#include "config_validator.h"
#include <cstdio>
#include <cmath>
#include <cstring>

bool validate_parent_index_ordering(SimulationState* sim) {
    for (int i = 0; i < sim->body_count; i++) {
        if (sim->bodies[i].parent_index != -1 && sim->bodies[i].parent_index >= i) {
            printf("Error: Body '%s' (index %d) has invalid parent_index %d - must be < %d or -1\n",
                   sim->bodies[i].name, i, sim->bodies[i].parent_index, i);
            return false;
        }
    }

    for (int i = 0; i < sim->craft_count; i++) {
        Spacecraft* craft = &sim->spacecraft[i];
        if (craft->parent_index < 0 || craft->parent_index >= sim->body_count) {
            printf("Error: Spacecraft '%s' has invalid parent_index %d (valid: 0-%d)\n",
                   craft->name, craft->parent_index, sim->body_count - 1);
            return false;
        }
    }

    return true;
}

bool validate_orbital_elements(SimulationState* sim) {
    for (int i = 0; i < sim->body_count; i++) {
        CelestialBody* body = &sim->bodies[i];

        if (body->parent_index < 0) {
            continue;
        }

        bool is_parabolic = (fabs(body->orbit.eccentricity - 1.0) < 0.005);

        if (body->orbit.eccentricity < 0.0) {
            printf("Error: Body '%s' has invalid eccentricity: %.2e (must be >= 0)\n",
                   body->name, body->orbit.eccentricity);
            return false;
        }

        if (is_parabolic) {
            if (body->orbit.semi_latus_rectum <= 0.0) {
                printf("Error: Body '%s' has parabolic orbit but non-positive semi_latus_rectum: %.2e\n",
                       body->name, body->orbit.semi_latus_rectum);
                return false;
            }
        } else {
            if (body->orbit.semi_major_axis == 0.0) {
                printf("Error: Body '%s' has invalid semi_major_axis: %.2e (must not be zero)\n",
                       body->name, body->orbit.semi_major_axis);
                return false;
            }

            if (body->orbit.eccentricity < 1.0 && body->orbit.semi_major_axis <= 0.0) {
                printf("Error: Body '%s' has elliptical orbit but non-positive semi_major_axis: %.2e\n",
                       body->name, body->orbit.semi_major_axis);
                return false;
            }
        }
    }

    for (int i = 0; i < sim->craft_count; i++) {
        Spacecraft* craft = &sim->spacecraft[i];

        bool is_parabolic = (fabs(craft->orbit.eccentricity - 1.0) < 0.005);

        if (is_parabolic) {
            if (craft->orbit.semi_latus_rectum <= 0.0) {
                printf("Error: Spacecraft '%s' has parabolic orbit but non-positive semi_latus_rectum: %.2e\n",
                       craft->name, craft->orbit.semi_latus_rectum);
                return false;
            }
        } else {
            if (fabs(craft->orbit.semi_major_axis) < 1e-10) {
                printf("Error: Spacecraft '%s' has invalid semi_major_axis: %.2e (must not be zero)\n",
                       craft->name, craft->orbit.semi_major_axis);
                return false;
            }

            if (craft->orbit.eccentricity < 1.0 && craft->orbit.semi_major_axis <= 0.0) {
                printf("Error: Spacecraft '%s' has elliptical orbit but non-positive semi_major_axis: %.2e\n",
                       craft->name, craft->orbit.semi_major_axis);
                return false;
            }
        }

        if (craft->orbit.eccentricity < 0.0) {
            printf("Error: Spacecraft '%s' has invalid eccentricity: %.3f (must be >= 0)\n",
                   craft->name, craft->orbit.eccentricity);
            return false;
        }
    }

    return true;
}

bool validate_mass_ratios(SimulationState* sim) {
    for (int i = 0; i < sim->body_count; i++) {
        CelestialBody* body = &sim->bodies[i];

        if (body->parent_index < 0 || body->parent_index >= sim->body_count) {
            continue;
        }

        CelestialBody* parent = &sim->bodies[body->parent_index];
        double mass_ratio = parent->mass / body->mass;
        double radius_ratio = body->radius / parent->radius;

        if (parent->parent_index < 0 && radius_ratio > 0.5 && mass_ratio < MIN_MASS_RATIO) {
            printf("Error: Body '%s' (mass=%.2e kg, radius=%.2e m) has insufficient mass ratio with root parent '%s' (mass=%.2e kg, radius=%.2e m)\n",
                   body->name, body->mass, body->radius, parent->name, parent->mass, parent->radius);
            printf("  Mass ratio: %.2f (minimum required: %.2f)\n", mass_ratio, MIN_MASS_RATIO);
            printf("  Radius ratio: %.2f (triggers validation for radius > 50%% of parent)\n", radius_ratio);
            return false;
        }
    }

    return true;
}

bool validate_soi_overlap(SimulationState* sim) {
    for (int i = 0; i < sim->body_count; i++) {
        CelestialBody* body_i = &sim->bodies[i];

        if (body_i->parent_index < 0) {
            continue;
        }

        for (int j = i + 1; j < sim->body_count; j++) {
            CelestialBody* body_j = &sim->bodies[j];

            if (body_j->parent_index != body_i->parent_index) {
                continue;
            }

            double distance = vec3_distance(body_i->global_position, body_j->global_position);
            double combined_soi = body_i->soi_radius + body_j->soi_radius;

            if (distance < combined_soi) {
                printf("Error: Bodies '%s' and '%s' have overlapping SOIs while sharing same parent '%s'\n",
                       body_i->name, body_j->name, sim->bodies[body_i->parent_index].name);
                printf("  Separation: %.2e m\n", distance);
                printf("  Combined SOI: %.2e m (%.2e + %.2e)\n",
                       combined_soi, body_i->soi_radius, body_j->soi_radius);
                printf("  SOI overlap: %.2e m\n", combined_soi - distance);
                return false;
            }
        }
    }

    return true;
}

bool validate_nested_orbits(SimulationState* sim) {
    for (int i = 0; i < sim->body_count; i++) {
        CelestialBody* body = &sim->bodies[i];

        if (body->parent_index < 0 || body->parent_index >= sim->body_count) {
            continue;
        }

        CelestialBody* parent = &sim->bodies[body->parent_index];

        if (parent->parent_index < 0) {
            continue;
        }

        double radius_ratio = body->radius / parent->radius;

        if (radius_ratio > 0.3) {
            continue;
        }

        if (body->orbit.eccentricity > 0.5) {
            continue;
        }

        if (body->mass < 1e20) {
            continue;
        }

        double child_orbit_radius = body->orbit.semi_major_axis;
        double parent_soi = parent->soi_radius;
        double max_allowed = NESTED_ORBIT_FRACTION * parent_soi;

        if (child_orbit_radius > max_allowed) {
            printf("Error: Body '%s' orbit extends too far from parent '%s'\n",
                   body->name, parent->name);
            printf("  Child orbit radius: %.2e m\n", child_orbit_radius);
            printf("  Parent SOI radius: %.2e m\n", parent_soi);
            printf("  Maximum allowed: %.2e m (%.2f%% of parent SOI)\n",
                   max_allowed, NESTED_ORBIT_FRACTION * 100.0);
            return false;
        }
    }

    return true;
}

bool validate_initial_positions(SimulationState* sim) {
    for (int i = 0; i < sim->body_count; i++) {
        CelestialBody* body = &sim->bodies[i];

        if (body->parent_index >= 0 && body->parent_index < sim->body_count) {
            CelestialBody* parent = &sim->bodies[body->parent_index];
            double distance = vec3_magnitude(vec3_sub(body->global_position, parent->global_position));
            double min_distance = parent->radius + body->radius;

            if (distance < min_distance) {
                printf("Error: Body '%s' (index %d) too close to parent '%s' (index %d)\n",
                       body->name, i, parent->name, body->parent_index);
                printf("  Distance: %.2e m\n", distance);
                printf("  Minimum required: %.2e m (parent radius + body radius)\n", min_distance);
                return false;
            }
        }
    }

    for (int i = 0; i < sim->craft_count; i++) {
        Spacecraft* craft = &sim->spacecraft[i];

        if (craft->parent_index >= 0 && craft->parent_index < sim->body_count) {
            CelestialBody* parent = &sim->bodies[craft->parent_index];
            double distance = vec3_magnitude(vec3_sub(craft->global_position, parent->global_position));
            double min_distance = parent->radius;

            if (distance < min_distance) {
                printf("Error: Spacecraft '%s' too close to parent '%s'\n",
                       craft->name, parent->name);
                printf("  Distance: %.2e m\n", distance);
                printf("  Minimum required: %.2e m (parent radius)\n", min_distance);
                return false;
            }
        }
    }

    return true;
}

bool run_all_config_validations(SimulationState* sim) {
    if (!validate_parent_index_ordering(sim)) {
        return false;
    }

    if (!validate_orbital_elements(sim)) {
        return false;
    }

    if (!validate_mass_ratios(sim)) {
        return false;
    }

    if (!validate_soi_overlap(sim)) {
        return false;
    }

    if (!validate_nested_orbits(sim)) {
        return false;
    }

    if (!validate_initial_positions(sim)) {
        return false;
    }

    return true;
}