#!/usr/bin/env python3
import argparse
import sys
from pathlib import Path

import cv2 as cv


parser = argparse.ArgumentParser(description="Display a video file with OpenCV HighGUI.")
parser.add_argument("video", help="path to a readable video file")
parser.add_argument("--delay-ms", type=int, default=25, help="wait time between frames")
parser.add_argument("--max-frames", type=int, default=0, help="stop after this many frames; 0 means no limit")
parser.add_argument("--window-title", default="OpenCV video preview", help="HighGUI window title")
args = parser.parse_args()

video_path = Path(args.video)
cap = cv.VideoCapture(str(video_path))

if not cap.isOpened():
    sys.exit(f"Cannot open video: {video_path}")

backend = cap.getBackendName()
width = int(cap.get(cv.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv.CAP_PROP_FRAME_HEIGHT))
frames_displayed = 0
stopped_by_key = False

try:
    while True:
        ok, frame = cap.read()
        if not ok or frame is None:
            break

        cv.imshow(args.window_title, frame)
        frames_displayed += 1

        key = cv.waitKey(args.delay_ms) & 0xFF
        if key == ord("q"):
            stopped_by_key = True
            break

        if args.max_frames and frames_displayed >= args.max_frames:
            break
finally:
    cap.release()
    cv.destroyAllWindows()

if frames_displayed == 0:
    sys.exit(f"No frames were displayed from {video_path}")

print(f"Opened: {video_path}")
print(f"Backend: {backend}")
print(f"Frame size: {width}x{height}")
print(f"Displayed frames: {frames_displayed}")
if stopped_by_key:
    print("Stopped by key: q")
print("Closed OpenCV window")