import argparse
import os
import sys

# Assuming these modules will be created and populated later
import converter
import utils
import config
import downloader # Import downloader module

def main():
    parser = argparse.ArgumentParser(
        description="Convert video files to DaVinci Resolve compatible formats."
    )
    parser.add_argument(
        "input_file",
        nargs='?',
        help="Path to the input video file.",
        type=str
    )
    parser.add_argument(
        "-u", "--url",
        help="URL of the video to download and convert.",
        type=str,
        default=None
    )
    parser.add_argument(
        "-o", "--output_dir",
        help="Optional: Directory to save the converted file. Defaults to the input file's directory.",
        type=str,
        default=None
    )

    args = parser.parse_args()

    input_source = None
    if args.url:
        print(f"Downloading video from URL: {args.url}")
        downloaded_file = downloader.download_video(args.url)
        if not downloaded_file:
            print("Error: Video download failed.", file=sys.stderr)
            sys.exit(1)
        input_source = downloaded_file
        # If output_dir is not specified, use the directory of the downloaded file
        if not args.output_dir:
            args.output_dir = os.path.dirname(downloaded_file)
    elif args.input_file:
        input_source = args.input_file
    
    while not input_source:
        user_input = input("Please enter the path to the input video file or a URL: ").strip()
        if not user_input:
            print("Input cannot be empty. Please try again.", file=sys.stderr)
            continue
        
        if user_input.startswith("http://") or user_input.startswith("https://"):
            print(f"Downloading video from URL: {user_input}")
            downloaded_file = downloader.download_video(user_input)
            if not downloaded_file:
                print("Error: Video download failed.", file=sys.stderr)
                sys.exit(1)
            input_source = downloaded_file
            if not args.output_dir:
                args.output_dir = os.path.dirname(downloaded_file)
        else:
            input_source = user_input

    input_file_path = os.path.abspath(input_source)
    
    if not os.path.exists(input_file_path):
        print(f"Error: Input file not found at '{input_file_path}'", file=sys.stderr)
        sys.exit(1)
    
    if not os.path.isfile(input_file_path):
        print(f"Error: '{input_file_path}' is not a file.", file=sys.stderr)
        sys.exit(1)

    if not os.access(input_file_path, os.R_OK):
        print(f"Error: No read permission for input file '{input_file_path}'.", file=sys.stderr)
        sys.exit(1)

    output_dir = args.output_dir
    if output_dir:
        output_dir = os.path.abspath(output_dir)
        if not os.path.isdir(output_dir):
            print(f"Error: Output directory '{output_dir}' does not exist or is not a directory.", file=sys.stderr)
            sys.exit(1)
        if not os.access(output_dir, os.W_OK):
            print(f"Error: No write permission for output directory '{output_dir}'.", file=sys.stderr)
            sys.exit(1)
    else:
        output_dir = os.path.dirname(input_file_path)
        if not os.access(output_dir, os.W_OK):
            print(f"Error: No write permission for input file's directory '{output_dir}'.", file=sys.stderr)
            sys.exit(1)

    # Perform conversion
    print(f"Starting conversion for {input_file_path}...")
    success = converter.convert_video(input_file_path, output_dir)

    if success:
        print("Conversion completed successfully.")
    else:
        print("Conversion failed.", file=sys.stderr)
        sys.exit(1)

if __name__ == "__main__":
    main()