from __future__ import annotations

import struct

from bakrest.usn_journal import (
    USN_REASON_BASIC_INFO_CHANGE,
    USN_REASON_CLOSE,
    USN_REASON_DATA_EXTEND,
    USN_REASON_DATA_OVERWRITE,
    USN_REASON_FILE_CREATE,
    USN_REASON_RENAME_NEW_NAME,
    is_meaningful_usn_reason,
    parse_usn_records,
)


def test_usn_reason_filter_accepts_real_data_changes() -> None:
    assert is_meaningful_usn_reason(USN_REASON_DATA_OVERWRITE)
    assert is_meaningful_usn_reason(USN_REASON_DATA_EXTEND | USN_REASON_CLOSE)
    assert is_meaningful_usn_reason(USN_REASON_FILE_CREATE)
    assert is_meaningful_usn_reason(USN_REASON_RENAME_NEW_NAME)


def test_usn_reason_filter_rejects_metadata_only_changes() -> None:
    assert not is_meaningful_usn_reason(USN_REASON_BASIC_INFO_CHANGE)
    assert not is_meaningful_usn_reason(USN_REASON_CLOSE)


def test_parse_usn_record_v2_reason_and_file_reference() -> None:
    record = bytearray(64)
    struct.pack_into("<IHH", record, 0, 64, 2, 0)
    struct.pack_into("<Q", record, 8, 12345)
    struct.pack_into("<I", record, 40, USN_REASON_DATA_OVERWRITE)

    records = parse_usn_records(bytes(record))

    assert len(records) == 1
    assert records[0].file_reference_number == 12345
    assert records[0].reason == USN_REASON_DATA_OVERWRITE


def test_parse_usn_record_v3_reason_and_file_reference() -> None:
    record = bytearray(80)
    struct.pack_into("<IHH", record, 0, 80, 3, 0)
    record[8:24] = (12345).to_bytes(16, "little")
    struct.pack_into("<I", record, 56, USN_REASON_FILE_CREATE)

    records = parse_usn_records(bytes(record))

    assert len(records) == 1
    assert records[0].file_reference_number == 12345
    assert records[0].reason == USN_REASON_FILE_CREATE