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

using Catch::Matchers::WithinAbs;

SCENARIO("Orbital period measurement with analytical propagation",
         "[period][analytical]") {
    const double TIME_STEP = 60.0;
    const double SECONDS_PER_DAY = 86400.0;

    SimulationState* sim = create_simulation(10, 0, 0, TIME_STEP);
    REQUIRE(load_system_config(sim, "tests/test_orbital_period.toml"));

    SECTION("Earth completes one orbit in ~365 days") {
        OrbitTracker* tracker = create_orbit_tracker(1);
        CelestialBody* earth = &sim->bodies[1];
        CelestialBody* sun = &sim->bodies[0];

        const double MAX_DAYS = 400.0;
        const double max_time = MAX_DAYS * SECONDS_PER_DAY;

        while (sim->time < max_time && !tracker->orbit_completed) {
            update_simulation(sim);
            update_orbit_tracker(tracker, earth, sun, sim->time);
        }

        REQUIRE(tracker->orbit_completed);

        double measured_days = tracker->time_at_completion / SECONDS_PER_DAY;
        INFO("Measured period: " << measured_days << " days");

        REQUIRE_THAT(measured_days, WithinAbs(365.2105, 0.1));

        destroy_orbit_tracker(tracker);
    }

    SECTION("Mars completes one orbit in ~671 days") {
        OrbitTracker* tracker = create_orbit_tracker(2);
        CelestialBody* mars = &sim->bodies[2];
        CelestialBody* sun = &sim->bodies[0];

        const double MAX_DAYS = 750.0;
        const double max_time = MAX_DAYS * SECONDS_PER_DAY;

        while (sim->time < max_time && !tracker->orbit_completed) {
            update_simulation(sim);
            update_orbit_tracker(tracker, mars, sun, sim->time);
        }

        REQUIRE(tracker->orbit_completed);

        double measured_days = tracker->time_at_completion / SECONDS_PER_DAY;
        INFO("Measured period: " << measured_days << " days");

        REQUIRE_THAT(measured_days, WithinAbs(670.9345, 0.1));

        destroy_orbit_tracker(tracker);
    }
}

SCENARIO("Orbit direction for zero inclination",
         "[direction][sanity]") {
    const double TIME_STEP = 60.0;
    const double TEST_DURATION_DAYS = 1.0;
    const int STEPS = (int)(TEST_DURATION_DAYS * 86400.0 / 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 = vec3_sub(earth->global_position, sun->global_position);
    double theta_start = atan2(initial_rel.y, initial_rel.x);

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

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

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

    REQUIRE_THAT(delta, WithinAbs(0.0172042841, 1e-6));
    REQUIRE(delta > 0.0);
}