from decimal import Decimal
from pathlib import Path

from scripts.p1_probe import IntegrityStatus, TelegramFramer, parse_telegram


FIXTURES = Path(__file__).parent / "fixtures"


def _fixture(name: str) -> bytes:
    return (FIXTURES / name).read_bytes()


def test_standard_dsmr_fixture_has_a_valid_frame_and_crc():
    frame = _fixture("dsmr_p1_valid.txt")
    framer = TelegramFramer()

    assert framer.feed(frame[:23]) == []
    assert framer.feed(frame[23:]) == [frame]

    telegram = parse_telegram(frame)
    assert telegram.integrity is IntegrityStatus.VALID
    assert telegram.header == b"/ISk5\\2MT382-1000"
    assert telegram.timestamp == "240822120000S"


def test_warmtelink_fixture_is_unverifiable_but_parses_channels_by_obis_code():
    telegram = parse_telegram(_fixture("warmtelink_p1_7n1.txt"))

    assert telegram.integrity is IntegrityStatus.UNVERIFIABLE
    assert "missing standard" in telegram.integrity_reason
    assert [channel.number for channel in telegram.channels] == [1, 2]
    values = {
        channel.number: [(field.value, field.unit) for field in channel.readings]
        for channel in telegram.channels
    }
    assert values[1] == [(Decimal("5.900"), "m3")]
    assert values[2] == [(Decimal("0.017"), "GJ")]


def test_arbitrary_chunk_boundaries_and_field_order_do_not_change_parsing():
    frame = _fixture("warmtelink_p1_7n1.txt")
    framer = TelegramFramer()
    frames = []
    for byte in frame:
        frames.extend(framer.feed(bytes([byte])))

    assert frames == [frame]
    assert parse_telegram(frames[0]).channels == parse_telegram(frame).channels


def test_unknown_fields_are_preserved_verbatim():
    frame = b")HEADER\n9-9:9.9.9(opaque)(still-opaque)\n!nope\n"

    telegram = parse_telegram(frame)

    assert len(telegram.fields) == 1
    assert telegram.fields[0].code == "9-9:9.9.9"
    assert telegram.fields[0].raw_values == ("opaque", "still-opaque")
    assert telegram.fields[0].value is None


def test_missing_header_and_non_hex_footer_are_unverifiable():
    telegram = parse_telegram(b")HEADER\n0-0:1.0.0(240822120000S)\n!zzzz\n")

    assert telegram.integrity is IntegrityStatus.UNVERIFIABLE
    assert telegram.footer == b"zzzz"


def test_crc_mismatch_is_invalid_when_standard_framing_is_present():
    frame = _fixture("dsmr_p1_valid.txt")
    invalid = frame[:-5] + b"0000\n"

    telegram = parse_telegram(invalid)

    assert telegram.integrity is IntegrityStatus.INVALID