"""Проверки protocol/bpsk_radio.py.

Модуль был собран переносом функций из Lab018, Lab019 и Lab023. Главная
задача этих проверок — доказать, что перенос ничего не изменил: результаты
сравниваются с оригиналами, загруженными из лабораторных в изоляции, без
выполнения их модульного кода.
"""

from __future__ import annotations

import ast
import math
import pathlib
import struct

import numpy as np
import pytest

from protocol import bpsk_radio as radio
from protocol.packet import MESSAGE_TYPE_IMAGE_FRAGMENT, build_packet, parse_packet


PROJECT_ROOT = pathlib.Path(__file__).resolve().parent.parent
SHARED_CONSTANTS = {
    "RADIO_SYNC_WORD",
    "PREAMBLE_BIT_COUNT",
    "SYMBOL_RATE",
    "CFO_REFINEMENT_HALF_WIDTH_HZ",
    "CFO_REFINEMENT_STEP_HZ",
}


def _load_isolated(relative_path: str, function_names: set[str]) -> dict:
    """Выполнить только заданные функции лабораторной, без кода модуля.

    Лабораторные при импорте создают каталоги и пишут файлы, поэтому
    импортировать их в тестах нельзя.
    """

    path = PROJECT_ROOT / relative_path
    tree = ast.parse(path.read_text(encoding="utf-8"))
    kept = [
        node
        for node in tree.body
        if (isinstance(node, ast.FunctionDef) and node.name in function_names)
        or (isinstance(node, ast.Assign) and ast.unparse(node.targets[0]) in SHARED_CONSTANTS)
    ]
    namespace: dict = {"np": np, "struct": struct}
    exec(compile(ast.Module(body=kept, type_ignores=[]), str(path), "exec"), namespace)
    return namespace


@pytest.fixture(scope="module")
def original_lab023() -> dict:
    return _load_isolated(
        "experiments/lab023_guarded_cfo_correction.py",
        {
            "bytes_to_bits",
            "bits_to_bytes",
            "bpsk_modulate",
            "bpsk_demodulate",
            "estimate_carrier_parameters",
            "correct_phase_and_frequency",
        },
    )


@pytest.fixture(scope="module")
def original_lab019() -> dict:
    return _load_isolated(
        "experiments/lab019_bpsk_receiver.py",
        {
            "build_frame_marker",
            "find_radio_frame",
            "bytes_to_bits",
            "bits_to_bytes",
            "bpsk_modulate",
            "bpsk_demodulate",
            "root_raised_cosine_taps",
        },
    )


@pytest.fixture(scope="module")
def original_lab018() -> dict:
    return _load_isolated("experiments/lab018_bpsk_radio_frame.py", {"root_raised_cosine_taps"})


def _identical(left, right) -> bool:
    if isinstance(left, np.ndarray) or isinstance(right, np.ndarray):
        return np.array_equal(np.asarray(left), np.asarray(right))
    if isinstance(left, dict):
        return sorted(left) == sorted(right) and all(_identical(left[k], right[k]) for k in left)
    if isinstance(left, (tuple, list)):
        return len(left) == len(right) and all(_identical(a, b) for a, b in zip(left, right))
    return left == right


# ---------------------------------------------------------------- эквивалентность


@pytest.mark.parametrize("length", [1, 7, 64, 255])
def test_bit_conversion_matches_lab023(original_lab023: dict, length: int) -> None:
    data = bytes(np.random.default_rng(length).integers(0, 256, size=length, dtype=np.uint8))
    ours = radio.bytes_to_bits(data)
    assert _identical(ours, original_lab023["bytes_to_bits"](data))
    assert _identical(radio.bits_to_bytes(ours), original_lab023["bits_to_bytes"](ours))


@pytest.mark.parametrize("length", [8, 64, 256])
def test_modulation_matches_lab023(original_lab023: dict, length: int) -> None:
    bits = np.random.default_rng(length).integers(0, 2, size=length).astype(np.uint8)
    ours = radio.bpsk_modulate(bits)
    assert _identical(ours, original_lab023["bpsk_modulate"](bits))
    assert _identical(radio.bpsk_demodulate(ours), original_lab023["bpsk_demodulate"](ours))


@pytest.mark.parametrize("rolloff,sps,span", [(0.35, 32, 10), (0.35, 128, 10), (0.5, 64, 8)])
def test_shaping_filter_matches_lab018(original_lab018: dict, rolloff: float, sps: int, span: int) -> None:
    assert _identical(
        radio.root_raised_cosine_taps(rolloff, sps, span),
        original_lab018["root_raised_cosine_taps"](rolloff, sps, span),
    )


def test_frame_marker_matches_lab019(original_lab019: dict) -> None:
    """Маркер возвращает пару: биты и символы. Совпасть должны обе."""

    assert _identical(radio.build_frame_marker(), original_lab019["build_frame_marker"]())


@pytest.mark.parametrize("seed", [1, 2, 3])
def test_carrier_estimation_matches_lab023(original_lab023: dict, seed: int) -> None:
    """Оценка ухода частоты обязана совпасть при произвольных фазе и уходе."""

    rng = np.random.default_rng(seed)
    _, marker = radio.build_frame_marker()
    phase = float(rng.uniform(-3.0, 3.0))
    increment = float(rng.uniform(-0.005, 0.005))
    impaired = marker * np.exp(1j * (phase + increment * np.arange(len(marker))))
    impaired = impaired + 0.02 * rng.standard_normal(len(marker))

    assert _identical(
        radio.estimate_carrier_parameters(impaired, marker),
        original_lab023["estimate_carrier_parameters"](impaired, marker),
    )
    assert _identical(
        radio.correct_phase_and_frequency(impaired, phase, increment),
        original_lab023["correct_phase_and_frequency"](impaired, phase, increment),
    )


# ---------------------------------------------------------------- новые функции кадра


@pytest.mark.parametrize("payload_size", [1, 17, 512, radio.MAXIMUM_PROTOCOL_PACKET_BYTES])
def test_frame_roundtrip(payload_size: int) -> None:
    packet = bytes(np.random.default_rng(payload_size).integers(0, 256, size=payload_size, dtype=np.uint8))
    bits, symbols, marker = radio.build_radio_frame(packet)

    assert len(bits) == radio.radio_frame_bit_count(payload_size)
    assert len(symbols) == len(bits)
    assert len(marker) == radio.MARKER_BIT_COUNT
    assert radio.parse_radio_frame(bits) == packet


def test_frame_rejects_sizes_outside_range() -> None:
    with pytest.raises(ValueError):
        radio.build_radio_frame(b"")
    with pytest.raises(ValueError):
        radio.build_radio_frame(b"\x00" * (radio.MAXIMUM_PROTOCOL_PACKET_BYTES + 1))
    with pytest.raises(TypeError):
        radio.build_radio_frame("не байты")


def test_frame_with_broken_sync_word_is_rejected() -> None:
    bits, _, _ = radio.build_radio_frame(b"payload")
    broken = bits.copy()
    broken[radio.PREAMBLE_BIT_COUNT] ^= 1
    assert radio.parse_radio_frame(broken) is None


def test_truncated_frame_is_rejected() -> None:
    bits, _, _ = radio.build_radio_frame(b"payload")
    assert radio.parse_radio_frame(bits[:10]) is None
    assert radio.parse_radio_frame(bits[:-8]) is None


def test_frame_carries_a_protocol_packet() -> None:
    """Кадр должен переносить настоящий пакет так, чтобы CRC32 сошлась."""

    packet = build_packet(b"fragment payload", MESSAGE_TYPE_IMAGE_FRAGMENT, 5)
    bits, _, _ = radio.build_radio_frame(packet)
    assert parse_packet(radio.parse_radio_frame(bits)).payload == b"fragment payload"


def test_frame_search_finds_the_start_in_a_shaped_signal() -> None:
    """Сквозная проверка: формирование, фильтрация и поиск кадра."""

    samples_per_symbol = 32
    taps = radio.root_raised_cosine_taps(0.35, samples_per_symbol, 10)
    packet = build_packet(b"HELLO SDR", MESSAGE_TYPE_IMAGE_FRAGMENT, 1)
    bits, symbols, marker = radio.build_radio_frame(packet)

    upsampled = np.zeros(len(symbols) * samples_per_symbol, dtype=complex)
    upsampled[::samples_per_symbol] = symbols
    matched = np.convolve(np.convolve(upsampled, taps, mode="full"), taps, mode="full")

    found = radio.find_radio_frame(matched, marker, samples_per_symbol)
    start = found["start_symbol_index"]
    recovered = found["symbol_samples"][start : start + len(bits)]

    assert radio.parse_radio_frame(radio.bpsk_demodulate(recovered)) == packet


# ------------------------------------------------------ Lab043: общие примитивы


def test_known_tone_peak_search_finds_both_windows() -> None:
    frequencies = np.linspace(-100_000.0, 100_000.0, 4001)
    powers = np.ones_like(frequencies)
    powers[np.argmin(np.abs(frequencies + 51_200.0))] = 100.0
    powers[np.argmin(np.abs(frequencies - 49_300.0))] = 80.0

    peaks = radio.find_known_tone_peaks(frequencies, powers, 50_000.0, 30_000.0)

    assert math.isclose(peaks["low_frequency_hz"], -51_200.0, abs_tol=1.0)
    assert math.isclose(peaks["high_frequency_hz"], 49_300.0, abs_tol=1.0)
    assert peaks["low_power"] == 100.0
    assert peaks["high_power"] == 80.0


def test_known_tone_peak_search_returns_nan_without_bins() -> None:
    frequencies = np.linspace(-1_000.0, 1_000.0, 101)
    powers = np.ones_like(frequencies)
    peaks = radio.find_known_tone_peaks(frequencies, powers, 50_000.0, 1_000.0)

    assert math.isnan(peaks["low_frequency_hz"])
    assert math.isnan(peaks["high_frequency_hz"])


@pytest.mark.parametrize("ppm", [20.0, -20.0, 100.0, -100.0])
def test_two_tone_clock_estimate_has_correct_sign_and_magnitude(ppm: float) -> None:
    scale = 1.0 + ppm * 1e-6
    carrier_offset_hz = -1_250.0
    low = carrier_offset_hz - 50_000.0 * scale
    high = carrier_offset_hz + 50_000.0 * scale

    estimate = radio.estimate_two_tone_offsets(low, high, 50_000.0)

    assert math.isclose(estimate["carrier_offset_hz"], carrier_offset_hz, abs_tol=1e-9)
    assert math.isclose(estimate["clock_scale"], scale, abs_tol=1e-12)
    assert math.isclose(estimate["sample_clock_error_ppm"], ppm, abs_tol=1e-6)


def test_two_tone_invalid_estimate_is_nan_not_zero() -> None:
    estimate = radio.estimate_two_tone_offsets(float("nan"), 50_000.0, 50_000.0)
    assert all(math.isnan(value) for value in estimate.values())


@pytest.mark.parametrize("carrier_offset_hz", [730.0, -730.0])
def test_coarse_frequency_correction_handles_both_signs(carrier_offset_hz: float) -> None:
    sample_rate_hz = 20_000.0
    indexes = np.arange(20_000, dtype=np.float64)
    impaired = np.exp(1j * 2.0 * np.pi * carrier_offset_hz * indexes / sample_rate_hz)

    corrected = radio.apply_coarse_frequency_correction(
        impaired,
        carrier_offset_hz,
        sample_rate_hz,
    )

    assert np.max(np.abs(corrected - 1.0)) < 1e-9


@pytest.mark.parametrize(
    "carrier_offset_hz",
    [-10.0, -5.0, -2.0, -1.2, -1.0, -0.5, 0.5, 1.0, 1.2, 2.0, 5.0, 10.0],
)
def test_known_pilot_estimator_resolves_sub_hertz_cfo_with_hardware_like_phase_noise(
    carrier_offset_hz: float,
) -> None:
    symbol_count = 1_280
    indexes = np.arange(symbol_count, dtype=np.float64)
    known = np.where((indexes.astype(np.int64) * 73 + 19) % 127 < 64, 1.0, -1.0).astype(
        np.complex128
    )
    estimates: list[float] = []
    valid_flags: list[bool] = []
    for repetition in range(96):
        random_generator = np.random.default_rng(
            43_000_000
            + int(round((carrier_offset_hz + 20.0) * 1_000.0))
            + repetition
        )
        phase_noise = random_generator.normal(0.0, 0.4691, symbol_count)
        received = known * np.exp(
            1j
            * (
                2.0 * np.pi * carrier_offset_hz * indexes / radio.SYMBOL_RATE
                + phase_noise
            )
        )
        estimate = radio.estimate_known_pilot_carrier(received, known)
        valid_flags.append(estimate.valid)
        estimates.append(estimate.frequency_hz)

    errors = np.asarray(estimates) - carrier_offset_hz
    assert all(valid_flags)
    assert np.all(np.sign(estimates) == np.sign(carrier_offset_hz))
    assert abs(float(np.mean(errors))) < 0.08
    assert float(np.std(errors, ddof=1)) < 0.18
    assert float(np.percentile(np.abs(errors), 95.0)) < 0.35


def test_known_pilot_estimator_rejects_noise_instead_of_reporting_false_cfo() -> None:
    random_generator = np.random.default_rng(43_043)
    known = np.resize(np.asarray([-1.0, 1.0], dtype=np.complex128), 1_280)
    noise = (
        random_generator.normal(0.0, 1.0, len(known))
        + 1j * random_generator.normal(0.0, 1.0, len(known))
    )

    estimate = radio.estimate_known_pilot_carrier(noise, known)

    assert not estimate.valid
    assert estimate.invalid_reason
    assert math.isnan(estimate.frequency_hz)
    assert math.isnan(estimate.phase_increment_rad_per_symbol)


def _sample_at_positions(signal: np.ndarray, positions: np.ndarray) -> np.ndarray:
    indexes = np.arange(len(signal), dtype=np.float64)
    real = np.interp(positions, indexes, signal.real)
    imaginary = np.interp(positions, indexes, signal.imag)
    return real + 1j * imaginary


@pytest.mark.parametrize("ppm", [20.0, -20.0, 100.0, -100.0])
def test_clock_resampling_direction_reduces_timing_error(ppm: float) -> None:
    scale = 1.0 + ppm * 1e-6
    sample_count = 200_000
    indexes = np.arange(sample_count, dtype=np.float64)
    reference = np.exp(1j * 2.0 * np.pi * 0.071 * indexes)

    received_length = math.floor(sample_count / scale)
    received_positions = np.arange(received_length, dtype=np.float64) * scale
    received = _sample_at_positions(reference, received_positions)

    corrected = radio.resample_for_clock_scale(received, scale)
    wrong_direction = radio.resample_for_clock_scale(received, 1.0 / scale)

    uncorrected_count = min(len(received), len(reference))
    corrected_count = min(len(corrected), len(reference)) - 2
    wrong_count = min(len(wrong_direction), len(reference)) - 2
    uncorrected_error = float(
        np.mean(np.abs(received[:uncorrected_count] - reference[:uncorrected_count]) ** 2)
    )
    corrected_error = float(
        np.mean(np.abs(corrected[:corrected_count] - reference[:corrected_count]) ** 2)
    )
    wrong_error = float(
        np.mean(np.abs(wrong_direction[:wrong_count] - reference[:wrong_count]) ** 2)
    )

    assert len(corrected) == round(len(received) * scale)
    assert corrected_error < uncorrected_error
    assert corrected_error < wrong_error