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

struct snake* add_snake (struct snake* snake, int x, int y) {
    struct snake* head = NULL;

    head = malloc(sizeof(struct snake));

    if (!head) {
        return snake;
    }    
        head->x = x;
        head->y = y;

        head->next = NULL;

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

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

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

    struct snake* temp = snake;
    while (temp->next->next != NULL) {
        temp = temp->next;
    }

    free(temp->next);
    temp->next = NULL;

    return snake;
}

void free_snake(struct snake* sn) {
    struct snake* walker = sn;
    struct snake* next_part = NULL;
    while (walker !=NULL) {
        next_part = walker->next;
        free(walker);
        walker = next_part;
    }
}

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

    while (current !=NULL) {
        if ((current->x==x) && (current->y==y)) {
            return 1;
        }
        current = current->next;
    }
    return 0;
}

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

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

    if (is_snake(state->snake, new_x, new_y)) {
        return END_SNAKE;
    }

    for (int i = 0; i < FOOD_COUNT; i++) {
        if (state->foodx[i] == new_x && state->foody[i] == new_y) {
            state->foodx[i] = -1;
            state->foody[i] = -1;

            state->snake = add_snake(state->snake, new_x, new_y);

            int any_food_left = 0;
            for (int j = 0; j < FOOD_COUNT; j++) {
                if (state->foodx[j] >= 0 && state->foody[j] >= 0) {
                    any_food_left = 1;
                    break;
                }
            }
            if (any_food_left) {
                return END_CONTINUE;
            } else {
                return END_FOOD;
            }
        }
    }
    state->snake = add_snake(state->snake, new_x, new_y);
    state->snake = remove_snake(state->snake);
    return END_CONTINUE;
}