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

struct TransitionEvent {
    double time_seconds;
    double time_days;
    int old_parent;
    int new_parent;
    char old_name[64];
    char new_name[64];
    double x_position;
    double y_position;
    double z_position;
};

TEST_CASE("Root body transition - Earth to Sun", "[root][transition]") {
    const double TIME_STEP = 60.0;
    const double DAYS_TO_SIMULATE = 500.0;
    const double SECONDS_PER_DAY = 86400.0;
    const double AU = 1.496e11;

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

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

    const int PROBE_INDEX = 3;
    const int SUN_INDEX = 0;

    std::vector<TransitionEvent> transitions;
    int previous_parent = sim->bodies[PROBE_INDEX].parent_index;

    INFO("Initial parent: " << sim->bodies[PROBE_INDEX].name
         << " (parent_index: " << previous_parent << ")");

    double max_time = DAYS_TO_SIMULATE * SECONDS_PER_DAY;
    while (sim->time < max_time) {
        update_simulation(sim);

        int current_parent = sim->bodies[PROBE_INDEX].parent_index;
        if (current_parent != previous_parent) {
            TransitionEvent event;
            event.time_seconds = sim->time;
            event.time_days = sim->time / SECONDS_PER_DAY;
            event.old_parent = previous_parent;
            event.new_parent = current_parent;

            if (previous_parent >= 0 && previous_parent < sim->body_count) {
                strcpy(event.old_name, sim->bodies[previous_parent].name);
            } else {
                strcpy(event.old_name, "Sun");
            }

            if (current_parent >= 0 && current_parent < sim->body_count) {
                strcpy(event.new_name, sim->bodies[current_parent].name);
            } else {
                strcpy(event.new_name, "Sun");
            }

            event.x_position = sim->bodies[PROBE_INDEX].global_position.x;
            event.y_position = sim->bodies[PROBE_INDEX].global_position.y;
            event.z_position = sim->bodies[PROBE_INDEX].global_position.z;

            transitions.push_back(event);
            previous_parent = current_parent;

            INFO("Transition at day " << event.time_days
                 << ": " << event.old_name << " -> " << event.new_name);
        }
    }

    INFO("Total transitions: " << transitions.size());

    REQUIRE(transitions.size() > 0);

    bool found_sun_transition = false;
    for (const auto& event : transitions) {
        if (event.new_parent == SUN_INDEX || event.old_parent == SUN_INDEX) {
            found_sun_transition = true;
            INFO("Sun transition at day " << event.time_days
                 << ": " << event.old_name << " -> " << event.new_name
                 << " at position (" << event.x_position/AU << ", "
                 << event.y_position/AU << ", " << event.z_position/AU << ") AU");
        }
    }

    REQUIRE(found_sun_transition);

    destroy_simulation(sim);
}

TEST_CASE("Root body round-trip - Earth -> Sun -> Mars -> Sun", "[root][round-trip]") {
    const double TIME_STEP = 60.0;
    const double DAYS_TO_SIMULATE = 1000.0;
    const double SECONDS_PER_DAY = 86400.0;

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

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

    const int PROBE_INDEX = 3;
    const int SUN_INDEX = 0;

    std::vector<TransitionEvent> transitions;
    int previous_parent = sim->bodies[PROBE_INDEX].parent_index;

    INFO("Initial parent: " << sim->bodies[PROBE_INDEX].name
         << " (parent_index: " << previous_parent << ")");

    double max_time = DAYS_TO_SIMULATE * SECONDS_PER_DAY;
    while (sim->time < max_time) {
        update_simulation(sim);

        int current_parent = sim->bodies[PROBE_INDEX].parent_index;
        if (current_parent != previous_parent) {
            TransitionEvent event;
            event.time_seconds = sim->time;
            event.time_days = sim->time / SECONDS_PER_DAY;
            event.old_parent = previous_parent;
            event.new_parent = current_parent;

            if (previous_parent >= 0 && previous_parent < sim->body_count) {
                strcpy(event.old_name, sim->bodies[previous_parent].name);
            } else {
                strcpy(event.old_name, "Sun");
            }

            if (current_parent >= 0 && current_parent < sim->body_count) {
                strcpy(event.new_name, sim->bodies[current_parent].name);
            } else {
                strcpy(event.new_name, "Sun");
            }

            event.x_position = sim->bodies[PROBE_INDEX].global_position.x;
            event.y_position = sim->bodies[PROBE_INDEX].global_position.y;
            event.z_position = sim->bodies[PROBE_INDEX].global_position.z;

            transitions.push_back(event);
            previous_parent = current_parent;

            INFO("Transition at day " << event.time_days
                 << ": " << event.old_name << " -> " << event.new_name);
        }
    }

    INFO("Total transitions: " << transitions.size());

    REQUIRE(transitions.size() > 0);

    int sun_transitions = 0;
    for (const auto& event : transitions) {
        if (event.new_parent == SUN_INDEX || event.old_parent == SUN_INDEX) {
            sun_transitions++;
            INFO("Sun transition #" << sun_transitions << " at day " << event.time_days
                 << ": " << event.old_name << " -> " << event.new_name);
        }
    }

    REQUIRE(sun_transitions >= 1);
    INFO("Root body transitions validated: " << sun_transitions << " Sun transitions detected");

    destroy_simulation(sim);
}