services/video_service.py

import cv2
import os

# Global variables
cap = None
frame_index = 0
current_video_path = None

def preload_video(video_path="sample.mp4"):
    """
    Preload the video file.
    Args:
        video_path (str): Path to the video file.
    Returns:
        str: Status message indicating success or failure.
    """
    global cap, frame_index, current_video_path
    try:
        # Reset previous capture if any
        if cap is not None:
            cap.release()
        
        # Check if video file exists
        if not os.path.exists(video_path):
            raise FileNotFoundError(f"Video file {video_path} not found. Please upload a video file named 'sample.mp4' or provide a different path.")

        # Initialize video capture
        cap = cv2.VideoCapture(video_path)
        if not cap.isOpened():
            raise RuntimeError(f"Failed to open video file {video_path}. Ensure the file is a valid video format (e.g., .mp4).")

        frame_index = 0
        current_video_path = video_path
        return f"Successfully loaded video: {video_path}"
    except Exception as e:
        cap = None
        return f"Error loading video: {str(e)}"

def get_next_video_frame():
    """
    Get the next frame from the video.
    Returns:
        numpy array: Video frame
    Raises:
        RuntimeError: If video is not preloaded or frame cannot be read.
    """
    global cap, frame_index
    if cap is None:
        raise RuntimeError("Video not preloaded. Call preload_video() first.")
    
    ret, frame = cap.read()
    if not ret:
        # Loop the video
        cap.set(cv2.CAP_PROP_POS_FRAMES, 0)
        frame_index = 0
        ret, frame = cap.read()
        if not ret:
            raise RuntimeError(f"Failed to read frame from video {current_video_path}.")
    
    frame_index += 1
    return frame

def reset_video_index():
    """
    Reset the video frame index.
    """
    global frame_index
    frame_index = 0
    if cap is not None:
        cap.set(cv2.CAP_PROP_POS_FRAMES, 0)

def release_video():
    """
    Release the video capture object.
    """
    global cap
    if cap is not None:
        cap.release()
        cap = None