import argparse
import asyncio
from pathlib import Path

from ..core.config import THUMBS_DIR, YT_DIR


async def run (cmd: list[str]) -> tuple[int, bytes]:
    proc = await asyncio.create_subprocess_exec(
        *cmd,
        stdout=asyncio.subprocess.DEVNULL,
        stderr=asyncio.subprocess.PIPE,
    )

    _, err = await proc.communicate()
    return proc.returncode, err

async def extract_cover(video: Path, out: Path, sem: asyncio.Semaphore) -> bool:
    if ".Trash" in str(video) or any(part.startswith('.') for part in video.parts):
        return False
        
    # 1. Пропускаем временные файлы и аудио-дорожки yt-dlp
    if ".temp." in video.name or ".f" in video.name and video.suffix == ".webm":
        return False

    async with sem:
        out.parent.mkdir(parents=True, exist_ok=True)
        if out.exists() and out.stat().st_size > 0:
            return True

        # 2. Пытаемся взять ВТОРУЮ дорожку (с вопросительным знаком, чтобы не падало)
        code, err = await run([
            "ffmpeg", "-y", "-loglevel", "error",
            "-i", str(video),
            "-map", "0:v:1?", 
            "-c", "copy",
            str(out),
        ])

        if code != 0:
            # 3. Если второй нет, пытаемся взять ПЕРВУЮ (тоже с вопросительным знаком)
            code, err = await run([
                "ffmpeg", "-y", "-loglevel", "error",
                "-i", str(video),
                "-map", "0:v:0?",
                "-c", "copy",
                str(out),
            ])
            if code != 0:
                print(f"FAIL {video.name}: {err.decode()[:300]}")
                return False

        return True

async def main(workers: int):
    SEM = asyncio.Semaphore(workers)
    videos = [p for p in YT_DIR.rglob("*") if p.is_file() and p.suffix.lower() in {".mp4", ".mkv", ".webm"}]
    print(f"videos: {len(videos)}")

    tasks = []
    for video in videos:
        rel = video.relative_to(YT_DIR)
        out = THUMBS_DIR / rel.with_suffix(".jpg")
        tasks.append(extract_cover(video, out, SEM))

    results = await asyncio.gather(*tasks)
    ok = sum(1 for r in results if r)
    print(f"done: {ok}/{len(results)}")

def parse_args():
    parser = argparse.ArgumentParser(description="Extract video previews")
    parser.add_argument(
        "-w", "--workers",
        type=int,
        default=8,
        help="number of parallel ffmpeg processes (default: 8)",
    )
    return parser.parse_args()


if __name__ == "__main__":
    args = parse_args()
    asyncio.run(main(args.workers))