import hashlib
import csv
from pathlib import Path


BASE = Path(__file__).resolve().parent.parent / "temp" / "media"


def sha1_of_file(path: Path, buf_size: int = 65536) -> str:
    """Calcula el SHA1 de un fichero binario."""

    h = hashlib.sha1()
    with path.open("rb") as f:
        while True:
            chunk = f.read(buf_size)
            if not chunk:
                break
            h.update(chunk)
    return h.hexdigest()


def main() -> None:
    if not BASE.exists():
        raise SystemExit(f"No existe la carpeta {BASE}")

    rows: list[tuple[str, str]] = []
    subdirs = sorted(p for p in BASE.iterdir() if p.is_dir())

    # 1) Calcular SHA1 y guardar filas para el CSV
    for d in subdirs:
        video_path = d / "video.mp4"
        if not video_path.exists():
            print(f"[WARN] No se encontró video.mp4 en {d}, se omite esta carpeta.")
            continue

        digest = sha1_of_file(video_path)
        print(f"{d.name} -> {digest}")
        rows.append((d.name, digest))

    if not rows:
        print("[INFO] No se han encontrado carpetas con video.mp4, nada que hacer.")
        return

    # 2) Escribir CSV con mapping carpeta original -> sha1sum
    csv_path = BASE / "sha1sums.csv"
    with csv_path.open("w", newline="", encoding="utf-8") as f:
        writer = csv.writer(f)
        writer.writerow(["folder_name", "sha1sum"])
        writer.writerows(rows)

    print(f"[INFO] CSV generado en {csv_path}")

    # 3) Renombrar carpetas a su sha1sum
    #    Si dos carpetas tienen el mismo sha1, se deja la segunda sin renombrar.
    for old_name, digest in rows:
        old_path = BASE / old_name
        new_path = BASE / digest
        if not old_path.exists():
            print(f"[INFO] Carpeta {old_path} ya no existe, se omite.")
            continue
        if new_path.exists():
            print(
                f"[ERROR] Ya existe {new_path}, posible colisión de SHA1 o renombrado previo. "
                f"No se renombra {old_path}."
            )
            continue
        print(f"Renombrando {old_path} -> {new_path}")
        old_path.rename(new_path)


if __name__ == "__main__":
    main()