from argparse import ArgumentParser
from pathlib import Path

import cv2 as cv


parser = ArgumentParser()
parser.add_argument("--input", default="input/scene.png", help="Source image")
parser.add_argument("--output", default="output/scene-crop.png", help="Cropped output image")
parser.add_argument("--x", type=int, default=160, help="Left edge of the crop")
parser.add_argument("--y", type=int, default=90, help="Top edge of the crop")
parser.add_argument("--width", type=int, default=260, help="Crop width in pixels")
parser.add_argument("--height", type=int, default=180, help="Crop height in pixels")
args = parser.parse_args()

image = cv.imread(args.input)
if image is None:
    raise SystemExit(f"could not read input image: {args.input}")

source_height, source_width = image.shape[:2]
x1 = args.x
y1 = args.y
x2 = x1 + args.width
y2 = y1 + args.height

if x1 < 0 or y1 < 0 or x2 > source_width or y2 > source_height:
    raise SystemExit(
        "crop rectangle is outside the source image: "
        f"source={source_width}x{source_height}, "
        f"box=({x1},{y1})-({x2},{y2})"
    )

crop = image[y1:y2, x1:x2]

output_path = Path(args.output)
output_path.parent.mkdir(parents=True, exist_ok=True)
if not cv.imwrite(str(output_path), crop):
    raise SystemExit(f"could not write output image: {output_path}")

print(f"source shape: {source_width}x{source_height}")
print(f"crop box: x={x1}, y={y1}, width={args.width}, height={args.height}")
print(f"slice: image[{y1}:{y2}, {x1}:{x2}]")
print(f"crop shape: {crop.shape[1]}x{crop.shape[0]}")
print(f"wrote: {output_path}")