from __future__ import annotations

import tarfile
import unittest
from unittest.mock import patch

from govoplan_files.backend.storage.archives import _inspect_archive_content, _safe_member_path, inspect_archive
from govoplan_files.backend.storage.common import FileStorageError
from test_archives import _tar_bytes, _zip_bytes


class _HeadersOnly:
    def __init__(self, count: int, size: int = 0):
        self.count = count
        self.size = size
        self.seen = 0

    def __enter__(self):
        return self

    def __exit__(self, *args):
        return False

    def getmembers(self):
        raise AssertionError("TAR preview must not inflate every member before checking limits")

    def __iter__(self):
        for index in range(self.count):
            member = tarfile.TarInfo(f"file-{index}.txt")
            member.size = self.size
            self.seen += 1
            yield member
        raise AssertionError("Inspection advanced beyond the rejecting header")


class ArchiveInspectionBoundTests(unittest.TestCase):
    def test_tar_entry_limit_stops_at_first_excess_header(self):
        headers = _HeadersOnly(4)
        with patch("govoplan_files.backend.storage.archives._open_tar", return_value=headers):
            with self.assertRaisesRegex(FileStorageError, "too many entries"):
                _inspect_archive_content(b"fixture", filename="fixture.tar.gz", max_entries=2)
        self.assertEqual(3, headers.seen)

    def test_tar_expanded_size_rejected_before_payload_decompression(self):
        headers = _HeadersOnly(1, size=100)
        with patch("govoplan_files.backend.storage.archives._open_tar", return_value=headers):
            with self.assertRaisesRegex(FileStorageError, "too large after extraction"):
                _inspect_archive_content(b"fixture", filename="fixture.tar.gz", max_expanded_bytes=10)
        self.assertEqual(1, headers.seen)

    def test_tar_ratio_rejected_before_payload_decompression(self):
        headers = _HeadersOnly(1, size=100)
        with patch("govoplan_files.backend.storage.archives._open_tar", return_value=headers):
            with self.assertRaisesRegex(FileStorageError, "expansion ratio"):
                _inspect_archive_content(b"fixture", filename="fixture.tar.gz", max_expansion_ratio=2)

    def test_derived_directories_are_included_in_entry_limit(self):
        for filename, payload in (("fixture.zip", _zip_bytes({"a/b/c/file.txt": b"x"})), ("fixture.tar.gz", _tar_bytes({"a/b/c/file.txt": b"x"}))):
            with self.subTest(filename=filename), self.assertRaisesRegex(FileStorageError, "including parent directories"):
                inspect_archive(payload, filename=filename, max_entries=3)

    def test_extreme_path_depth_and_byte_lengths_fail_before_deriving_directories(self):
        for path, error in (("a/" * 128 + "file.txt", "components"), ("ü" * 2049, "UTF-8 bytes")):
            with self.subTest(path_length=len(path)), self.assertRaisesRegex(FileStorageError, error):
                inspect_archive(_zip_bytes({path: b"x"}), filename="fixture.zip")

    def test_directory_at_exact_depth_limit_accepts_trailing_separator(self):
        path = "a/" * 128
        self.assertEqual(path.rstrip("/"), _safe_member_path(path))

    def test_invalid_unicode_member_name_has_controlled_validation_error(self):
        with self.assertRaisesRegex(FileStorageError, "not valid Unicode"):
            _safe_member_path("invalid-\udcff.txt")


if __name__ == "__main__":
    unittest.main()