#! /usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Copyright 2019, Nils Hilbricht, Germany ( https://www.hilbricht.net )

This file is part of the Laborejo Software Suite ( https://www.laborejo.org ),
more specifically its template base application.

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/>.
"""

#Standar Library

#Third Party
from PyQt5 import QtCore, QtGui, QtWidgets

#Our Template Modules

#Client Modules
from .constantsAndConfigs import constantsAndConfigs

class GuiGrid(QtWidgets.QGraphicsItemGroup):
    """The grid consists of vertical and horizontal lines.
    Horiontal lines help to eyeball what pitch the cursor is on, vertical help to eyeball
    the rhythm or tick positions e.g. when trying to find the right place for a tempo change or CC.

    Horizontal lines have always a more-than-enough width and X position.
    Vertical lines are always at the top of the screen and reach down more-than-enough.

    We only need to take care that there are enough lines, not about their dimensions or positions.

    Never is a line deleted, only new lines are added if new tracks are added or the musics overall
    duration increases.

    Also GraphicsView resize event and zooming out adds new lines.

    A complete clean and redraw only happens when the tick rhythm changes.
    """

    def __init__(self, parent, horizontalSize=None):        
        super(GuiGrid, self).__init__()
        self.parent = parent #QGraphicsScene

        self.setAcceptedMouseButtons(QtCore.Qt.NoButton) #each line has this set as well
        self.setEnabled(False)

        self.initialGridExists = False
        self.gapVertical = None #gets recalculated if gridRhythm is changed by the user, or through stretching.
        self.gapHorizontal = None #is constant, but for symetry reasons this is put into redrawTickGrid as well

        self.width = None #recalculated in reactToresizeEventOrZoom
        self.height = None #recalculated in reactToresizeEventOrZoom
        self.reactToresizeEventOrZoom()

        self.linesHorizontal = [] #later the grid lines will be stored here
        self.linesVertical = [] #later the grid lines will be stored here

        self.horizontalScrollbarWaitForGapJump = 0
        self.oldHorizontalValue = 0

        self.verticalScrollbarWaitForGapJump = 0
        self.oldVerticalValue = 0

        self.parent.parentView.verticalScrollBar().valueChanged.connect(self.reactToVerticalScroll)
        self.parent.parentView.horizontalScrollBar().valueChanged.connect(self.reactToHorizontalScroll)

        self.setOpacity(constantsAndConfigs.gridOpacity)

    gridPen = QtGui.QPen(QtCore.Qt.DotLine)
    gridPen.setCosmetic(True)

    def reactToHorizontalScroll(self, value):
        if not self.initialGridExists:
            return

        #Keep horizontal lines in view
        leftBorderAsScenePos = self.parent.parentView.mapToScene(0, 0).x()
        for hline in self.linesHorizontal:
            hline.setX(leftBorderAsScenePos)

        #Shift vertical lines to new positions, respecting the grid steps
        delta = value - self.oldHorizontalValue #in pixel. positive=right, negative=left. the higher the number the faster the scrolling.
        delta *= 1/constantsAndConfigs.zoomFactor
        self.horizontalScrollbarWaitForGapJump += delta
        self.oldHorizontalValue = value
        if abs(self.horizontalScrollbarWaitForGapJump) > self.gapVertical: #collect scrollpixels until we scrolled more than one gap
            gapMultiplier, rest = divmod(self.horizontalScrollbarWaitForGapJump, self.gapVertical) #really fast scrolling can jump more than one gap
            for vline in self.linesVertical:
                vline.setX(vline.x() + gapMultiplier*self.gapVertical)
            self.horizontalScrollbarWaitForGapJump = rest #keep the rest for the next scroll
            assert abs(self.horizontalScrollbarWaitForGapJump) < self.gapVertical

    def reactToVerticalScroll(self, value):
        if not self.initialGridExists:
            return

        #Keep vertical lines in view
        topBorderAsScenePos = self.parent.parentView.mapToScene(0, 0).y()
        for vline in self.linesVertical:
            vline.setY(topBorderAsScenePos)

        #Shift horizontal lines to a new position, respecting the staffline gap
        delta = value - self.oldVerticalValue #in pixel. positive=down, negative=up. the higher the number the faster the scrolling.
        delta *= 1/constantsAndConfigs.zoomFactor
        self.verticalScrollbarWaitForGapJump += delta
        self.oldVerticalValue = value
        if abs(self.verticalScrollbarWaitForGapJump) > self.gapHorizontal: #collect scrollpixels until we scrolled more than one gap
            gapMultiplier, rest = divmod(self.verticalScrollbarWaitForGapJump, self.gapHorizontal) #really fast scrolling can jump more than one gap
            for hline in self.linesHorizontal:
                hline.setY(hline.y() + gapMultiplier*self.gapHorizontal)
            self.verticalScrollbarWaitForGapJump = rest #keep the rest for the next scroll
            assert abs(self.verticalScrollbarWaitForGapJump) < self.gapHorizontal


    def reactToresizeEventOrZoom(self):
        """Called by the Views resizeEvent.
        When the views geometry changes or zooms we may need to create more lines.
        Never delete and never make smaller though."""
        scoreViewWidgetHeight = self.parent.parentView.height()
        scoreViewWidgetWidth = self.parent.parentView.width()

        if (not self.height) or scoreViewWidgetHeight * 1.1 > self.height:
            self.height = scoreViewWidgetHeight * 1.1
        if (not self.width) or scoreViewWidgetWidth * 1.1 > self.width:
            self.width = scoreViewWidgetWidth * 1.1

        if self.initialGridExists:
            assert self.linesHorizontal and self.linesVertical, (self.linesHorizontal, self.linesVertical)
            assert self.parent.parentView.isVisible(), self.parent.parentView.isVisible()
            self._fillVerticalLines()
            self._fillHorizontalLines()
        #else:
            #reactToresizeEventOrZoom without grid
            #self.redrawTickGrid() #this happens only once, on program start. Afterwards it's user triggered by changing the grid rhythm

    def _fillVerticalLines(self):
        """Only allowed to get called by reactToresizeEventOrZoom because we need an updated
        self.height value"""
        #Check if we need longer lines. Do this before creating new lines, because new lines
        #have the heighest
        oldHeight = self.linesVertical[-1].line().y2() #this is a bit less than .length() so we use that
        if self.height > oldHeight:
            for vline in self.linesVertical:
                line = vline.line()
                line.setLength(self.height)
                vline.setLine(line)

        #Check if we need new lines
        newLineCount = int(self.width / self.gapVertical)
        if newLineCount > self.nrOfVerticalLines:
            newLineCount += int(newLineCount - self.nrOfVerticalLines)
            self._createVerticalLines(start=self.nrOfVerticalLines, end=newLineCount) #This draws only yet nonexisting lines.
            self.nrOfVerticalLines = newLineCount #for next time

    def _fillHorizontalLines(self):
        """Only allowed to get called by reactToresizeEventOrZoom because we need an updated
        self.width value.
        To be honest.. this is also called by stretchXCoordinates when shrinking the display so
        we need more lines. That does not depend on self.width but on the newLineCount """
        #Check if we need longer lines. Do this before creating new lines, because new lines
        #have the heighest
        oldWidth = self.linesHorizontal[-1].line().x2() #this is a bit less than .length() so we use that
        if self.width > oldWidth:
            for hline in self.linesHorizontal:
                line = hline.line()
                line.setLength(self.width)
                hline.setLine(line)

        #Check if we need new lines
        newLineCount = int(self.height / self.gapHorizontal)
        if newLineCount > self.nrOfHorizontalLines:
            newLineCount += int(newLineCount - self.nrOfHorizontalLines)
            self._createHorizontalLines(start=self.nrOfHorizontalLines, end=newLineCount) #This draws only yet nonexisting lines.
            self.nrOfHorizontalLines = newLineCount #for next time

    def stretchXCoordinates(self, factor):
        """Reposition the items on the X axis.
        Call goes through all parents/children, starting from ScoreView._stretchXCoordinates.
        Docstring there."""
        self.gapVertical = constantsAndConfigs.gridRhythm / constantsAndConfigs.ticksToPixelRatio #this is necessarry every time after stretching (ticksToPixelRatio) and after changing the gridRhythm

        for vline in self.linesVertical:
            vline.setX(vline.x() * factor)

        self._fillVerticalLines()

        #for hline in self.linesHorizontal:
        #    stretchLine(hline, factor)

    def updateMode(self, nameAsString):
        assert nameAsString in constantsAndConfigs.availableEditModes
        if nameAsString == "block":
            for l in self.linesVertical:
                l.hide()
        else:
            for l in self.linesVertical:
                l.show()

    def _createVerticalLines(self, start, end):
        """Lines get an offset that matches the grid-rythm.
        So we get more draw area left, if the sceneRect will move into that area for some reason"""
        for i in range(start, end): #range includes the first value but not the end. We know that and all functions in GuiGrid are designed accordingly. For example reactToLongerDuration starts on the highest value of the old number of lines since that was never drawn in the last round.
            vline = self.parent.addLine(0, -5*self.gapHorizontal, 0, self.height, GuiGrid.gridPen) #x1, y1, x2, y2, pen
            self.addToGroup(vline) #first add to group, then set pos
            vline.setPos(i * self.gapVertical, 0)
            vline.setEnabled(False)
            vline.setAcceptedMouseButtons(QtCore.Qt.NoButton)
            self.linesVertical.append(vline)

    def _createHorizontalLines(self, start, end):
        """Lines get an offset that matches the pitch and staff-lines
        So we get more draw area on top, if the sceneRect will move into that area for some reason"""
        for i in range(start, end): #range includes the first value but not the end. We know that and all functions in GuiGrid are designed accordingly. For example reactToMoreTracks starts on the highest value of the old number of lines since that was never drawn in the last round.
            hline = self.parent.addLine(0, 0, self.width, 0, GuiGrid.gridPen) #x1, y1, x2, y2, pen
            self.addToGroup(hline) #first add to group, then set pos
            hline.setPos(0, i * self.gapHorizontal)
            hline.setEnabled(False)
            hline.setAcceptedMouseButtons(QtCore.Qt.NoButton)
            self.linesHorizontal.append(hline)

    def redrawTickGrid(self):
        """A complete redraw.
        This gets called once after the main window gets shown. (in init main window).
        After that only called after the used changes the tick rhythm manually.
        """

        if self.initialGridExists:
            #it is possible that the grid did not change. proceed nevertheless
            for l in self.linesHorizontal + self.linesVertical:
                self.parent.removeWhenIdle(l)


        self.linesHorizontal = []  #like the staff lines
        self.linesVertical = []  #makes comparing tick positions easier by eye

        self.gapVertical = constantsAndConfigs.gridRhythm / constantsAndConfigs.ticksToPixelRatio #this is necessarry every time after stretching (ticksToPixelRatio) and after changing the gridRhythm
        self.gapHorizontal = constantsAndConfigs.stafflineGap  #never changes

        self.nrOfHorizontalLines = int(self.height / self.gapHorizontal) #we save that value if the score grows and we need more lines. Initially we use the screen size, not the content.
        self.nrOfVerticalLines = int(self.width / self.gapVertical) #we save that value if the score grows and we need more lines. Initially we use the screen size, not the content.

        self._createVerticalLines(0, self.nrOfVerticalLines)
        self._createHorizontalLines(0, self.nrOfHorizontalLines)

        self.initialGridExists = True