viewer.py

from PySide6.QtCore import QMimeData, Qt
from PySide6.QtGui import QDrag
from PySide6.QtWidgets import (
    QApplication,
    QFrame,
    QGridLayout,
    QLabel,
    QWidget,
)


class PDFViewer(QWidget):
    """
    PDF 页面缩略图预览与交互组件。
    支持页面多选、拖拽排序、右键菜单等功能。
    """

    def __init__(self, workspace):
        """
        :param workspace: Workspace 实例，管理所有 PDF 文件与页面
        """
        super().__init__()
        self.workspace = workspace
        self.grid_layout = QGridLayout()
        self.grid_layout.setSpacing(10)
        self.setLayout(self.grid_layout)
        self.selected_pages = []
        self.drag_label = None
        self._all_labels = []

    def clear_thumbnails(self):
        """清空所有页面缩略图控件。"""
        while self.grid_layout.count():
            widget = self.grid_layout.takeAt(0).widget()
            if widget:
                widget.deleteLater()

    def update_view(self):
        """根据 workspace 的页面数据刷新缩略图显示。"""
        self.clear_thumbnails()
        self.selected_pages.clear()
        self._all_labels.clear()
        row, col = 0, 0
        for pdf_file in self.workspace.pdf_files:
            for page in pdf_file.pages:
                label = DraggableLabel(page, self)
                label.setPixmap(page.thumbnail)
                label.setAlignment(Qt.AlignCenter)
                label.setFrameShape(QFrame.Box)
                label.setStyleSheet("background-color: white;")
                self.grid_layout.addWidget(label, row, col)
                self._all_labels.append(label)
                col += 1
                if col >= 4:
                    col = 0
                    row += 1

    def select_page(self, label, multi_select=False, range_select=False):
        """
        处理页面的选中逻辑。
        :param label: DraggableLabel 被选中的页面标签
        :param multi_select: 是否为Ctrl多选
        :param range_select: 是否为Shift连续选中
        """
        if not multi_select and not range_select:
            # 单选，清空其他选中页面
            for selected_label in self.selected_pages:
                selected_label.setStyleSheet("background-color: white;")
            self.selected_pages.clear()

        if range_select and self.selected_pages:
            # Shift连续选中
            all_labels = self._all_labels
            start_index = all_labels.index(self.selected_pages[-1])
            end_index = all_labels.index(label)
            for i in range(
                min(start_index, end_index), max(start_index, end_index) + 1
            ):
                if all_labels[i] not in self.selected_pages:
                    self.selected_pages.append(all_labels[i])
                    all_labels[i].setStyleSheet("background-color: lightblue;")
        else:
            # 单选或Ctrl多选
            if label not in self.selected_pages:
                self.selected_pages.append(label)
                label.setStyleSheet("background-color: lightblue;")
            elif multi_select:
                self.selected_pages.remove(label)
                label.setStyleSheet("background-color: white;")

    def get_label_index(self, label):
        """获取 label 在所有页面中的索引。"""
        return self._all_labels.index(label)

    def swap_labels(self, from_idx, to_idx, before=True):
        """
        将 from_idx 的 label 移动到 to_idx 前面（before=True）或后面（before=False）。
        """
        if from_idx == to_idx or from_idx < 0 or to_idx < 0:
            return
        label = self._all_labels.pop(from_idx)
        insert_pos = to_idx if before else to_idx + 1
        if from_idx < insert_pos:
            insert_pos -= 1
        self._all_labels.insert(insert_pos, label)
        self._relayout()

    def swap_labels_multi(self, from_indices, to_idx, before=True):
        """
        将 from_indices 对应的 labels（按原顺序）整体移动到 to_idx 前面（before=True）或后面（before=False）。
        """
        moving_labels = [self._all_labels[i] for i in from_indices]
        for idx in sorted(from_indices, reverse=True):
            self._all_labels.pop(idx)
        insert_pos = to_idx if before else to_idx + 1
        for idx in from_indices:
            if idx < insert_pos:
                insert_pos -= 1
        for i, label in enumerate(moving_labels):
            self._all_labels.insert(insert_pos + i, label)
        self._relayout()
        self.clear_highlight()

    def _relayout(self):
        """根据 _all_labels 顺序重新布局页面缩略图。"""
        for i, lbl in enumerate(self._all_labels):
            row, col = divmod(i, 4)
            self.grid_layout.addWidget(lbl, row, col)

    def highlight_label_at(self, index):
        """高亮显示插入目标页面的背景。"""
        for lbl in self._all_labels:
            if lbl not in self.selected_pages:
                lbl.setStyleSheet("background-color: white;")
            else:
                lbl.setStyleSheet("background-color: lightblue;")
        if 0 <= index < len(self._all_labels):
            self._all_labels[index].setStyleSheet("background-color: #ffe082;")

    def clear_highlight(self):
        """清除所有页面的插入高亮，仅保留选中高亮。"""
        for lbl in self._all_labels:
            if lbl in self.selected_pages:
                lbl.setStyleSheet("background-color: lightblue;")
            else:
                lbl.setStyleSheet("background-color: white;")

    def reorder_pages(self, insert_index):
        """
        处理页面的重新排序。
        :param insert_index: 插入位置的索引
        """
        if not self.selected_pages or insert_index < 0:
            return
        selected_labels = self.selected_pages[:]
        for label in selected_labels:
            self._all_labels.remove(label)
        for label in reversed(selected_labels):
            self._all_labels.insert(insert_index, label)
        self._relayout()
        mw = self.window()
        if hasattr(mw, "notify_pages_reordered"):
            mw.notify_pages_reordered()


class DraggableLabel(QLabel):
    """
    可拖拽的页面缩略图控件。
    """

    def __init__(self, page, viewer):
        """
        :param page: PDFPage 实例
        :param viewer: PDFViewer 实例
        """
        super().__init__()
        self.page = page
        self.viewer = viewer
        self.setAcceptDrops(True)
        self._mouse_pressed = False
        self._drag_start_pos = None

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self._mouse_pressed = True
            self._drag_start_pos = event.pos()
            modifiers = QApplication.keyboardModifiers()
            multi_select = modifiers == Qt.ControlModifier
            range_select = modifiers == Qt.ShiftModifier
            # 修改逻辑：如果是多选/连续选中且已经选中，则不改变选中状态
            if (multi_select or range_select) and self in self.viewer.selected_pages:
                pass  # 保持原有选中状态，不做任何操作
            else:
                if multi_select:
                    if self in self.viewer.selected_pages:
                        self.viewer.selected_pages.remove(self)
                        self.setStyleSheet("background-color: white;")
                    else:
                        self.viewer.selected_pages.append(self)
                        self.setStyleSheet("background-color: lightblue;")
                else:
                    self.viewer.select_page(self, multi_select, range_select)

    def mouseMoveEvent(self, event):
        if not self._mouse_pressed:
            return
        if (
            event.buttons() == Qt.LeftButton
            and (event.pos() - self._drag_start_pos).manhattanLength()
            > QApplication.startDragDistance()
        ):
            drag = QDrag(self)
            mime_data = QMimeData()
            drag.setMimeData(mime_data)
            drag.setPixmap(self.pixmap())
            self.viewer.drag_label = self
            # 记录拖拽时的多选状态
            modifiers = QApplication.keyboardModifiers()
            multi_select = modifiers == Qt.ControlModifier
            range_select = modifiers == Qt.ShiftModifier
            # 计算拖拽涉及的所有页面
            if (multi_select or range_select) and self in self.viewer.selected_pages:
                self.viewer._drag_indices = [
                    self.viewer.get_label_index(lbl)
                    for lbl in self.viewer.selected_pages
                ]
            else:
                self.viewer._drag_indices = [self.viewer.get_label_index(self)]
            drag.exec(Qt.MoveAction)
            self.viewer._drag_indices = None

    def mouseReleaseEvent(self, event):
        self._mouse_pressed = False

    def dragEnterEvent(self, event):
        if self.viewer.drag_label and self.viewer.drag_label != self:
            event.acceptProposedAction()
        else:
            event.ignore()

    def dragMoveEvent(self, event):
        if self.viewer.drag_label and self.viewer.drag_label != self:
            event.acceptProposedAction()
            idx = self.viewer.get_label_index(self)
            rect = self.rect()
            mouse_x = (
                event.position().x() if hasattr(event, "position") else event.pos().x()
            )
            # 仅第一页支持左右判断插入位置，其余页面默认插入到该页面后面
            if idx == 0:
                before = mouse_x < rect.width() / 2
                highlight_idx = idx if before else idx
            else:
                before = False
                highlight_idx = idx
            self.viewer.highlight_label_at(highlight_idx)
        else:
            event.ignore()
            self.viewer.clear_highlight()

    def dropEvent(self, event):
        if self.viewer.drag_label and self.viewer.drag_label != self:
            rect = self.rect()
            mouse_x = (
                event.position().x() if hasattr(event, "position") else event.pos().x()
            )
            to_idx = self.viewer.get_label_index(self)
            # 仅第一页支持左右判断插入位置，其余页面默认插入到该页面后面
            if to_idx == 0:
                before = mouse_x < rect.width() / 2
            else:
                before = False
            # 多选拖拽
            drag_indices = getattr(self.viewer, "_drag_indices", None)
            if drag_indices is not None and len(drag_indices) > 1:
                # 保证顺序
                drag_indices = sorted(drag_indices)
                self.viewer.swap_labels_multi(drag_indices, to_idx, before=before)
            else:
                from_idx = self.viewer.get_label_index(self.viewer.drag_label)
                self.viewer.swap_labels(from_idx, to_idx, before=before)
            self.viewer.drag_label = None
            self.viewer.clear_highlight()
            event.acceptProposedAction()
        else:
            event.ignore()
            self.viewer.clear_highlight()

    def contextMenuEvent(self, event):
        """
        右键菜单由 MainWindow 统一处理，这里只触发父控件的 customContextMenuRequested 信号。
        """
        self.viewer.customContextMenuRequested.emit(self.mapToParent(event.pos()))