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

struct snake* add_snake(struct snake* snake,int x,int y)
{
    //vytvor novu prazdnu instanciu a alokuj jej pamat
   struct snake* newSnake = (struct snake*)malloc(sizeof(struct snake));
   //prida X,Y suradnice do polia do novej hlavicky
   newSnake->x = x;
   newSnake->y = y;

   //nalinkuje ju na staru hlavicku
   newSnake->next = snake;
   
   return newSnake;
}

struct snake* remove_snake(struct snake* snake){

    struct snake* currentPtr = snake;
    struct snake* prevPtr;
    
    if (snake == NULL)
    {
        return NULL;
    }
    while (1)
    {
        //pomocny pointer -> ulozenie predoslej casti/node-u
        prevPtr = currentPtr;
        //skontroluje, ze ci dalsia cast je PRAZDNA.
        if (currentPtr->next == NULL)
        {
            //uprava listu -> odlinkje tuto cast (tak aby prevPtr->next NEFERENCOVAL na uz uvolnenu cast)
            prevPtr->next = NULL;
            //uvolni pamat pre akt. cast (uvolni pamat)
            free(currentPtr);
            break;
        }
        //iteruj ku dalsiej casti (node)
        currentPtr = currentPtr->next;
    }
    return snake;
}

void free_snake(struct snake* sn)
{
    //pomocna smernikova premenna
    struct snake* currentPtr = sn;
    while (currentPtr != NULL)
    {
        //uloz dalsiu cast, zmaz aktualnu a posun sa na dalsiu
        struct snake* nextPtr = currentPtr->next;
        free(currentPtr);
        currentPtr = nextPtr;
    }
}

int is_snake(struct snake* snake,int x,int y){
    
    //helper pointer/smernikova premena
    struct snake* currentPtr = snake;
    
    //iteracia cez vsetky casti az dokial nenajdeme cast/node s rovnakymi suradnicami
    while (currentPtr != NULL)
    {
        if (currentPtr->x == x && currentPtr->y == y)
        {
            return 1;
        }
        //prejdi na dalsiu cast
        currentPtr = currentPtr->next;
    }
    return 0;
}

int step_state(struct state* st){
	int nx = (st->snake->x + st->sx);
    int ny = (st->snake->y + st->sy);
    return END_CONTINUE;
}