"""Deterministic archive primitives shared by host and optional plugin builders."""

import gzip
import io
import tarfile
from pathlib import PurePosixPath


def tarball(files):
    names = [name for name, _, _ in files]
    if len(set(names)) != len(names):
        raise ValueError("Duplicate package member")
    if any(PurePosixPath(n).is_absolute() or ".." in PurePosixPath(n).parts for n in names):
        raise ValueError("Unsafe package member")
    stream = io.BytesIO()
    with tarfile.open(fileobj=stream, mode="w", format=tarfile.GNU_FORMAT) as archive:
        directories = {
            str(parent)
            for name in names
            for parent in PurePosixPath(name).parents
            if str(parent) != "."
        }
        for name in sorted(directories):
            item = tarfile.TarInfo(name + "/")
            item.type, item.mode = tarfile.DIRTYPE, 0o755
            item.uname = item.gname = "root"
            archive.addfile(item)
        for name, data, mode in sorted(files):
            item = tarfile.TarInfo(name)
            item.size, item.mode, item.uid, item.gid = len(data), mode, 0, 0
            item.uname = item.gname = "root"
            archive.addfile(item, io.BytesIO(data))
    return gzip.compress(stream.getvalue(), mtime=0)


def ar_member(name, data):
    header = f"{name + '/':<16}{0:<12}{0:<6}{0:<6}{'100644':<8}{len(data):<10}`\n".encode()
    if len(header) != 60:
        raise ValueError("Invalid archive header")
    return header + data + (b"\n" if len(data) % 2 else b"")


def package(controls, files):
    return (
        b"!<arch>\n"
        + ar_member("debian-binary", b"2.0\n")
        + ar_member("control.tar.gz", tarball(controls))
        + ar_member("data.tar.gz", tarball(files))
    )