there is no change the GUI needs to be notified to redraw its checkboxes that may have been enabled GUI-side.
    callbacks._setCursor()

def unhideTrack(trId):
    trackObject = session.data.trackById(trId)
    session.data.unhideTrack(trackObject) #always succeeds, or throws error.
    session.history.register(lambda trId=trId: hideTrack(trId), descriptionString = "unhide track")
    callbacks._tracksChanged()
    callbacks._updateTrack(trId)
    #the cursor is uneffected

def trackAudible(trId, state:bool):
    """
    Send midi notes or not.  CCs and instrument changes are unaffected.
    Not managed by undo/redo.
    Does not need updateTrack. There is no new midi data to generate. cbox handles mute on its own"""
    trackObject = session.data.trackById(trId)
    trackObject.sequencerInterface.enable(state)
    callbacks._tracksChanged() #even if there is no change the GUI needs to be notified to redraw its checkboxes that may have been enabled GUI-side.

def listOfTrackIds():
    return session.data.listOfTrackIds()

def listOfHiddenTrackIds():
    return [id(track) for track in session.data.hiddenTracks.keys()]

def rearrangeTracks(listOfTrackIds):
    if len(session.data.tracks) <= 1:
        return
    session.history.register(lambda l=session.data.asListOfTrackIds(): rearrangeTracks(l), descriptionString = "rearrange tracks")
    session.data.rearrangeTracks(listOfTrackIds)
    callbacks._tracksChanged()
    callbacks._setCursor()

def setTrackName(trId, nameString, initialInstrumentName, initialShortInstrumentName):
    trackObject = session.data.trackById(trId)
    session.history.register(lambda i=trId, n=trackObject.name, lyN=trackObject.initialInstrumentName, lySN=trackObject.initialShortInstrumentName: setTrackName(i, n, lyN, lySN), descriptionString = "change track name")
    trackObject.name = nameString # this is a setter. It changes calfbox as well.
    trackObject.initialInstrumentName = initialInstrumentName
    trackObject.initialShortInstrumentName = initialShortInstrumentName
    callbacks._tracksChanged()
    callbacks._setCursor() #cursor contains track name and thus needs updating

def setTrackUpbeat(trId, upbeatInTicks):
    trackObject = session.data.trackById(trId)
    session.history.register(lambda i=trId, u=trackObject.upbeatInTicks: setTrackUpbeat(i, u), descriptionString = "change track upbeat")
    trackObject.upbeatInTicks = upbeatInTicks
    callbacks._updateTrack(trId)

def setDoubleTrack(trId, statusBool):
    """It does not touch any important data because it is more or less
    a savefile-persistent visual convenience feature.
    So we don't need undo/redo"""
    trackObject = session.data.trackById(trId)
    trackObject.double = statusBool
    callbacks._tracksChanged()
    callbacks._updateTrack(trId)
    callbacks._setCursor()

def setTrackSettings(trId, dictionary):
    """We need to create a new playback of the track to update the midi data."""
    trackObject = session.data.trackById(trId)
    previousSettings = trackObject.staticTrackRepresentation()
    clean = True

    for key, value in dictionary.items():
        #this assumes keys are the same as track export. Will give a key error at least if not.
        if not previousSettings[key] == value:
            clean = False
            break

    if not clean:
        trackObject.initialClefKeyword = dictionary["initialClefKeyword"]

        trackObject.initialMidiChannel = dictionary["initialMidiChannel"]
        trackObject.initialMidiBankMsb = dictionary["initialMidiBankMsb"]
        trackObject.initialMidiBankLsb = dictionary["initialMidiBankLsb"]
        trackObject.initialMidiProgram = dictionary["initialMidiProgram"]
        trackObject.ccChannels = dictionary["ccChannels"]
        trackObject.midiTranspose = dictionary["midiTranspose"]

        trackObject.durationSettingsSignature.defaultOn = dictionary["duration.defaultOn"]
        trackObject.durationSettingsSignature.defaultOff = dictionary["duration.defaultOff"]
        trackObject.durationSettingsSignature.staccatoOn = dictionary["duration.staccatoOn"]
        trackObject.durationSettingsSignature.staccatoOff = dictionary["duration.staccatoOff"]
        trackObject.durationSettingsSignature.tenutoOn = dictionary["duration.tenutoOn"]
        trackObject.durationSettingsSignature.tenutoOff = dictionary["duration.tenutoOff"]
        trackObject.durationSettingsSignature.legatoOn = dictionary["duration.legatoOn"]
        trackObject.durationSettingsSignature.legatoOff = dictionary["duration.legatoOff"]

        trackObject.dynamicSettingsSignature.dynamics["ppppp"] = dictionary["dynamics.ppppp"]
        trackObject.dynamicSettingsSignature.dynamics["pppp"] = dictionary["dynamics.pppp"]
        trackObject.dynamicSettingsSignature.dynamics["ppp"] = dictionary["dynamics.ppp"]
        trackObject.dynamicSettingsSignature.dynamics["pp"] = dictionary["dynamics.pp"]
        trackObject.dynamicSettingsSignature.dynamics["p"] = dictionary["dynamics.p"]
        trackObject.dynamicSettingsSignature.dynamics["mp"] = dictionary["dynamics.mp"]
        trackObject.dynamicSettingsSignature.dynamics["mf"] = dictionary["dynamics.mf"]
        trackObject.dynamicSettingsSignature.dynamics["f"] = dictionary["dynamics.f"]
        trackObject.dynamicSettingsSignature.dynamics["ff"] = dictionary["dynamics.ff"]
        trackObject.dynamicSettingsSignature.dynamics["fff"] = dictionary["dynamics.fff"]
        trackObject.dynamicSettingsSignature.dynamics["ffff"] = dictionary["dynamics.ffff"]
        trackObject.dynamicSettingsSignature.dynamics["custom"] = dictionary["dynamics.custom"]
        trackObject.dynamicSettingsSignature.dynamics["tacet"] = dictionary["dynamics.tacet"]
        trackObject.dynamicSettingsSignature.dynamics["fp"] = dictionary["dynamics.fp"]
        trackObject.dynamicSettingsSignature.dynamics["sp"] = dictionary["dynamics.sp"]
        trackObject.dynamicSettingsSignature.dynamics["spp"] = dictionary["dynamics.spp"]
        trackObject.dynamicSettingsSignature.dynamics["sfz"] = dictionary["dynamics.sfz"]
        trackObject.dynamicSettingsSignature.dynamics["sf"] = dictionary["dynamics.sf"]
        trackObject.dynamicSettingsSignature.dynamics["sff"] = dictionary["dynamics.sff"]



        session.history.register(lambda trId=trId, previousSettings=previousSettings: setTrackSettings(trId, previousSettings), descriptionString = "change track settings")
        callbacks._tracksChanged()
        callbacks._updateSingleTrackAllCC(trId)
        callbacks._updateTrack(trId)
        callbacks._setCursor() #for midi channel RT thru

def resetDynamicSettingsSignature(trId):
    trackObject = session.data.trackById(trId)
    previousSettings = trackObject.staticTrackRepresentation()
    trackObject.dynamicSettingsSignature.reset()
    session.history.register(lambda trId=trId, previousSettings=previousSettings: setTrackSettings(trId, previousSettings), descriptionString = "reset track dynamic settings")
    callbacks._tracksChanged()
    #We only need this for midi changes. callbacks._updateSingleTrackAllCC(trId)

    callbacks._updateTrack(trId)

def resetDuationSettingsSignature(trId):
    trackObject = session.data.trackById(trId)
    previousSettings = trackObject.staticTrackRepresentation()
    trackObject.durationSettingsSignature.reset()
    session.history.register(lambda trId=trId, previousSettings=previousSettings: setTrackSettings(trId, previousSettings), descriptionString = "reset track duration settings")
    callbacks._tracksChanged()
    #We only need this for midi changes. callbacks._updateSingleTrackAllCC(trId)
    callbacks._updateTrack(trId)

#Blocks
def currentBlockExport():
    """Return the static export item of the current block.
    Compatible with getDataAsDict and putDataFromDict
    such as names and minimum tick duration"""
    return session.data.currentTrack().currentBlock().getDataAsDict()

def appendBlock(trackid = None):
    """
    Has dynamic behaviour:
        If we are at the end of track appending a Block switches into
        that new block.
        On any other position it just appends a block and the cursor
        stays where it is. This gives a better typing from left-to-right
        experience."""
    if trackid:
        tr = session.data.trackById(trackid)
    else:
        tr = session.data.currentTrack()
    block = tr.appendBlock()
    if tr.state.isAppending() and len(tr.blocks)-2 == tr.state.blockindex: #end of track?
        moveFunction = _createLambdaMoveToForCurrentPosition()
        def registeredUndoFunction():
            moveFunction()
            deleteBlock(id(block))
        session.history.register(registeredUndoFunction, descriptionString = "append block")
        session.data.currentTrack().right()
    else:
        session.history.register(lambda blId = id(block): deleteBlock(blId), descriptionString = "append block")
    callbacks._updateTrack(id(tr))
    callbacks._setCursor()

def splitBlock():
    tr = session.data.currentTrack()
    if tr.state.isAppending() and len(tr.blocks)-1 == tr.state.blockindex: #end of track? Yes len-1 here and len-2 in append() is correct. I don't know why :(
        appendBlock()
    else: #a real split
        dictOfTrackIdsWithListOfBlockIds = session.data.splitCurrentBlockAndAllContentLinks() #do the split. We get the current state as return value for undo
        if dictOfTrackIdsWithListOfBlockIds:
            rearrangeBlocksInMultipleTracks(dictOfTrackIdsWithListOfBlockIds)  #handles undo and callbacks for redrawing
        callbacks._setCursor() #cursor is still on the same item. But the item might be further to the right now when additional block boundaries have been introduced to the left through contentLinks
        right() # continue typing on the right side. This was added in 2020 to create a "split is an item" feeling

def joinBlockWithNext(blockId):
    """written for the GUI which can join blocks with the mouse"""
    track, block = session.data.blockById(blockId)
    session.data.goTo(session.data.tracks.index(track), track.blocks.index(block), 0)
    joinBlock()

def joinBlock():
    """Opposite of splitBlock (but not undo)
    Take the current block and join it with the one after it.
    Does the same automatically for all content linked blocks.
    If there is no next block this will do nothing.

    It only works on content linked blocks if ALL content linked blocks have a different
    content linked block after them. So a block A needs always to be followed by block B.
    Joining those will result in one big new content linked block in the whole track.
    It is exactly the same as splitting a content linked block which will result in two new
    content links."""
    where = session.data.where() #just for the user experience.

    dictOfTrackIdsWithListOfBlockIds = session.data.joinCurrentBlockAndAllContentLinks()
    if dictOfTrackIdsWithListOfBlockIds:
        rearrangeBlocksInMultipleTracks(dictOfTrackIdsWithListOfBlockIds)  #handles undo and callbacks for redrawing

    session.data.goTo(*where) #just for the user experience.
    callbacks._setCursor()

def deleteBlock(blockId):
    track, block = session.data.blockById(blockId)
    oldBlockArrangement = track.asListOfBlockIds()
    result = track.deleteBlock(block)
    if result: #not the last block
        parentTrack, deletedBlock = result
        #Blocks are never truly deleted but a stored in the Block.allBlocks dict. This keeps the reference to this deleted block alive and it can be added through rearrange, which gets its blocks from this dict.
        session.history.register(lambda i=id(track), l=oldBlockArrangement: rearrangeBlocks(i, l), descriptionString = "delete block")
        callbacks._updateTrack(id(track))
        callbacks._setCursor()
        return True
    else:
        return False

def deleteCurrentBlock():
    currentBlockId = id(session.data.currentTrack().currentBlock())
    deleteBlock(currentBlockId) #handles callbacks and undo

def deleteEmptyBlocks():
    """whole score"""
    dictOfTrackIdsWithListOfBlockIds = session.data.removeEmptyBlocks()
    #We keep everything in dictOfTrackIdsWithListOfBlockIds. Empty blocks have been removed from this data.
    if dictOfTrackIdsWithListOfBlockIds and all(l for l in dictOfTrackIdsWithListOfBlockIds.values()):
        rearrangeBlocksInMultipleTracks(dictOfTrackIdsWithListOfBlockIds)  #handles undo and callbacks for redrawing
    callbacks._setCursor()

def duplicateCurrentBlock():
    currentBlockId = id(session.data.currentTrack().currentBlock())
    duplicateBlock(currentBlockId, 1) #handles callbacks and undo

def duplicateContentLinkCurrentBlock():
    currentBlockId = id(session.data.currentTrack().currentBlock())
    duplicateContentLinkBlock(currentBlockId, 1) #handles callbacks and undo

def duplicateBlock(blockId, times = 1):
    track, block = session.data.blockById(blockId)
    session.history.register(lambda i=id(track), l=track.asListOfBlockIds(): rearrangeBlocks(i, l), descriptionString = "duplicate block")
    for i in range(times):
        track.duplicateBlock(block)
    callbacks._updateTrack(id(track))
    callbacks._setCursor()

def duplicateContentLinkBlock(blockId, times = 1):
    track, block = session.data.blockById(blockId)
    session.history.register(lambda i=id(track), l=track.asListOfBlockIds(): rearrangeBlocks(i, l), descriptionString = "content link block")
    for i in range(times):
        track.duplicateContentLinkBlock(block)
    callbacks._updateTrack(id(track))
    callbacks._setCursor()

def moveBlockToOtherTrack(blockId, newTrackId, listOfBlockIdsForNewTrack):
    """First move the block to the new track and then
    rearrange both tracks

    It is by design only possible that a block will be copied/linked
    in the same track, next to the original block.
    If you want the dual action of "copy this block to a new track" you need to do it in two steps.
    First copy.  It can be moved later by this api function."""
    oldTrack, block = session.data.blockById(blockId)
    assert oldTrack
    assert block

    if len(oldTrack.blocks) == 1:
        return False #it is not possible to move the last block.

    session.history.register(lambda blId=blockId, trId=id(oldTrack), l=oldTrack.asListOfBlockIds(): moveBlockToOtherTrack(blId, trId, l), descriptionString = "move block to other track")
    newTrack = session.data.trackById(newTrackId)
    newTrack.appendExistingBlock(block)
    newTrack.rearrangeBlocks(listOfBlockIdsForNewTrack)
    #We don't need to check if deleting succeeded because we already checked if there are more than 1 blocks in the track above.
    oldTrack.deleteBlock(block) #Check for last block is above. It is important that we delete the block at exactly this point in time, not ealier. Otherwise the reference for undo will go away.
    block.parentTrack = newTrack

    callbacks._updateTrack(id(oldTrack))
    callbacks._updateTrack(newTrackId)
    callbacks._setCursor()

def rearrangeBlocks(trackid, listOfBlockIds):
    track = session.data.trackById(trackid)
    oldBlockOrder = track.asListOfBlockIds()
    track.rearrangeBlocks(listOfBlockIds)

    moveFunction = _createLambdaMoveToForCurrentPosition()
    def registeredUndoFunction():
        moveFunction()
        rearrangeBlocks(trackid, oldBlockOrder)
    session.history.register(registeredUndoFunction, descriptionString = "rearrange blocks")
    callbacks._updateTrack(trackid)

def rearrangeBlocksInMultipleTracks(dictOfTrackIdsWithListOfBlockIds):
    """dictOfTrackIdsWithListOfBlockIds is [trackId] = [listOfBlockIds]"""
    forUndo = {}
    for trackId, listOfBlockIds in dictOfTrackIdsWithListOfBlockIds.items():
        track = session.data.trackById(trackId)
        oldBlockOrder = track.asListOfBlockIds()
        track.rearrangeBlocks(listOfBlockIds)
        forUndo[trackId] = oldBlockOrder

    moveFunction = _createLambdaMoveToForCurrentPosition()
    def registeredUndoFunction():
        moveFunction()
        rearrangeBlocksInMultipleTracks(forUndo)
    session.history.register(registeredUndoFunction, descriptionString = "multi-track rearrange block")

    for trackId in dictOfTrackIdsWithListOfBlockIds.keys():
        callbacks._updateTrack(trackId)
    callbacks._setCursor()

def changeBlock(blockId, newParametersDict):
    """for example "name" or "minimumInTicks"  """
    track, block = session.data.blockById(blockId)
    moveFunction = _createLambdaMoveToForCurrentPosition()
    oldData = block.getDataAsDict()
    def registeredUndoFunction():
        moveFunction()
        changeBlock(blockId, oldData)
    session.history.register(registeredUndoFunction, descriptionString = "change block")
    block.putDataFromDict(newParametersDict)
    callbacks._updateTrack(id(track))
    #callbacks._setCursor() #this will make the GUI jump around because it centers on the cursor

def unlinkCurrentBlock():
    currentBlockId = id(session.data.currentTrack().currentBlock())
    unlinkBlock(currentBlockId)

def unlinkBlock(blockId):
    track, block = session.data.blockById(blockId)
    #if len(block.linkedContentBlocks) == 1: return  #This will not work because block is still the old one. unlink replaces with a standalone copy but we keep the original for undo.

    with session.history.sequence("unlink block"):
        duplicateBlock(blockId)
        deleteBlock(blockId) #original one
    callbacks._historyChanged()

    #Does not work properly:
    #newData = block.getUnlinkedData()
    #assert newData
    #_setBlockData(block, newData) #handles undo and callbacks

def moveBlockToEndOfTrack(blockId):
    """Get a list of all blocks. Take the given one and place it at the end.
    This is a high level function using rearrangeBlocks(), which does all the callbacks and
    history"""

    track, block = session.data.blockById(blockId)

    currentBlockOrder = track.asListOfBlockIds()

    if len(currentBlockOrder) == 1:
        return

    assert currentBlockOrder.count(blockId) == 1
    currentBlockOrder.remove(blockId) #modifies list in place
    currentBlockOrder.append(blockId)

    rearrangeBlocks(id(track), currentBlockOrder)

def moveBlockToStartOfTrack(blockId):
    """Like moveBlockToEndOfTrack, but to the start"""

    track, block = session.data.blockById(blockId)

    currentBlockOrder = track.asListOfBlockIds()

    if len(currentBlockOrder) == 1:
        return

    assert currentBlockOrder.count(blockId) == 1
    currentBlockOrder.remove(blockId) #modifies list in place
    currentBlockOrder.insert(0, blockId)

    rearrangeBlocks(id(track), currentBlockOrder)

def moveCurrentBlockToEndOfTrack():
    """moveBlockToEndOfTrack for cursor operation"""
    moveBlockToEndOfTrack(id(session.data.currentTrack().currentBlock()))

def moveCurrentBlockToStartOfTrack():
    """moveBlockToEndOfTrack for cursor operation"""
    moveBlockToStartOfTrack(id(session.data.currentTrack().currentBlock()))


#deprecated
def _setBlockData(block, newData):
    """DEPRECATED. This did not work. The linked blocks were not reduced.
    At point of the bug reports, instead of fixing this, we used
    duplicate block and delete which already provides all functionality"""
    session.history.register(lambda bl=block, old=block.data: _setBlockData(bl, old), descriptionString = "set block data")
    block.data = newData
    #no callbacks needed.

#Cursor

def getCursorPitch():
    keysig = session.data.currentTrack().state.keySignature()
    return pitchmath.toScale(session.data.cursor.pitchindex, keysig)

def getCursorSimpleLyNote():
    """Return the note on the the cursor pitch position as simple lilypond note, without octave.
    This is mainly intended for occasional GUI information display, such as in sub menus"""
    pitch = getCursorPitch()
    lyNote = pitchmath.pitch2ly[pitch].strip("'").strip(",").lower()
    return lyNote

def getCursorPlainNote():
    """get the cursor pitch as plain note, for usage in a keysig etc."""
    root = pitchmath.plain(session.data.cursor.pitchindex)
    keysig = session.data.currentTrack().state.keySignature()
    pitchToInsert = pitchmath.toScale(root, keysig)
    return pitchToInsert

def toPosition(position:int):
    """Move the cursor to this position in the current track. """
    session.data.currentTrack().toPosition(position=position, strict=True)
    callbacks._setCursor()

def left():
    """move the currently active tracks cursor one position to the left.
    Can be directly used by a user interface"""
    session.data.currentTrack().left()
    callbacks._setCursor()

def right():
    """move the currently active tracks cursor one position to the right.
    Can be directly used by a user interface"""
    session.data.currentTrack().right()
    callbacks._setCursor()

def selectLeft():
    session.data.setSelectionBeginning() #or not, if there is already one.
    session.data.currentTrack().left()
    callbacks._setCursor(destroySelection = False)

def selectRight():
    session.data.setSelectionBeginning()
    session.data.currentTrack().right()
    callbacks._setCursor(destroySelection = False)

def measureLeft():
    """Goes a few steps left when not in metrical context"""
    session.data.currentTrack().measureLeft()
    callbacks._setCursor()

def measureRight():
    """Goes a few right left when not in metrical context"""
    session.data.currentTrack().measureRight()
    callbacks._setCursor()

def selectMeasureLeft():
    session.data.setSelectionBeginning()
    session.data.currentTrack().measureLeft()
    callbacks._setCursor(destroySelection = False)

def selectMeasureRight():
    session.data.setSelectionBeginning()
    session.data.currentTrack().measureRight()
    callbacks._setCursor(destroySelection = False)

def measureStart():
    session.data.currentTrack().measureStart()
    callbacks._setCursor(destroySelection = True)

def selectMeasureStart():
    session.data.setSelectionBeginning()
    session.data.currentTrack().measureStart()
    callbacks._setCursor(destroySelection = False)


def blockLeft():
    if session.data.currentTrack().currentBlock().localCursorIndex == 0:
        session.data.currentTrack().left()
    session.data.currentTrack().startOfBlock()
    session.data.currentTrack().left()
    callbacks._setCursor()

def blockRight():
    if session.data.currentTrack().currentBlock().isAppending():
        session.data.currentTrack().right()
    session.data.currentTrack().endOfBlock()
    session.data.currentTrack().right()
    callbacks._setCursor()

def selectBlockLeft():
    if session.data.currentTrack().currentBlock().localCursorIndex == 0:
        session.data.currentTrack().left()
    session.data.setSelectionBeginning()
    session.data.currentTrack().startOfBlock()
    session.data.currentTrack().left()
    callbacks._setCursor(destroySelection = False)

def selectBlockRight():
    if session.data.currentTrack().currentBlock().isAppending():
        session.data.currentTrack().right()
    session.data.setSelectionBeginning()
    session.data.currentTrack().endOfBlock()
    session.data.currentTrack().right()
    callbacks._setCursor(destroySelection = False)

def head():
    session.data.currentTrack().head()
    callbacks._setCursor()

def tail():
    session.data.currentTrack().tail()
    callbacks._setCursor()

def selectHead():
    session.data.setSelectionBeginning()
    session.data.currentTrack().head()
    callbacks._setCursor(destroySelection = False)

def selectTail():
    session.data.setSelectionBeginning()
    session.data.currentTrack().tail()
    callbacks._setCursor(destroySelection = False)

def trackUp():
    session.data.trackUp()
    callbacks._setCursor()

def trackDown():
    session.data.trackDown()
    callbacks._setCursor()

def trackFirst():
    session.data.trackFirst()
    callbacks._setCursor()

def trackLast():
    session.data.trackLast()
    callbacks._setCursor()

def selectTrackUp():
    session.data.setSelectionBeginning()
    session.data.trackUp()
    callbacks._setCursor(destroySelection = False)

def selectTrackDown():
    session.data.setSelectionBeginning()
    session.data.trackDown()
    callbacks._setCursor(destroySelection = False)

def selectTrackFirst():
    session.data.setSelectionBeginning()
    session.data.trackFirst()
    callbacks._setCursor(destroySelection = False)

def selectTrackLast():
    session.data.setSelectionBeginning()
    session.data.trackLast()
    callbacks._setCursor(destroySelection = False)

def selectAllTracks():
    shortestTrack = sorted(session.data.tracks, key = lambda track: track.duration())[0]
    trackIndex = session.data.tracks.index(shortestTrack)
    session.data.goTo(trackIndex, 0, 0) #the position in the track doesn't matter. we just want into the track.
    tail()
    tickindexShortestTrack = session.data.currentTrack().state.tickindex
    #assert session.data.currentTrack().state.tickindex == tickindexShortestTrack == shortestTrack.duration(), (session.data.currentTrack().state.tickindex, tickindexShortestTrack, shortestTrack.duration())
    session.data.trackFirst()
    session.data.currentTrack().head()
    #Create Selection
    session.data.setSelectionBeginning()
    session.data.trackLast()
    session.data.currentTrack().goToTickindex(tickindexShortestTrack)
    callbacks._setCursor(destroySelection = False)

def selectTrack():
    head()
    selectTail()

def selectMeasureColumn():
    measureStart()
    trackFirst()
    measureStart()
    selectMeasureRight()
    selectTrackLast()

def toTickindex(trackid, tickindex, destroySelection = True):
    """Was implemented for mouse clicking in a GUI Score"""
    if tickindex < 0:
        tickindex = 0
        session.data
    trackObject = session.data.trackById(trackid)
    session.data.trackIndex = session.data.tracks.index(trackObject)
    trackObject.goToTickindex(tickindex)
    callbacks._setCursor(destroySelection)

def selectToTickindex(trackid, tickindex):
    session.data.setSelectionBeginning()
    toTickindex(trackid, tickindex, destroySelection = False)

#####Pitches

def toPitch(pitchindex:int):
    session.data.cursor.pitchindex = pitchindex
    callbacks._setCursor(destroySelection = False) #does not modify the pitch to keysig etc.


def up():
    session.data.cursor.up()
    callbacks._setCursor(destroySelection = False)
    #this does not create a selection if there was none.
    #You need to call setSelectionBeginning() to start a selection.
    #However, this does modify an existing selection since the cursor value changes

def down():
    session.data.cursor.down()
    callbacks._setCursor(destroySelection = False)


def selectUp():
    session.data.currentTrack().right()
    session.data.setSelectionBeginning()
    session.data.currentTrack().left()
    session.data.cursor.up()
    callbacks._setCursor(destroySelection = False)

def selectDown():
    session.data.currentTrack().right()
    session.data.setSelectionBeginning()
    session.data.currentTrack().left()
    session.data.cursor.down()
    callbacks._setCursor(destroySelection = False)

def upOctave():
    session.data.cursor.upOctave()
    callbacks._setCursor(destroySelection = False)

def downOctave():
    session.data.cursor.downOctave()
    callbacks._setCursor(destroySelection = False)

def _delete(backspace = False):
    def undoDelete(deletedItemCopy):
        """We need to go back one position after insert"""
        insertItem(deletedItemCopy)
        left() #sets the cursor

    if backspace:  #this is not in backspace() itself because it disturbs _deleteSelection() when we go left before deleting.
        session.data.currentTrack().left() #does not trigger a callback.

    moveFunction = _createLambdaMoveToForCurrentPosition()
    deletedItemCopy = session.data.currentTrack().delete()  #this is obviously _not_ track-delete but item delete
    if deletedItemCopy: #and not None / appending position
        if backspace:
            def registeredUndoFunction():
                moveFunction()
                insertItem(deletedItemCopy)
            session.history.register(registeredUndoFunction, descriptionString = "delete item")
        else:
            def registeredUndoFunction():
                moveFunction()
                undoDelete(deletedItemCopy)
            session.history.register(registeredUndoFunction, descriptionString = "delete item")
        callbacks._updateChangedTracks()
        callbacks._setCursor()

def backspace():
    """Callback and Undo are done via delete"""
    delete(backspaceForSingleItemDelete = True)

def delete(backspaceForSingleItemDelete = None):
    """Choose wether to delete a single item or a selection.
    Delete selections is tricky thats why this is done not
    in the usual apply-function-to-selection way"""
    if session.data.cursorWhenSelectionStarted:
        _deleteSelection()
    else:
        _delete(backspaceForSingleItemDelete)

#Chose prevailing durations

def prevailingLonga():
    pass #TODO
def prevailingBrevis():
    pass #TODO
def prevailing1():
    session.data.cursor.prevailingBaseDuration = D1
    callbacks._prevailingBaseDurationChanged(D1)
def prevailing2():
    session.data.cursor.prevailingBaseDuration = D2
    callbacks._prevailingBaseDurationChanged(D2)
def prevailing4():
    session.data.cursor.prevailingBaseDuration = D4
    callbacks._prevailingBaseDurationChanged(D4)
def prevailing8():
    session.data.cursor.prevailingBaseDuration = D8
    callbacks._prevailingBaseDurationChanged(D8)
def prevailing16():
    session.data.cursor.prevailingBaseDuration = D16
    callbacks._prevailingBaseDurationChanged(D16)
def prevailing32():
    session.data.cursor.prevailingBaseDuration = D32
    callbacks._prevailingBaseDurationChanged(D32)


##Chords and duration modification

def insertChord(baseDuration, pitchToInsert):
    duration = items.Duration(baseDuration)
    #duration.dots = session.data.cursor.getPrevailingDot()
    duration.dots = 0

    #audio Feedback as callback? #TODO
    chord = items.Chord(duration, pitchToInsert)
    insertItem(chord)

def insertCursorChord(baseDuration):
    """Insert a new chord with one note to the track.
    The intial note gets its pitch from the cursor position, to scale"""
    if session.data.cursor.cursorWasMovedAfterChoosingPitchViaMidi: #we had cursor arrow keys movement
        keysig = session.data.currentTrack().state.keySignature()
        pitchToInsert = pitchmath.toScale(session.data.cursor.pitchindex, keysig)
    else:
        pitchToInsert = session.data.cursor.pitchindex
    insertChord(baseDuration, pitchToInsert)

def addNoteToChord(pitchToInsert):
    """Utilized by midi-in"""
    #TODO: in the past this was possible with prevailing duration as well. But it got too complex with undo. Just pitch for now.
    _applyToItem("addNote", parameters = [pitchToInsert])

def addCursorNoteToChord():
    if session.data.cursorWhenSelectionStarted:
        return False
    else:
        keysig = session.data.currentTrack().state.keySignature()
        pitchToInsert = pitchmath.toScale(session.data.cursor.pitchindex, keysig)
        _applyToItem("addNote", parameters = [pitchToInsert])

def deleteCursorNoteFromChord():
    if session.data.cursorWhenSelectionStarted:
        return False
    else:
        _applyToItem("removeNoteNearPitch", parameters = [session.data.cursor.pitchindex])


def insertBrevis():
    pass #TODO
def insertLonga():
    pass #TODO
def insert1():
    insertCursorChord(D1)
def insert2():
    insertCursorChord(D2)
def insert4():
    insertCursorChord(D4)
def insert8():
    insertCursorChord(D8)
def insert16():
    insertCursorChord(D16)
def insert32():
    insertCursorChord(D32)
def insert64():
    insertCursorChord(D64)
def insert128():
    insertCursorChord(D128)

#and so on

functionType = type(lambda: print()) #not a built-in function or method, just <class "function">
def _applyToItem(functionAsString, parameters = []):
    """
    see history.py / undo docstring

    This is the entry point. Further undo and redo are done by
    _applyToItemCircularUndoRedo()

    Internal functions that do something but do not return an undoFunction
    are considered broken. Not returning an undo function is assumed
    as "nothing happened, nothing changed".

    """
    #TODO: If getattr with string turns out to be a performance problem we must change that to a lambda function as only parameter and the api function has to get the item itself. Then we can use _applyToItemCircularUndoRedo directly (and rename it)
    def do():
        i = session.data.currentItem()
        if not i: return None #Appending Position or otherwise no item.
        undoFunction = getattr(i, functionAsString)(*parameters)  #Get the real function, execute it and take the return as undo function. Each function returns an undo function (if it supports undo. see below)
        if undoFunction:  #the command was supported by the item. e.g. rests don't support shiftUp.
            assert type(undoFunction) is functionType

            moveFunction = _createLambdaMoveToForCurrentPosition()
            def registeredUndoFunction():
                moveFunction()
                _applyToItemCircularUndoRedo(undoFunction)

            session.history.register(registeredUndoFunction, descriptionString = functionAsString)
    simpleCommand(do)


def _applyToItemCircularUndoRedo(function):
    """called by _applyToItem and by itself.
    Function must be a command that can precisely undo itself:
    see history / undo docstring

    Toggles (e.g. bools) are not suitable undo functions.
    For example beamGroups. They are just True and False, so at first glance you could think that
    "do" is toggle so undo is toggle as well. But "do" can also be "removeBeams" in a selection.
    A precise function is a function that stores or restores the exact old state as lambda parameter
    or similar.
    """
    def do():
        undoFunction = function()
        moveFunction = _createLambdaMoveToForCurrentPosition()
        def registeredUndoFunction():
            moveFunction()
            _applyToItemCircularUndoRedo(undoFunction)
        session.history.register(registeredUndoFunction, descriptionString = function.__name__ )
    simpleCommand(do)


def _applyToSelection(itemFunctionAsString, parameterListForEachSelectedItem = []):
    """
    Apply a function to a selection and undo.
    The function must not rely on track.state, especially not on
    the current keysignature etc.

    Even if the functions add or remove the content (like api.split does) it will work.

    There is an optional parameter which is a list of parameter-iterables.
    The top level list must have exactly the len() as items in selection.

    It was written for undo because you know the number of items
    exactly here. This function itself creates this list for undo/redo.

    Format of parameterListForEachSelectedItem. In this example we already know
    that we apply to a selection with 3 items.:

        Our function expects two parameters, float and bool.
        parameterSet_One = [parameterValue=3.1415, parameterVerbose=True]
        parameterSet_Two = [parameterValue=42.42, parameterVerbose=False]
        parameterSet_Three = [parameterValue=100.001, parameterVerbose=False]
        parameterListForEachSelectedItem = [parameterSet_One, parameterSet_Two, parameterSet_Three]
        _applyToSelection("doFunction", parameterListForEachSelectedItem)

    You also can use a len of one for the parameterListForEachSelectedItem. It will be
    applied to all items in the selection.
        onlyParameterSet = [parameterValue=42.0, parameterVerbose=True]
        parameterListForAllSelectedItem = [onlyParameterSet]
        _applyToSelection("doFunction", parameterListForAllSelectedItem)


    Or, a typical case, just one parameter, the same, for each item in
    the selection. The parameter itself can be a list itself as well.

    The Following example is outdated. Tuplets are no longer a list but just a single tuple, no nesting. We leave this here as example only!
    For example a duration.tuplets, which is list of tuples(!)
        theParameter = [[(2,3)]] #This is a tuplet with only one fraction, triplet. It is for a notelist with only one note.
        #theParameter = [ [(2,3), (4,5)], [(4,5), (1,2), (3,4)] ] #notelist of 2 with a double-nested tuplet for the first and a triple nested tuplet for the second note.
        onlyParameterSet = [theParameter]
        parameterListForAllSelectedItem = [onlyParameterSet]
        _applyToSelection("setTuplet", parameterListForAllSelectedItem)

    Now look how that would look written out, especially since there is only one parameter.
    It is crazy, but neccessary.
    _applyToSelection("setTuplet", [[[[(2,3)]]]])
    """

    def _replaceMagicStringParameters(listOfParameters, cachedTrackState):
        """
        Replaces the magic strings in our parameterlist
        with the actual values saved for this moment by
        score.listOfSelectedItems()

        listOfParameters is a list with parameters for the
        called function. This function is sometimes another list.
        For example a parameter for each note in a chord.
        """
        result = []
        for param in listOfParameters:
            if type(param) is list:
                result.append(_replaceMagicStringParameters(param, cachedTrackState))
            else:
                if param in cachedTrackState:
                    result.append(cachedTrackState[param])
                else:
                    result.append(param)
        return result

    withMagicString = any(type(elem) is str for elem in flatList(parameterListForEachSelectedItem))

    validSelection, topLeftCursor, bottomRightCursor, listOfChangedTrackIds, *selectedTracksAndItems = session.data.listOfSelectedItems(removeContentLinkedData = True)
    if validSelection:
        if len(parameterListForEachSelectedItem) == 1: #only one value. Use it for all function calls. This is expected most of the time when we get a value from the user directly. Like "make all notes quintuplets!".
            parameterGenerator = EndlessGenerator(parameterListForEachSelectedItem[0])
        else:
            parameterGenerator = (iterable for iterable in parameterListForEachSelectedItem) #we make a generator because that works across tracks in the nested for loop. zip() does not.

        cursorWasAtSelectionStart = session.data.goToSelectionEnd() #Moves the cursor to the bottom right end of the selection. This alone will make the selection correct at the end of processing if the duration was changed. But it is still not enough for functions that change the number of items in the selection, e.g. split
        #We may be in a different track now.
        trackIndex, blockIndex, localCursorIndexInBlock = session.data.where() #localCursorIndexInBlock is unreliable...
        itemRightOfTheSelection = session.data.currentTrack().currentItem()       #so we replace it with an item. Since the selection ends left of the current item (current one not included) it cannot be affected by the process below. it is safe to remember as marker.

        undoFunctions = []
        for track in selectedTracksAndItems:
            for item, cachedTrackState in track: #cachedTrackState is a selected set of cached track.state values, specifically designed to assist apply to selection
                listOfParameters = next(parameterGenerator) if parameterListForEachSelectedItem else ()
                assert listOfParameters.__iter__  #will not throw an assert but an AttributeError. But who cares.
                if withMagicString:
                    listOfParameters = _replaceMagicStringParameters(listOfParameters, cachedTrackState)
                undoFunction = getattr(item, itemFunctionAsString)(*listOfParameters) #ACTION!

                if undoFunction: #the command was supported by the item. e.g. rests don't support shiftUp.
                    assert type(undoFunction) is functionType
                    undoFunctions.append(undoFunction)

        moveFunction = _createLambdaMoveToForCurrentPosition()
        def registeredUndoFunction():
            moveFunction()
            _applyToSelectionCircularRedoUndo(undoFunctions, listOfChangedTrackIds)
        session.history.register(registeredUndoFunction, descriptionString = "selection: {}".format(itemFunctionAsString))

        #Go to the end of the selection + all new items and durations.
        session.data.goToItemInCurrentBlock(itemRightOfTheSelection)
        _updateCallbackForListOfTrackIDs(listOfChangedTrackIds)

        #The selection now has the right boundaries. Now we return the cursor where it was for the user.
        if cursorWasAtSelectionStart: #we were at the selection start before processing. returning...
            session.data.goToSelectionStart() #keeps the selection as it is, just switches the cursor position from one end of the S. to the other.

        callbacks._setCursor(destroySelection = False)

def _applyToSelectionCircularRedoUndo(functions, listOfChangedTrackIds):
    """
    Functions are a list of functions which don't need any parameters.
    They are defined as lambdas with preset parameters.

    We don't need a selection for actually making applyToSelection undo.
    All affected tracks, items, methods and values are already known.

    Functions must not be be apply-to-selection functions. To avoid
    callback confusion best practice is to use no api function at all
    in the functions list.

    When this was written there were only score/track/item functions
    possible at all. Keep it that way.
    """
    session.data.cursorWhenSelectionStarted = None #better safe than sorry. It will be destroyed by setCursor below anyway.
    undoFunctions = [f() for f in functions] #side effect: make undo happen.
    moveFunction = _createLambdaMoveToForCurrentPosition()
    def registeredUndoFunction():
        moveFunction()
        _applyToSelectionCircularRedoUndo(undoFunctions, listOfChangedTrackIds)
    session.history.register(registeredUndoFunction, descriptionString = "selection stuff")
    _updateCallbackForListOfTrackIDs(listOfChangedTrackIds)
    callbacks._setCursor()

def augment():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("augment")
    else:
        _applyToItem("augmentNoteNearPitch", parameters = [session.data.cursor.pitchindex])

def diminish():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("diminish")
    else:
        _applyToItem("diminishNoteNearPitch", parameters = [session.data.cursor.pitchindex])

def dot():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("toggleDot")
    else:
        _applyToItem("toggleDotNearPitch", parameters = [session.data.cursor.pitchindex])

def triplet():
    """
    From anything (empty, other tuplet) to triplet
    and back to empty"""
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("toggleTriplet")
    else:
        _applyToItem("toggleTripletNearPitch", parameters =  [session.data.cursor.pitchindex])

def quintuplet():
    """
    Make it a quintuplet, no toggle
    !setTuplet has a different parameter format than setTupletNearPitch!
    """
    if session.data.cursorWhenSelectionStarted:
        tupletListForDuration = [[[[(4,5)]]]] #see docstring for _applyToSelection
        _applyToSelection("setTuplet", parameterListForEachSelectedItem = tupletListForDuration)
    else:
        tupletListForSingleNoteDuration = [(4,5)]
        _applyToItem("setTupletNearPitch", parameters = [session.data.cursor.pitchindex, tupletListForSingleNoteDuration])

def tie():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("toggleDurationKeyword", parameterListForEachSelectedItem = [[[D_TIE]]])
    else:
        _applyToItem("toggleDurationKeywordNearPitch", parameters = [session.data.cursor.pitchindex, D_TIE])

def tenuto():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("toggleDurationKeyword", parameterListForEachSelectedItem = [[[D_TENUTO]]])
    else:
        _applyToItem("toggleDurationKeywordNearPitch", parameters = [session.data.cursor.pitchindex, D_TENUTO])

def staccato():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("toggleDurationKeyword", parameterListForEachSelectedItem = [[[D_STACCATO]]])
    else:
        _applyToItem("toggleDurationKeywordNearPitch", parameters = [session.data.cursor.pitchindex, D_STACCATO])

def split(newparts):
    """
    Split a chord into two or more.
    This is only for chords.
    Technically this works with rests as well.
    However, there is little musical meaning in splitted rests.
    And it does not make sense for further editing.
    """

    #TODO: Test this for the whole selection before doing something. And as always: test first, not during performing the changes.
    #if currentItem.durationGroup.hasTuplet() and not newparts in (2,4,8):
        #return False #no further splitting

    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("split", parameterListForEachSelectedItem = [[newparts]],) #chord.split does not expect a list as parameter. just one parameter.
        #Split introduces more items. The selection needs extension.

    else:
        _applyToItem("split", parameters = [newparts])
        for i in range(newparts):
            right()

#Pitch modifications
def sharpenNote():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("sharpen")
    else:
        _applyToItem("sharpenNoteNearPitch", parameters = [session.data.cursor.pitchindex])

def flattenNote():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("flatten")
    else:
        _applyToItem("flattenNoteNearPitch", parameters = [session.data.cursor.pitchindex])


def stepUp():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("stepUp", parameterListForEachSelectedItem = [[["keySignature"]]])
    else:
        _applyToItem("stepUpNoteNearPitch", parameters = [session.data.cursor.pitchindex, session.data.currentTrack().state.keySignature()])
        up()


def stepDown():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("stepDown", parameterListForEachSelectedItem = [[["keySignature"]]])
    else:
        _applyToItem("stepDownNoteNearPitch", parameters = [session.data.cursor.pitchindex, session.data.currentTrack().state.keySignature()])
        down()

def stepUpOctave():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("stepUpOctave")
    else:
        _applyToItem("stepUpOctaveNoteNearPitch", parameters = [session.data.cursor.pitchindex])
        upOctave()

def stepDownOctave():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("stepDownOctave")
    else:
        _applyToItem("stepDownOctaveNoteNearPitch", parameters = [session.data.cursor.pitchindex])
        downOctave()

def transpose(rootPitch, targetPitch):
    """For the cursor position. Based on automatic transpose. The interval is caculated from
    two pitches.
    There is also tranposeScore. But no transposeTrack, this is just select track and transpose."""
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("intervalAutomatic", parameterListForEachSelectedItem = [[rootPitch, targetPitch]])
    else:
        _applyToItem("intervalAutomatic", parameters = [rootPitch, targetPitch])
    #no cursor movement.



def toggleBeam():
    """Place a beam at each end of the selection if all durations are <= D8"""
    if session.data.cursorWhenSelectionStarted:
        validSelection, topLeftCursor, bottomRightCursor, listOfChangedTrackIds, *selectedTracksAndItems = session.data.listOfSelectedItems(removeContentLinkedData = True)
        if validSelection and len(listOfChangedTrackIds) == 1 :
            #a valid selection has >=2 items.
            filteredList = [item for item, props in selectedTracksAndItems[0] if type(item) in (items.Chord, items.Rest)]  #only music items of the only track, which are themselves tuples (item, propertiesLikeKeysigs)
            #oneDur = filteredList[0].durationGroup.baseDuration
            #correctDurations = oneDur <= D8 and all(item.durationGroup.baseDuration == oneDur for item in filteredList)
            correctDurations = all(item.durationGroup.baseDuration <= D8 for item in filteredList)
            if correctDurations:
                first = filteredList[0]
                last = filteredList[-1]
                if type(first) is items.Chord and type(last) is items.Chord:
                    removeBeam() #clean up before setting a new boundary
                    first.toggleBeam()
                    last.toggleBeam()
                    callbacks._updateTrack(*listOfChangedTrackIds)
                    return True

        return False #all branches except the only True one end here.
    else:
        _applyToItem("toggleBeam")

def removeBeam():
    """Get rid of all beams in the selection. This is meant as clean-up tool for the user
    but also utilized in toggleBeam"""
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("removeBeam")
    else:
        _applyToItem("removeBeam")

#Rests
def insertRest(baseDuration):
    duration = items.Duration(baseDuration)
    #duration.dots = session.data.cursor.getPrevailingDot()
    duration.dots = 0

    #audio Feedback?
    rest = items.Rest(duration)
    insertItem(rest)

def insertRest1():
    insertRest(D1)
def insertRest2():
    insertRest(D2)
def insertRest4():
    insertRest(D4)
def insertRest8():
    insertRest(D8)
def insertRest16():
    insertRest(D16)
def insertRest32():
    insertRest(D32)
def insertRest64():
    insertRest(D64)
def insertRest128():
    insertRest(D128)
def insertRestBrevis():
    insertRest(DB)
def insertRestLonga():
    insertRest(DL)
def insertRestMaxima():
    insertRest(DM)

def insertMultiMeasureRest(numberOfMeasures):
    """MultiMeasureRests get calculated on export"""
    assert int(numberOfMeasures) == numberOfMeasures and numberOfMeasures > 0
    if session.data.currentTrack().state.metricalInstruction().oneMeasureInTicks > 0:
        insertItem(items.MultiMeasureRest(numberOfMeasures))

#Clefs
def getPossibleClefKeywords():
    """GUI can use this to fill drop down lists etc.
    Not sorted, but will use the new python sorted-as-inserted dict feature,
    so a little bit of consistency is probable."""
    return list(items.Clef.inComparisonToTrebleClef.keys())

def insertClef(clefString):
    clef = items.Clef(clefString)
    insertItem(clef)

#Slurs
def insertLegatoSlur():
    """no open and close. The context and order determines what
    type of slur we insert, even export. Dynamically adjusts"""
    slur = items.LegatoSlur()
    insertItem(slur)


#Key Signatures

def insertKeySignature(root:int, scheme:list, lilypondOverride:str=None):
    """Scheme is deviation from _a_ major scale, relative to the root note"""
    keysig = items.KeySignature(root, scheme)
    if lilypondOverride:
        keysig.lilypondParameters["override"] = lilypondOverride
    insertItem(keysig)

def setInitialKeySignatures(root:int, scheme:list, lilypondOverride:str=None):
    """Variation of insertKeySignature to set the initial key sig for ALL tracks"""
    keysig = items.KeySignature(root, scheme)
    if lilypondOverride:
        keysig.lilypondParameters["override"] = lilypondOverride

    for track in session.data.tracks:
        track.initialKeySignature = keysig.copy()

    callbacks._tracksChanged()
    for trId in session.data.listOfTrackIds():
        callbacks._updateTrack(trId) #create content: music items
    callbacks._setCursor() #In case we have a different accidental for the pitch cursor

def commonKeySignaturesAsList():
    """For the GUIs convenience so they can populate their
    drop down lists.
    Yes, we could use the dict from insertCommonKeySignature but
    we want a special order which is not the same as the alphabetical.
    So a bit of redundancy is ok."""
    return [
        "Major",
        "Minor",
        "Dorian",
        "Phrygian",
        "Lydian",
        "Mixolydian",
        "Locrian",
        "Hollywood",
        ]

def insertCommonKeySignature(root:int, scheme:str):
    """example:
    insertCommonKeySignature(P_C, "Major")
    """
    schemes = { #Scheme is deviation from _a_ major scale, relative to the root note
        "Major": [0,0,0,0,0,0,0],
        "Minor": [0,0,-10,0,0,-10,-10],
        "Dorian": [0,0,-10,0,0,0,-10],
        "Phrygian": [0,-10,-10,0,0,-10,-10],
        "Lydian": [0,0,0,+10,0,0,0],
        "Mixolydian": [0,0,0,0,0,0,-10],
        "Locrian": [0,-10,-10,0,-10,-10,-10],
        "Hollywood": [0,0,0,0,0,-10,-10], #The "Hollywood"-Scale. Stargate, Lord of the Rings etc.
        #TODO: MOAR!
        }

    #Lilypond knows some standard key signature modes, which produce cleaner output than our default verbose note-for-note one.
    lySupported = ("major", "minor", "dorian", "phrygian", "lydian", "mixolydian", "locrian")

    if scheme.lower() in lySupported:
        lyRootNote = pitchmath.pitch2ly[root].strip("'").strip(",").lower()
        lyovrd = f"\\key {lyRootNote} \\{scheme.lower()}"
    else:
        lyovrd = None

    insertKeySignature(root, schemes[scheme], lilypondOverride=lyovrd)

def insertCursorCommonKeySignature(scheme:str):
    """Root note is generated from the cursor pitch position and takes the previous keysig
    into account.

    Scheme is a string as seen in commonKeySignaturesAsList()
    Scheme is deviation from _a_ major scale, relative to the root note
    """
    if not scheme in commonKeySignaturesAsList():
        raise ValueError("Unknown key signature scheme string: " + scheme)

    root = pitchmath.plain(session.data.cursor.pitchindex)
    keysig = session.data.currentTrack().state.keySignature()
    #pitchToInsert = pitchmath.toScale(session.data.cursor.pitchindex, keysig)
    pitchToInsert = pitchmath.toScale(root, keysig)

    insertCommonKeySignature(pitchToInsert, scheme)



#def insertTimeSignature(demoniator, nominator): #upper/lower.
#    """example:
#    insertTimeSignature(4, 210*2**8) #4/4
#    """
#    insertItem(items.TimeSignature(demoniator, nominator))


#Metrical Instructions
def insertMetricalInstruction(treeOfInstructions, lilypondOverride = None):
    item = items.MetricalInstruction(treeOfInstructions)
    if lilypondOverride:
        item.lilypondParameters["override"] = lilypondOverride
    insertItem(item)


def setInitialMetricalInstruction(treeOfInstructions, lilypondOverride:str=None):
    """Variation of insertMetricalInstruction to set the initial one for ALL tracks"""
    item = items.MetricalInstruction(treeOfInstructions)

    if lilypondOverride:
        item.lilypondParameters["override"] = lilypondOverride

    for track in session.data.tracks:
        track.initialMetricalInstruction = item.copy()

    callbacks._tracksChanged()
    for trId in session.data.listOfTrackIds():
        callbacks._updateTrack(trId) #create content: music items
    callbacks._setCursor() #In case we have a different accidental for the pitch cursor


def commonMetricalInstructionsAsList():
    """for musical reasons 5/4 and 7/8 and other a-symetrical
    metrical instructions cannot be in here since it is unknown which
    internal version the user wants. And we don't want to pollute this with all possible
    permutations like 5/4: 3+2+2;  5/4: 2+3+2 etc."""
    return [
        "off",
        "4/4",
        "3/4",
        "6/8",
        "2/4",
        "12/8",
        "6/4",
        "3/8",
        "1/1",
        "3/2",
        ]

def insertCommonMetricalInstrucions(scheme, setInitialInsteadCursorInsert=False):
    """A metrical instruction requires a lilypond override. You can use them without of course but
    they will not work when exported."""
    schemes = {
        "off" : (),
        "2/4" : (D4, D4),
        "3/4" : (D4, D4, D4),
        "4/4" : ((D4, D4), (D4, D4)),
        "6/8" : (int(D4*1.5),int(D4*1.5)), #aka 2/4 with triplet sub-level
        "12/8" : ((D8, D8, D8), (D8, D8, D8), (D8, D8, D8), (D8, D8, D8)),  #aka 4/4 with triplet sub-level
        "6/4" : ((D4, D4, D4),(D4, D4, D4)),
        "3/8" : (D8, D8, D8),
        "1/1" : (D1,),
        "3/2" : (D2, D2, D2),
        }
    lilypond = {
        "off" : "\\mark \"X\" \\cadenzaOn",
        "2/4" : "\\cadenzaOff \\time 2/4",
        "3/4" : "\\cadenzaOff \\time 3/4",
        "4/4" : "\\cadenzaOff \\time 4/4",
        "6/8" : "\\cadenzaOff \\time 6/8",
        "12/8" : "\\cadenzaOff \\time 12/8",
        "6/4" : "\\cadenzaOff \\time 6/4",
        "3/8" : "\\cadenzaOff \\time 3/8",
        "1/1" : "\\cadenzaOff \\time 1/1",
        "3/2" : "\\cadenzaOff \\time 3/2",
        }

    if setInitialInsteadCursorInsert:
        setInitialMetricalInstruction(schemes[scheme], lilypondOverride = lilypond[scheme])
    else: #item insert
        insertMetricalInstruction(schemes[scheme], lilypondOverride = lilypond[scheme])


def metricalTest():
    scheme = ((D4, D4, D4), D4, D4) # wrong. should be...
    scheme = (D4, D4, D4, D4, D4) #... just this.
    scheme = ((D4, D4), (D4, D4, D4)) #real 5/4  as 2+3
    scheme = (   ((D4, D4), (D4, D4)),  ((D4, D4, D4), (D4, D4))  ) #3 level 9/4
    insertMetricalInstruction( scheme, lilypondOverride = "\\time 9/4" )

#Velocity and Dynamic Signatures
def insertDynamicSignature(keyword):
    dynSig = items.DynamicSignature(keyword)
    insertItem(dynSig)

def insertDynamicPiano():
    insertDynamicSignature("p")

def insertDynamicForte():
    insertDynamicSignature("f")

def insertDynamicTacet():
    insertDynamicSignature("tacet")

def insertDynamicRamp():
    """Crescendo or Decrescendo. Determined automatically"""
    dynRamp = items.DynamicRamp()
    insertItem(dynRamp)


def setNoteDynamic(noteId, value):
    listOfTracks, note = session.data.noteById(noteId)
    session.history.register(lambda nId=noteId, v=note.dynamic.velocityModification: setNoteDynamic(nId, v), descriptionString = "set note dynamic")
    #todo: better undo?
    note.dynamic.velocityModification = value
    for track in listOfTracks:
        callbacks._updateTrack(id(track))

def clearNoteDynamic(noteId):
    listOfTracks, note = session.data.noteById(noteId)
    session.history.register(lambda nId=noteId, v=note.dynamic.velocityModification: setNoteDynamic(nId, v), descriptionString = "clear note dynamic")
    #todo: better undo?
    note.dynamic.velocityModification = 0
    for track in listOfTracks:
        callbacks._updateTrack(id(track))

def setNoteMods(noteId, valueOn, valueOff):
    """
    value is a float that is added as percentage of the original value
     (without mods)

    Is used for a specific note, not the cursor position.
    """
    listOfTracks, note = session.data.noteById(noteId)
    session.history.register(lambda nId=noteId, on=note.duration.shiftStart, off=note.duration.shiftEnd: setNoteMods(nId, on, off), descriptionString = "fine tune note duration")
    #todo: better undo?
    note.duration.shiftStart = valueOn
    note.duration.shiftEnd = valueOff
    #we can't use callbacks._updateChangedTracks() here because that depends on the cursor position and checks for linked content for the currentBlock. the note can be anywhere
    for track in listOfTracks:
        callbacks._updateTrack(id(track))

def clearNoteMod(noteId):
    """see setNoteMods"""
    listOfTracks, note = session.data.noteById(noteId)
    session.history.register(lambda nId=noteId, on=note.duration.shiftStart, off=note.duration.shiftEnd: setNoteMods(nId, on, off), descriptionString = "clear note duration fine tuning")
    #todo: better undo?
    note.duration.shiftStart = 0
    note.duration.shiftEnd = 0
    for track in listOfTracks:
        callbacks._updateTrack(id(track))


#Cursor Variants of the above
def moreVelocity():
    """Increase the relative velocity modficator for the note
    nearest to the cursor. With selection/single support."""
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("moreVelocity")
    else:
        _applyToItem("moreVelocityNearPitch", parameters = [session.data.cursor.pitchindex])

def lessVelocity():
    """Opposite of moreVelocity"""
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("lessVelocity")
    else:
        _applyToItem("lessVelocityNearPitch", parameters = [session.data.cursor.pitchindex])

def moreDuration():
    """Increase the duration modficator for the note
    nearest to the cursor. With selection/single support.
    For simplicity reasons this only shifts the right end, the ending,
    of the note. The beginning needs the full command setNoteMods"""
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("moreDuration")
    else:
        _applyToItem("moreDurationNearPitch", parameters = [session.data.cursor.pitchindex])

def lessDuration():
    """Opposite of moreDuration. But still for the ending of the note,
    not the beginning"""
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("lessDuration")
    else:
        _applyToItem("lessDurationNearPitch", parameters = [session.data.cursor.pitchindex])

def resetDurationVelocity():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("resetVelocityAndDurationMods")
    else:
        _applyToItem("resetVelocityAndDurationModsNearPitch", parameters = [session.data.cursor.pitchindex])

#Graphs. Tempo and CC
def getListOfGraphInterpolationTypesAsStrings():
    return ["linear", "standalone"]


#Control Change Subtracks
def _lazyCCUndoRedo(trId:int, cc:int,  data, description:str): #For items and blocks, not for tracks.
    """
    Lazy Undo for CCs deals with one CC in one Track at a time. No blocks are involved.

    The CC tracks are not full of data. We can afford it to use the save/load system to
    store complete states instead of incremental changes.
    """
    track = session.data.trackById(trId)
    oldData = track.ccGraphTracks[cc].serialize()
    track.ccGraphTracks[cc] = GraphTrackCC.instanceFromSerializedData(data, parentTrack=track)
    session.history.register(lambda: _lazyCCUndoRedo(trId, cc, oldData, description), descriptionString=description)
    callbacks._historyChanged()
    callbacks._updateGraphTrackCC(trId, cc)

def _CCUndoCreater(trId:int, cc:int, description:str=""): #For items and blocks, not for tracks.
    """Can be used whenever saving the old state and actually registering undo does not depend
    on the success of a function. In other words: if you could write all undo related lines
    in a row, use this instead."""
    track = session.data.trackById(trId)
    oldData = track.ccGraphTracks[cc].serialize()
    session.history.register(lambda: _lazyCCUndoRedo(trId, cc, oldData, description), descriptionString=description)
    callbacks._historyChanged()


##CC Tracks
def newGraphTrackCC(trId, cc):
    """add a new CC Path for CC to the given Track.
    Do nothing if already existent."""
    track = session.data.trackById(trId)
    track.newGraphTrackCC(cc)
    session.history.clear()
    callbacks._graphCCTracksChanged(trId) #create structure: all CC graphs, accessed by CC number (0-127)
    callbacks._updateGraphTrackCC(trId, cc)

def _addExistingGraphTrackCC(trId, cc, graphTrackObject):
    """For undo deleteGraphTrackCC"""
    track = session.data.trackById(trId)
    track.addExistingGraphTrackCC(cc, graphTrackObject)
    session.history.clear()
    callbacks._graphCCTracksChanged(trId) #create structure: all CC graphs, accessed by CC number (0-127)
    callbacks._updateGraphTrackCC(trId, cc)

def deleteGraphTrackCC(trId, cc):
    track = session.data.trackById(trId)
    deletedGraphTrackObject = track.deleteGraphTrackCC(cc)
    session.history.clear()
    callbacks._graphCCTracksChanged(trId) #this should delete any GUI cc track

## CC Blocks

def changeGraphBlockDuration(graphBlockId, newDurationInTicks):
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    _CCUndoCreater(trId, cc, "CC Block Duration")
    graphBlock.duration = newDurationInTicks
    callbacks._updateGraphTrackCC(trId, cc)

def appendGraphBlock(trId, cc):
    """Append a small duration block to the current cc track"""
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    _CCUndoCreater(trId, cc, "Append CC Block")
    newBlock = ccTrack.appendGraphBlock()
    callbacks._updateGraphTrackCC(trId, cc)

def rearrangeCCBlocks(trId, cc, listOfBlockIds):
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    _CCUndoCreater(trId, cc, "Move CC Block")
    ccTrack.rearrangeBlocks(listOfBlockIds)
    callbacks._updateGraphTrackCC(trId, cc)

def moveCCBlockToOtherTrack(graphBlockId, newTrackId, listOfBlockIdsForNewTrack):
    """Modified copy of api.moveBlockToOtherTrack.
    This only moves to the same CC value. not from volume to modwheel."""
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    oldccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    newGraphTrack = session.data.trackById(newTrackId).ccGraphTracks[cc] #we assume this track has this CC already activated.

    if len(oldccTrack.blocks) == 1:
        return False #it is not possible to move the only block.

    with session.history.sequence("Move CC to other track"):
        _CCUndoCreater(trId, cc, "MoveToOther Old")
        _CCUndoCreater(newTrackId, cc, "MoveToOther New")
    callbacks._historyChanged()

    newGraphTrack.appendExistingGraphBlock(graphBlock)
    newGraphTrack.rearrangeBlocks(listOfBlockIdsForNewTrack)
    oldccTrack.deleteBlock(graphBlock) #Check for last block is above. It is important that we delete the block at exactly this point in time, not earlier. Otherwise the reference for undo will go away.
    graphBlock.parentGraphTrack = newGraphTrack

    callbacks._updateGraphTrackCC(trId, cc)
    callbacks._updateGraphTrackCC(newTrackId, cc) #in case of a linked block this is redundant, but for a normal move it is not redundant.

def changeCCBlock(graphBlockId, newParametersDict):
    """Mostly Duration changes. But includes the name as well"""
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    _CCUndoCreater(trId, cc, "Change CC Block")
    graphBlock.putDataFromDict(newParametersDict)
    callbacks._updateGraphTrackCC(trId, cc)

def duplicateCCBlock(graphBlockId, times = 1):
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    _CCUndoCreater(trId, cc, "Duplicate CC Block")
    for i in range(times):
        ccTrack.duplicateBlock(graphBlock)
    callbacks._updateGraphTrackCC(trId, cc)

def duplicateContentLinkCCBlock(graphBlockId, times = 1):
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    _CCUndoCreater(trId, cc, "Content Link CC Block")
    for i in range(times):
        ccTrack.duplicateContentLinkBlock(graphBlock)
    callbacks._updateGraphTrackCC(trId, cc)

def unlinkCCBlock(graphBlockId):
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    _CCUndoCreater(trId, cc, "Unlink CC Block")
    newData, newLinkedContentBlocks, newDuration = graphBlock.getUnlinkedData()
    assert newData, newData
    assert newDuration, newDuration
    graphBlock.data = newData
    graphBlock.linkedContentBlocks = newLinkedContentBlocks
    graphBlock._duration = newDuration

def deleteCCBlock(graphBlockId):
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    oldData = ccTrack.serialize()
    deletedBlock = ccTrack.deleteBlock(graphBlock)
    if deletedBlock:  #not the last block
        #Blocks are never truly deleted but stored in the GraphBlock.allBlocks dict. This keeps the reference to this deleted block alive and it can be added through rearrange, which gets its blocks from this dict.
        description = "Delete CC Block"
        session.history.register(lambda: _lazyCCUndoRedo(trId, cc, oldData, description), descriptionString=description)
        callbacks._historyChanged()
        callbacks._updateGraphTrackCC(trId, cc)

def extendLastCCBlockToTrackLength(trId, cc):
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    lastCCBlock = ccTrack.blocks[-1]
    _CCUndoCreater(trId, cc, "Extend last CC Block to Track length")
    lastCCBlock.extendToTrackLength(ccTrack)
    callbacks._updateGraphTrackCC(trId, cc)

def splitCCBlock(graphBlockId, positionInTicksRelativeToBlock):
    """tick position is relative to block start"""
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    oldData = ccTrack.serialize()
    success = ccTrack.splitGraphBlock(graphBlock, positionInTicksRelativeToBlock)
    if success:
        description = "Split CC Block"
        session.history.register(lambda: _lazyCCUndoRedo(trId, cc, oldData, description), descriptionString=description)
        callbacks._historyChanged()
        callbacks._updateGraphTrackCC(trId, cc)

def mergeWithNextGraphBlock(graphBlockId):
    trId, cc, graphBlock = session.data.graphBlockById(graphBlockId)
    ccTrack = session.data.trackById(trId).ccGraphTracks[cc]
    oldData = ccTrack.serialize()
    positionForSplit = ccTrack.mergeWithNextGraphBlock(graphBlock)
    if positionForSplit:
        description = "Split CC Block"
        session.history.register(lambda: _lazyCCUndoRedo(trId, cc, oldData, description), descriptionString=description)
        callbacks._historyChanged()
        callbacks._updateGraphTrackCC(trId, cc)

##CC Blocks and User Points

def addGraphItem(blockId, positionInTicksRelativeToBlock, newCCValue):
    """blockId includes the track as well as the CC"""
    trId, cc, graphBlock = session.data.graphBlockById(blockId)
    graphItem = GraphItem(newCCValue)
    _addExistingGraphItem(blockId, positionInTicksRelativeToBlock, graphItem)

def _addExistingGraphItem(blockId, positionInTicksRelativeToBlock, graphItem):
    """blockId includes the track as well as the CC"""
    trId, cc, graphBlock = session.data.graphBlockById(blockId)
    _CCUndoCreater(trId, cc, "Add CC Point")
    graphBlock.insert(graphItem, positionInTicksRelativeToBlock)
    callbacks._updateGraphTrackCC(trId, cc)

def removeGraphItem(graphItemId):
    trId, cc, graphBlock, graphItem = session.data.graphItemById(graphItemId)
    _CCUndoCreater(trId, cc, "Remove CC Point")
    tickPositionRelativeToBlockStart = graphBlock.find(graphItem)
    graphBlock.remove(tickPositionRelativeToBlockStart)
    callbacks._updateGraphTrackCC(trId, cc)

def changeGraphItem(graphItemId, moveInTicks, newCCValue):
    trId, cc, graphBlock, graphItem = session.data.graphItemById(graphItemId)
    _CCUndoCreater(trId, cc, "Change CC Point")
    currentTickPositionRelativeToBlock = graphBlock.find(graphItem)
    graphBlock.move(currentTickPositionRelativeToBlock, currentTickPositionRelativeToBlock + moveInTicks)
    graphItem.ccStart = newCCValue
    callbacks._updateGraphTrackCC(trId, cc)

def changeGraphItemInterpolation(graphItemId, graphType):
    """graphType is "linear" or "standalone" """
    trId, cc, graphBlock, graphItem = session.data.graphItemById(graphItemId)
    _CCUndoCreater(trId, cc, "CC Point Interpolation")
    graphItem.graphType = graphType
    callbacks._updateGraphTrackCC(trId, cc)


#Tempo Track

def _lazyTempoTrackUndoRedo(new, description:str):
    """The tempo track is not full of data. We can afford it to use the save/load system to
    store complete states instead of incremental changes."""
    old = session.data.tempoTrack.serialize()
    session.data.tempoTrack = TempoTrack.instanceFromSerializedData(new, parentData=session.data)
    session.history.register(lambda d=old:  _lazyTempoTrackUndoRedo(d, description), descriptionString=description)
    callbacks._historyChanged()
    callbacks._updateTempoTrack()

def _tempoTrackUndoCreater(description:str):
    """Can be used whenever saving the old state and actually registering undo does not depend
    on the success of a function. In other words: if you could write all undo related lines
    in a row, use this instead."""
    old = session.data.tempoTrack.serialize()
    session.history.register(lambda d=old: _lazyTempoTrackUndoRedo(d, description), descriptionString=description)
    callbacks._historyChanged()

def addTempoItem(blockId, positionInTicksRelativeToBlock, unitsPerMinute, referenceTicks, graphType="standalone", description:str=""):
    """blockId includes the track as well as the CC"""
    tempoItem = TempoItem(unitsPerMinute, referenceTicks, description)
    tempoItem.graphType = graphType
    _addExistingTempoItem(blockId, positionInTicksRelativeToBlock, tempoItem) #handles undo and callbacks
    return tempoItem

def _addExistingTempoItem(blockId, positionInTicksRelativeToBlock, tempoItem):
    _tempoTrackUndoCreater("Add Tempo Change")
    tempoBlock = session.data.tempoTrack.tempoBlockById(blockId)
    tempoBlock.insert(tempoItem, positionInTicksRelativeToBlock)
    callbacks._updateTempoTrack()

def removeTempoItem(tempoItemId):
    _tempoTrackUndoCreater("Delete Tempo Change")
    tempoBlock, tempoItem = session.data.tempoTrack.tempoItemById(tempoItemId)
    tickPositionRelativeToBlockStart = tempoBlock.find(tempoItem)
    tempoBlock.remove(tickPositionRelativeToBlockStart)
    callbacks._updateTempoTrack()


def moveTempoItem(tempoItemId, tickPositionAbsolute):
    """Figures out the target block automatically"""
    blockId, blockPosition = session.data.tempoTrack.tempoBlocKByAbsolutePosition(tickPositionAbsolute)
    new_positionInTicksRelativeToBlock = tickPositionAbsolute - blockPosition
    tempoBlock, tempoItem = session.data.tempoTrack.tempoItemById(tempoItemId)
    tempoBlock.remove(tempoBlock.find(tempoItem))
    _addExistingTempoItem(blockId, new_positionInTicksRelativeToBlock, tempoItem)

def removeCurrentTempoItem():
    """remove the tempo item which is at the tickindex of the cursor or left of it"""
    tempoItem = session.data.tempoTrack.tempoAtTickPosition(session.data.currentTrack().state.tickindex) #This returns the leftmost item of the tick position
    removeTempoItem(id(tempoItem)) #undo and callback

def changeTempoBlockDuration(tempoBlockId, newDurationInTicks):
    _tempoTrackUndoCreater("Tempo Block Duration")
    tempoBlock = session.data.tempoTrack.tempoBlockById(tempoBlockId)
    tempoBlock.duration = newDurationInTicks
    callbacks._updateTempoTrack()

def rearrangeTempoBlocks(listOfBlockIds):
    _tempoTrackUndoCreater("Move Tempo Block")
    session.data.tempoTrack.rearrangeBlocks(listOfBlockIds)
    callbacks._updateTempoTrack()

def appendTempoBlock():
    _tempoTrackUndoCreater("Append Tempo Block")
    newBlock = session.data.tempoTrack.appendTempoBlock()
    callbacks._updateTempoTrack()

def duplicateTempoBlock(tempoBlockId, times = 1):
    _tempoTrackUndoCreater("Duplicate Tempo Block")
    tempoBlock = session.data.tempoTrack.tempoBlockById(tempoBlockId)
    for i in range(times):
        session.data.tempoTrack.duplicateBlock(tempoBlock)
    callbacks._updateTempoTrack()

def duplicateContentLinkTempoBlock(tempoBlockId, times = 1):
    """This is also create content link"""
    _tempoTrackUndoCreater("Content Link Tempo Block")
    tempoBlock = session.data.tempoTrack.tempoBlockById(tempoBlockId)
    for i in range(times):
        session.data.tempoTrack.duplicateContentLinkBlock(tempoBlock)
    callbacks._updateTempoTrack()


def changeTempoBlock(tempoBlockId, newParametersDict):
    _tempoTrackUndoCreater("Change Tempo Block")
    tempoBlock = session.data.tempoTrack.tempoBlockById(tempoBlockId)
    tempoBlock.putDataFromDict(newParametersDict)
    callbacks._updateTempoTrack()

def unlinkTempoBlock(tempoBlockId):
    tempoBlock = session.data.tempoTrack.tempoBlockById(tempoBlockId)
    if len(tempoBlock.linkedContentBlocks) == 1:
        return #This is not a content link block

    _tempoTrackUndoCreater("Unlink Tempo Block")

    newData, newLinkedContentBlocks, newDuration = tempoBlock.getUnlinkedData() #does not set itself, just returns
    tempoBlock.data = newData
    tempoBlock.linkedContentBlocks.remove(tempoBlock) #the block still exists, so WeakRef will not remove it.
    tempoBlock.linkedContentBlocks = newLinkedContentBlocks
    tempoBlock._duration = newDuration  #mutable list of length 1
    callbacks._updateTempoTrack()


def splitTempoBlock(tempoBlockId, positionInTicksRelativeToBlock:int):
    """tick position is relative to block start"""
    old = session.data.tempoTrack.serialize()
    success = session.data.tempoTrack.splitTempoBlock(tempoBlockId, positionInTicksRelativeToBlock)
    if success:
        session.history.register(lambda d=old, desc="Split Tempo Block": _lazyTempoTrackUndoRedo(d, desc), descriptionString="Split Tempo Block")
        callbacks._updateTempoTrack()

def mergeWithNextTempoBlock(tempoBlockId):
    old = session.data.tempoTrack.serialize()
    positionForSplit = session.data.tempoTrack.mergeWithNextTempoBlock(tempoBlockId)
    if positionForSplit:
        session.history.register(lambda d=old, desc="Join Tempo Block": _lazyTempoTrackUndoRedo(d, desc), descriptionString="Join Tempo Block")
        callbacks._historyChanged()
        callbacks._updateTempoTrack()

def deleteTempoBlock(tempoBlockId):
    old = session.data.tempoTrack.serialize()
    tempoBlock = session.data.tempoTrack.tempoBlockById(tempoBlockId)
    deletedBlock = session.data.tempoTrack.deleteBlock(tempoBlock)
    if deletedBlock:
        session.history.register(lambda d=old, desc="Delete Tempo Block": _lazyTempoTrackUndoRedo(d, desc), descriptionString="Delete Tempo Block")
        callbacks._updateTempoTrack()

def insertTempoItemAtAbsolutePosition(tickPositionAbsolute, unitsPerMinute, referenceTicks, graphType, description:str):
    blockId, blockPosition = session.data.tempoTrack.tempoBlocKByAbsolutePosition(tickPositionAbsolute)
    positionInTicksRelativeToBlock = tickPositionAbsolute - blockPosition
    return addTempoItem(blockId, positionInTicksRelativeToBlock, unitsPerMinute, referenceTicks, graphType, description)

def tempoAtTickPosition(tick):
    tempoItem = session.data.tempoTrack.tempoAtTickPosition(tick)
    return tempoItem.unitsPerMinute, tempoItem.referenceTicks

def insertTempoChangeDuringDuration(percentageUnitsPerMinuteAsFloat):
    """Instead of a fermata this sets a tempo change which start- and end-point are derived
    from the current items duration

    To enable the user to compare the tempo values we keep the original referenceTicks.
    The new units per minute value is given as percentage parameter. The reasoning behind that is
    that the user should think 'I want that duration to be double as long as normal = half tempo = 0.5' """

    if percentageUnitsPerMinuteAsFloat <= 0:
        raise ValueError("Give a float value bigger than zero. 1.0 is no modification. 0.5 is half tempo, 2.0 is double tempo")

    curItem = session.data.currentItem()
    if curItem: # not appending(None)
        dur = curItem.logicalDuration()
        if not dur: #not a clef
            return None
        startTick = session.data.currentTrack().state.tickindex
        endTick = startTick + dur #we don't need to worry about the next note starting on that value or not. midi tempo changes can happen between note on and note off.
        tempoItem = session.data.tempoTrack.tempoAtTickPosition(startTick)
        #originalUnitsPerMinute, originalReferenceTicks = session.data.tempoTrack.tempoAtTickPosition(startTick)
        newUnitsPerMinute = tempoItem.unitsPerMinute * percentageUnitsPerMinuteAsFloat
        t = insertTempoItemAtAbsolutePosition(startTick, newUnitsPerMinute, tempoItem.referenceTicks, graphType = "standalone", description="tmp")
        t.lilypondParameters["hide"] = True #Replace with Fermata or so
        t = insertTempoItemAtAbsolutePosition(endTick, tempoItem.unitsPerMinute, tempoItem.referenceTicks, graphType = "standalone", description="tmp") # a tempo
        t.lilypondParameters["hide"] = True



def currentTempoScalingFactor():
    return session.data.tempoTrack.factor

def changeTempoScaling(factor:float):
    """The factor is always a factor from x1, not from the previous
    value"""
    session.data.tempoTrack.setFactor(float(factor))
    callbacks._tempoScalingChanged(session.data.tempoTrack.factor)

#Toolbox
#High Level commands

def pedalNotes(pedalDuration):
    """Split the chord so that it consists of all *pedalDuration*s and use the cursor as a pitch
    for all but the first, which keeps its original notelist.

    Since the cursor note is in the current keysig only it will be used even if applied to multiple
    tracks. E.g. treble clef middle line in Track 1 has F-Major and will input a Bes but if Track 2
    is in C-Major it will still use Bes as the pedal note, and not B.

    This is a musically unlikely corner case so we accept the inaccuracy.
    """
    #TODO: To iron out the corner case in the docstring we would have to look at each notes cached keysig.
    def replaceWithPedalNotes(self):
        if not type(self) == items.Chord:
            return False

        newParts = int(self.durationGroup.baseDuration / pedalDuration)
        if newParts < 2:
            return False
        originalPitches = self.notelist #keep the actual list, not only the contents
        keysig = session.data.currentTrack().state.keySignature()
        pitchToInsert = pitchmath.toScale(session.data.cursor.pitchindex, keysig)
        pedalNote = self.notelist[0].copy(self)
        pedalNote.pitch = pitchToInsert
        self.notelist = [pedalNote]
        undoSplit = self.split(newParts) #split uses the temporary note
        targetDuration = self.durationGroup.minimumNote.duration.copy()

        #Restore the first note to original pitch, but keep the new duration, at least in the mininumNote
        self.notelist = originalPitches
        self.durationGroup.cacheMinimumNote()
        #self.notelist[self.notelist.index(self.durationGroup.minimumNote)] =
        self.durationGroup.minimumNote.duration = targetDuration
        self.durationGroup.cacheMinimumNote()
        return undoSplit

    items.Item._replaceWithPedalNotes = replaceWithPedalNotes #this happens each time api.pedalNotes gets called, which is good because the "duration" parameter changes each time.

    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("_replaceWithPedalNotes")
    else:
        _applyToItem("_replaceWithPedalNotes")


def mirrorAroundCursor():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("mirrorAroundCursor", parameterListForEachSelectedItem = [[session.data.cursor.pitchindex]])
    else:
        _applyToItem("mirrorAroundCursor", parameters = [session.data.cursor.pitchindex])

#All the random inserts work on prevailing duration.
def _randomPitch(lowest, highest, mode = "inScale"):
    """
    returns a pitch integer

    Does depend on the track state and cursor. This is a function that is supposed to be called (indirectly)
    by the user and not suited for a script where the cursor stays at the beginning.

    lowest is a pitch value like 1420
    Modes:
    -1 = full spectrum, reserved for microintervals
    0 = enharmonic spectrum.
    1 = without double-b and x
    2 = in Scale, default"""

    note = random.randrange(lowest, highest, 10) #step-size 10
    keysig = session.data.currentTrack().state.keySignature()
    if mode == "inScale":
        return pitchmath.toScale(note, keysig)
    elif mode == "chromatic":
        #A conversion to midi is just an abstract frequency and back to the current keysig
        return pitchmath.fromMidi(pitchmath.toMidi[note], keysig)
    elif mode == "enharmonic":
        return note
    elif mode == "microintervals":
        raise NotImplementedError
    else:
        raise ValueError("Mode unknown: {}".format(mode))

def insertRandomChromaticInClefRange():
    clef = session.data.currentTrack().state.clef()
    insertChord(session.data.cursor.prevailingBaseDuration, _randomPitch(clef.rangeLowest, clef.rangeHighest, mode="chromatic"))

def insertRandomFromScaleInClefRange():
    clef = session.data.currentTrack().state.clef()
    insertChord(session.data.cursor.prevailingBaseDuration, _randomPitch(clef.rangeLowest, clef.rangeHighest))

def insertRandomFromScaleAuthenticModeCursor():
    insertChord(session.data.cursor.prevailingBaseDuration, _randomPitch(session.data.cursor.pitchindex, session.data.cursor.pitchindex + 350, mode = "inScale"))

def insertRandomFromScaleHypoModeCursor():
    insertChord(session.data.cursor.prevailingBaseDuration, _randomPitch(session.data.cursor.pitchindex - 3*50, session.data.cursor.pitchindex + 4*50, mode = "inScale"))

def insertRandomFromClipboard():
    """Only the pitch, not the duration"""
    #TODO: After real world testing decide if this works with the clipboard or if we need a separate buffer
    #TODO currently the pool is created each time a note is requested. This could easily moved into the copy function.
    if session.data.copyObjectsBuffer:
        pool = set(flatList(session.data.copyObjectsBuffer)) #set to remove content links
        pool = [i for i in pool if type(i) is items.Chord]
        if pool: #all chords
            completeDuration=session.data.cursor.prevailingBaseDuration
            pitchlist = random.choice(pool).copy().pitchlist()
            velocityModification = 0 #signed int which will simply get added to the current dynamic signatures value.
            item = items.createChordOrRest(completeDuration, pitchlist, velocityModification)
            insertItem(item)

#Ordering
def _listOChordsFromSelection():
    """Returns (None, None) or a tuple(listOfChangedTrackIds, list of notelists (per track))"""
    if session.data.cursorWhenSelectionStarted:
        validSelection, topLeftCursor, bottomRightCursor, listOfChangedTrackIds, *selectedTracksAndItems = session.data.listOfSelectedItems(removeContentLinkedData=True)
        if not validSelection:
            return None, None
        chordlists = []
        for track in selectedTracksAndItems:
            chordlists.append(list())
            #[(object, {"keySignature": keysigobject}), (object, {"keySignature": keysigobject}), (object, {"keySignature": keysigobject}), ...], #track 1
            #[(object, {"keySignature": keysigobject}), (object, {"keySignature": keysigobject}), ...], #track 2

            if len(track) >= 2:
                for item, keysig in track:
                    if type(item) is items.Chord:
                        chordlists[-1].append(item)

        if not tuple(flatList(chordlists)):
            return None, None
        return listOfChangedTrackIds, chordlists
    else:
        return None, None


def _reorderChords(functionToGenerateChordOrder, descriptionString):
    """Works track by track.
    It is assumed that each chord is only once in generatorOfChords and also exists in the score
    """
    listOfChangedTrackIds, chordlists = _listOChordsFromSelection()
    if not listOfChangedTrackIds:
        return

    orderBeforeInsert = session.data.getBlockAndItemOrder()
    moveFunction = _createLambdaMoveToForCurrentPosition()
    def registeredUndoFunction():
        moveFunction()
        _changeBlockAndItemOrder(orderBeforeInsert)
    session.history.register(registeredUndoFunction, descriptionString)

    seentest = set()

    recreateSelection = _createLambdaRecreateSelection()

    for track in chordlists: #read-only
        generatorOfChords = functionToGenerateChordOrder(track)

        #We need to gather the indices of the original items all at once.
        #Otherwise, if we replace step by step, we will find items multiple times leading to little or no shuffling.

        originalOrder = [] #tuples. we delete from the original track so the indices will be all wrong in the end, except the first! and after we insert a new item at that first position the second index will be correct again. and so on...
        for chord in track: #iterate over the original order
            #Replace each chord with a random one by removing the original chord from block data. This keeps the chord objects unchanged, ready for undo by simply reordering.
            assert not chord in seentest #shared between all tracks.
            seentest.add(chord)
            data =  next(bl for bl in chord.parentBlocks).data #just take any block. data is shared between all of them. Content linked data was removed from the selection
            index = data.index(chord)
            originalOrder.append((data, index, chord))

        for chord in track:
            data =  next(bl for bl in chord.parentBlocks).data #just take any block. data is shared between all of them. Content linked data was removed from the selection
            data.remove(chord)

        for data, index, chord in originalOrder:
            new = next(generatorOfChords)
            data.insert(index, new)

    callbacks._historyChanged()
    _updateCallbackForListOfTrackIDs(listOfChangedTrackIds)

    recreateSelection() #the bottom right position is now at a different position but we want the selection to stay the same to call reorder again
    callbacks._setCursor(destroySelection = False)

def reorderShuffle():
    """Only for valid selections.
    Works track by track"""
    def functionToGenerateChordOrder(track):
        shuffledTrack = random.sample(track, len(track))
        shuffledTrack = (chrd for chrd in shuffledTrack) #make generator so we can use next()
        return shuffledTrack

    _reorderChords(functionToGenerateChordOrder, descriptionString="Shuffle Notes") #handles undo and callbacks

def reorderReverse():
    """Only for valid selections.
    Works track by track"""
    def functionToGenerateChordOrder(track):
        return reversed(track) #already a generator
    _reorderChords(functionToGenerateChordOrder, descriptionString="Reverse Notes") #handles undo and callbacks

def reorderAscending():
    """Only for valid selections.
    Works track by track"""
    def functionToGenerateChordOrder(track):
        asc = sorted(track, key=lambda item: item.notelist[0].pitch) #notelist[0] is the lowest pitch in a chord
        return (chrd for chrd in asc) #make generator
    _reorderChords(functionToGenerateChordOrder, descriptionString="Shuffle Notes") #handles undo and callbacks

def reoderdDescending():
    """Only for valid selections.
    Works track by track"""
    def functionToGenerateChordOrder(track):
        asc = sorted(track, key=lambda item: item.notelist[0].pitch) #notelist[0] is the lowest pitch in a chord
        return reversed(asc) #already a generator
    _reorderChords(functionToGenerateChordOrder, descriptionString="Shuffle Notes") #handles undo and callbacks


#Midi only
def instrumentChange(program, msb, lsb, shortInstrumentName):
    change = items.InstrumentChange(program, msb, lsb, shortInstrumentName)
    insertItem(change)

def channelChange(value, text):
    change = items.ChannelChange(value, text)
    insertItem(change)

def midiRelativeChannelPlus():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("midiRelativeChannelPlus")
    else:
        _applyToItem("midiRelativeChannelPlus")

def midiRelativeChannelMinus():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("midiRelativeChannelMinus")
    else:
        _applyToItem("midiRelativeChannelMinus")

def midiRelativeChannelReset():
    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("midiRelativeChannelReset")
    else:
        _applyToItem("midiRelativeChannelReset")

#Lilypond

def lilypondText(text:str):
    """This is the generic lilypond item. It will get inserted as-is"""
    try:
        insertItem(items.LilypondText(text))
    except Exception as err:
        logger.error(f"Text Item Lilypond Error for '{text}': " + err)

def lilypondMark(text:str, aboveStaff=True):
    """This is actual human-readable text, called a Mark by lilypond.
    By default is will be above the staff, but it can be below as well.

    It needs to be attached to another item. Lilypond doesn't allow "just place text here".

    https://lilypond.org/doc/v2.23/Documentation/notation/writing-text
    """

    text = lilypond.lilyfy(text)

    if aboveStaff:
        text = '^"' + text + '"' #add quotes "" for lilypond
    else:
        text = '-"' + text + '"' #add quotes "" for lilypond

    insertItem(items.LilypondText(text))


def exportLilypond(absoluteFilePath):
    save()
    lilypond.saveAsLilypond(session.data, absoluteFilePath)
    try:
        lilypond.saveAsLilypond(session.data, absoluteFilePath)
    except Exception as err:
        logger.error(err)

def showPDF():
    try:
        save()
        lilypond.saveAsLilypondPDF(session.data, openPDF = True)
    except Exception as err:
        logger.error("PDF/Lilypond Exception. The following is a PYTHON, not a lilypond error:")
        print (err)
        logger.error(err)


def getLilypondBarlineList()->Iterable[Tuple[str, Callable]]:
    """Return a list of very similar functions for a convenience menu in a GUI.
    They are trivial so we don't need to create seperate api function for them individually.
    the qt gui submenus ChooseOne uses this format."""

    return [
        #("Bold", lambda: lilypondText('\\bar "."')),
        ("Double", lambda: lilypondText('\\bar "||"')),
        #("Bold Double", lambda: lilypondText('\\bar ".."')),
        ("Open", lambda: lilypondText('\\bar ".|"')),
        ("End/Open", lambda: lilypondText('\\bar "|.|"')),
        ("End", lambda: lilypondText('\\bar "|."')),
    ]

def getLilypondRepeatList()->Iterable[Tuple[str, Callable]]:
    return [
        ("Open", lambda: lilypondText('\\bar ".|:"')),
        ("Close/Open", lambda: lilypondText('\\bar ":|.|:"')),
        ("Close", lambda: lilypondText('\\bar ":|."')),
    ]



#This and That

def connectModMidiMerger():
    """Connect our global step midi in to mod-midi-merger, if present"""
    jackClientName = cbox.JackIO.status().client_name
    try:
        cbox.JackIO.port_connect("mod-midi-merger:out", jackClientName + ":in")
    except:
        pass


def connectMetronomeToSystemPorts():
    try:
        hardwareAudioPorts = cbox.JackIO.get_ports("system*", cbox.JackIO.AUDIO_TYPE, cbox.JackIO.PORT_IS_SINK | cbox.JackIO.PORT_IS_PHYSICAL) #don't sort. This is correctly sorted. Another sorted will do 1, 10, 11,
        l, r = session.data.metronome.getPortNames()
        cbox.JackIO.port_connect(l, hardwareAudioPorts[0])
        cbox.JackIO.port_connect(r, hardwareAudioPorts[1])
    except:
        pass






#Debug
def printPitches():
    track = session.data.currentTrack()
    for block in track.blocks:
        for chord in block.data:
            print ([note.pitch for note in chord.notelist])

def highStaccatoLowTenuto():
    """
    How to apply to selection without changing the item in the code?

    An example command. Normally this would be in an extra-package
    because of its high level nature and non-standard purpose.

    First we add new methods to the Chord class.
    At least during the current session this will allow undo and redo.
    The inserted note however does not need these methods anymore.
    Even if we remove this function forever the data will remain.

    This function is noteworthy because undo and redo get a notelist
    with different duration values which need to be remembered
    separately.
    """
    def _stacAndTen(self):
        if len(self.notelist) == 2:
            oldValues = []
            for note in self.notelist:
                oldValues.append(note.duration.copy()) #see _setDurationlist

            self.notelist[0].duration.toggleDurationKeyword(D_TENUTO) #lower note
            self.notelist[1].duration.toggleDurationKeyword(D_STACCATO) #higher note
            return lambda: self._setDurationlist(oldValues)
    items.Chord._stacAndTen = _stacAndTen

    if session.data.cursorWhenSelectionStarted:
        _applyToSelection("_stacAndTen") #This is now a chord-instance method.