"""Быстрые проверки формата управляющих сообщений: protocol/control_messages.py.

Перенесено из функциональных проверок Lab041, где эти свойства
проверялись только при полном запуске лабораторной.
"""

from __future__ import annotations

import pytest

from protocol.control_messages import (
    COMMON_SIZE,
    ControlMessageError,
    ControlStateMessage,
    EmergencyAck,
    EmergencyStop,
    MessageContext,
    MessageType,
    MovementAuthorizeAck,
    MovementAuthorizeRequest,
    ResetAck,
    ResetRequest,
    RoverSafetyCode,
    SequenceComparison,
    SessionHello,
    SessionReject,
    SessionRejectReason,
    SessionStatus,
    compare_sequence,
    decode_message,
    encode_message,
)


CONTEXT = MessageContext(11, 22, 33, 44)

ALL_MESSAGES = (
    SessionHello(CONTEXT, True, 101),
    SessionStatus(CONTEXT, RoverSafetyCode.ROVER_SESSION_SYNCED_SAFE, False, 0),
    MovementAuthorizeRequest(CONTEXT, 201),
    MovementAuthorizeAck(CONTEXT, 201, True),
    ControlStateMessage(CONTEXT, 1.25, -0.5, False, True),
    EmergencyStop(CONTEXT, 301),
    EmergencyAck(CONTEXT, 301),
    ResetRequest(CONTEXT, 301, 401, 0.0, False),
    ResetAck(CONTEXT, 301, 401, True, SessionRejectReason.ACCEPTED),
    SessionReject(CONTEXT, MessageType.CONTROL_STATE, SessionRejectReason.CONTROL_EPOCH),
)


@pytest.mark.parametrize("message", ALL_MESSAGES, ids=lambda m: type(m).__name__)
def test_roundtrip_is_exact(message) -> None:
    assert decode_message(encode_message(message)) == message


def test_every_message_type_is_covered() -> None:
    """Если добавится тип сообщения, этот тест обязан упасть."""

    assert len(ALL_MESSAGES) == len(MessageType)


@pytest.mark.parametrize("message", ALL_MESSAGES, ids=lambda m: type(m).__name__)
def test_encoding_starts_with_the_common_header(message) -> None:
    encoded = encode_message(message)
    assert len(encoded) >= COMMON_SIZE
    assert encoded[0] == 1


def test_wrong_version_is_rejected() -> None:
    payload = bytearray(encode_message(SessionHello(CONTEXT, False, 0)))
    payload[0] = 2
    with pytest.raises(ControlMessageError):
        decode_message(bytes(payload))


def test_unknown_type_is_rejected() -> None:
    payload = bytearray(encode_message(SessionHello(CONTEXT, False, 0)))
    payload[1] = 255
    with pytest.raises(ControlMessageError):
        decode_message(bytes(payload))


def test_truncated_message_is_rejected() -> None:
    payload = encode_message(SessionHello(CONTEXT, False, 0))
    for cut in (0, 1, COMMON_SIZE - 1, len(payload) - 1):
        with pytest.raises(ControlMessageError):
            decode_message(payload[:cut])


# ------------------------------------------------------- диапазоны команд движения


@pytest.mark.parametrize(
    "speed,turn,braking,permitted",
    [
        (15.1, 0.0, False, True),   # выше предела
        (-0.1, 0.0, False, True),   # отрицательная скорость
        (-5.0, 0.0, False, True),
        (1.0, 1.1, False, True),    # поворот вне диапазона
        (1.0, -1.1, False, True),
        (1.0, 0.0, True, False),    # торможение при ненулевой скорости
        (1.0, 0.0, False, False),   # движение без разрешения
    ],
)
def test_invalid_control_state_is_rejected(speed, turn, braking, permitted) -> None:
    with pytest.raises(ControlMessageError):
        encode_message(ControlStateMessage(CONTEXT, speed, turn, braking, permitted))


@pytest.mark.parametrize(
    "speed,turn,braking,permitted",
    [
        (0.0, 0.0, True, False),
        (15.0, 0.0, False, True),
        (0.0, 0.0, False, False),
        (7.5, 1.0, False, True),
        (7.5, -1.0, False, True),
    ],
)
def test_valid_control_state_is_accepted(speed, turn, braking, permitted) -> None:
    message = ControlStateMessage(CONTEXT, speed, turn, braking, permitted)
    assert decode_message(encode_message(message)) == message


@pytest.mark.parametrize("bad", [float("nan"), float("inf"), float("-inf")])
def test_non_finite_speed_is_rejected(bad: float) -> None:
    with pytest.raises(ControlMessageError):
        encode_message(ControlStateMessage(CONTEXT, bad, 0.0, False, True))


# ------------------------------------------------------- сравнение номеров сообщений


def test_sequence_comparison_basic_order() -> None:
    assert compare_sequence(5, 4) is SequenceComparison.NEWER
    assert compare_sequence(4, 5) is SequenceComparison.NOT_NEWER
    assert compare_sequence(4, 4) is SequenceComparison.NOT_NEWER


def test_sequence_comparison_wraps_at_32_bits() -> None:
    """Переход через 0xFFFFFFFF обязан считаться новым, а не откатом."""

    assert compare_sequence(0, 0xFFFFFFFF) is SequenceComparison.NEWER
    assert compare_sequence(1, 0xFFFFFFFE) is SequenceComparison.NEWER


def test_ambiguous_half_range_is_rejected() -> None:
    """Разность ровно 2^31 неотличима от отката и должна отклоняться."""

    assert compare_sequence(0x80000000, 0) is SequenceComparison.AMBIGUOUS
    assert compare_sequence(0, 0x80000000) is SequenceComparison.AMBIGUOUS


def test_just_below_the_ambiguous_boundary_is_newer() -> None:
    assert compare_sequence(0x7FFFFFFF, 0) is SequenceComparison.NEWER