"""zstd streaming compression + 7z extraction.

Ported from: JoshSteam CDN/Utils/compression.py
No behavior changes; just type hints and path-objects.
"""

from __future__ import annotations

import os
import tarfile
from pathlib import Path
from typing import BinaryIO

import py7zr
import zstandard as zstd


def generate_tar_zstd_stream(depot_path: Path | str, output_stream: BinaryIO) -> None:
    """Stream tarball of `depot_path` contents into an output binary stream."""
    depot_path = Path(depot_path)
    with tarfile.open(fileobj=output_stream, mode="w|") as tar:
        for root, _, files in os.walk(depot_path):
            for file in files:
                file_path = Path(root) / file
                relative_path = file_path.relative_to(depot_path)
                tar.add(file_path, arcname=str(relative_path))


def compress_and_save_zstd(
    depot_path: Path | str, temp_zstd_path: Path | str, final_zstd_path: Path | str
) -> None:
    """Tar+zstd `depot_path` to a temp file, then atomically rename to final.

    No intermediate uncompressed .tar is created on disk.
    """
    temp_zstd_path = Path(temp_zstd_path)
    final_zstd_path = Path(final_zstd_path)
    temp_zstd_path.parent.mkdir(parents=True, exist_ok=True)

    with open(temp_zstd_path, "wb") as out_file:
        cctx = zstd.ZstdCompressor(level=3)
        with cctx.stream_writer(out_file) as compressor:
            generate_tar_zstd_stream(depot_path, compressor)

    os.replace(temp_zstd_path, final_zstd_path)


def extract_7z(archive_path: Path | str, destination_path: Path | str) -> None:
    """Extract a .7z archive into `destination_path`."""
    archive_path = Path(archive_path)
    destination_path = Path(destination_path)
    if not archive_path.exists():
        raise FileNotFoundError(f"The archive {archive_path} does not exist.")
    destination_path.mkdir(parents=True, exist_ok=True)
    with py7zr.SevenZipFile(archive_path, mode="r") as archive:
        archive.extractall(path=destination_path)