import io
import sys
from pathlib import Path

from PIL import Image
from PyQt6.QtCore import Qt
from PyQt6.QtGui import QImage, QPixmap
from PyQt6.QtWidgets import (
    QApplication,
    QGraphicsPixmapItem,
    QGraphicsScene,
    QGraphicsView,
    QMainWindow,
    QPushButton,
    QVBoxLayout,
    QWidget,
)

# For PyQt5 users, change the imports above to this:
# from PyQt5.QtWidgets import QApplication, QMainWindow, QGraphicsView, QGraphicsScene, QGraphicsPixmapItem, QVBoxLayout, QWidget, QPushButton, QFileDialog
# from PyQt5.QtGui import QPixmap
# from PyQt5.QtCore import Qt


class ZoomableView(QGraphicsView):
    """
    A custom QGraphicsView that provides zoom functionality with the mouse wheel.
    """

    def __init__(self, scene):
        super().__init__(scene)
        # Set anchor points for zooming and resizing
        self.setTransformationAnchor(QGraphicsView.ViewportAnchor.AnchorUnderMouse)
        self.setResizeAnchor(QGraphicsView.ViewportAnchor.AnchorViewCenter)

    def wheelEvent(self, event):
        """
        Handles mouse wheel events to zoom in or out.
        """
        # Get the amount of scroll
        angle = event.angleDelta().y()

        if angle > 0:
            # Zoom in
            factor = 1.25
        else:
            # Zoom out
            factor = 0.8

        self.scale(factor, factor)


class ImageViewer(QMainWindow):
    """
    Main application window for viewing an image.
    Includes loading, zooming, and panning functionality.
    """

    def __init__(self):
        super().__init__()

        self.setWindowTitle("PyQt Image Viewer (Load, Zoom, Pan)")
        self.setGeometry(100, 100, 800, 700)

        # Main widget and layout
        central_widget = QWidget()
        self.setCentralWidget(central_widget)
        layout = QVBoxLayout(central_widget)

        # 1. Create the QGraphicsScene
        # The scene is the container for all 2D graphical items
        self.scene = QGraphicsScene()

        # 2. Create the custom QGraphicsView
        # This is our custom view with zoom capabilities
        self.view = ZoomableView(self.scene)

        # 3. Enable panning (drag the scene with the mouse)
        # The hand cursor will appear when you click and drag.
        self.view.setDragMode(QGraphicsView.DragMode.ScrollHandDrag)

        # Add a button to load an image
        self.load_button = QPushButton("Load Image")
        self.load_button.clicked.connect(self.load_image)

        # Add widgets to the layout
        layout.addWidget(self.load_button)
        layout.addWidget(self.view)

        # A variable to hold the currently displayed image item
        self.pixmap_item = None

    def load_image(self):
        file_path = Path(
            "/home/lambda/Downloads/f546ed6d35ee05338b8403d57dda10103ac3b1b8.jpg@672w_378h_1c_!web-home-common-cover.avif"
        )
        image_data = file_path.read_bytes()
        im = Image.open(io.BytesIO(image_data))
        pixmap = QPixmap.fromImage(
            QImage(im.tobytes(), im.size[0], im.size[1], QImage.Format.Format_RGB888)
        )
        if pixmap.isNull():
            print(f"Error: Failed to load image from {file_path}")
            return
        # If an image is already loaded, remove the old one first
        if self.pixmap_item:
            self.scene.removeItem(self.pixmap_item)

        # 5. Create a QGraphicsPixmapItem to hold the image
        self.pixmap_item = QGraphicsPixmapItem(pixmap)

        # 6. Add the item to the scene
        self.scene.addItem(self.pixmap_item)

        # --- Optional: Improve the viewing experience ---
        # Reset any previous transformations (like zoom/pan)
        self.view.resetTransform()
        # Fit the entire image within the view, maintaining aspect ratio
        self.view.fitInView(self.pixmap_item, Qt.AspectRatioMode.KeepAspectRatio)


if __name__ == "__main__":
    # Create the application instance
    app = QApplication(sys.argv)

    # Create and show the main window
    viewer = ImageViewer()
    viewer.show()

    # Start the application's event loop
    sys.exit(app.exec())