#include <iterator>
#include <mutex>
#include <print>
#include <random>
#include <raylib.h>
#include <thread>

#include "types.h"

float screen_width = 800;
float screen_height = 600;
Rectangle walls[] = {};

Player player;
auto player_speed = 5.0f;
auto player_invulnerability = 1.0f;

uint32_t score;

Tear tears[100] = {};
float tear_speed = 10;
float tear_range = 500;
float tear_radius = 10.0f;
double last_fired = 0;
double fire_rate = .5;

std::mutex enemy_mutex;
float enemy_max_speed = 3.0;
float enemy_radius = 25.0;

struct Rng {
    static std::random_device dev;
    static std::mt19937 rng;

    static float generate() {
        return static_cast<float>(rng()) / static_cast<float>(std::mt19937::max());
    }

    static float generate(const uint32_t max) {
        return generate() * static_cast<float>(max);
    }

    static float generate(const int min, const int max) {
        return generate() * (static_cast<float>(max) - static_cast<float>(min)) + static_cast<float>(min);
    }
};

std::random_device Rng::dev{};
std::mt19937 Rng::rng{dev()};

Vector2 Player::center() const noexcept {
    return {.x = this->x + this->width / 2, .y = this->y + this->height / 2};
}

Rectangle Player::rect() const noexcept {
    return {.x = x, .y = y, .width = width, .height = height};
}

bool Player::is_invulnerable(const double now) const noexcept {
    return now < this->last_hit + player_invulnerability;
}

void Player::move(const float delta_x, const float delta_y) {
    const auto x = std::min(
        std::max(this->x + delta_x, 0.0f),
        screen_width - this->width);

    const auto y = std::min(
        std::max(this->y + delta_y, 0.0f),
        screen_height - this->height);

    bool collided = false;
    const Rectangle next_position = {
        .x = x,
        .y = y,
        .width = this->width,
        .height = this->height
    };

    for (const auto wall: walls) {
        if (CheckCollisionRecs(wall, next_position)) {
            collided = true;
            break;
        }
    }

    if (collided) {
    } else {
        this->x = x;
        this->y = y;
    }
}

template <typename T, size_t N>
struct Spawner {
    std::mutex mutex;
    std::condition_variable cv;
    std::atomic<bool> running;
    std::atomic<bool> paused;
    std::optional<std::thread> timer;
    long long rate_secs;
    T values[N];

    explicit Spawner(const long long rate_secs)
        : rate_secs(rate_secs) {
    }

    virtual void spawn() {}

    void start() {
        running.store(true);
        timer = std::thread([&] {
            while (running.load()) {
                const auto start = std::chrono::steady_clock::now();

                if (!paused.load()) {
                    std::lock_guard lock(mutex);

                    spawn();
                }

                auto next = start + std::chrono::seconds(rate_secs);
                std::unique_lock lock{mutex};
                cv.wait_until(lock, next, [&] { return !running.load(); });
            }
        });
    }

    virtual ~Spawner() {
        running.store(false);
        cv.notify_all();
        if (timer) {
            timer.value().join();
        }
    }
};

struct EnemySpawner final : Spawner<Enemy, 100> {
    explicit EnemySpawner(const long long rate_secs)
        : Spawner<Enemy, 100>(rate_secs) {
    }

    void spawn() override {
        const auto num = Rng::generate();
        const auto starting_x = Rng::generate(static_cast<uint32_t>(screen_width));
        const auto starting_y = Rng::generate(static_cast<uint32_t>(screen_height));

        for (auto &[center, radius, speed, alive]: this->values) {
            if (alive) continue;
            alive = true;
            radius = enemy_radius;
            if (num < 0.25) {
                center = {.x = starting_x, .y = 0};
            } else if (0.25 <= num && num < 0.5) {
                center = {
                    .x = starting_x, .y = (screen_height)
                };
            } else if (0.5 <= num && num < 0.75) {
                center = {.x = 0, .y = starting_y};
            } else {
                center = {
                    .x = (screen_width), .y = starting_y
                };
            }

            speed = Rng::generate(static_cast<uint32_t>(enemy_max_speed));

            break;
        }
    }
};

EnemySpawner enemy_spawner{2};

void spawn_tear(const Vector2 center, const Direction direction) {
    for (auto &[tear_center, tear_direction, tear_active, starting_center]: tears) {
        if (!tear_active) {
            tear_center = center;
            tear_direction = direction;
            tear_active = true;
            starting_center = center;
            break;
        }
    }
}

void update_tears() {
    for (auto &[center, direction, active, starting_center]: tears) {
        if (active) {
            for (const auto wall: walls) {
                if (CheckCollisionCircleRec(center, tear_radius, wall)) {
                    active = false;
                    break;
                }
            }

            for (auto &enemy: enemy_spawner.values) {
                if (enemy.alive && CheckCollisionCircles(center, tear_radius, enemy.center, enemy.radius)) {
                    active = false;
                    enemy.alive = false;
                    score++;
                }
            }

            switch (direction) {
                case UP:
                    center.y -= tear_speed;
                    break;
                case DOWN:
                    center.y += tear_speed;
                    break;
                case LEFT:
                    center.x -= tear_speed;
                    break;
                case RIGHT:
                    center.x += tear_speed;
                    break;
            }

            if (tear_range < Vector2Distance(center, starting_center)) {
                active = false;
            }
        }
    }
}

int main() {
    InitWindow(800, 600, "Isaac++");
    SetTargetFPS(60);


    enemy_spawner.start();

    player.width = 50;
    player.height = 50;
    player.x = screen_width / 2 - player.width / 2;
    player.y = screen_height / 2 - player.height / 2;
    player.lives = 3;
    player.last_hit = -10;

    std::string score_text_buffer;
    score_text_buffer.reserve(64);

    std::string lives_text_buffer;
    lives_text_buffer.reserve(64);

    while (!WindowShouldClose()) {
        if (IsWindowResized()) {
            screen_height = static_cast<float>(GetScreenHeight());
            screen_width = static_cast<float>(GetScreenWidth());
        }

        float delta_x = 0;
        float delta_y = 0;

        if (IsKeyDown(KEY_W)) delta_y -= player_speed;
        if (IsKeyDown(KEY_S)) delta_y += player_speed;
        if (IsKeyDown(KEY_A)) delta_x -= player_speed;
        if (IsKeyDown(KEY_D)) delta_x += player_speed;
        player.move(delta_x, delta_y);


        std::optional<Direction> tear_direction;
        if (IsKeyDown(KEY_LEFT)) {
            tear_direction = LEFT;
        }
        if (IsKeyDown(KEY_UP)) {
            tear_direction = UP;
        }
        if (IsKeyDown(KEY_RIGHT)) {
            tear_direction = RIGHT;
        }
        if (IsKeyDown(KEY_DOWN)) {
            tear_direction = DOWN;
        }

        const auto now = GetTime();
        if (last_fired + fire_rate < now && tear_direction.has_value()) {
            last_fired = now;
            spawn_tear(player.center(), tear_direction.value());
        }

        update_tears();

        BeginDrawing();
        ClearBackground(RAYWHITE);
        DrawRectangleRec(player.rect(), player.is_invulnerable(now) ? GOLD : BLUE);

        for (const auto wall: walls) {
            DrawRectangleRec(wall, GREEN);
        }

        for (const auto tear: tears) {
            if (tear.active) {
                DrawCircleV(tear.center, tear_radius, SKYBLUE);
            }
        }

        {
            std::lock_guard enemy_guard{enemy_mutex};
            for (auto &[center, radius, speed, alive]: enemy_spawner.values) {
                if (alive) {
                    center = Vector2MoveTowards(center, player.center(), speed);
                    DrawCircleV(center, radius, RED);

                    if (center.x < 0 || screen_width < center.x ||
                        center.y < 0 || screen_height < center.y) {
                        alive = false;
                    }

                    if (CheckCollisionCircleRec(center, radius, player.rect()) &&
                        player.last_hit + player_invulnerability < now) {
                        player.lives--;
                        player.last_hit = now;
                    }
                }
            }
        }

        std::format_to(std::back_inserter(score_text_buffer), "Score: {}", score);
        DrawText(score_text_buffer.c_str(), 50, static_cast<int>(screen_height) - 100, 20, BLACK);
        score_text_buffer.clear();

        std::format_to(std::back_inserter(lives_text_buffer), "Lives: {}", player.lives);
        DrawText(lives_text_buffer.c_str(), 50, static_cast<int>(screen_height) - 50, 20, BLACK);
        lives_text_buffer.clear();

        EndDrawing();
    }
    CloseWindow();
    return 0;
}