from PyQt6.QtWidgets import QApplication, QWidget, QVBoxLayout, QHBoxLayout, QTextEdit, QLabel
from PyQt6.QtCore import Qt, pyqtSignal, QPoint
from PyQt6.QtGui import QColor, QTextCursor, QMouseEvent

from .config import OverlayCfg

_TITLE = "AI 答题助手"
_LOADING_TEXT = "正在分析截图，请稍候..."


class _CloseBtn(QLabel):
    def __init__(self, on_click, parent=None):
        super().__init__("×", parent)
        self._on_click = on_click
        self.setCursor(Qt.CursorShape.PointingHandCursor)

    def mousePressEvent(self, event) -> None:
        if event.button() == Qt.MouseButton.LeftButton:
            self._on_click()


class _TitleBar(QWidget):
    def __init__(self, win: "OverlayWindow", cfg: OverlayCfg):
        super().__init__(win)
        self._win = win
        self.setFixedHeight(24)
        self.setStyleSheet(f"background-color: {cfg.bg_color}; border-radius: 6px 6px 0 0;")

        self.setMouseTracking(True)
        self.setAttribute(Qt.WidgetAttribute.WA_StyledBackground, True)

        self._drag_pos = None

        layout = QHBoxLayout(self)
        layout.setContentsMargins(10, 0, 6, 0)

        title_lbl = QLabel(f"· {_TITLE}")
        title_lbl.setStyleSheet(f"color: {cfg.accent_color}; font-size: 11px;")
        # 让标签对鼠标透明，事件穿透到 _TitleBar
        title_lbl.setAttribute(Qt.WidgetAttribute.WA_TransparentForMouseEvents)

        close_btn = _CloseBtn(win._on_hide)
        close_btn.setStyleSheet(f"color: {cfg.accent_color}; padding: 0 4px; font-size: 14px;")

        layout.addWidget(title_lbl)
        layout.addStretch()
        layout.addWidget(close_btn)
        
    def mousePressEvent(self, event):
        if event.button() == Qt.MouseButton.LeftButton:
            # 👇 就是在这里用 frameGeometry()
            self._drag_pos = event.globalPosition().toPoint() - self._win.frameGeometry().topLeft()

    def mouseMoveEvent(self, event):
        if self._drag_pos is not None and event.buttons() & Qt.MouseButton.LeftButton:
            self._win.move(event.globalPosition().toPoint() - self._drag_pos)

    def mouseReleaseEvent(self, event):
        self._drag_pos = None



class OverlayWindow(QWidget):
    _sig_append = pyqtSignal(str)
    _sig_loading = pyqtSignal()
    _sig_clear = pyqtSignal()
    _sig_show = pyqtSignal()
    _sig_hide = pyqtSignal()
    _sig_toggle = pyqtSignal()

    def __init__(self, cfg: OverlayCfg):
        self._app = QApplication.instance() or QApplication([])
        super().__init__()
        self._cfg = cfg
        self._drag_pos: QPoint | None = None

        self._sig_append.connect(self._on_append)
        self._sig_loading.connect(self._on_loading)
        self._sig_clear.connect(self._on_clear)
        self._sig_show.connect(self._on_show)
        self._sig_hide.connect(self._on_hide)
        self._sig_toggle.connect(self._on_toggle)

        self._setup_window()
        self._setup_ui()
        self._position_bottom_right()
        self.show()

    def _setup_window(self) -> None:
        self.setWindowFlags(
            Qt.WindowType.WindowStaysOnTopHint |
            Qt.WindowType.Tool
        )
        self.setAttribute(Qt.WidgetAttribute.WA_TranslucentBackground)
        self.setWindowOpacity(self._cfg.alpha)
        self.resize(self._cfg.width, self._cfg.height)

    def _setup_ui(self) -> None:
        cfg = self._cfg
        outer = QVBoxLayout(self)
        outer.setContentsMargins(0, 0, 0, 0)

        container = QWidget()
        container.setObjectName("container")
        container.setStyleSheet(f"""
            #container {{
                background-color: {cfg.bg_color};
                border-radius: 6px;
            }}
        """)
        outer.addWidget(container)

        inner = QVBoxLayout(container)
        inner.setContentsMargins(0, 0, 0, 0)
        inner.setSpacing(0)

        inner.addWidget(_TitleBar(self, cfg))

        self._text = QTextEdit()
        self._text.setReadOnly(True)
        self._text.setStyleSheet(f"""
            QTextEdit {{
                background-color: {cfg.bg_color};
                color: {cfg.fg_color};
                border: none;
                padding: 6px 8px;
                font-size: 13px;
            }}
            QScrollBar:vertical {{
                background: transparent;
                width: 4px;
                border: none;
            }}
            QScrollBar::handle:vertical {{
                background: {cfg.accent_color};
                border-radius: 2px;
            }}
            QScrollBar::add-line:vertical, QScrollBar::sub-line:vertical {{
                height: 0;
            }}
        """)
        self._text.setAttribute(Qt.WidgetAttribute.WA_TransparentForMouseEvents)
        inner.addWidget(self._text)

    def _position_bottom_right(self) -> None:
        cfg = self._cfg
        screen = QApplication.primaryScreen().availableGeometry()
        x = screen.width() - cfg.width - cfg.margin_right
        y = screen.height() - cfg.height - cfg.margin_bottom
        self.move(x, y)

    # ------------------------------------------------------------------
    # 公开 API
    # ------------------------------------------------------------------

    def set_loading(self) -> None:
        self._sig_loading.emit()

    def append_text(self, chunk: str) -> None:
        self._sig_append.emit(chunk)

    def clear(self) -> None:
        self._sig_clear.emit()

    def toggle(self) -> None:
        self._sig_toggle.emit()

    # ------------------------------------------------------------------
    # 槽
    # ------------------------------------------------------------------

    def _on_loading(self) -> None:
        self._text.clear()
        self._text.setTextColor(QColor(self._cfg.accent_color))
        self._text.insertPlainText(_LOADING_TEXT)
        self._text.setTextColor(QColor(self._cfg.fg_color))
        self._on_show()

    def _on_append(self, chunk: str) -> None:
        current = self._text.toPlainText()
        if current in (_LOADING_TEXT, _LOADING_TEXT + "\n"):
            self._text.clear()
        cursor = self._text.textCursor()
        cursor.movePosition(QTextCursor.MoveOperation.End)
        self._text.setTextCursor(cursor)
        self._text.insertPlainText(chunk)
        self._text.ensureCursorVisible()

    def _on_clear(self) -> None:
        self._text.clear()

    def _on_show(self) -> None:
        self.show()
        self.raise_()

    def _on_hide(self) -> None:
        self.hide()

    def _on_toggle(self) -> None:
        if self.isVisible():
            self.hide()
        else:
            self.show()
            self.raise_()

    @property
    def app(self) -> QApplication:
        return self._app