"""Archive writers for canonical Codex package directories."""

import shutil
import subprocess
import tarfile
import tempfile
import zipfile
from collections.abc import Callable
from pathlib import Path

from .targets import REPO_ROOT


ZSTD_DOTSLASH = REPO_ROOT / ".github" / "workflows" / "zstd"


def write_archive(package_dir: Path, archive_path: Path, *, force: bool) -> None:
    if is_relative_to(archive_path, package_dir):
        raise RuntimeError(
            f"Archive output must be outside the package directory: {archive_path}"
        )

    archive_path.parent.mkdir(parents=True, exist_ok=True)
    if archive_path.exists():
        if not force:
            raise RuntimeError(f"Archive output already exists: {archive_path}")
        archive_path.unlink()

    archive_format = archive_format_for_path(archive_path)
    if archive_format == "tar.gz":
        write_tar_archive(package_dir, archive_path, mode="w:gz")
    elif archive_format == "tar.zst":
        write_tar_zst_archive(package_dir, archive_path)
    elif archive_format == "zip":
        write_zip_archive(package_dir, archive_path)
    else:
        raise AssertionError(f"unexpected archive format: {archive_format}")


def is_relative_to(path: Path, parent: Path) -> bool:
    try:
        path.relative_to(parent)
        return True
    except ValueError:
        return False


def archive_format_for_path(path: Path) -> str:
    suffixes = path.suffixes
    if suffixes[-2:] == [".tar", ".gz"] or path.suffix == ".tgz":
        return "tar.gz"
    if suffixes[-2:] == [".tar", ".zst"]:
        return "tar.zst"
    if path.suffix == ".zip":
        return "zip"
    raise RuntimeError(
        f"Unsupported archive suffix for {path}. Use .tar.gz, .tgz, .tar.zst, or .zip."
    )


def write_tar_archive(package_dir: Path, archive_path: Path, *, mode: str) -> None:
    with tarfile.open(archive_path, mode) as archive:
        for path in package_entries(package_dir):
            archive.add(
                path,
                arcname=path.relative_to(package_dir),
                recursive=False,
            )


def write_tar_zst_archive(package_dir: Path, archive_path: Path) -> None:
    zstd_command = resolve_zstd_command()

    with tempfile.TemporaryDirectory(prefix="codex-package-archive-") as temp_dir_str:
        tar_path = Path(temp_dir_str) / "package.tar"
        write_tar_archive(package_dir, tar_path, mode="w")
        subprocess.check_call(
            [*zstd_command, "-T0", "-19", "-f", str(tar_path), "-o", str(archive_path)]
        )


def resolve_zstd_command(
    *,
    dotslash_manifest: Path = ZSTD_DOTSLASH,
    which: Callable[[str], str | None] = shutil.which,
) -> list[str]:
    zstd = which("zstd")
    if zstd is not None:
        return [zstd]

    dotslash = which("dotslash")
    if dotslash is not None and dotslash_manifest.is_file():
        return [dotslash, str(dotslash_manifest)]

    raise RuntimeError(
        "zstd is required to write .tar.zst archives. Install zstd, or install "
        f"DotSlash so the repository wrapper can run: {dotslash_manifest}"
    )


def write_zip_archive(package_dir: Path, archive_path: Path) -> None:
    with zipfile.ZipFile(
        archive_path, "w", compression=zipfile.ZIP_DEFLATED
    ) as archive:
        for path in package_entries(package_dir):
            relative_path = path.relative_to(package_dir)
            if path.is_dir():
                archive.write(path, f"{relative_path}/")
            else:
                archive.write(path, relative_path)


def package_entries(package_dir: Path) -> list[Path]:
    return sorted(
        package_dir.rglob("*"),
        key=lambda path: path.relative_to(package_dir).as_posix(),
    )