import numpy as np
from PySide6.QtCore import QRectF, Qt
from PySide6.QtGui import QColor, QFont, QPainter, QPen


class CanvasRenderMixin:
    def paintEvent(self, event):
        painter = QPainter(self)
        painter.fillRect(self.rect(), self.OFF_CANVAS_COLOR)

        if self.image is None:
            return

        img_rect = self._image_rect_view()
        painter.drawImage(img_rect, self.image)

        label_font = QFont(painter.font())
        label_font.setPointSize(18)
        label_font.setBold(True)

        for si, s in enumerate(self.slices):
            points = [self._image_to_view(p) for p in s.bbox]

            for i in range(4):
                a = points[i]
                b = points[(i + 1) % 4]
                if i == 0:
                    color = QColor("red")
                elif i == 1:
                    color = QColor("green")
                elif i == 2:
                    color = QColor("orange")
                else:
                    color = QColor("blue") if s.locked else QColor("lightgreen")
                painter.setPen(QPen(color, 3))
                painter.drawLine(a, b)

            # Corners are color-coded: left = orange, right = cyan.
            # Edge 0 (top, red) runs TL->TR, so corners 0 and 3 are the left
            # side and corners 1 and 2 are the right side.
            corner_colors = (QColor("orange"), QColor("cyan"), QColor("cyan"), QColor("orange"))
            for p, color in zip(points, corner_colors):
                painter.setPen(QPen(QColor("blue"), 2))
                painter.setBrush(color)
                painter.drawRect(QRectF(p.x() - 5, p.y() - 5, 10, 10))

            center = np.mean(s.bbox, axis=0)
            center_view = self._image_to_view(center)
            if si == self.active_slice_index:
                text_color = QColor("gold")
            else:
                text_color = QColor("blue") if s.locked else QColor("lightgreen")
            painter.setPen(QPen(text_color, 1))
            painter.setFont(label_font)
            painter.drawText(
                QRectF(center_view.x() - 20, center_view.y() - 16, 40, 32),
                Qt.AlignCenter,
                str(si),
            )

            if s.side_handles_enabled and s.is_perfect_rectangle():
                handle_color = QColor("orange") if si == self.active_slice_index else QColor(255, 170, 0)
                painter.setPen(QPen(handle_color, 2))
                painter.setBrush(QColor(handle_color.red(), handle_color.green(), handle_color.blue(), 170))
                handle_size = (
                    float(getattr(self, "SIDE_HANDLE_SIZE_ACTIVE", 11.0))
                    if si == self.active_slice_index
                    else float(getattr(self, "SIDE_HANDLE_SIZE_INACTIVE", 9.0))
                )
                for ei in range(4):
                    mid = (s.bbox[ei] + s.bbox[(ei + 1) % 4]) / 2.0
                    mid_view = self._image_to_view(mid)
                    painter.drawRect(
                        QRectF(
                            mid_view.x() - handle_size / 2.0,
                            mid_view.y() - handle_size / 2.0,
                            handle_size,
                            handle_size,
                        )
                    )