"""Widget de visualisation PDF avec pypdfium2 — V2.3.1 avec selection."""

from PyQt6.QtWidgets import (QWidget, QVBoxLayout, QLabel,
                              QScrollArea, QSizePolicy, QApplication)
from PyQt6.QtGui import (QImage, QPixmap, QWheelEvent, QPainter, QPen, QColor,
                          QMouseEvent, QCursor)
from PyQt6.QtCore import Qt, pyqtSignal, QRect, QPoint
import pypdfium2 as pdfium


class SelectableImageLabel(QLabel):
    """QLabel avec possibilite de dessiner un rectangle de selection."""

    selection_changed = pyqtSignal(float, float, float, float)  # left, top, right, bottom en ratio (0-1)
    selection_done = pyqtSignal()

    def __init__(self, parent=None):
        super().__init__(parent)
        self._selecting = False
        self._select_mode = False
        self._start = QPoint()
        self._end = QPoint()
        self._rect = QRect()
        self._has_selection = False
        self._img_rect = QRect()  # zone de l'image dans le label

    def set_select_mode(self, enabled):
        self._select_mode = enabled
        self.setCursor(QCursor(Qt.CursorShape.CrossCursor if enabled else Qt.CursorShape.ArrowCursor))
        if not enabled:
            self._has_selection = False
            self.update()

    def clear_selection(self):
        self._has_selection = False
        self.update()

    def set_selection_from_margins(self, left_ratio, top_ratio, right_ratio, bottom_ratio):
        """Afficher un rectangle de selection a partir de ratios (0-1)."""
        if not self.pixmap():
            return
        pm = self.pixmap()
        img_w, img_h = pm.width(), pm.height()
        # Calculer la position de l'image dans le label (centree)
        lbl_w, lbl_h = self.width(), self.height()
        off_x = max(0, (lbl_w - img_w) // 2)
        off_y = max(0, (lbl_h - img_h) // 2)

        x1 = off_x + int(left_ratio * img_w)
        y1 = off_y + int(top_ratio * img_h)
        x2 = off_x + int(right_ratio * img_w)
        y2 = off_y + int(bottom_ratio * img_h)
        self._rect = QRect(QPoint(x1, y1), QPoint(x2, y2))
        self._has_selection = True
        self.update()

    def mousePressEvent(self, event: QMouseEvent):
        if self._select_mode and event.button() == Qt.MouseButton.LeftButton:
            self._selecting = True
            self._start = event.pos()
            self._end = event.pos()
            self._rect = QRect(self._start, self._end).normalized()
            self._has_selection = True
            self.update()
        else:
            super().mousePressEvent(event)

    def mouseMoveEvent(self, event: QMouseEvent):
        if self._selecting:
            self._end = event.pos()
            self._rect = QRect(self._start, self._end).normalized()
            self.update()
            self._emit_ratios()
        else:
            super().mouseMoveEvent(event)

    def mouseReleaseEvent(self, event: QMouseEvent):
        if self._selecting:
            self._selecting = False
            self._end = event.pos()
            self._rect = QRect(self._start, self._end).normalized()
            self.update()
            self._emit_ratios()
            self.selection_done.emit()
        else:
            super().mouseReleaseEvent(event)

    def _emit_ratios(self):
        if not self.pixmap():
            return
        pm = self.pixmap()
        img_w, img_h = pm.width(), pm.height()
        lbl_w, lbl_h = self.width(), self.height()
        off_x = max(0, (lbl_w - img_w) // 2)
        off_y = max(0, (lbl_h - img_h) // 2)

        left = max(0, (self._rect.left() - off_x)) / img_w
        top = max(0, (self._rect.top() - off_y)) / img_h
        right = min(1, (self._rect.right() - off_x)) / img_w
        bottom = min(1, (self._rect.bottom() - off_y)) / img_h

        left = max(0, min(1, left))
        top = max(0, min(1, top))
        right = max(0, min(1, right))
        bottom = max(0, min(1, bottom))

        self.selection_changed.emit(left, top, right, bottom)

    def paintEvent(self, event):
        super().paintEvent(event)
        if self._has_selection and not self._rect.isNull():
            painter = QPainter(self)
            # Zone sombre en dehors de la selection
            painter.setBrush(QColor(0, 0, 0, 100))
            painter.setPen(Qt.PenStyle.NoPen)
            full = self.rect()
            r = self._rect.normalized()
            # Haut
            painter.drawRect(full.left(), full.top(), full.width(), r.top() - full.top())
            # Bas
            painter.drawRect(full.left(), r.bottom(), full.width(), full.bottom() - r.bottom())
            # Gauche
            painter.drawRect(full.left(), r.top(), r.left() - full.left(), r.height())
            # Droite
            painter.drawRect(r.right(), r.top(), full.right() - r.right(), r.height())

            # Cadre de selection
            pen = QPen(QColor(0, 120, 255), 2, Qt.PenStyle.DashLine)
            painter.setPen(pen)
            painter.setBrush(Qt.BrushStyle.NoBrush)
            painter.drawRect(r)

            # Dimensions en mm (affichees dans le coin)
            painter.setPen(QColor(0, 120, 255))
            painter.drawText(r.left() + 4, r.top() - 4,
                             f"{r.width()}x{r.height()} px")
            painter.end()


class PdfViewer(QWidget):
    """Widget d'apercu PDF avec zoom molette, navigation et selection."""

    page_changed = pyqtSignal(int, int)
    selection_changed = pyqtSignal(float, float, float, float)  # ratios
    selection_done = pyqtSignal()

    def __init__(self, parent=None):
        super().__init__(parent)
        self._pdf = None
        self._pdf_path = None
        self._current_page = 0
        self._total_pages = 0
        self._zoom = 1.0
        self._page_width_pt = 0
        self._page_height_pt = 0
        self._setup_ui()

    def _setup_ui(self):
        layout = QVBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)

        self._scroll = QScrollArea()
        self._scroll.setWidgetResizable(True)
        self._scroll.setAlignment(Qt.AlignmentFlag.AlignCenter)
        self._scroll.setStyleSheet("QScrollArea { background: #11111b; border: none; }")

        self._image_label = SelectableImageLabel()
        self._image_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
        self._image_label.setSizePolicy(QSizePolicy.Policy.Ignored, QSizePolicy.Policy.Ignored)
        self._image_label.setStyleSheet("background: #11111b;")
        self._image_label.selection_changed.connect(self.selection_changed.emit)
        self._image_label.selection_done.connect(self.selection_done.emit)
        self._scroll.setWidget(self._image_label)

        self._scroll.wheelEvent = self._on_wheel
        layout.addWidget(self._scroll, 1)

    def set_select_mode(self, enabled):
        self._image_label.set_select_mode(enabled)

    def clear_selection(self):
        self._image_label.clear_selection()

    def show_selection(self, left_ratio, top_ratio, right_ratio, bottom_ratio):
        self._image_label.set_selection_from_margins(left_ratio, top_ratio, right_ratio, bottom_ratio)

    def _on_wheel(self, event: QWheelEvent):
        if event.modifiers() & Qt.KeyboardModifier.ControlModifier:
            delta = event.angleDelta().y()
            if delta > 0:
                self._zoom = min(self._zoom * 1.15, 5.0)
            else:
                self._zoom = max(self._zoom / 1.15, 0.2)
            self._render_page()
        else:
            delta = event.angleDelta().y()
            if delta < 0:
                self.next_page()
            elif delta > 0:
                self.prev_page()

    def load_pdf(self, path):
        try:
            self._pdf_path = path
            self._pdf = pdfium.PdfDocument(path)
            self._total_pages = len(self._pdf)
            self._current_page = 0
            self._zoom_fit()
            self._render_page()
        except Exception as e:
            self._image_label.setText(f"Erreur: {e}")

    def load_pdf_bytes(self, data):
        try:
            self._pdf = pdfium.PdfDocument(data)
            self._total_pages = len(self._pdf)
            self._current_page = 0
            self._zoom_fit()
            self._render_page()
        except Exception as e:
            self._image_label.setText(f"Erreur: {e}")

    def _render_page(self):
        if not self._pdf or self._current_page >= self._total_pages:
            return
        page = self._pdf[self._current_page]
        self._page_width_pt, self._page_height_pt = page.get_size()
        scale = 150 / 72 * self._zoom
        bitmap = page.render(scale=scale)
        pil_image = bitmap.to_pil()
        data = pil_image.tobytes("raw", "RGBA")
        qimage = QImage(data, pil_image.width, pil_image.height, QImage.Format.Format_RGBA8888)
        pixmap = QPixmap.fromImage(qimage)
        self._image_label.setPixmap(pixmap)
        self._image_label.adjustSize()
        self.page_changed.emit(self._current_page, self._total_pages)

    def _zoom_fit(self):
        if not self._pdf or self._current_page >= self._total_pages:
            return
        page = self._pdf[self._current_page]
        pw, ph = page.get_size()
        vw = self._scroll.viewport().width() - 20
        vh = self._scroll.viewport().height() - 20
        if vw <= 0 or vh <= 0:
            self._zoom = 1.0
            return
        scale_x = vw / pw
        scale_y = vh / ph
        self._zoom = min(scale_x, scale_y) * (72 / 150)

    def prev_page(self):
        if self._current_page > 0:
            self._current_page -= 1
            self._render_page()

    def next_page(self):
        if self._current_page < self._total_pages - 1:
            self._current_page += 1
            self._render_page()

    def go_to_page(self, page_index):
        if 0 <= page_index < self._total_pages and page_index != self._current_page:
            self._current_page = page_index
            self._render_page()

    def zoom_in(self):
        self._zoom = min(self._zoom * 1.25, 5.0)
        self._render_page()

    def zoom_out(self):
        self._zoom = max(self._zoom / 1.25, 0.2)
        self._render_page()

    def zoom_fit(self):
        self._zoom_fit()
        self._render_page()

    def refresh(self):
        self._render_page()

    def get_page_thumbnail(self, page_index, width=120):
        if not self._pdf or page_index >= self._total_pages:
            return None
        page = self._pdf[page_index]
        pw, ph = page.get_size()
        scale = width / pw
        bitmap = page.render(scale=scale)
        pil_image = bitmap.to_pil()
        data = pil_image.tobytes("raw", "RGBA")
        qimage = QImage(data, pil_image.width, pil_image.height, QImage.Format.Format_RGBA8888)
        return QPixmap.fromImage(qimage)

    @property
    def current_page(self):
        return self._current_page

    @property
    def total_pages(self):
        return self._total_pages

    @property
    def zoom_level(self):
        return self._zoom

    @property
    def pdf_path(self):
        return self._pdf_path

    @property
    def page_width_pt(self):
        return self._page_width_pt

    @property
    def page_height_pt(self):
        return self._page_height_pt