Patroneo/engine/api.py

#! /usr/bin/env python3
# -*- coding: utf-8 -*-

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

#Standard Library Modules
from typing import List, Set, Dict, Tuple

#Third Party Modules
from calfbox import cbox

#Template Modules
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 baseDurationToTraditionalNumber
from template.helper import compress

#Our own engine Modules
pass

DEFAULT_FACTOR = 1 #for the GUI.

#Swing Lookup Table for functions and callbacks
_percentToSwing_Table = {}
_swingToPercent_Table = {}
for value in range(-100, 100+1):
    #Lookup table.
    if value == 0:
        result = 0
    elif value > 80: #81% - 100% is  0.33 - 0.5
        result = compress(value, 81, 100, 0.33, 0.5)
    elif value > 30: #31% - 80% is  0.15 - 0.33
        result = compress(value, 31, 80, 0.15, 0.32)
    else:
        result = compress(value, 0, 30, 0.01, 0.14)
    r = round(result,8)
    _percentToSwing_Table[value] = r
    _swingToPercent_Table[r] = value  #TODO: this is risky! it only works because we round to digits and percents are integers.



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

        self.timeSignatureChanged = []
        self.scoreChanged = []
        self.numberOfMeasuresChanged = []
        self.trackStructureChanged = []
        self.trackMetaDataChanged = []
        self.patternChanged = []
        self.stepChanged = []
        self.removeStep = []
        self.exportCacheChanged = []
        self.subdivisionsChanged = []
        self.quarterNotesPerMinuteChanged = []
        self.loopChanged = []
        self.loopMeasureFactorChanged = []
        self.patternLengthMultiplicatorChanged = []
        self.swingChanged = []
        self.swingPercentChanged = []

    def _quarterNotesPerMinuteChanged(self):
        """There is one tempo for the entire song in quarter notes per mintue.
        score.isTransportMaster to False means we do not create our own changes
        and leave everything to the default. Negative values are not possible"""
        if session.data.tempoMap.isTransportMaster:
            export = session.data.tempoMap.getQuarterNotesPerMinute()
        else:
            export = None
        for func in self.quarterNotesPerMinuteChanged:
            func(export)
        callbacks._dataChanged()

    def _setPlaybackTicks(self): #Differs from the template because it has subdivisions.
        ppqn = cbox.Transport.status().pos_ppqn * session.data.subdivisions
        status = playbackStatus()
        for func in self.setPlaybackTicks:
            func(ppqn, status)

    def _loopChanged(self, measurenumber, loopStart, loopEnd):
        export = measurenumber
        for func in self.loopChanged:
            func(export)

    def _loopMeasureFactorChanged(self):
        """Very atomic callback. Used only for one value: how many measures are in one loop"""
        export = session.data.loopMeasureFactor
        for func in self.loopMeasureFactorChanged:
            func(export)

    def _timeSignatureChanged(self):
        nr = session.data.howManyUnits
        typ = session.data.whatTypeOfUnit
        for func in self.timeSignatureChanged:
            func(nr, typ)

        ##All patterns and tracks need updates:
        for track in session.data.tracks:
            self._patternChanged(track)

        self._subdivisionsChanged() #update subdivisions. We do not include them in the score or track export on purpose.
        callbacks._dataChanged()

    def _subdivisionsChanged(self):
        """Subdivisions are tricky, therefore we keep them isolated in their own callback.
        You don't need to redraw anything if you don't want to. One recommendation is to
        draw every n step a little more important (bigger, different color).
        where n = subdivions

        We also place JACK BBT via tempoMap here because we need it every time the time sig
        changes (which calls _subdivisionsChanged) and if subdivisions change.
        """
        typ = baseDurationToTraditionalNumber[session.data.whatTypeOfUnit]
        nr = session.data.howManyUnits
        tradNr = int(nr / session.data.subdivisions)
        #JACK BBT for Timebase Master. No matter if we are master at the moment or not.
        if tradNr == nr / session.data.subdivisions:
            #Easier to read than the else case. Not possible with 9 Steps per Pattern in Groups of 2 because that is a 4.5/4 timesig.
            session.data.tempoMap.setTimeSignature(tradNr, typ)
        else:
            #Always possible, compared to first if case.
            session.data.tempoMap.setTimeSignature(nr, typ*session.data.subdivisions)

        export = session.data.subdivisions
        for func in self.subdivisionsChanged:
            func(export)
        callbacks._dataChanged()


    def _scoreChanged(self):
        """This includes the time signature as well, but is not send on a timesig change.
        A timesig change needs to update all tracks as playback as well as for the GUI
        so it is its own callback.
        Use this for fast and inexpensive updates like drawing a label or adjusting the
        GUI that shows your measure groups (a label each 8 measures or so)"""
        export = session.data.export()
        for func in self.scoreChanged:
            func(export)
        callbacks._dataChanged()

    def _exportCacheChanged(self, track):
        """Send the export cache for GUI caching reasons. Don't react by redrawing immediately!
        This is sent often, redundantly and more than you need.
        Example: If you only show one pattern at the same time use this to cache the data
        in all hidden patterns and redraw only if you change the active pattern.
        You can react to real changes in your active pattern by using patternChanged
        and stepChanged."""
        export = track.export()
        for func in self.exportCacheChanged:
            func(export)

    def _patternChanged(self, track):
        """each track has only one pattern. We can identify the pattern by track and vice versa.
        Don't use this to react to clicks on the pattern editor. Use stepChanged instead and
        keep book of your incremental updates.
        This is used for the whole pattern: timesig changes, invert, clean etc.
        """
        export = track.export()
        self._exportCacheChanged(track)
        for func in self.patternChanged:
            func(export)
        callbacks._dataChanged()

    def _stepChanged(self, track, stepDict):
        """A simple GUI will most like not listen to that callback since they
        already changed the step on their side. Only useful for parallel
        views.
        We do not export anything but just sent back the change we received
        as dict message."""
        self._exportCacheChanged(track)
        for func in self.stepChanged:
            func(stepDict)
        callbacks._dataChanged()

    def _removeStep(self, track, index, pitch):
        """Opposite of _stepChanged"""
        self._exportCacheChanged(track)
        for func in self.stepChanged:
            func(index, pitch)
        callbacks._dataChanged()

    def _trackStructureChanged(self, track):
        """update one track structure. Does not export cbox.
        Also includes transposition """
        export = track.export()
        for func in self.trackStructureChanged:
            func(export)
        callbacks._dataChanged()

    def _trackMetaDataChanged(self, track):
        """a low cost function that should not trigger anything costly to redraw
        but some text and simple widgets."""
        export = track.export()
        for func in self.trackMetaDataChanged:
            func(export)
        callbacks._dataChanged()

    def _numberOfMeasuresChanged(self):
        export = session.data.export()
        for func in self.numberOfMeasuresChanged:
            func(export)
        callbacks._dataChanged()

    def _patternLengthMultiplicatorChanged(self, track):
        export = track.export()
        for func in self.patternLengthMultiplicatorChanged:
            func(export)
        self._patternChanged(track) #includes dataChanged
        callbacks._dataChanged()

    def _swingChanged(self):
        export = session.data.swing
        for func in self.swingChanged:
            func(export)

        for func in self.swingPercentChanged:
            func(_swingToPercent_Table[export])
        callbacks._dataChanged()

    #Override template one
    def _setPlaybackTicks(self):
        """This gets called very very often (~60 times per second).
        Any connected function needs to watch closely
        for performance issues"""
        ppqn = cbox.Transport.status().pos_ppqn - session.data.cachedOffsetInTicks
        status = playbackStatus()
        for func in self.setPlaybackTicks:
            func(ppqn, status)
        self._dataChanged() #includes _historyChanged


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

_templateStartEngine = startEngine

def updatePlayback():
    #TODO: use template.sequencer.py internal updates instead
    cbox.Document.get_song().update_playback()

def startEngine(nsmClient):
    _templateStartEngine(nsmClient)

    session.inLoopMode = None # remember if we are in loop mode or not. Positive value is None or  a tuple with start and end

    #Send initial Callbacks to create the first GUI state.
    #The order of initial callbacks must not change to avoid GUI problems.
    #For example it is important that the tracks get created first and only then the number of measures
    logger.info("Sending initial callbacks to GUI")
    callbacks._numberOfTracksChanged()
    callbacks._timeSignatureChanged()
    callbacks._numberOfMeasuresChanged()
    callbacks._subdivisionsChanged()
    callbacks._quarterNotesPerMinuteChanged()
    callbacks._loopMeasureFactorChanged()
    callbacks._swingChanged()

    for track in session.data.tracks:
        callbacks._trackMetaDataChanged(track) #for colors, scale and simpleNoteNames
        callbacks._patternLengthMultiplicatorChanged(track) #for colors, scale and simpleNoteNames

    session.data.buildAllTracks(buildSongDuration=True) #will set to max track length, we always have a song duration.

    updatePlayback()
    logger.info("Patroneo api startEngine complete")


def _loopOff():
    session.data.buildSongDuration() #no parameter removes the loop
    updatePlayback()
    session.inLoopMode = None
    callbacks._loopChanged(None, None, None)

def _loopNow():
    now = cbox.Transport.status().pos_ppqn
    _setLoop(now)

def _setLoop(loopMeasureAroundPpqn:int):
    """This function is used with context.
    The loopFactor, how many measures are looped, is saved value """

    if loopMeasureAroundPpqn < 0:
        _loopOff()
        return

    #loopMeasureAroundPpqn = max(0, loopMeasureAroundPpqn + session.data.cachedOffsetInTicks)
    loopMeasureAroundPpqn = loopMeasureAroundPpqn - session.data.cachedOffsetInTicks

    loopStart, loopEnd = session.data.buildSongDuration(loopMeasureAroundPpqn) #includes global tick offset
    session.data._lastLoopStart = loopStart

    updatePlayback()
    session.inLoopMode = (loopStart, loopEnd)

    assert loopStart <= loopMeasureAroundPpqn+session.data.cachedOffsetInTicks < loopEnd, (loopStart, loopMeasureAroundPpqn, loopEnd)
    if not playbackStatus():
        cbox.Transport.play()

    oneMeasureInTicks = (session.data.howManyUnits * session.data.whatTypeOfUnit) / session.data.subdivisions

    measurenumber, rest = divmod(loopStart-session.data.cachedOffsetInTicks, oneMeasureInTicks) #We substract the offset from the measure number because for a GUI it is still the visible measure number

    callbacks._loopChanged(int(measurenumber), loopStart, loopEnd)

def setLoopMeasureFactor(newValue:int):
    """How many measures are looped at once."""
    if newValue < 1:
        newValue = 1
    session.data.loopMeasureFactor = newValue
    callbacks._loopMeasureFactorChanged()
    if session.inLoopMode:
        _setLoop(session.data._lastLoopStart)

def toggleLoop():
    """Plays the current measure as loop.
    Current measure is where the playback cursor is

    session.inLoopMode is a tuple (start, end)
    """
    if session.inLoopMode:
        _loopOff()
    else:
        _loopNow()

def rewind():
    """template.toStart, but removes our loop"""
    _loopOff()
    toStart()

def seek(value):
    """override template one, which does not have a loop"""
    if value < 0:
        value = 0
    if session.inLoopMode and not session.inLoopMode[0] <= value < session.inLoopMode[1]: #if you seek outside the loop the loop will be destroyed.
        toggleLoop()

    value = max(0, value + session.data.cachedOffsetInTicks)
    cbox.Transport.seek_ppqn(value)


def getGlobalOffset():
    """Return the current offsets in full measures + free tick value 3rd: Cached abolute tick value
    gets updated everytime the time signature changes or setGlobalOffset is called"""
    return session.data.globalOffsetMeasures, session.data.globalOffsetTicks, session.data.cachedOffsetInTicks


def setGlobalOffset(fullMeasures, absoluteTicks):
    session.history.register(lambda f=session.data.globalOffsetMeasures, t=session.data.globalOffsetTicks: setGlobalOffset(f,t), descriptionString="Global Rhythm Offset")
    session.data.globalOffsetMeasures = fullMeasures
    session.data.globalOffsetTicks = absoluteTicks
    session.data.buildAllTracks() #includes refreshing the tick offset cache
    updatePlayback()

##Score
def set_quarterNotesPerMinute(value):
    """Transport Master is set implicitly. If value == None Patroneo will switch into
    JackTransport Slave mode"""
    if session.data.tempoMap.isTransportMaster:
        oldValue = session.data.tempoMap.getQuarterNotesPerMinute()
    else:
        oldValue = None

    if oldValue == value: return # no change

    session.history.register(lambda v=oldValue: set_quarterNotesPerMinute(v), descriptionString="Tempo")

    if value is None:
        session.data.tempoMap.isTransportMaster = False #triggers rebuild
    elif value == "on":
        assert not session.data.tempoMap.isTransportMaster
        #keep old bpm value. 120 bpm is default.
        session.data.tempoMap.isTransportMaster = True #triggers rebuild
    else:
        assert value > 0
        session.data.tempoMap.setQuarterNotesPerMinute(value)
        session.data.tempoMap.isTransportMaster = True #triggers rebuild
    #Does not need track rebuilding
    updatePlayback()
    callbacks._quarterNotesPerMinuteChanged()


def set_whatTypeOfUnit(ticks):
    """Denominator of Time Signature = Each Group produces a Quarter """
    if session.data.whatTypeOfUnit == ticks: return #no change

    session.history.register(lambda v=session.data.whatTypeOfUnit: set_whatTypeOfUnit(v), descriptionString="Group Duration")
    session.data.whatTypeOfUnit = ticks
    session.data.buildAllTracks()
    if session.inLoopMode:
        _loopNow()
    updatePlayback()
    callbacks._timeSignatureChanged()

def set_howManyUnits(value):
    """Numerator of Time Signature = Steps per Pattern"""
    if session.data.howManyUnits == value: return #no change

    session.history.register(lambda v=session.data.howManyUnits: set_howManyUnits(v), descriptionString="Steps per Pattern")
    session.data.howManyUnits = value
    session.data.buildAllTracks()
    if session.inLoopMode:
        _loopNow()
    updatePlayback()
    callbacks._timeSignatureChanged()


def set_subdivisions(value):
    """In groups of 1, 2, 4"""
    if session.data.subdivisions == value: return #no change
    session.history.register(lambda v=session.data.subdivisions: set_subdivisions(v), descriptionString="Group Size")
    session.data.subdivisions = value
    session.data.buildAllTracks()
    if session.inLoopMode:
        _loopNow()
    updatePlayback()
    callbacks._subdivisionsChanged()

def convert_subdivisions(value, errorHandling):
    """"errorHandling can be fail, delete or merge"""
    oldValue = session.data.subdivisions
    result = session.data.convertSubdivisions(value, errorHandling)
    if result: #bool for success
        session.history.register(lambda v=oldValue: convert_subdivisions(v, "delete"), descriptionString="Convert Grouping") #the error handling = delete should not matter at all. We are always in a position where this is possible because we just converted to the current state.
        session.data.buildAllTracks()
        updatePlayback()
        callbacks._timeSignatureChanged() #includes subdivisions
        for tr in session.data.tracks:
            callbacks._patternChanged(tr)
    else:
        callbacks._subdivisionsChanged() #to reset the GUI value back to the working one.
    if session.inLoopMode:
        _loopNow()
    return result


def set_swing(value:float):
    """A swing that feels natural is not linear. This function sets the absolute value
    between -0.5 and 0.5 but you most likely want to use setSwingPercent which has a non-linear
    mapping"""
    if value < -0.5 or value > 0.5:
        logger.warning(f"Swing can only be between -0.5 and 0.5, not {value}")
        return

    session.history.register(lambda v=session.data.swing: set_swing(v), descriptionString="Swing")
    session.data.swing = value
    session.data.buildAllTracks()
    updatePlayback()
    callbacks._swingChanged()


def setSwingPercent(value:int):
    """Give value between -100 and 100. 0 is "off" and default.
    It will be converted to a number between -0.5 and 0.5 behind the scenes. This is the value
    that gets saved.
    Our function will use a lookup-table to convert percentage in a musical way.

    The first 80% will be used for normal musical values. The other 20 for more extreme sounds.
    """
    if value < -100 or value > 100:
        logger.warning(f"Swing in percent can only be between -100 and +100, not {value}")
        return
    set_swing(_percentToSwing_Table[value]) #handles undo and callbacks


def set_numberOfMeasures(value):
    if session.data.numberOfMeasures == value:
        return

    session.history.register(lambda v=session.data.numberOfMeasures: set_numberOfMeasures(v), descriptionString="Measures per Track")
    session.data.numberOfMeasures = value
    session.data.buildSongDuration()
    updatePlayback()
    callbacks._numberOfMeasuresChanged()
    callbacks._scoreChanged() #redundant but cheap and convenient

def set_measuresPerGroup(value):
    if session.data.measuresPerGroup == value:
        return
    session.history.register(lambda v=session.data.measuresPerGroup: set_measuresPerGroup(v), descriptionString="Measures per Group")
    session.data.measuresPerGroup = value
    #No playback change
    callbacks._scoreChanged()

def changeTrackName(trackId, name):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.sequencerInterface.name: changeTrackName(trId,v), descriptionString="Track Name")
    track.sequencerInterface.name = " ".join(name.split())
    callbacks._trackMetaDataChanged(track)

def changeTrackColor(trackId, colorInHex):
    """Expects "#rrggbb"""
    track = session.data.trackById(trackId)
    assert len(colorInHex) == 7, colorInHex
    session.history.register(lambda trId=trackId, v=track.color: changeTrackColor(trId,v), descriptionString="Track Color")
    track.color = colorInHex
    callbacks._trackMetaDataChanged(track)

def changeTrackMidiChannel(trackId, newChannel:int):
    """newChannel is 1-16, we convert here to internal format 0-15.
    Callbacks export data sends 1-16 again"""
    if newChannel < 1 or newChannel > 16:
        logger.warning(f"Midi Channel must be between 1-16 for this function, was: {newChannel}. Doing nothing.")
        return
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.midiChannel: changeTrackMidiChannel(trId,v), descriptionString="Track Midi Channel")
    track.midiChannel = newChannel-1
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._trackMetaDataChanged(track)

def addTrack(scale=None):
    if scale:
        assert type(scale) == tuple
    track = session.data.addTrack(scale=scale)
    assert track
    trackId = id(track)
    session.history.register(lambda trId=trackId: deleteTrack(trId), descriptionString="Add Track")
    callbacks._numberOfTracksChanged()

def createSiblingTrack(trackId):
    """Create a new track with scale, color and jack midi out the same as the given track.
    The jack midi out will be independent after creation, but connected to the same instrument
    (if any)"""
    track = session.data.trackById(trackId)
    assert type(track.pattern.scale) == tuple
    newTrack = session.data.addTrack(name=track.sequencerInterface.name, scale=track.pattern.scale, color=track.color, simpleNoteNames=track.pattern.simpleNoteNames) #track name increments itself from "Track A" to "Track B" or "Track 1" -> "Track 2"
    newTrack.pattern.averageVelocity = track.pattern.averageVelocity
    newTrack.patternLengthMultiplicator = track.patternLengthMultiplicator
    newTrack.midiChannel = track.midiChannel
    jackConnections = cbox.JackIO.get_connected_ports(track.sequencerInterface.cboxPortName())
    for port in jackConnections:
        cbox.JackIO.port_connect(newTrack.sequencerInterface.cboxPortName(), port)
    #Move new track to neighbour the old one.
    oldIndex = session.data.tracks.index(track)
    newIndex = session.data.tracks.index(newTrack)
    newTrackAgain = session.data.tracks.pop(newIndex)
    assert newTrackAgain is newTrack
    session.data.tracks.insert(oldIndex+1, newTrackAgain)
    session.history.register(lambda trId=id(newTrackAgain): deleteTrack(trId), descriptionString="Clone Track")
    callbacks._numberOfTracksChanged()
    return newTrack.export()

def _reinsertDeletedTrack(track, trackIndex):
    """For undo"""
    track.sequencerInterface.recreateThroughUndo()
    session.data.tracks.insert(trackIndex, track)
    session.history.register(lambda trId=id(track): deleteTrack(trId), descriptionString="Add deleted Track again")
    updatePlayback()
    callbacks._numberOfTracksChanged()

def deleteTrack(trackId):
    track = session.data.trackById(trackId)
    oldIndex = session.data.tracks.index(track)
    deletedTrack = session.data.deleteTrack(track)

    if not session.data.tracks: #always keep at least one track
        with session.history.sequence("Delete Track and autocreated Track"):
            addTrack() #has it's own undo
            session.history.register(lambda tr=deletedTrack, pos=oldIndex: _reinsertDeletedTrack(tr, pos), descriptionString="Delete Track")
    else:
        session.history.register(lambda tr=deletedTrack, pos=oldIndex: _reinsertDeletedTrack(tr, pos), descriptionString="Delete Track")

    updatePlayback()
    callbacks._numberOfTracksChanged()

def moveTrack(trackId, newIndex):
    """index is 0 based"""
    track = session.data.trackById(trackId)
    oldIndex = session.data.tracks.index(track)
    if not oldIndex == newIndex:
        session.history.register(lambda tr=trackId, pos=oldIndex: moveTrack(trackId, pos), descriptionString="Move Track")
        session.data.tracks.pop(oldIndex)
        session.data.tracks.insert(newIndex, track)
        callbacks._numberOfTracksChanged()

def setTrackPatternLengthMultiplicator(trackId, newMultiplicator:int):
    if newMultiplicator < 1 or not isinstance(newMultiplicator, int):
        return #Invalid input

    track = session.data.trackById(trackId)
    session.history.register(lambda tr=trackId, v=track.patternLengthMultiplicator: setTrackPatternLengthMultiplicator(trackId, v), descriptionString="Pattern Multiplier")
    track.patternLengthMultiplicator = newMultiplicator
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()

    #Order is important! Otherwise the GUI doesn't know that new empty steps need to exist to fill in.
    callbacks._patternLengthMultiplicatorChanged(track)
    callbacks._patternChanged(track)


#Track Switches
#Aka measures

def _setTrackStructure(trackId, structure, undoMessage):
    """For undo. Used by all functions as entry point, then calls itself for undo/redo.
    structure is a set of integers which we can copy with .copy()"""
    track = session.data.trackById(trackId)

    session.history.register(lambda tr=trackId, v=track.structure.copy(), msg=undoMessage: _setTrackStructure(trackId, v, msg), descriptionString=undoMessage)

    track.structure = structure #restore data
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)


def setSwitches(trackId, setOfPositions, newBool):
    """Used in the GUI to select multiple switches in a row by dragging the mouse"""
    track = session.data.trackById(trackId)
    session.history.register(lambda tr=trackId, v=track.structure.copy(): _setTrackStructure(trackId, v, "Set Measures"), descriptionString="Set Measures")
    if newBool:
        track.structure = track.structure.union(setOfPositions) #merge: add setOfPositions to the existing one
    else:
        track.structure = track.structure.difference(setOfPositions) #replace: remove everything from setOfPositions that is in the existing one, ignore entries from setOfPositions not in existing.
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)

def setSwitch(trackId, position, newBool):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Set Measures"), descriptionString="Set Measures")
    if newBool:
        if position in track.structure: return
        track.structure.add(position)
    else:
        if not position in track.structure: return
        track.structure.remove(position)
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)
    return True

def trackInvertSwitches(trackId):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Invert Measures"), descriptionString="Invert Measures")
    """
    if track.structure:
        new = set(i for i in range(max(track.structure)))
        track.structure = new.difference(track.structure)
    else:
        track.structure = set(i for i in range(session.data.numberOfMeasures))
    """
    new = set(i for i in range(session.data.numberOfMeasures))
    track.structure = new.difference(track.structure)
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)

def trackOffAllSwitches(trackId):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Track Measures Off"), descriptionString="Track Measures Off")
    track.structure = set()
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)

def trackOnAllSwitches(trackId):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Track Measures On"), descriptionString="Track Measures On")
    track.structure = set(i for i in range(session.data.numberOfMeasures))
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)

def trackMergeCopyFrom(sourceTrackId, targetTrackId):
    if not sourceTrackId == targetTrackId:
        sourceTrack = session.data.trackById(sourceTrackId)
        targetTrack = session.data.trackById(targetTrackId)
        session.history.register(lambda trId=id(targetTrack), v=targetTrack.structure.copy(): _setTrackStructure(trId, v, "Copy Measures"), descriptionString="Copy Measures")
        targetTrack.structure = targetTrack.structure.union(sourceTrack.structure)
        targetTrack.whichPatternsAreScaleTransposed.update(sourceTrack.whichPatternsAreScaleTransposed)
        targetTrack.whichPatternsAreHalftoneTransposed.update(sourceTrack.whichPatternsAreHalftoneTransposed)
        targetTrack.buildTrack()
        updatePlayback()
        callbacks._trackStructureChanged(targetTrack)

def trackPatternReplaceFrom(sourceTrackId, targetTrackId):
    if not sourceTrackId == targetTrackId:
        sourceTrack = session.data.trackById(sourceTrackId)
        targetTrack = session.data.trackById(targetTrackId)
        session.history.register(lambda trId=id(targetTrack), v=targetTrack.structure.copy(): _setTrackStructure(trId, v, "Replace Measures"), descriptionString="Replace Measures")

        copyPattern = sourceTrack.pattern.copy(newParentTrack = targetTrack)
        targetTrack.pattern = copyPattern

        targetTrack.buildTrack()
        updatePlayback()
        callbacks._patternChanged(targetTrack)

#Transpositions and Modal Shifts

def _setSwitchesScaleTranspose(trackId, whichPatternsAreScaleTransposed):
    """For undo. Used by all functions as entry point, then calls itself for undo/redo.
    whichPatternsAreScaleTransposed is a dicts of int:int which we can copy with .copy()"""
    track = session.data.trackById(trackId)

    session.history.register(lambda tr=trackId, v=track.whichPatternsAreScaleTransposed.copy(): _setSwitchesScaleTranspose(trackId, v), descriptionString="Set Modal Shift")

    track.whichPatternsAreScaleTransposed = whichPatternsAreScaleTransposed #restore data
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)


def setSwitchScaleTranspose(trackId, position, transpose):
    """Scale transposition is flipped. lower value means higher pitch"""
    track = session.data.trackById(trackId)
    session.history.register(lambda tr=trackId, v=track.whichPatternsAreScaleTransposed.copy(): _setSwitchesScaleTranspose(trackId, v), descriptionString="Set Modal Shift")
    track.whichPatternsAreScaleTransposed[position] = transpose
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)
    return True


def _setSwitchHalftoneTranspose(trackId, whichPatternsAreHalftoneTransposed):
    """For undo. Used by all functions as entry point, then calls itself for undo/redo.
    whichPatternsAreScaleTransposed is a dicts of int:int which we can copy with .copy()"""
    track = session.data.trackById(trackId)

    session.history.register(lambda tr=trackId, v=track.whichPatternsAreHalftoneTransposed.copy(): _setSwitchHalftoneTranspose(trackId, v), descriptionString="Set Half Tone Shift")

    track.whichPatternsAreHalftoneTransposed = whichPatternsAreHalftoneTransposed #restore data
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)

def setSwitchHalftoneTranspose(trackId, position, transpose):
    """Halftone transposition is not flipped. Higher value means higher pitch"""
    track = session.data.trackById(trackId)
    session.history.register(lambda tr=trackId, v=track.whichPatternsAreHalftoneTransposed.copy(): _setSwitchHalftoneTranspose(trackId, v), descriptionString="Set Half Tone Shift")
    track.whichPatternsAreHalftoneTransposed[position] = transpose
    track.buildTrack()
    updatePlayback()
    callbacks._trackStructureChanged(track)
    return True

def _registerHistoryWholeTrackSwitches(track):
    """This is used by insertSilence, clearSwitchGroupTranspositions etc.
    It assumes to run inside the context:
        with session.history.sequence(""):
    """
    trackId = id(track)
    session.history.register(lambda trId=trackId, v=track.patternLengthMultiplicator: setTrackPatternLengthMultiplicator(trId, v), descriptionString="Pattern Multiplier")
    session.history.register(lambda trId=trackId, v=track.structure.copy(): _setTrackStructure(trId, v, "Change Group"), descriptionString="Change Group")
    session.history.register(lambda trId=trackId, v=track.whichPatternsAreScaleTransposed.copy(): _setSwitchesScaleTranspose(trId, v), descriptionString="Set Modal Shift")
    session.history.register(lambda trId=trackId, v=track.whichPatternsAreHalftoneTransposed.copy(): _setSwitchHalftoneTranspose(trId, v), descriptionString="Set Half Tone Shift")


def insertSilence(howMany:int, beforeMeasureNumber:int):
    """Insert empty measures into all tracks.
    Parameters are un-multiplied."""

    #In each track shift every switch to the right if it is before the dividing measure number
    #Keep the concept of a "group" even if there are multiplicators in the track.
    #If you insert 4 normal measures then a multiplicator-track of two gets only 2 new ones.
    with session.history.sequence("Insert/Duplicate Group"):  #this actually handles duplicateSwitchGroup undo as well!!!
        for track in session.data.tracks:
            _registerHistoryWholeTrackSwitches(track)

            thisTrackWhere = beforeMeasureNumber // track.patternLengthMultiplicator #integer division
            thisTrackHowMany = howMany // track.patternLengthMultiplicator #integer division
            track.structure = set( (switch + thisTrackHowMany if switch >= thisTrackWhere else switch) for switch in track.structure )
            track.whichPatternsAreScaleTransposed = { (k+thisTrackHowMany if k >= thisTrackWhere else k):v for k,v in track.whichPatternsAreScaleTransposed.items() }
            track.whichPatternsAreHalftoneTransposed = { (k+thisTrackHowMany if k >= thisTrackWhere else k):v for k,v in track.whichPatternsAreHalftoneTransposed.items() }
            callbacks._trackStructureChanged(track)

    callbacks._dataChanged() #register undo
    session.data.buildAllTracks()
    updatePlayback()

def duplicateSwitchGroup(startMeasureForGroup:int, endMeasureExclusive:int):
    """startMeasureForGroup and endMeasureExclusive are in the global, un-multiplied measure counting
    format."""

    groupSize = endMeasureExclusive-startMeasureForGroup

    #Undo:   InsertSilence has a complete undo already registered. We chose a neutral undo description so it handles both duplicate and insert silence.
    insertSilence(groupSize, endMeasureExclusive) #insert silence handles multiplicator-tracks on its own
    for track in session.data.tracks:
        thisTrackStartMeasure = startMeasureForGroup // track.patternLengthMultiplicator #integer division
        thisTrackEndMeasure = endMeasureExclusive // track.patternLengthMultiplicator
        thisGroupSize = groupSize // track.patternLengthMultiplicator

        for switch in range(thisTrackStartMeasure+thisGroupSize, thisTrackEndMeasure+thisGroupSize): #One group after the given one.
            if switch-thisGroupSize in track.structure:
                track.structure.add(switch)
            if switch-thisGroupSize in track.whichPatternsAreScaleTransposed:
                track.whichPatternsAreScaleTransposed[switch] = track.whichPatternsAreScaleTransposed[switch-thisGroupSize]
            if switch-thisGroupSize in track.whichPatternsAreHalftoneTransposed:
                track.whichPatternsAreHalftoneTransposed[switch] = track.whichPatternsAreHalftoneTransposed[switch-thisGroupSize]
            callbacks._trackStructureChanged(track)

    session.data.buildAllTracks()
    updatePlayback()


def exchangeSwitchGroupWithGroupToTheRight(startMeasureForGroup:int, endMeasureExclusive:int):
    """The group is defined by the given measure range. The group right of it has the same dimensions.
    In a GUI you can use that to move groups left and right. We only supply the "switch with right"
    variant (and not left) because that is easier to comprehend.
    """

    with session.history.sequence("Exchange Group Order"):
        for track in session.data.tracks:
            _registerHistoryWholeTrackSwitches(track)

            thisTrackStartMeasure = startMeasureForGroup // track.patternLengthMultiplicator #integer division
            thisTrackEndMeasure = endMeasureExclusive // track.patternLengthMultiplicator
            groupSize = thisTrackEndMeasure - thisTrackStartMeasure

            assert thisTrackStartMeasure + groupSize == thisTrackEndMeasure, (thisTrackStartMeasure, groupSize, thisTrackEndMeasure)

            tempStructure = set() #integers
            tempScaleTransposed  = dict()  #position:integers
            tempHalfToneTransposed = dict() #position:integers

            #Remember for later testing
            lenStructure = len(track.structure)
            lenScaleTransposed = len(track.whichPatternsAreScaleTransposed.keys())
            lenHalfToneTransposed = len(track.whichPatternsAreHalftoneTransposed.keys())

            #First move right group into a temporary buffer to have it out of the way
            for switch in range(thisTrackStartMeasure+groupSize, thisTrackEndMeasure+groupSize): #switch is a number
                if switch in track.structure:
                    tempStructure.add(switch)
                    track.structure.remove(switch)
                if switch in track.whichPatternsAreScaleTransposed:
                    tempScaleTransposed[switch] = track.whichPatternsAreScaleTransposed[switch]
                    del track.whichPatternsAreScaleTransposed[switch]
                if switch in track.whichPatternsAreHalftoneTransposed:
                    tempHalfToneTransposed[switch] = track.whichPatternsAreHalftoneTransposed[switch]
                    del track.whichPatternsAreHalftoneTransposed[switch]

            #Now move current group to the right, which is now empty.
            for switch in range(thisTrackStartMeasure, thisTrackEndMeasure): #switch is a number
                if switch in track.structure:
                    track.structure.add(switch + groupSize)
                    track.structure.remove(switch)
                if switch in track.whichPatternsAreScaleTransposed:
                    track.whichPatternsAreScaleTransposed[switch+groupSize] = track.whichPatternsAreScaleTransposed[switch]
                    del track.whichPatternsAreScaleTransposed[switch]
                if switch in track.whichPatternsAreHalftoneTransposed:
                    track.whichPatternsAreHalftoneTransposed[switch+groupSize] = track.whichPatternsAreHalftoneTransposed[switch]
                    del track.whichPatternsAreHalftoneTransposed[switch]

            #Move old right-group into its new place
            for sw in tempStructure:
                track.structure.add(sw-groupSize)
            for stPos, stVal in tempScaleTransposed.items():
                track.whichPatternsAreScaleTransposed[stPos-groupSize] = stVal
            for htPos, htVal in tempScaleTransposed.items():
                track.whichPatternsAreHalftoneTransposed[hPos-groupSize] = htVal

            callbacks._trackStructureChanged(track)

            #Do some tests
            assert lenStructure == len(track.structure), (lenStructure, len(track.structure))
            assert lenScaleTransposed == len(track.whichPatternsAreScaleTransposed.keys()), (lenScaleTransposed, len(track.whichPatternsAreScaleTransposed.keys()))
            assert lenHalfToneTransposed == len(track.whichPatternsAreHalftoneTransposed.keys()), (lenHalfToneTransposed, len(track.whichPatternsAreHalftoneTransposed.keys()))

    callbacks._dataChanged() #register undo
    session.data.buildAllTracks()
    updatePlayback()


def clearSwitchGroupTranspositions(startMeasureForGroup:int, endMeasureExclusive:int):
    """startMeasureForGroup and endMeasureExclusive are in the global, un-multiplied measure counting
    format."""
    with session.history.sequence("Clear all Group Transpositions"):
        for track in session.data.tracks:
            _registerHistoryWholeTrackSwitches(track)
            thisTrackStartMeasure = startMeasureForGroup // track.patternLengthMultiplicator #integer division
            thisTrackEndMeasure = endMeasureExclusive // track.patternLengthMultiplicator
            for switch in range(thisTrackStartMeasure, thisTrackEndMeasure):
                if switch in track.whichPatternsAreScaleTransposed:
                    del track.whichPatternsAreScaleTransposed[switch]
                if switch in track.whichPatternsAreHalftoneTransposed:
                    del track.whichPatternsAreHalftoneTransposed[switch]
            callbacks._trackStructureChanged(track)
    callbacks._dataChanged() #register undo
    session.data.buildAllTracks()
    updatePlayback()

def deleteSwitches(howMany, fromMeasureNumber):
    """Parameters are un-multiplied measures."""

    with session.history.sequence("Delete whole Group"):
        for track in session.data.tracks:
            _registerHistoryWholeTrackSwitches(track)

            thisTrackHowMany = howMany // track.patternLengthMultiplicator #integer division
            thisTrackWhere = fromMeasureNumber // track.patternLengthMultiplicator #integer division

            new_structure = set()

            for switch in track.structure:
                if switch < thisTrackWhere:
                    new_structure.add(switch)
                elif switch >= thisTrackWhere+thisTrackHowMany: #like a text editor let gravitate left into the hole left by the deleted range
                    new_structure.add(switch-thisTrackHowMany)
                #else: #discard all in range to delete
            track.structure = new_structure

            new_scaleTransposed = dict()
            for k,v in track.whichPatternsAreScaleTransposed.items():
                if k < thisTrackWhere:
                    new_scaleTransposed[k] = v
                elif k >= thisTrackWhere+thisTrackHowMany: #like a text editor let gravitate left into the hole left by the deleted range
                    new_scaleTransposed[k-thisTrackHowMany] = v
                #else: #discard all in range to delete
            track.whichPatternsAreScaleTransposed = new_scaleTransposed

            new_halftoneTransposed = dict()
            for k,v in track.whichPatternsAreHalftoneTransposed.items():
                if k < thisTrackWhere:
                    new_halftoneTransposed[k] = v
                elif k >= thisTrackWhere+thisTrackHowMany: #like a text editor let gravitate left into the hole left by the deleted range
                    new_halftoneTransposed[k-thisTrackHowMany] = v
                #else: #discard all in range to delete
            track.whichPatternsAreHalftoneTransposed = new_halftoneTransposed

            callbacks._trackStructureChanged(track)

    callbacks._dataChanged() #register undo
    session.data.buildAllTracks()
    updatePlayback()

#Pattern Steps

def setPattern(trackId, patternList, undoMessage):
    """Change the whole pattern, send a callback with the whole pattern.
    This is also the main undo/redo function.

    It is rarely used directly by the GUI, if at all. Normal changes are atomic.
    """
    track = session.data.trackById(trackId)

    session.history.register(lambda trId=trackId, v=track.pattern.copyData(), msg=undoMessage: setPattern(trId, v, msg), descriptionString=undoMessage)

    track.pattern.data = patternList
    track.pattern.buildExportCache()
    track.buildTrack()
    callbacks._patternChanged(track)

def getAverageVelocity(trackId):
    """If a GUI wants to add a new note and choose a sensible velocity it can use this function"""
    return session.data.trackById(trackId).pattern.averageVelocity

def setStep(trackId, stepExportDict):
    """This is an atomic operation that only sets one switch and
    only sends that switch back via callback. A simple GUI
    will most like not listen to that callback since they
    already changed the step on their side. Only useful for parallel
    views.

    This is also for velocity!
    """
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Change Step"), descriptionString="Change Step")
    oldNote = track.pattern.stepByIndexAndPitch(index=stepExportDict["index"], pitch=stepExportDict["pitch"])
    if oldNote:  #modify existing note
        oldNoteIndex = track.pattern.data.index(oldNote)
        track.pattern.data.remove(oldNote)
        track.pattern.data.insert(oldNoteIndex, stepExportDict) #for what its worth, insert at the old place. It doesn't really matter though.
    else: #new note
        track.pattern.data.append(stepExportDict)

    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._stepChanged(track, stepExportDict)

def removeStep(trackId, index, pitch):
    """Reverse of setStep"""
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Remove Step"), descriptionString="Remove Step")
    oldNote = track.pattern.stepByIndexAndPitch(index, pitch)
    track.pattern.data.remove(oldNote)
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._removeStep(track, index, pitch)

def setScale(trackId, scale, callback = True):
    """Expects a scale list or tuple from lowest index to highest.
    Actual pitches don't matter."""
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.scale[:]: setScale(trId, v, callback=True), descriptionString="Set Scale")
    track.pattern.scale = scale #tuple, or list if oversight in json loading :)
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    if callback:
        callbacks._trackMetaDataChanged(track)

def setSimpleNoteNames(trackId, simpleNoteNames):
    """note names is a list of strings with length 128. One name for each midi note.
    It is saved to file"""
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.simpleNoteNames[:]: setSimpleNoteNames(trId, v), descriptionString="Note Names")
    track.pattern.simpleNoteNames = simpleNoteNames #list of strings
    callbacks._trackMetaDataChanged(track)

def transposeHalftoneSteps(trackId, steps):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.scale[:]: setScale(trId, v, callback=True), descriptionString="Transpose Scale")
    track.pattern.scale = [midipitch+steps for midipitch in track.pattern.scale]
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._trackMetaDataChanged(track)

def patternInvertSteps(trackId):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Invert Steps"), descriptionString="Invert Steps")
    track.pattern.invert()
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)

def patternOnAllSteps(trackId):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "All Steps On"), descriptionString="All Steps On")
    track.pattern.fill()
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)

def patternOffAllSteps(trackId):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "All Steps Off"), descriptionString="All Steps Off")
    track.pattern.empty()
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)

def patternInvertRow(trackId, pitchindex):
    """Pitchindex is the row"""
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Invert Row"), descriptionString="Invert Row")
    track.pattern.invertRow(pitchindex)
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)

def patternClearRow(trackId, pitchindex):
    """Pitchindex is the row.
    Index is the column"""
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Clear Row"), descriptionString="Clear Row")
    track.pattern.clearRow(pitchindex)
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)

def patternRowRepeatFromStep(trackId, pitchindex, index):
    """Pitchindex is the row.
    Index is the column"""
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Fill Row with Repeat"), descriptionString="Fill Row with Repeat")
    track.pattern.repeatFromStep(pitchindex, index)
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)

def patternRowChangeVelocity(trackId, pitchindex, delta):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Change Row Velocity"), descriptionString="Change Row Velocity")
    for note in track.pattern.getRow(pitchindex):
        new = note["velocity"] + delta
        note["velocity"] = min(max(new,0), 127)

    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)


major = [0, 2, 4, 5, 7, 9, 11] #this is sorted by pitch, lowest to highest. Patroneo works in reverse order to accomodate the row/column approach of a grid. We reverse in setScaleToKeyword
schemesDict = {
    #this if sorted by pitch, lowest to highest. Patroneo works in reverse order to accomodate the row/column approach of a grid. We reverse in setScaleToKeyword
    #The lowest/first pitch is always 0 because it is just the given root note.
    "Major": [0,0,0,0,0,0,0],
    "Minor": [0,0,-1,0,0,-1,-1],
    "Dorian": [0,0,-1,0,0,0,-1],
    "Phrygian": [0,-1,-1,0,0,-1,-1],
    "Lydian": [0,0,0,+1,0,0,0],
    "Mixolydian": [0,0,0,0,0,0,-1],
    "Locrian": [0,-1,-1,0,-1,-1,-1],
    #"Blues": [0,-2,-1,0,-1,-2,-1],  #blues is a special case. It has less notes than we offer.
    "Blues": [0, +1, +1, +1, 0, +2, +1], #broden. Needs double octave in the middle. better than completely wrong.
    "Hollywood": [0,0,0,0,0,-1,-1], #The "Hollywood"-Scale. Stargate, Lord of the Rings etc.
    "Chromatic": [0,-1,-2,-2,-3,-4,-5,-5,-6, -7, -7, -8, -9, -10, -10], #crude... also broken > 2 octaves
}
major.reverse()
for l in schemesDict.values():
    l.reverse()

#Ordered version
schemes = [
   "Major",
    "Minor",
    "Dorian",
    "Phrygian",
    "Lydian",
    "Mixolydian",
    "Locrian",
    "Blues",
    "Hollywood",
    "Chromatic",
]

def setScaleToKeyword(trackId, keyword):
    """Use a builtin base scale and apply to all notes in a pattern. If there are more more ore
    fewer notes in the pattern than in the scale we will calculate the rest.

    This function is called not often and does not need to be performant.
    """
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.scale[:]: setScale(trId, v, callback=True), descriptionString="Set Scale")

    rememberRootNote = track.pattern.scale[-1] #The last note has a special role by convention. No matter if this is the lowest midi-pitch or not. Most of the time it is the lowest though.

    #Create a modified scalePattern for the tracks numberOfSteps.
    #We technically only need to worry about creating additional steps. less steps is covered by zip(), see below
    majorExt = []
    schemeExt = []
    mrev = list(reversed(major*16)) #pad major to the maximum possible notes. We just need the basis to make it possible long schemes like chromatic fit
    srev = list(reversed(schemesDict[keyword]*16))
    for i in range(track.pattern.numberOfSteps):
        l = len(srev)
        octaveOffset = i // l * 12 #starts with 0*12
        majorExt.append( mrev[i % l ] + octaveOffset)
        schemeExt.append( srev[i % l] )  #this is always the same. it is only the difference to the major scale

    majorExt = list(reversed(majorExt))
    schemeExt = list(reversed(schemeExt))

    scale = [x + y for x, y in zip(majorExt, schemeExt)] #zip just creates pairs until it reached the end of one of its arguments. This is reversed order.
    #scale = [x + y for x, y in zip(major, schemesDict[keyword])] #zip just creates pairs until it reached the end of one of its arguments. This is reversed order.
    difference = rememberRootNote - scale[-1] #isn't this the same as rootnote since scale[-1] is always 0? Well, we could have hypo-scales in the future.
    result = [midipitch+difference for midipitch in scale] #create actual midi pitches from the root note and the scale.  This is reversed order because "scale" is.

    #Here is a hack because chromatic didn't work with octave wrap-around. We want to make sure we don't fall back to a lower octave
    r = reversed(result)
    result = []
    oldPitch = 0
    for p in r:
        while p < oldPitch:
            p += 12
        result.append(p)
        oldPitch = p
    result = reversed(result)

    #Done. Inform all parties.
    track.pattern.scale = result
    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._trackMetaDataChanged(track)

def changePatternVelocity(trackId, steps):
    track = session.data.trackById(trackId)
    session.history.register(lambda trId=trackId, v=track.pattern.copyData(): setPattern(trId, v, "Change Pattern Velocity"), descriptionString="Change Pattern Velocity")
    for note in track.pattern.data:
        new = note["velocity"] + steps
        note["velocity"] = min(max(new,0), 127)

    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)

def resizePatternWithoutScale(trackId, steps):
    """Resize a patterns number of steps without changing the scale.
    Can't go below 1 step.

    Our editing end is the bottom one, where new steps are removed or added.

    We also cannot know if there the user set a scale through an api scheme. At the very least
    this needs analyzing and taking an educated guess. For now we just add notes a semitone below.
    """
    if steps < 1 or steps > 128:
        logger.warning(f"Pattern must have >= 1 and <= 127 steps but {steps} was requested. Doing nothing.")
        return

    track = session.data.trackById(trackId)

    #We could use setScale for undo. But this requires a different set of callbacks. We use our own function, eventhough some of the calculations are not needed for undo.

    session.history.register(lambda trId=trackId, v=track.pattern.numberOfSteps: resizePatternWithoutScale(trId, v), descriptionString="Number of Notes in Pattern")

    currentNr = track.pattern.numberOfSteps #int
    oldid = id(track.pattern.scale)
    s = track.pattern.scale #GUI view: from top to bottom. Usually from higher pitches to lower. (49, 53, 50, 45, 42, 39, 38, 36)
    if steps == currentNr:
        return

    if steps < currentNr: #just reduce
        track.pattern.scale = tuple(s[:steps])
    else: #new
        currentLowest = s[-1] #int
        result = list(s) #can be edited.
        for i in range(steps-currentNr):
            currentLowest -= 1
            result.append(currentLowest)
        track.pattern.scale = tuple(result)
        assert track.pattern.numberOfSteps == steps, (track.pattern.numberOfSteps, steps)

    assert not oldid == id(track.pattern.scale)

    track.pattern.buildExportCache()
    track.buildTrack()
    updatePlayback()
    callbacks._patternChanged(track)


#Other functions. These can't be template functions because they use a specific track and Patroneos row and scale system.
def noteOn(trackId, row):
    track = session.data.trackById(trackId)
    midipitch = track.pattern.scale[row]
    cbox.send_midi_event(0x90+track.midiChannel, midipitch, track.pattern.averageVelocity, output=track.sequencerInterface.cboxMidiOutUuid)

def noteOff(trackId, row):
    track = session.data.trackById(trackId)
    midipitch = track.pattern.scale[row]
    cbox.send_midi_event(0x80+track.midiChannel, midipitch, track.pattern.averageVelocity, output=track.sequencerInterface.cboxMidiOutUuid)