# core/archive.py

import os
import zipfile
import rarfile
import shutil


class ArchiveError(Exception):
    pass


def detect_real_format(path: str) -> str | None:
    """Devuelve 'zip', 'rar' o None según los magic bytes del archivo."""
    try:
        zipfile.ZipFile(path).close()
        return "zip"
    except Exception:
        pass

    try:
        rarfile.RarFile(path).close()
        return "rar"
    except Exception:
        pass

    return None


def open_archive(path: str):
    """Devuelve un ZipFile o RarFile abierto en modo lectura."""
    fmt = detect_real_format(path)
    if fmt == "zip":
        return zipfile.ZipFile(path, "r")
    if fmt == "rar":
        return rarfile.RarFile(path, "r")
    raise ArchiveError(f"Formato desconocido o archivo corrupto: {path}")


def extract_archive(path: str, dest_dir: str) -> str:
    """Extrae el archivo en dest_dir. Devuelve dest_dir."""
    archive = open_archive(path)
    try:
        archive.extractall(dest_dir)
    finally:
        archive.close()
    return dest_dir


def repack_as_cbz(source_dir: str, target_path: str) -> None:
    """Empaqueta todos los archivos de source_dir en un CBZ (ZIP deflated)."""
    with zipfile.ZipFile(target_path, "w", zipfile.ZIP_DEFLATED) as zf:
        for root, _, files in os.walk(source_dir):
            for f in files:
                full = os.path.join(root, f)
                rel = os.path.relpath(full, source_dir)
                zf.write(full, rel)