"""Common keyboard and wheel gestures for all plot canvases (Qt 5/6)."""
try:
    from PySide6.QtCore import Qt
    from PySide6.QtWidgets import QScrollArea
except ImportError:
    from PySide2.QtCore import Qt
    from PySide2.QtWidgets import QScrollArea

NAVIGATION_HINT = ('Колесо и +/− — масштаб X; Ctrl + колесо и Ctrl + +/− — масштаб Y. '
                   'ЛКМ на свободном поле — перемещение; ←/→ — перемещение по X; Home/End — начало/конец.')


class PlotNavigation:
    def setup_navigation(self):
        self.setFocusPolicy(Qt.StrongFocus)
        self.setToolTip(NAVIGATION_HINT)

    def keyPressEvent(self, event):
        key = event.key()
        modifiers = event.modifiers()
        if modifiers & (Qt.AltModifier | Qt.MetaModifier):
            return super().keyPressEvent(event)
        if key in (Qt.Key_Plus, Qt.Key_Equal, Qt.Key_Minus):
            self._navigation_zoom(1.25 if key != Qt.Key_Minus else .8,
                                  bool(modifiers & Qt.ControlModifier))
        elif key in (Qt.Key_Left, Qt.Key_Right) and not (modifiers & Qt.ControlModifier):
            self._navigation_pan(-.1 if key == Qt.Key_Left else .1)
        elif key in (Qt.Key_Home, Qt.Key_End):
            self._navigation_edge(key == Qt.Key_End)
        else:
            return super().keyPressEvent(event)
        event.accept()

    def wheelEvent(self, event):
        position = event.position() if hasattr(event, 'position') else event.posF()
        rect = self.plot_rect() if hasattr(self, 'plot_rect') else self.rect()
        if not rect.contains(position.toPoint()):
            event.ignore()
            return
        delta = event.angleDelta()
        ticks = delta.y() or delta.x()
        if not ticks:
            pixels = event.pixelDelta()
            ticks = (pixels.y() or pixels.x()) * 2
        if ticks:
            self.setFocus(Qt.MouseFocusReason)
            self._navigation_zoom(1.25 ** max(-8, min(8, ticks / 120)),
                                  bool(event.modifiers() & Qt.ControlModifier), position)
        event.accept()


class ScrollPlotNavigation(PlotNavigation):
    """Canvas navigation for waveforms whose viewport is a QScrollArea."""
    def scroll_area(self):
        parent = self.parentWidget()
        while parent is not None and not isinstance(parent, QScrollArea):
            parent = parent.parentWidget()
        return parent

    def _navigation_zoom(self, factor, vertical, position=None):
        scroll = self.scroll_area()
        size = self.height() if vertical else self.width()
        if position is not None:
            anchor = position.y() if vertical else position.x()
        elif scroll is not None:
            bar = scroll.verticalScrollBar() if vertical else scroll.horizontalScrollBar()
            anchor = bar.value() + bar.pageStep() / 2
        else:
            anchor = size / 2
        self.zoom_dragged.emit('y' if vertical else 'x', factor, anchor / max(1, size))

    def _navigation_pan(self, fraction):
        scroll = self.scroll_area()
        if scroll is not None:
            bar = scroll.horizontalScrollBar()
            bar.setValue(round(bar.value() + fraction * bar.pageStep()))
            self.navigation_panned()

    def _navigation_edge(self, end):
        scroll = self.scroll_area()
        if scroll is not None:
            bar = scroll.horizontalScrollBar()
            bar.setValue(bar.maximum() if end else bar.minimum())
            self.navigation_panned()

    def navigation_panned(self):
        pass

    def begin_pan(self, event):
        self.setFocus(Qt.MouseFocusReason)
        self._pan_position = event.globalPosition() if hasattr(event, 'globalPosition') else event.globalPos()
        self.setCursor(Qt.ClosedHandCursor)

    def move_pan(self, event):
        previous = getattr(self, '_pan_position', None)
        if previous is None:
            return
        position = event.globalPosition() if hasattr(event, 'globalPosition') else event.globalPos()
        delta = position - previous
        self._pan_position = position
        scroll = self.scroll_area()
        if scroll is not None:
            for bar, amount in ((scroll.horizontalScrollBar(), delta.x()), (scroll.verticalScrollBar(), delta.y())):
                bar.setValue(round(bar.value() - amount))
            if delta.x():
                self.navigation_panned()

    def end_pan(self, event):
        self.move_pan(event)
        self._pan_position = None
        self.unsetCursor()