"""Borderless desktop window controls, with native move and resize gestures."""

from PySide6.QtCore import QEvent, Qt
from PySide6.QtWidgets import QHBoxLayout, QMenuBar, QPushButton, QWidget


class _ResizeHandle(QWidget):
    def __init__(self, window, edges, cursor):
        super().__init__(window)
        self.edges = edges
        self.setCursor(cursor)
        self.setStyleSheet("background: transparent; border: none;")

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            handle = self.window().windowHandle()
            if handle and handle.startSystemResize(self.edges):
                event.accept()
                return
        super().mousePressEvent(event)


class DesktopWindowBar(QMenuBar):
    """Keep account menus and window actions without the Windows frame."""

    RESIZE_MARGIN = 5

    def __init__(self, window):
        super().__init__(window)
        self.host = window
        window.setWindowFlag(Qt.FramelessWindowHint, True)
        window.setContentsMargins(0, 0, 0, 0)
        self.setNativeMenuBar(False)
        self.setFixedHeight(32)
        self.setStyleSheet("""
            QMenuBar { background: #F4F8FF; border: none; padding: 0 8px;
                       color: #52658E; font-size: 12px; }
            QMenuBar::item { background: transparent; padding: 6px 10px; }
            QMenuBar::item:selected { background: #E8EFFC; border-radius: 6px; }
            QPushButton { background: transparent; border: none; border-radius: 0;
                          padding: 0; margin: 0; color: #52658E; }
            QPushButton:hover { background: #E3EBFA; }
            QPushButton#WindowClose:hover { background: #E95060; color: white; }
        """)
        actions = QWidget(self)
        layout = QHBoxLayout(actions)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)
        self.minimize_button = self._button("−", "最小化", window.showMinimized, actions)
        self.maximize_button = self._button("□", "最大化", self.toggle_maximized, actions)
        self.close_button = self._button("×", "关闭", window.close, actions)
        self.close_button.setObjectName("WindowClose")
        for button in (self.minimize_button, self.maximize_button, self.close_button):
            layout.addWidget(button)
        self.setCornerWidget(actions, Qt.TopRightCorner)

        left, right, top, bottom = Qt.LeftEdge, Qt.RightEdge, Qt.TopEdge, Qt.BottomEdge
        self._resize_handles = {
            edges: _ResizeHandle(window, edges, cursor)
            for edges, cursor in (
                (left, Qt.SizeHorCursor), (right, Qt.SizeHorCursor),
                (top, Qt.SizeVerCursor), (bottom, Qt.SizeVerCursor),
                (top | left, Qt.SizeFDiagCursor), (bottom | right, Qt.SizeFDiagCursor),
                (top | right, Qt.SizeBDiagCursor), (bottom | left, Qt.SizeBDiagCursor),
            )
        }
        window.installEventFilter(self)

    @staticmethod
    def _button(text, label, callback, parent):
        button = QPushButton(text, parent)
        button.setFixedSize(42, 32)
        button.setToolTip(label)
        button.setAccessibleName(label)
        button.clicked.connect(callback)
        return button

    def toggle_maximized(self):
        if self.host.isMaximized():
            self.host.showNormal()
        else:
            self.host.showMaximized()

    def mousePressEvent(self, event):
        # Menu items keep their usual click behavior; empty space moves the window.
        if event.button() == Qt.LeftButton and self.actionAt(event.position().toPoint()) is None:
            handle = self.host.windowHandle()
            if handle and handle.startSystemMove():
                event.accept()
                return
        super().mousePressEvent(event)

    def mouseDoubleClickEvent(self, event):
        if event.button() == Qt.LeftButton and self.actionAt(event.position().toPoint()) is None:
            self.toggle_maximized()
            event.accept()
            return
        super().mouseDoubleClickEvent(event)

    def eventFilter(self, watched, event):
        if watched is self.host and event.type() in (
            QEvent.Resize, QEvent.Show, QEvent.WindowStateChange,
        ):
            self._update_handles()
            label = "还原" if self.host.isMaximized() else "最大化"
            self.maximize_button.setText("❐" if self.host.isMaximized() else "□")
            self.maximize_button.setToolTip(label)
            self.maximize_button.setAccessibleName(label)
        return super().eventFilter(watched, event)

    def _update_handles(self):
        margin = self.RESIZE_MARGIN
        width, height = self.host.width(), self.host.height()
        for edges, handle in self._resize_handles.items():
            horizontal = bool(edges & (Qt.LeftEdge | Qt.RightEdge))
            vertical = bool(edges & (Qt.TopEdge | Qt.BottomEdge))
            x = width - margin if edges & Qt.RightEdge else (0 if horizontal else margin)
            y = height - margin if edges & Qt.BottomEdge else (0 if vertical else margin)
            handle.setGeometry(
                x, y,
                margin if horizontal else max(0, width - 2 * margin),
                margin if vertical else max(0, height - 2 * margin),
            )
            handle.setVisible(not (self.host.isMaximized() or self.host.isFullScreen()))
            handle.raise_()