#define _USE_MATH_DEFINES
#include <allegro5/allegro.h>
#include <allegro5/allegro_primitives.h>
#include <math.h>

void matrix_2D_handler(float _angle, float _Matrix_2D[][2], float &_x_pos, float &_y_pos)
{
    float New_X = 0.0f;
    float New_Y = 0.0f;

    // X axis
    _Matrix_2D[0][0] = cosf(_angle);
    _Matrix_2D[0][1] = -sinf(_angle);
    New_X = (_Matrix_2D[0][0] * _x_pos) + (_Matrix_2D[0][1] * _y_pos);

    // Y axis
    _Matrix_2D[1][0] = sinf(_angle);
    _Matrix_2D[1][1] = cos(_angle);
    New_Y = (_Matrix_2D[1][0] * _x_pos) + (_Matrix_2D[1][1] * _y_pos);

    _x_pos = New_X;
    _y_pos = New_Y;
}

// Needs to be radians.
float deg_to_rad(float deg)
{
    return deg * ((float)M_PI / 180.0f);
}

int main(int argc, char *argv[])
{
    int SCREEN_X = 800;
    int SCREEN_Y = 600;

    float FPS = 60.0f;

    float degree_rotate_angle = 0.5f;

    bool loop = true;
    bool draw = false;

    float x_pos = 175.0f;
    float y_pos = 25.0f;

    float Matrix_2D[2][2] = {{0.0f,0.0f}, {0.0f,0.0f}};

    ALLEGRO_DISPLAY *display = NULL;
    ALLEGRO_EVENT_QUEUE *event_queue = NULL;
    ALLEGRO_TIMER *timer = NULL;

    al_init();
    al_init_primitives_addon();

    //al_set_new_display_option(ALLEGRO_VSYNC, 1, ALLEGRO_SUGGEST);
    display = al_create_display(SCREEN_X, SCREEN_Y);
    event_queue = al_create_event_queue();
    timer = al_create_timer(1.0f / FPS);

    al_register_event_source(event_queue, al_get_display_event_source(display));
    al_register_event_source(event_queue, al_get_timer_event_source(timer));

    al_start_timer(timer);

    while(loop)
    {
        ALLEGRO_EVENT event;
        al_wait_for_event(event_queue, &event);

        switch(event.type)
        {
            case ALLEGRO_EVENT_DISPLAY_CLOSE:
                loop = false;
                break;

            case ALLEGRO_EVENT_TIMER:
                draw = true;
                break;

            default:
                break;
        }

        if(draw == true)
        {
            draw = false;
            al_clear_to_color(al_map_rgb(0,0,0));
            matrix_2D_handler(deg_to_rad(degree_rotate_angle), Matrix_2D, x_pos, y_pos);
            al_draw_circle(x_pos  + ((float)SCREEN_X / 2.0f), y_pos + ((float)SCREEN_Y / 2.0f), 10.0f, al_map_rgb(200,0,50), 0.0f);
            al_flip_display();
        }

    }

    // Clean up...
    al_stop_timer(timer);
    al_destroy_timer(timer);
    al_flush_event_queue(event_queue);
    al_destroy_event_queue(event_queue);
    al_destroy_display(display);

    return 0;
}