#include <stdlib.h>
#include "snake.h"


struct snake* add_snake(struct snake* snake, int x, int y){
    struct snake* nova_cast = (struct snake*) calloc(1, sizeof(struct snake));

    if (nova_cast == NULL){
        return snake;
    }

    nova_cast->x = x;
    nova_cast->y = y;
    nova_cast->next = snake;

    return nova_cast;
}

struct snake* remove_snake(struct snake* snake){
    if (snake == NULL){
        return NULL;
    }

    if (snake->next == NULL){
        free(snake);
        return NULL;
    }

    struct snake* predposledny = snake;
    struct snake* posledny = snake->next;

    while (posledny->next != NULL){
        predposledny = posledny;
        posledny = posledny->next;
    }

    free(posledny);
    predposledny->next = NULL;

    return snake;
}

int is_snake(struct snake* snake, int x, int y){
    struct snake* aktualny = snake;

    while (aktualny != NULL){
        if (aktualny->x == x && aktualny->y == y){
            return 1;
        }
        aktualny = aktualny->next;
    }

    return 0;
}

void free_snake(struct snake* sn){
    struct snake* dalsi;

    while (sn != NULL){
        dalsi = sn->next;
        free(sn);
        sn = dalsi;
    }
}

int step_state(struct state* state){
    int nova_x = state->snake->x + state->sx;
    int nova_y = state->snake->y + state->sy;

    if (nova_x < 0 || nova_y < 0 || nova_x >= state->width || nova_y >= state->height){
        return END_WALL;
    }

    if (is_snake(state->snake, nova_x, nova_y)){
        return END_SNAKE;
    }

    for (int i = 0; i < FOOD_COUNT; i++){
        if (state->foodx[i] == nova_x && state->foody[i] == nova_y){
            state->snake = add_snake(state->snake, nova_x, nova_y);
            state->foodx[i] = -1;
            state->foody[i] = -1;

            int jedlo_ostalo = 0;
            for (int j = 0; j < FOOD_COUNT; j++){
                if (state->foodx[j] != -1 && state->foody[j] != -1){
                    jedlo_ostalo = 1;
                }
            }

            if (jedlo_ostalo == 0){
                return END_FOOD;
            }

            return END_CONTINUE;
        }
    }

    state->snake = add_snake(state->snake, nova_x, nova_y);
    state->snake = remove_snake(state->snake);

    return END_CONTINUE;
}