#include <catch2/catch_test_macros.hpp>
#include "../src/physics.h"
#include "../src/simulation.h"
#include "../src/config_loader.h"
#include "../src/test_utilities.h"
#include <cmath>

TEST_CASE("Orbital period - Earth (RK4)", "[period][rk4]") {
    const double TIME_STEP = 60.0;
    const double EXPECTED_PERIOD_DAYS = 365.0;
    const double SECONDS_PER_DAY = 86400.0;
    const double MAX_SIMULATION_DAYS = 400.0;

    SimulationState* sim = create_simulation(10, 0, 0, TIME_STEP);

    REQUIRE(load_system_config(sim, "tests/test_orbital_period.toml"));

    OrbitTracker* tracker = create_orbit_tracker(1);

    double max_time = MAX_SIMULATION_DAYS * SECONDS_PER_DAY;
    while (sim->time < max_time && !tracker->orbit_completed) {
        update_simulation(sim);
        update_orbit_tracker(tracker, &sim->bodies[1], &sim->bodies[0], sim->time);
    }

    REQUIRE(tracker->orbit_completed);

    double measured_period_days = tracker->time_at_completion / SECONDS_PER_DAY;
    double period_error_days = fabs(measured_period_days - EXPECTED_PERIOD_DAYS);

    INFO("Expected period: " << EXPECTED_PERIOD_DAYS << " days");
    INFO("Measured period: " << measured_period_days << " days");
    INFO("Error: " << period_error_days << " days");

    REQUIRE(period_error_days < 5.0);

    destroy_orbit_tracker(tracker);
    destroy_simulation(sim);
}

TEST_CASE("Orbital period - Mars (RK4)", "[period][rk4]") {
    const double TIME_STEP = 60.0;
    const double EXPECTED_PERIOD_DAYS = 687.0;
    const double SECONDS_PER_DAY = 86400.0;
    const double MAX_SIMULATION_DAYS = 750.0;

    SimulationState* sim = create_simulation(10, 0, 0, TIME_STEP);

    REQUIRE(load_system_config(sim, "tests/test_orbital_period.toml"));

    OrbitTracker* tracker = create_orbit_tracker(2);

    double max_time = MAX_SIMULATION_DAYS * SECONDS_PER_DAY;
    while (sim->time < max_time && !tracker->orbit_completed) {
        update_simulation(sim);
        update_orbit_tracker(tracker, &sim->bodies[2], &sim->bodies[0], sim->time);
    }

    REQUIRE(tracker->orbit_completed);

    double measured_period_days = tracker->time_at_completion / SECONDS_PER_DAY;
    double period_error_days = fabs(measured_period_days - EXPECTED_PERIOD_DAYS);

    INFO("Expected period: " << EXPECTED_PERIOD_DAYS << " days");
    INFO("Measured period: " << measured_period_days << " days");
    INFO("Error: " << period_error_days << " days");

    REQUIRE(period_error_days < 25.0);

    destroy_orbit_tracker(tracker);
    destroy_simulation(sim);
}

TEST_CASE("Orbit direction - prograde for zero inclination", "[direction]") {
    const double TIME_STEP = 60.0;
    const double TEST_DURATION_DAYS = 1.0;
    const double SECONDS_PER_DAY = 86400.0;
    const int STEPS = (int)(TEST_DURATION_DAYS * SECONDS_PER_DAY / TIME_STEP);

    SimulationState* sim = create_simulation(2, 0, 0, TIME_STEP);
    REQUIRE(load_system_config(sim, "tests/test_energy.toml"));

    CelestialBody* sun = &sim->bodies[0];
    CelestialBody* earth = &sim->bodies[1];

    Vec3 initial_rel_pos = vec3_sub(earth->global_position, sun->global_position);
    double theta_start = atan2(initial_rel_pos.y, initial_rel_pos.x);

    for (int i = 0; i < STEPS; i++) {
        update_simulation(sim);
    }

    Vec3 final_rel_pos = vec3_sub(earth->global_position, sun->global_position);
    double theta_final = atan2(final_rel_pos.y, final_rel_pos.x);

    INFO("Initial angle: " << theta_start << " rad");
    INFO("Final angle: " << theta_final << " rad");

    REQUIRE(theta_final > theta_start);

    destroy_simulation(sim);
}