import os
import subprocess
from pathlib import Path
from concurrent.futures import ProcessPoolExecutor, as_completed
import multiprocessing

def convert_file(filepath, out_dir):
    filename = os.path.basename(filepath)
    basename, _ = os.path.splitext(filename)
    out_filename = basename + ".m4a"
    out_path = os.path.join(out_dir, out_filename)

    # ffmpeg command to copy audio
    proc = subprocess.run(
        ["ffmpeg", "-i", filepath, "-vn", "-c:a", "copy", out_path],
        capture_output=True
    )

    if proc.returncode != 0:
        return f"ERROR: Failed to convert {filename}\n{proc.stderr.decode()}"
    return f"Converted: {filename}"

def main():
    cwd = Path.cwd()
    in_dir = cwd / "playlists"
    out_dir = cwd / "audios"

    os.makedirs(out_dir, exist_ok=True)

    files = [str(in_dir / f) for f in os.listdir(in_dir) if f.lower().endswith(('.mp4', '.mkv', '.mov'))]

    # Use number of CPU cores, with 16 files max per core
    num_cores = multiprocessing.cpu_count()
    max_workers = min(len(files), num_cores)

    print(f"Converting {len(files)} files using {max_workers} workers...")

    results = []
    with ProcessPoolExecutor(max_workers=max_workers) as executor:
        futures = {executor.submit(convert_file, f, str(out_dir)): f for f in files}
        for future in as_completed(futures):
            print(future.result())

if __name__ == "__main__":
    main()