#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <allegro.h>
#include <allegro_primitives.h>

const int W = 500;
const int H = 500;
const float FPS = 15.0;
const int recSize = 10;
int gameOver = 1;
int draw = 1;
int moveSpeed = 10;

enum Direction { DOWN, UP, LEFT, RIGHT };
enum Direction dir = DOWN;

struct Node
{
    int x, y;
};

struct Snake
{
    int length;
    struct Node *head;
    struct Node *nodes;
};

void logic        (struct Snake **snake, struct Node *fruit, struct Node **prev);
void updatePrevPos(const struct Snake *snake, struct Node *previous);
void updatePos    (struct Snake *snake, const struct Node *previous);
void drawNodes    (const struct Snake *snake);

int main()
{
   if(!al_init())
   {
      fprintf(stderr, "Nie udalo sie zainicjalizowac Allegro!\n");
      return -1;
   }

   //SETUP
   ALLEGRO_DISPLAY *display = al_create_display(W, H);
   al_set_window_position(display, 700, 200);
   al_set_window_title(display, "SNAKE");

   al_init_primitives_addon();
   al_install_keyboard();

   ALLEGRO_TIMER *timer = al_create_timer(1.0 / FPS);
   ALLEGRO_EVENT_QUEUE *event_q = al_create_event_queue();
   al_register_event_source(event_q, al_get_keyboard_event_source());
   al_register_event_source(event_q, al_get_timer_event_source(timer));
   al_register_event_source(event_q, al_get_display_event_source(display));

   al_start_timer(timer);

   if(!display)
   {
      fprintf(stderr, "Nie udalo sie stworzyc okna!\n");
      return -1;
   }

   ALLEGRO_COLOR black = al_map_rgb(0, 0, 0);
   ALLEGRO_COLOR white = al_map_rgb(255,255,255);
   ALLEGRO_COLOR rand_color;

   struct Snake *snake = malloc(sizeof(struct Snake));
   snake->length   = 1;
   snake->head     = (struct Node *)malloc(sizeof(struct Node));
   snake->nodes    = (struct Node *)malloc(sizeof(struct Node));
   snake->head->x  = W / 2;
   snake->head->y  = H / 2;

   struct Node *prev_positions = (struct Node *)malloc(sizeof(struct Node));

   struct Node *fruit = (struct Node *)malloc(sizeof(struct Node));
   srand(time(NULL));
   fruit->x = (rand() % (W / recSize - 1) + 1) * recSize;
   fruit->y = (rand() % (H / recSize - 1) + 1) * recSize;

   while(gameOver)
   {
        ALLEGRO_EVENT events;
        al_wait_for_event(event_q, &events);

        updatePrevPos(snake, prev_positions);           //aktualizacja pozycji ogona z poprzedniej klatki

        //OBSLUGA KLAWIATURY I OKNA
        if (events.type == ALLEGRO_EVENT_KEY_DOWN)
        {
            switch(events.keyboard.keycode)
            {
                case ALLEGRO_KEY_UP:
                    if (dir != DOWN && snake->length > 1)
                        dir = UP;
                    else if (snake->length <= 1)
                        dir = UP;
                    break;

                case ALLEGRO_KEY_DOWN:
                    if (dir != UP && snake->length > 1)
                        dir = DOWN;
                    else if (snake->length <= 1)
                        dir = DOWN;
                    break;

                case ALLEGRO_KEY_LEFT:
                    if (dir != RIGHT && snake->length > 1)
                        dir = LEFT;
                    else if (snake->length <= 1)
                        dir = LEFT;
                    break;

                case ALLEGRO_KEY_RIGHT:
                    if (dir != LEFT && snake->length > 1)
                        dir = RIGHT;
                    else if (snake->length <= 1)
                        dir = RIGHT;
                    break;

                case ALLEGRO_KEY_ESCAPE:
                    gameOver = 0;
                    break;
            }
        }
        else if (events.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
            gameOver = 0;

        if (events.type == ALLEGRO_EVENT_TIMER)
        {
            switch(dir)
            {
                case UP:
                    snake->head->y -= moveSpeed;
                    break;

                case DOWN:
                    snake->head->y += moveSpeed;
                    break;

                case LEFT:
                    snake->head->x -= moveSpeed;
                    break;

                case RIGHT:
                    snake->head->x += moveSpeed;
                    break;
            }
            draw = 1;
        }

        if (draw && gameOver != 0)
        {
            draw = 0;

            if (ALLEGRO_EVENT_TIMER % 15 == 0)
                rand_color = al_map_rgb(rand() % 255 + 1, rand() % 255 + 1, rand() % 255 + 1);
            al_draw_filled_rectangle(fruit->x, fruit->y, fruit->x + recSize, fruit->y + recSize, rand_color);

            updatePos(snake, prev_positions);           //aktualizacja pozycji ogona z aktualnej klatki
            drawNodes(snake);                           //rysowanie weza na ekran

            al_flip_display();
            al_clear_to_color(black);
        }

        logic(&snake, fruit, &prev_positions);          //logika gry
   }

   free(snake);
   free(prev_positions);
   free(fruit);

   al_destroy_event_queue(event_q);
   al_destroy_timer(timer);
   al_destroy_display(display);

   return 0;
}

void logic(struct Snake **snake, struct Node *fruit, struct Node **prev)
{
    //KOLIZJA Z GRANICAMI PLANSZY
    if ((*snake)->head->y < 0)
        gameOver = 0;

    if ((*snake)->head->y > H - recSize)
        gameOver = 0;

    if ((*snake)->head->x < 0)
        gameOver = 0;

    if ((*snake)->head->x > W - recSize)
        gameOver = 0;

    //ZJEDZENIE OWOCU
    if ((*snake)->head->x == fruit->x && (*snake)->head->y == fruit->y)
    {
        (*snake)->length++;
        (*snake)->nodes = (struct Node *)realloc((*snake)->nodes, (*snake)->length * sizeof(struct Node));
        *prev = (struct Node *)realloc(*prev, (*snake)->length * sizeof(struct Node));

        fruit->x = (rand() % (W / recSize - 1) + 1) * recSize;
        fruit->y = (rand() % (H / recSize - 1) + 1) * recSize;
    }

    //KOLIZJA Z OGONEM
    for (int i = 0; i < (*snake)->length; i++)
        if ((*snake)->head->x == (*snake)->nodes[i].x && (*snake)->head->y == (*snake)->nodes[i].y)
            gameOver = 0;
}

void updatePrevPos(const struct Snake *snake, struct Node *previous)
{
     previous[0].x = snake->head->x;
     previous[0].y = snake->head->y;

     for (int i = 1; i < snake->length; i++)
     {
        previous[i].x = snake->nodes[i - 1].x;
        previous[i].y = snake->nodes[i - 1].y;
     }
}

void updatePos(struct Snake *snake, const struct Node *previous)
{
    for (int i = 0; i < snake->length; i++)
    {
        snake->nodes[i].x = previous[i].x;
        snake->nodes[i].y = previous[i].y;
    }
}

void drawNodes(const struct Snake *snake)
{
    al_draw_rectangle(snake->head->x + 1, snake->head->y + 1, snake->head->x + recSize, snake->head->y + recSize, al_map_rgb(255,255,255), 1.0);

    for (int i = 0; i < snake->length; i++)
        al_draw_rectangle(snake->nodes[i].x + 1, snake->nodes[i].y + 1, snake->nodes[i].x + recSize, snake->nodes[i].y + recSize, al_map_rgb(255,255,255), 1.0);
}