"""Unit: phase 106 task 03 — mtime-preserving archive unpack (D2).

Pins the date source of the upload path: a zip member's DOS
``date_time`` and a tar member's ``mtime`` survive the unpack as the
extracted file's atime+mtime, so the importer (task 04) reads the
archive's ORIGINAL file dates — the owner's "file metadata (hopefully)
preserved in the tar or zip archive process" made real.

Regular files only: directories/symlinks/hardlinks are untouched (they
carry the extraction-time values, never the member's). The safety
behavior (zip-slip, absolute members, link targets, the extraction
cap) is unchanged and pinned by ``tests/unit/test_archive_upload.py``
— this file adds only the date pins.
"""
from __future__ import annotations

import os
import tarfile
import zipfile
from datetime import UTC, datetime
from io import BytesIO
from pathlib import Path

from app.rag.archive_upload import unpack_archive

#: The old member timestamp both fixtures carry: 2020-01-02 03:04:06
#: UTC — the zip as the DOS tuple ``(2020, 1, 2, 3, 4, 6)``, the tar
#: as the epoch seconds.
OLD_MTIME = datetime(2020, 1, 2, 3, 4, 6, tzinfo=UTC)
OLD_EPOCH = OLD_MTIME.timestamp()  # 1577934246.0

#: mtime granularity tolerance (the task pin: ±1 s).
_TOLERANCE_S = 1.0

_PAYLOAD = b"# Old note\ncontent from 2020\n"


def _zip_with_old_mtime(path: Path) -> None:
    """A two-member zip (a directory + one file), both carrying the
    old fixed ``date_time`` tuple."""
    with zipfile.ZipFile(path, "w") as zf:
        dir_info = zipfile.ZipInfo("docs/", date_time=(2020, 1, 2, 3, 4, 6))
        dir_info.external_attr = (0o40755 << 16)
        zf.writestr(dir_info, b"")
        file_info = zipfile.ZipInfo("docs/note.md", date_time=(2020, 1, 2, 3, 4, 6))
        file_info.external_attr = (0o100644 << 16)
        zf.writestr(file_info, _PAYLOAD)


def _tar_with_old_mtime(path: Path) -> None:
    """A two-member tar (a directory + one file), both carrying the
    old epoch ``mtime``."""
    with tarfile.open(path, "w") as tf:
        dir_ti = tarfile.TarInfo("docs/")
        dir_ti.type = tarfile.DIRTYPE
        dir_ti.mode = 0o755
        dir_ti.mtime = OLD_EPOCH
        tf.addfile(dir_ti)
        file_ti = tarfile.TarInfo("docs/note.md")
        file_ti.size = len(_PAYLOAD)
        file_ti.mode = 0o644
        file_ti.mtime = OLD_EPOCH
        tf.addfile(file_ti, BytesIO(_PAYLOAD))


def _extract(archive: Path, tmp_path: Path) -> tuple[Path, os.stat_result]:
    """Unpack ``archive``; return (file path, pre-read stat). The stat
    happens BEFORE the content read (a read refreshes atime under
    relatime — the atime pin needs the unpacked value); the content is
    asserted byte-identical (the mtime work moved no bytes)."""
    target = tmp_path / "out"
    unpack_archive(archive, target, max_extract_bytes=1 << 20)
    dest = target / "docs" / "note.md"
    st = dest.stat()  # before the read — reading would refresh atime
    assert dest.read_bytes() == _PAYLOAD
    return dest, st


def test_zip_member_mtime_is_restored(tmp_path: Path) -> None:
    """A zip member's DOS ``date_time`` lands as the extracted file's
    mtime (and atime — ``os.utime(ns=(t, t))`` sets both), within the
    mtime-granularity tolerance."""
    archive = tmp_path / "old.zip"
    _zip_with_old_mtime(archive)
    _dest, st = _extract(archive, tmp_path)
    assert abs(st.st_mtime - OLD_EPOCH) <= _TOLERANCE_S
    assert abs(st.st_atime - OLD_EPOCH) <= _TOLERANCE_S


def test_tar_member_mtime_is_restored(tmp_path: Path) -> None:
    """A tar member's epoch ``mtime`` lands as the extracted file's
    mtime (and atime), within the mtime-granularity tolerance."""
    archive = tmp_path / "old.tar"
    _tar_with_old_mtime(archive)
    _dest, st = _extract(archive, tmp_path)
    assert abs(st.st_mtime - OLD_EPOCH) <= _TOLERANCE_S
    assert abs(st.st_atime - OLD_EPOCH) <= _TOLERANCE_S


def test_zip_directory_member_mtime_is_not_restored(tmp_path: Path) -> None:
    """Regular files ONLY: a zip directory member carrying the old
    ``date_time`` keeps the EXTRACTION-time mtime (≈ now, long after
    the old 2020 value) — directories are never indexed, so their
    dates don't matter; the pin is that the unpacker doesn't utime
    them (the task contract)."""
    archive = tmp_path / "old.zip"
    _zip_with_old_mtime(archive)
    target = tmp_path / "out"
    unpack_archive(archive, target, max_extract_bytes=1 << 20)
    assert (target / "docs").stat().st_mtime > OLD_EPOCH + _TOLERANCE_S


def test_tar_directory_member_mtime_is_not_restored(tmp_path: Path) -> None:
    """The tar twin of the zip directory pin: a directory member with
    the old ``mtime`` is not utime'd (regular files only)."""
    archive = tmp_path / "old.tar"
    _tar_with_old_mtime(archive)
    target = tmp_path / "out"
    unpack_archive(archive, target, max_extract_bytes=1 << 20)
    assert (target / "docs").stat().st_mtime > OLD_EPOCH + _TOLERANCE_S