import math

from triangulation import (
    PropagationModel,
    ReceiverSignal,
    SPEED_OF_LIGHT_M_S,
    build_result_payload,
    rssi_to_distance_m,
    solve_from_signal_amplitudes,
    solve_three_sphere_intersection,
    Sphere,
)


def _distance_to_rssi(distance_m: float, frequency_hz: float, model: PropagationModel) -> float:
    fspl_ref_db = 20.0 * math.log10(
        4.0 * math.pi * model.reference_distance_m * frequency_hz / SPEED_OF_LIGHT_M_S
    )
    rx_power_at_ref_dbm = (
        model.tx_power_dbm + model.tx_gain_dbi + model.rx_gain_dbi - fspl_ref_db
    )
    return rx_power_at_ref_dbm - 10.0 * model.path_loss_exponent * math.log10(
        distance_m / model.reference_distance_m
    )


def test_exact_three_sphere_intersection():
    true_point = (2.0, 3.0, 4.0)
    spheres = [
        Sphere(center=(0.0, 0.0, 0.0), radius=math.dist(true_point, (0.0, 0.0, 0.0))),
        Sphere(center=(10.0, 0.0, 0.0), radius=math.dist(true_point, (10.0, 0.0, 0.0))),
        Sphere(center=(0.0, 8.0, 0.0), radius=math.dist(true_point, (0.0, 8.0, 0.0))),
    ]

    result = solve_three_sphere_intersection(spheres=spheres, z_preference="positive")
    assert result.exact
    assert math.isclose(result.point[0], true_point[0], abs_tol=1e-9, rel_tol=0.0)
    assert math.isclose(result.point[1], true_point[1], abs_tol=1e-9, rel_tol=0.0)
    assert math.isclose(result.point[2], true_point[2], abs_tol=1e-9, rel_tol=0.0)


def test_frequency_affects_distance_conversion():
    model = PropagationModel(tx_power_dbm=20.0)
    amplitude = -60.0

    low_freq_distance = rssi_to_distance_m(amplitude, 433e6, model)
    high_freq_distance = rssi_to_distance_m(amplitude, 2.4e9, model)
    assert high_freq_distance < low_freq_distance


def test_pipeline_from_signal_to_payload():
    model = PropagationModel(tx_power_dbm=18.0, path_loss_exponent=2.0)
    true_point = (3.0, 2.0, 1.5)
    receiver_centers = [
        ("r0", (0.0, 0.0, 0.0)),
        ("r1", (8.0, 0.0, 0.0)),
        ("r2", (0.0, 7.0, 0.0)),
    ]
    freqs = [915e6, 920e6, 930e6]

    signals = []
    for (receiver_id, center), freq in zip(receiver_centers, freqs):
        distance = math.dist(true_point, center)
        amplitude = _distance_to_rssi(distance, freq, model)
        signals.append(
            ReceiverSignal(
                receiver_id=receiver_id,
                center=center,
                amplitude_dbm=amplitude,
                frequency_hz=freq,
            )
        )

    result, spheres = solve_from_signal_amplitudes(
        signals=signals, model=model, z_preference="positive"
    )
    payload = build_result_payload(signals, spheres, result, model)

    assert result.exact
    assert math.isclose(result.point[0], true_point[0], abs_tol=1e-7, rel_tol=0.0)
    assert math.isclose(result.point[1], true_point[1], abs_tol=1e-7, rel_tol=0.0)
    assert math.isclose(result.point[2], true_point[2], abs_tol=1e-7, rel_tol=0.0)
    assert "position" in payload
    assert len(payload["receivers"]) == 3