import sys
import inspect
import textwrap
from collections import OrderedDict, UserString
from PyQt5 import QtCore, QtGui
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QIcon
from PyQt5.QtWidgets import *


# source for the accordion = https://stackoverflow.com/questions/32476006/how-to-make-an-expandable-collapsable-section-widget-in-qt
class QStyleSheet(UserString):
    """
    Represent stylesheets as dictionary key value pairs.
    Update complex stylesheets easily modifying only the attributes you need
    Allow for attribute inheritance or defaulting of stylesheets.

    # TODO support [readOnly="true"] attribute-selectors
            QTextEdit, QListView  <-- you can have multiple classes.
            QCheckBox::indicator  <-- some psuedo classes have double colons
    """
    def __init__(self, cls=None, name=None, psuedo=None, **styles):
        """
        Arguments to the constructor allow you to default different properties of the CSS Class.
        Any argument defined here will be global to this StyleSheet and cannot be overidden later.

        :param cls: Default style prefix class to ``cls``
        :param name: Default object name to ``name`` (hashtag) is not needed.
        :param psuedo: Default psuedo class to ``psuedo``, example: ``:hover``
        """
        self.cls_scope = cls
        self.psuedo_scope = psuedo
        self.name_scope = name
        self._styles = OrderedDict() # we'll preserve the order of attributes given - python 3.6+
        if styles:
            self.setStylesDict(OrderedDict(styles))

    def _ident(self, cls=None, name=None, psuedo=None):

        # -- ensure value is of correct type ----------------------------------------
        if cls is not None and not inspect.isclass(cls):
            raise ValueError(f'cls must be None or a class object, got: {type(cls)}')

        if name is not None and not isinstance(name, str):
            raise ValueError(f'name must be None or a str, got: {type(name)}')

        if psuedo is not None and not isinstance(psuedo, str):
            raise ValueError(f'psuedo must be None or a str, got: {type(psuedo)}')

        # -- ensure not overiding defaults -------------------------------------------
        if cls is not None and self.cls_scope is not None:
            raise ValueError(f'cls was set in __init__, you cannot override it')

        if name is not None and self.name_scope is not None:
            raise ValueError(f'name was set in __init__, you cannot override it')

        if psuedo is not None and self.psuedo_scope is not None:
            raise ValueError(f'psuedo was set in __init__, you cannot override it')

        # -- apply defaults if set ---------------------------------------------------
        if cls is None and self.cls_scope is not None:
            cls = self.cls_scope

        if name is None and self.name_scope is not None:
            name = self.name_scope

        if psuedo is None and self.psuedo_scope is not None:
            psuedo = self.psuedo_scope

        # return a tuple that can be used as a dictionary key.
        ident = tuple([getattr(cls, '__name__', None), name or None, psuedo or None])
        return ident

    def _class_definition(self, ident):
        """Get the class definition string"""
        cls, name, psuedo = ident
        return '%s%s%s' % (cls or '', name or '', psuedo or '')

    def _fix_underscores(self, styles):
        return OrderedDict([(k.replace('_', '-'), v) for k,v in styles.items()])

    def setStylesStr(self, styles):
        """
        Parse styles from a string and set them on this object.
        """
        raise NotImplementedError()
        self._update()

    def setStylesDict(self, styles, cls=None, name=None, psuedo=None):
        """
        Set styles using a dictionary instead of keyword arguments
        """
        styles = self._fix_underscores(styles)
        if not isinstance(styles, dict):
            raise ValueError(f'`styles` must be dict, got: {type(styles)}')
        if not styles:
            raise ValueError('`styles` cannot be empty')

        ident = self._ident(cls, name, psuedo)
        stored = self._styles.get(ident, OrderedDict())
        stored.update(styles)
        self._styles[ident] = stored

        self._update()

    def setStyles(self, cls=None, name=None, psuedo=None, **styles):
        """
        Set or update styles according to the CSS Class definition provided by (cls, name, psuedo) using keyword-arguments.

        Any css attribute with a hyphen ``-`` character should be changed to an underscore ``_`` when passed as a keyword argument.

        Example::

            Lets suppose we want to create the css class:

                QFrame#BorderTest { background-color: white; margin:4px; border:1px solid #a5a5a5; border-radius: 10px;}

            >>> stylesheet.setStyle(cls=QFrameBorderTest, background_color='white', margin='4px', border_radius='10px')

            >>> print(stylesheet)

            QFrame#BorderTest { background-color: white; margin:4px; border:1px solid #a5a5a5; border-radius: 10px;}
        """
        styles = OrderedDict(styles)
        self.setStylesDict(styles=styles, cls=cls, name=name, psuedo=psuedo)

    def getStyles(self, cls=None, name=None, psuedo=None):
        """
        Return the dictionary representations of styles for the CSS Class definition provided by (cls, name, psuedo)

        :returns: styles dict (keys with hyphens)
        """
        ident = self._ident(cls, name, psuedo)
        return self._styles.get(ident)

    def getClassIdents(self):
        """Get all class identifier tuples"""
        return list(self._styles.keys())

    def getClassDefinitions(self):
        """Get all css class definitions, but not the css attributes/body"""
        return [self._class_definition(ident) for ident in self.getClassIdents()]

    def validate(self):
        """
        Validate all the styles and attributes on this class
        """
        raise NotImplementedError()

    def merge(self, stylesheet, overwrite=True):
        """
        Merge another QStyleSheet with this QStyleSheet.
        The QStyleSheet passed as an argument will be left un-modified.

        :param overwrite: if set to True the matching class definitions will be overwritten
                          with attributes and values from ``stylesheet``.
                          Otherwise, the css attributes will be updated from ``stylesheet``
        :type overwrite: QStyleSheet
        """
        for ident in stylesheet.getClassIdents():
            styles = stylesheet.getStyles(ident)
            cls, name, psuedo = ident
            self.setStylesDict(styles, cls=cls, name=name, psuedo=psuedo)

        self._update()

    def clear(self, cls=None, name=None, psuedo=None):
        """
        Clear styles matching the Class definition

        The style dictionary cleared will be returned

        None will be returned if nothing was cleared.
        """
        ident = self._ident(cls, name, psuedo)
        return self._styles.pop(ident, None)

    def _update(self):
        """Update the internal string representation"""
        stylesheet = []
        for ident, styles in self._styles.items():
            if not styles:
                continue
            css_cls = self._class_definition(ident)
            css_cls = css_cls + ' ' if css_cls else ''
            styles_str = '\n'.join([f'{k}: {v};' for k, v in styles.items()])

            styles_str = textwrap.indent(styles_str, ''.ljust(4))
            stylesheet.append('%s{\n%s\n}' % (css_cls, styles_str))

        self.data = '\n\n'.join(stylesheet)


class Expander(QWidget):
    def __init__(self, parent=None, title=None, animationDuration=200):
        super().__init__(parent=parent)

        self.animationDuration = animationDuration
        self.toggleAnimation = QtCore.QParallelAnimationGroup()
        self.contentArea = QScrollArea()
        self.headerLine = QFrame()
        self.toggleButton = QToolButton()
        self.mainLayout = QGridLayout()

        toggleButton = self.toggleButton
        self.toggleButtonQStyle = QStyleSheet(QToolButton, border='none')
        toggleButton.setStyleSheet(str(self.toggleButtonQStyle))
        toggleButton.setToolButtonStyle(QtCore.Qt.ToolButtonTextBesideIcon)
        toggleButton.setArrowType(QtCore.Qt.RightArrow)
        toggleButton.setText(title or '')
        toggleButton.setCheckable(True)
        toggleButton.setChecked(False)
        toggleButton.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)

        headerLine = self.headerLine
        self.headerLineQStyle = QStyleSheet(QFrame)
        headerLine.setFrameShape(QFrame.NoFrame)  # see: https://doc.qt.io/archives/qt-4.8/qframe.html#Shape-enum
        headerLine.setFrameShadow(QFrame.Plain)   # see: https://doc.qt.io/archives/qt-4.8/qframe.html#Shape-enum
        headerLine.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Maximum)

        self.contentAreaQStyle = QStyleSheet(QScrollArea, border='none')
        self.contentArea.setStyleSheet(str(self.contentAreaQStyle))
        self.contentArea.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
        # start out collapsed
        self.contentArea.setMaximumHeight(0)
        self.contentArea.setMinimumHeight(0)
        # let the entire widget grow and shrink with its content
        toggleAnimation = self.toggleAnimation
        toggleAnimation.addAnimation(QtCore.QPropertyAnimation(self, b"minimumHeight"))
        toggleAnimation.addAnimation(QtCore.QPropertyAnimation(self, b"maximumHeight"))
        toggleAnimation.addAnimation(QtCore.QPropertyAnimation(self.contentArea, b"maximumHeight"))
        # don't waste space
        mainLayout = self.mainLayout
        mainLayout.setVerticalSpacing(0)
        mainLayout.setContentsMargins(0, 0, 0, 0)
        row = 0
        mainLayout.addWidget(self.toggleButton, row, 0, 1, 1, QtCore.Qt.AlignLeft)
        mainLayout.addWidget(self.headerLine, row, 2, 1, 1)
        row += 1
        mainLayout.addWidget(self.contentArea, row, 0, 1, 3)
        super().setLayout(self.mainLayout)

        def start_animation(checked):
            arrow_type = QtCore.Qt.DownArrow if checked else QtCore.Qt.RightArrow
            direction = QtCore.QAbstractAnimation.Forward if checked else QtCore.QAbstractAnimation.Backward
            toggleButton.setArrowType(arrow_type)
            self.toggleAnimation.setDirection(direction)
            self.toggleAnimation.start()

        self.toggleButton.clicked.connect(start_animation)

    def setHeaderFrameStyles(self, styles):
        self._setWidgetStyles(self.headerLine, self.headerLineQStyle, styles)

    def setToggleButtonStyles(self, styles):
        self._setWidgetStyles(self.toggleButton, self.toggleButtonQStyle, styles)

    def setContentAreaStyles(self, styles):
        self._setWidgetStyles(self.contentArea, self.contentAreaQStyle, styles)

    def _setWidgetStyles(self, widget, qstylesheet, var):
        if isinstance(var, QStyleSheet):
            qstylesheet.merge(var)
            widget.setStyleSheet(str(qstylesheet))
        elif isinstance(var, dict):
            qstylesheet.setStylesDict(var)
            widget.setStyleSheet(str(qstylesheet))
        elif isinstance(var, str):
            widget.setStyleSheet(var)
        else:
            raise ValueError('invalid argument type: {type(var)}')


    def setWidget(self, widget):
        self.contentArea.destroy()
        self.contentArea.setLayout(QVBoxLayout())
        self.contentArea.layout().addWidget(widget)
        collapsedHeight = self.toggleButton.sizeHint().height()
        contentHeight = widget.sizeHint().height()
        for i in range(self.toggleAnimation.animationCount() - 1):
            spoilerAnimation = self.toggleAnimation.animationAt(i)
            spoilerAnimation.setDuration(self.animationDuration)
            spoilerAnimation.setStartValue(collapsedHeight)
            spoilerAnimation.setEndValue(collapsedHeight + contentHeight)
        contentAnimation = self.toggleAnimation.animationAt(self.toggleAnimation.animationCount() - 1)
        contentAnimation.setDuration(self.animationDuration)
        contentAnimation.setStartValue(0)
        contentAnimation.setEndValue(contentHeight)

    def setLayout(self, contentLayout):
        """
        Set the layout container that you would like to expand/collapse.

        This should be called after all styles are set.
        """
        # Not sure if this is equivalent to self.contentArea.destroy()
        self.contentArea.destroy()
        self.contentArea.setLayout(contentLayout)
        collapsedHeight = self.toggleButton.sizeHint().height()
        contentHeight = contentLayout.sizeHint().height()
        for i in range(self.toggleAnimation.animationCount()-1):
            spoilerAnimation = self.toggleAnimation.animationAt(i)
            spoilerAnimation.setDuration(self.animationDuration)
            spoilerAnimation.setStartValue(collapsedHeight)
            spoilerAnimation.setEndValue(collapsedHeight + contentHeight)
        contentAnimation = self.toggleAnimation.animationAt(self.toggleAnimation.animationCount() - 1)
        contentAnimation.setDuration(self.animationDuration)
        contentAnimation.setStartValue(0)
        contentAnimation.setEndValue(contentHeight)


class MainWindow(QMainWindow):
    LIGHT_BLUE = '#148cc1'
    MED_BLUE = '#0c6a94'
    DARK_BLUE = '#0a3a6b'
    PALE_SALMON = '#fd756d'
    LIGHT_GREY = '#d2d5da'
    SLATE = '#525863'

    def __init__(self):
        super().__init__()

        self.WINDOW_STYLE = QStyleSheet(QMainWindow, background_color=self.SLATE)
        self.WINDOW_STYLE = str(self.WINDOW_STYLE)

        self.LABEL_STYLE = QStyleSheet(QLabel, color=self.DARK_BLUE, font_weight=400, font_size='9pt')
        self.LABEL_STYLE = str(self.LABEL_STYLE)

        # -- QPushButton stylesheet ---------------------
        self.BUTTON_STYLE = s1 = QStyleSheet()

        s1.setStyles(cls=QPushButton,
                    color='white',
                    font_weight=400,
                    border_style='solid',
                    padding='4px',
                    background_color=self.LIGHT_BLUE)

        s1.setStyles(cls=QPushButton, psuedo=':pressed',
                    background_color=self.PALE_SALMON)

        s1.setStyles(cls=QPushButton, psuedo=':focus-pressed',
                    background_color=self.PALE_SALMON)

        s1.setStyles(cls=QPushButton, psuedo=':disabled',
                    background_color=self.LIGHT_GREY)

        s1.setStyles(cls=QPushButton, psuedo=':checked',
                    background_color=self.PALE_SALMON)

        s1.setStyles(cls=QPushButton, psuedo=':hover:!pressed:!checked',
                    background_color=self.MED_BLUE)
        self.BUTTON_STYLE = str(self.BUTTON_STYLE)

        self.BUTTON_GROUPBOX_STYLE = QStyleSheet(QGroupBox, border='none', font_weight='bold', color='white')
        self.BUTTON_GROUPBOX_STYLE = str(self.BUTTON_GROUPBOX_STYLE)

        self.TEXT_EDIT_STYLE = QStyleSheet(QTextEdit, color='white', border=f'1px solid {self.LIGHT_BLUE}', background_color=self.MED_BLUE)
        self.TEXT_EDIT_STYLE = str(self.TEXT_EDIT_STYLE)

        self.initUI()

    def initUI(self):
        contents_vbox = QVBoxLayout()
        label_box = QHBoxLayout()
        for text in ('hello', 'goodbye', 'adios'):
            lbl = QLabel(text)
            lbl.setStyleSheet(self.LABEL_STYLE)
            lbl.setAlignment(Qt.AlignCenter)
            label_box.addWidget(lbl)

        button_group = QButtonGroup()
        button_group.setExclusive(True)
        button_group.buttonClicked.connect(self._button_clicked)
        self.button_group = button_group

        button_hbox = QHBoxLayout()


        for _id, text in enumerate(('small', 'medium', 'large')):
            btn = QPushButton(text)
            btn.setCheckable(True)
            btn.setStyleSheet(self.BUTTON_STYLE)
            button_group.addButton(btn)
            button_group.setId(btn, _id)
            button_hbox.addWidget(btn)

        button_group.buttons()[0].toggle()

        text_area = QTextEdit()
        text_area.setPlaceholderText('Type a greeting here')
        text_area.setStyleSheet(self.TEXT_EDIT_STYLE)

        contents_vbox.addLayout(label_box)
        contents_vbox.addLayout(button_hbox)
        contents_vbox.addWidget(text_area)

        collapsible = Expander(self, 'Expander')
        collapsible.setToggleButtonStyles({'padding': '4px', 'background-color': 'white'})
        collapsible.setContentAreaStyles({'background-color': 'white'})
        collapsible.setLayout(contents_vbox)

        vbox = QVBoxLayout()
        vbox.addWidget(collapsible)
        vbox.setAlignment(Qt.AlignTop)
        widget = QWidget()
        widget.setLayout(vbox)

        self.setCentralWidget(widget)


        self.setGeometry(200, 200, 500, 400)
        self.setWindowTitle('Expander')
        self.setStyleSheet(self.WINDOW_STYLE)
        self.show()

    def _button_clicked(self, button):
        """
        For the toggle behavior of a QButtonGroup to work you must
        connect the clicked signal!
        """
        print('button-active', self.button_group.id(button))


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = MainWindow()
    sys.exit(app.exec_())
import sys
import inspect
import textwrap
from collections import OrderedDict, UserString
from PyQt5 import QtCore, QtGui
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QIcon
from PyQt5.QtWidgets import *


# source for the accordion = https://stackoverflow.com/questions/32476006/how-to-make-an-expandable-collapsable-section-widget-in-qt
class QStyleSheet(UserString):
    """
    Represent stylesheets as dictionary key value pairs.
    Update complex stylesheets easily modifying only the attributes you need
    Allow for attribute inheritance or defaulting of stylesheets.

    # TODO support [readOnly="true"] attribute-selectors
            QTextEdit, QListView  <-- you can have multiple classes.
            QCheckBox::indicator  <-- some psuedo classes have double colons
    """
    def __init__(self, cls=None, name=None, psuedo=None, **styles):
        """
        Arguments to the constructor allow you to default different properties of the CSS Class.
        Any argument defined here will be global to this StyleSheet and cannot be overidden later.

        :param cls: Default style prefix class to ``cls``
        :param name: Default object name to ``name`` (hashtag) is not needed.
        :param psuedo: Default psuedo class to ``psuedo``, example: ``:hover``
        """
        self.cls_scope = cls
        self.psuedo_scope = psuedo
        self.name_scope = name
        self._styles = OrderedDict() # we'll preserve the order of attributes given - python 3.6+
        if styles:
            self.setStylesDict(OrderedDict(styles))

    def _ident(self, cls=None, name=None, psuedo=None):

        # -- ensure value is of correct type ----------------------------------------
        if cls is not None and not inspect.isclass(cls):
            raise ValueError(f'cls must be None or a class object, got: {type(cls)}')

        if name is not None and not isinstance(name, str):
            raise ValueError(f'name must be None or a str, got: {type(name)}')

        if psuedo is not None and not isinstance(psuedo, str):
            raise ValueError(f'psuedo must be None or a str, got: {type(psuedo)}')

        # -- ensure not overiding defaults -------------------------------------------
        if cls is not None and self.cls_scope is not None:
            raise ValueError(f'cls was set in __init__, you cannot override it')

        if name is not None and self.name_scope is not None:
            raise ValueError(f'name was set in __init__, you cannot override it')

        if psuedo is not None and self.psuedo_scope is not None:
            raise ValueError(f'psuedo was set in __init__, you cannot override it')

        # -- apply defaults if set ---------------------------------------------------
        if cls is None and self.cls_scope is not None:
            cls = self.cls_scope

        if name is None and self.name_scope is not None:
            name = self.name_scope

        if psuedo is None and self.psuedo_scope is not None:
            psuedo = self.psuedo_scope

        # return a tuple that can be used as a dictionary key.
        ident = tuple([getattr(cls, '__name__', None), name or None, psuedo or None])
        return ident

    def _class_definition(self, ident):
        """Get the class definition string"""
        cls, name, psuedo = ident
        return '%s%s%s' % (cls or '', name or '', psuedo or '')

    def _fix_underscores(self, styles):
        return OrderedDict([(k.replace('_', '-'), v) for k,v in styles.items()])

    def setStylesStr(self, styles):
        """
        Parse styles from a string and set them on this object.
        """
        raise NotImplementedError()
        self._update()

    def setStylesDict(self, styles, cls=None, name=None, psuedo=None):
        """
        Set styles using a dictionary instead of keyword arguments
        """
        styles = self._fix_underscores(styles)
        if not isinstance(styles, dict):
            raise ValueError(f'`styles` must be dict, got: {type(styles)}')
        if not styles:
            raise ValueError('`styles` cannot be empty')

        ident = self._ident(cls, name, psuedo)
        stored = self._styles.get(ident, OrderedDict())
        stored.update(styles)
        self._styles[ident] = stored

        self._update()

    def setStyles(self, cls=None, name=None, psuedo=None, **styles):
        """
        Set or update styles according to the CSS Class definition provided by (cls, name, psuedo) using keyword-arguments.

        Any css attribute with a hyphen ``-`` character should be changed to an underscore ``_`` when passed as a keyword argument.

        Example::

            Lets suppose we want to create the css class:

                QFrame#BorderTest { background-color: white; margin:4px; border:1px solid #a5a5a5; border-radius: 10px;}

            >>> stylesheet.setStyle(cls=QFrameBorderTest, background_color='white', margin='4px', border_radius='10px')

            >>> print(stylesheet)

            QFrame#BorderTest { background-color: white; margin:4px; border:1px solid #a5a5a5; border-radius: 10px;}
        """
        styles = OrderedDict(styles)
        self.setStylesDict(styles=styles, cls=cls, name=name, psuedo=psuedo)

    def getStyles(self, cls=None, name=None, psuedo=None):
        """
        Return the dictionary representations of styles for the CSS Class definition provided by (cls, name, psuedo)

        :returns: styles dict (keys with hyphens)
        """
        ident = self._ident(cls, name, psuedo)
        return self._styles.get(ident)

    def getClassIdents(self):
        """Get all class identifier tuples"""
        return list(self._styles.keys())

    def getClassDefinitions(self):
        """Get all css class definitions, but not the css attributes/body"""
        return [self._class_definition(ident) for ident in self.getClassIdents()]

    def validate(self):
        """
        Validate all the styles and attributes on this class
        """
        raise NotImplementedError()

    def merge(self, stylesheet, overwrite=True):
        """
        Merge another QStyleSheet with this QStyleSheet.
        The QStyleSheet passed as an argument will be left un-modified.

        :param overwrite: if set to True the matching class definitions will be overwritten
                          with attributes and values from ``stylesheet``.
                          Otherwise, the css attributes will be updated from ``stylesheet``
        :type overwrite: QStyleSheet
        """
        for ident in stylesheet.getClassIdents():
            styles = stylesheet.getStyles(ident)
            cls, name, psuedo = ident
            self.setStylesDict(styles, cls=cls, name=name, psuedo=psuedo)

        self._update()

    def clear(self, cls=None, name=None, psuedo=None):
        """
        Clear styles matching the Class definition

        The style dictionary cleared will be returned

        None will be returned if nothing was cleared.
        """
        ident = self._ident(cls, name, psuedo)
        return self._styles.pop(ident, None)

    def _update(self):
        """Update the internal string representation"""
        stylesheet = []
        for ident, styles in self._styles.items():
            if not styles:
                continue
            css_cls = self._class_definition(ident)
            css_cls = css_cls + ' ' if css_cls else ''
            styles_str = '\n'.join([f'{k}: {v};' for k, v in styles.items()])

            styles_str = textwrap.indent(styles_str, ''.ljust(4))
            stylesheet.append('%s{\n%s\n}' % (css_cls, styles_str))

        self.data = '\n\n'.join(stylesheet)


class Expander(QWidget):
    def __init__(self, parent=None, title=None, animationDuration=200):
        super().__init__(parent=parent)

        self.animationDuration = animationDuration
        self.toggleAnimation = QtCore.QParallelAnimationGroup()
        self.contentArea = QScrollArea()
        self.headerLine = QFrame()
        self.toggleButton = QToolButton()
        self.mainLayout = QGridLayout()

        toggleButton = self.toggleButton
        self.toggleButtonQStyle = QStyleSheet(QToolButton, border='none')
        toggleButton.setStyleSheet(str(self.toggleButtonQStyle))
        toggleButton.setToolButtonStyle(QtCore.Qt.ToolButtonTextBesideIcon)
        toggleButton.setArrowType(QtCore.Qt.RightArrow)
        toggleButton.setText(title or '')
        toggleButton.setCheckable(True)
        toggleButton.setChecked(False)
        toggleButton.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)

        headerLine = self.headerLine
        self.headerLineQStyle = QStyleSheet(QFrame)
        headerLine.setFrameShape(QFrame.NoFrame)  # see: https://doc.qt.io/archives/qt-4.8/qframe.html#Shape-enum
        headerLine.setFrameShadow(QFrame.Plain)   # see: https://doc.qt.io/archives/qt-4.8/qframe.html#Shape-enum
        headerLine.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Maximum)

        self.contentAreaQStyle = QStyleSheet(QScrollArea, border='none')
        self.contentArea.setStyleSheet(str(self.contentAreaQStyle))
        self.contentArea.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
        # start out collapsed
        self.contentArea.setMaximumHeight(0)
        self.contentArea.setMinimumHeight(0)
        # let the entire widget grow and shrink with its content
        toggleAnimation = self.toggleAnimation
        toggleAnimation.addAnimation(QtCore.QPropertyAnimation(self, b"minimumHeight"))
        toggleAnimation.addAnimation(QtCore.QPropertyAnimation(self, b"maximumHeight"))
        toggleAnimation.addAnimation(QtCore.QPropertyAnimation(self.contentArea, b"maximumHeight"))
        # don't waste space
        mainLayout = self.mainLayout
        mainLayout.setVerticalSpacing(0)
        mainLayout.setContentsMargins(0, 0, 0, 0)
        row = 0
        mainLayout.addWidget(self.toggleButton, row, 0, 1, 1, QtCore.Qt.AlignLeft)
        mainLayout.addWidget(self.headerLine, row, 2, 1, 1)
        row += 1
        mainLayout.addWidget(self.contentArea, row, 0, 1, 3)
        super().setLayout(self.mainLayout)

        def start_animation(checked):
            arrow_type = QtCore.Qt.DownArrow if checked else QtCore.Qt.RightArrow
            direction = QtCore.QAbstractAnimation.Forward if checked else QtCore.QAbstractAnimation.Backward
            toggleButton.setArrowType(arrow_type)
            self.toggleAnimation.setDirection(direction)
            self.toggleAnimation.start()

        self.toggleButton.clicked.connect(start_animation)

    def setHeaderFrameStyles(self, styles):
        self._setWidgetStyles(self.headerLine, self.headerLineQStyle, styles)

    def setToggleButtonStyles(self, styles):
        self._setWidgetStyles(self.toggleButton, self.toggleButtonQStyle, styles)

    def setContentAreaStyles(self, styles):
        self._setWidgetStyles(self.contentArea, self.contentAreaQStyle, styles)

    def _setWidgetStyles(self, widget, qstylesheet, var):
        if isinstance(var, QStyleSheet):
            qstylesheet.merge(var)
            widget.setStyleSheet(str(qstylesheet))
        elif isinstance(var, dict):
            qstylesheet.setStylesDict(var)
            widget.setStyleSheet(str(qstylesheet))
        elif isinstance(var, str):
            widget.setStyleSheet(var)
        else:
            raise ValueError('invalid argument type: {type(var)}')


    def setWidget(self, widget):
        self.contentArea.destroy()
        self.contentArea.setLayout(QVBoxLayout())
        self.contentArea.layout().addWidget(widget)
        collapsedHeight = self.toggleButton.sizeHint().height()
        contentHeight = widget.sizeHint().height()
        for i in range(self.toggleAnimation.animationCount() - 1):
            spoilerAnimation = self.toggleAnimation.animationAt(i)
            spoilerAnimation.setDuration(self.animationDuration)
            spoilerAnimation.setStartValue(collapsedHeight)
            spoilerAnimation.setEndValue(collapsedHeight + contentHeight)
        contentAnimation = self.toggleAnimation.animationAt(self.toggleAnimation.animationCount() - 1)
        contentAnimation.setDuration(self.animationDuration)
        contentAnimation.setStartValue(0)
        contentAnimation.setEndValue(contentHeight)

    def setLayout(self, contentLayout):
        """
        Set the layout container that you would like to expand/collapse.

        This should be called after all styles are set.
        """
        # Not sure if this is equivalent to self.contentArea.destroy()
        self.contentArea.destroy()
        self.contentArea.setLayout(contentLayout)
        collapsedHeight = self.toggleButton.sizeHint().height()
        contentHeight = contentLayout.sizeHint().height()
        for i in range(self.toggleAnimation.animationCount()-1):
            spoilerAnimation = self.toggleAnimation.animationAt(i)
            spoilerAnimation.setDuration(self.animationDuration)
            spoilerAnimation.setStartValue(collapsedHeight)
            spoilerAnimation.setEndValue(collapsedHeight + contentHeight)
        contentAnimation = self.toggleAnimation.animationAt(self.toggleAnimation.animationCount() - 1)
        contentAnimation.setDuration(self.animationDuration)
        contentAnimation.setStartValue(0)
        contentAnimation.setEndValue(contentHeight)


class MainWindow(QMainWindow):
    LIGHT_BLUE = '#148cc1'
    MED_BLUE = '#0c6a94'
    DARK_BLUE = '#0a3a6b'
    PALE_SALMON = '#fd756d'
    LIGHT_GREY = '#d2d5da'
    SLATE = '#525863'

    def __init__(self):
        super().__init__()

        self.WINDOW_STYLE = QStyleSheet(QMainWindow, background_color=self.SLATE)
        self.WINDOW_STYLE = str(self.WINDOW_STYLE)

        self.LABEL_STYLE = QStyleSheet(QLabel, color=self.DARK_BLUE, font_weight=400, font_size='9pt')
        self.LABEL_STYLE = str(self.LABEL_STYLE)

        # -- QPushButton stylesheet ---------------------
        self.BUTTON_STYLE = s1 = QStyleSheet()

        s1.setStyles(cls=QPushButton,
                    color='white',
                    font_weight=400,
                    border_style='solid',
                    padding='4px',
                    background_color=self.LIGHT_BLUE)

        s1.setStyles(cls=QPushButton, psuedo=':pressed',
                    background_color=self.PALE_SALMON)

        s1.setStyles(cls=QPushButton, psuedo=':focus-pressed',
                    background_color=self.PALE_SALMON)

        s1.setStyles(cls=QPushButton, psuedo=':disabled',
                    background_color=self.LIGHT_GREY)

        s1.setStyles(cls=QPushButton, psuedo=':checked',
                    background_color=self.PALE_SALMON)

        s1.setStyles(cls=QPushButton, psuedo=':hover:!pressed:!checked',
                    background_color=self.MED_BLUE)
        self.BUTTON_STYLE = str(self.BUTTON_STYLE)

        self.BUTTON_GROUPBOX_STYLE = QStyleSheet(QGroupBox, border='none', font_weight='bold', color='white')
        self.BUTTON_GROUPBOX_STYLE = str(self.BUTTON_GROUPBOX_STYLE)

        self.TEXT_EDIT_STYLE = QStyleSheet(QTextEdit, color='white', border=f'1px solid {self.LIGHT_BLUE}', background_color=self.MED_BLUE)
        self.TEXT_EDIT_STYLE = str(self.TEXT_EDIT_STYLE)

        self.initUI()

    def initUI(self):
        contents_vbox = QVBoxLayout()
        label_box = QHBoxLayout()
        for text in ('hello', 'goodbye', 'adios'):
            lbl = QLabel(text)
            lbl.setStyleSheet(self.LABEL_STYLE)
            lbl.setAlignment(Qt.AlignCenter)
            label_box.addWidget(lbl)

        button_group = QButtonGroup()
        button_group.setExclusive(True)
        button_group.buttonClicked.connect(self._button_clicked)
        self.button_group = button_group

        button_hbox = QHBoxLayout()


        for _id, text in enumerate(('small', 'medium', 'large')):
            btn = QPushButton(text)
            btn.setCheckable(True)
            btn.setStyleSheet(self.BUTTON_STYLE)
            button_group.addButton(btn)
            button_group.setId(btn, _id)
            button_hbox.addWidget(btn)

        button_group.buttons()[0].toggle()

        text_area = QTextEdit()
        text_area.setPlaceholderText('Type a greeting here')
        text_area.setStyleSheet(self.TEXT_EDIT_STYLE)

        contents_vbox.addLayout(label_box)
        contents_vbox.addLayout(button_hbox)
        contents_vbox.addWidget(text_area)

        collapsible = Expander(self, 'Expander')
        collapsible.setToggleButtonStyles({'padding': '4px', 'background-color': 'white'})
        collapsible.setContentAreaStyles({'background-color': 'white'})
        collapsible.setLayout(contents_vbox)

        vbox = QVBoxLayout()
        vbox.addWidget(collapsible)
        vbox.setAlignment(Qt.AlignTop)
        widget = QWidget()
        widget.setLayout(vbox)

        self.setCentralWidget(widget)


        self.setGeometry(200, 200, 500, 400)
        self.setWindowTitle('Expander')
        self.setStyleSheet(self.WINDOW_STYLE)
        self.show()

    def _button_clicked(self, button):
        """
        For the toggle behavior of a QButtonGroup to work you must
        connect the clicked signal!
        """
        print('button-active', self.button_group.id(button))


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = MainWindow()
    sys.exit(app.exec_())
# source for the accordion = https://stackoverflow.com/questions/32476006/how-to-make-an-expandable-collapsable-section-widget-in-qt Represent stylesheets as dictionary key value pairs.     Update complex stylesheets easily modifying only the attributes you need     Allow for attribute inheritance or defaulting of stylesheets.      # TODO support [readOnly="true"] attribute-selectors             QTextEdit, QListView  <-- you can have multiple classes.             QCheckBox::indicator  <-- some psuedo classes have double colons Arguments to the constructor allow you to default different properties of the CSS Class.         Any argument defined here will be global to this StyleSheet and cannot be overidden later.          :param cls: Default style prefix class to ``cls``         :param name: Default object name to ``name`` (hashtag) is not needed.         :param psuedo: Default psuedo class to ``psuedo``, example: ``:hover`` # we'll preserve the order of attributes given - python 3.6+ # -- ensure value is of correct type ---------------------------------------- # -- ensure not overiding defaults ------------------------------------------- # -- apply defaults if set --------------------------------------------------- # return a tuple that can be used as a dictionary key. Get the class definition string Parse styles from a string and set them on this object. Set styles using a dictionary instead of keyword arguments Set or update styles according to the CSS Class definition provided by (cls, name, psuedo) using keyword-arguments.          Any css attribute with a hyphen ``-`` character should be changed to an underscore ``_`` when passed as a keyword argument.          Example::              Lets suppose we want to create the css class:                  QFrame#BorderTest { background-color: white; margin:4px; border:1px solid #a5a5a5; border-radius: 10px;}              >>> stylesheet.setStyle(cls=QFrameBorderTest, background_color='white', margin='4px', border_radius='10px')              >>> print(stylesheet)              QFrame#BorderTest { background-color: white; margin:4px; border:1px solid #a5a5a5; border-radius: 10px;} Return the dictionary representations of styles for the CSS Class definition provided by (cls, name, psuedo)          :returns: styles dict (keys with hyphens) Get all class identifier tuples Get all css class definitions, but not the css attributes/body Validate all the styles and attributes on this class Merge another QStyleSheet with this QStyleSheet.         The QStyleSheet passed as an argument will be left un-modified.          :param overwrite: if set to True the matching class definitions will be overwritten                           with attributes and values from ``stylesheet``.                           Otherwise, the css attributes will be updated from ``stylesheet``         :type overwrite: QStyleSheet Clear styles matching the Class definition          The style dictionary cleared will be returned          None will be returned if nothing was cleared. Update the internal string representation # see: https://doc.qt.io/archives/qt-4.8/qframe.html#Shape-enum # see: https://doc.qt.io/archives/qt-4.8/qframe.html#Shape-enum # start out collapsed # let the entire widget grow and shrink with its content # don't waste space Set the layout container that you would like to expand/collapse.          This should be called after all styles are set. # Not sure if this is equivalent to self.contentArea.destroy() # -- QPushButton stylesheet --------------------- For the toggle behavior of a QButtonGroup to work you must         connect the clicked signal!