import cv2
import os

# Global state
VIDEO_DIR = "data"
video_files = [os.path.join(VIDEO_DIR, file) for file in sorted(os.listdir(VIDEO_DIR)) if file.endswith((".mp4", ".avi"))]
video_index = 0
cap = None

def get_next_video_frame():
    global cap, video_index

    if not video_files:
        raise RuntimeError("No video files found in the 'data' directory.")

    if cap is None or not cap.isOpened():
        cap = cv2.VideoCapture(video_files[video_index])

    ret, frame = cap.read()

    if not ret:
        cap.release()
        video_index = (video_index + 1) % len(video_files)
        cap = cv2.VideoCapture(video_files[video_index])
        ret, frame = cap.read()
        if not ret:
            raise RuntimeError(f"Cannot read video {video_files[video_index]}")

    return frame

def reset_video_index():
    global video_index
    video_index = 0