import pytest

from gausse.components.schema import (
    CapacitorSpec,
    ProjectileMaterialSpec,
    SensorSpec,
    SwitchSpec,
    WireSpec,
)
from gausse.sim.coilgun import CoilgunConfig, run_coilgun
from gausse.sim.stage import ProjectileConfig, StageConfig

STEEL = ProjectileMaterialSpec(
    name="steel", density_kg_m3=7850.0, mu_r=200.0, b_sat_tesla=1.8, price_per_kg=100.0, source="test"
)
PROJECTILE = ProjectileConfig(material=STEEL, diameter_m=0.008, length_m=0.02)
CAPACITOR = CapacitorSpec(
    part_number="c1", capacitance_uf=100.0, voltage_v=400.0, esr_ohm=0.05, max_current_a=300.0,
    price=300.0, source="test",
)
WIRE = WireSpec(
    part_id="w1", material="copper", gauge_mm=0.8, insulation_od_mm=0.85,
    resistivity_ohm_m=1.68e-8, max_current_a=10.0, price_per_m=3.0, source="test",
)
SWITCH = SwitchSpec(
    part_number="sw1", kind="MOSFET", max_current_a=200.0, max_voltage_v=500.0,
    on_resistance_ohm=0.02, on_voltage_drop_v=None, turn_on_time_ns=50.0, price=50.0, source="test",
)
OPTICAL_SENSOR = SensorSpec(
    part_number="s1", kind="optical", propagation_delay_ns=500.0, price=20.0, source="test"
)
WEAK_INDUCTIVE_SENSOR = SensorSpec(
    part_number="s2", kind="inductive", propagation_delay_ns=0.0, price=5.0, source="test",
    sensitivity_v_per_mps=0.001, threshold_v=1.0,
)


def _stage(sensor=OPTICAL_SENSOR, sensor_to_coil_distance_m=0.02):
    return StageConfig(
        wire=WIRE,
        capacitor=CAPACITOR,
        switch=SWITCH,
        sensor=sensor,
        tube_od_m=0.01,
        turns_per_layer=20,
        layers=4,
        sensor_to_coil_distance_m=sensor_to_coil_distance_m,
        charge_voltage_v=350.0,
    )


def test_three_stage_chain_is_feasible_and_accelerates():
    config = CoilgunConfig(
        stages=[_stage(), _stage(), _stage()],
        inter_stage_gaps_m=[0.05, 0.05],
        projectile=PROJECTILE,
        initial_x_m=-0.05,
        initial_v_mps=5.0,
    )
    result = run_coilgun(config)
    assert result.feasible, result.reason
    assert len(result.stage_outcomes) == 3
    assert result.exit_v_mps > 5.0
    assert 0.0 < result.efficiency < 1.0


def test_global_coil_centers_accumulate_gaps():
    config = CoilgunConfig(
        stages=[_stage(), _stage(), _stage()],
        inter_stage_gaps_m=[0.05, 0.07],
        projectile=PROJECTILE,
        initial_x_m=-0.05,
        initial_v_mps=5.0,
    )
    result = run_coilgun(config)
    assert result.feasible, result.reason
    centers = [o.global_coil_center_m for o in result.stage_outcomes]
    assert centers == pytest.approx([0.0, 0.05, 0.12])


def test_infeasible_stage_stops_chain_with_honest_reason():
    # у слабого индукционного датчика порог 1В при чувствительности 0.001В/(м/с)
    # требует скорости 1000 м/с, которой у снаряда не будет -> ступень 2 обязана провалиться
    config = CoilgunConfig(
        stages=[_stage(), _stage(sensor=WEAK_INDUCTIVE_SENSOR), _stage()],
        inter_stage_gaps_m=[0.05, 0.05],
        projectile=PROJECTILE,
        initial_x_m=-0.05,
        initial_v_mps=5.0,
    )
    result = run_coilgun(config)
    assert not result.feasible
    assert result.failed_stage_index == 1
    assert "индукционный датчик" in result.reason
    # ступень 2 (индекс 2) не должна была даже запуститься
    assert len(result.stage_outcomes) == 2


def test_efficiency_never_exceeds_one_even_with_large_initial_velocity():
    """Регрессия: КПД считался как exit_KE/energy_in, а не как ДОБАВЛЕННАЯ
    катушками энергия/energy_in. Для лёгкого снаряда с большой заданной
    initial_v_mps (внешний "толчок", не учтённый в energy_in) это давало
    КПД > 100% -- физически бессмысленно, найдено реальным sweep на Этапе 8."""
    light_projectile = ProjectileConfig(material=STEEL, diameter_m=0.003, length_m=0.005)
    config = CoilgunConfig(
        stages=[_stage()],
        inter_stage_gaps_m=[],
        projectile=light_projectile,
        initial_x_m=-0.05,
        initial_v_mps=50.0,  # заведомо большой "бесплатный" толчок относительно массы снаряда
    )
    result = run_coilgun(config)
    assert result.feasible, result.reason
    assert result.efficiency <= 1.0 + 1e-9
    # и КПД действительно равен добавленной энергии, а не абсолютной exit-КЭ
    expected = result.total_kinetic_energy_delta_j / result.total_energy_in_j
    assert result.efficiency == pytest.approx(expected)


def test_mismatched_gap_count_raises():
    with pytest.raises(ValueError):
        CoilgunConfig(
            stages=[_stage(), _stage()],
            inter_stage_gaps_m=[0.05, 0.05],
            projectile=PROJECTILE,
            initial_x_m=-0.05,
            initial_v_mps=5.0,
        )