#include <stdlib.h>

#include "snake.h"

//void freeAll(struct snake* prvok);

struct snake* add_snake(struct snake* snake,int x,int y){
    
    struct snake* head = calloc(1,sizeof(struct snake));
    head->x = x;
    head->y = y;
    head->next = snake;

    return head;
}

struct snake* remove_snake(struct snake* snake){
    if(!snake)
        return NULL; 
    if(!snake->next){
        free(snake);
        return NULL; 
    }
    struct snake* last = snake;
    struct snake* secondLast = snake; 

    while(1){
        if(!last->next){
            free(last);
            secondLast->next=NULL; 
            return snake;
        }
        secondLast=last;
        last=last->next;
    }
}


void free_snake(struct snake* sn){
    struct snake* this = sn;
    
    while(this){
        struct snake* next = this->next;
        free(this);
        this = next;
    }
}

/*
void freeAll(struct snake* prvok){
    if(!prvok) 
        break;

    else if(prvok->next)
        freeAll(prvok->next); 
 
    free(prvok); 
}*/


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

    while(this){
        if(this->x==x && this->y==y)
            return 1;

        this = this->next;
    }
    return 0;
}
//Spojkový zoznam =============================> celá hra


int step_state(struct state* st){

	int nx = (st->snake->x + st->sx);
    int ny = (st->snake->y + st->sy);
    
    if(is_snake(st->snake,nx, ny))
        return END_SNAKE; 
//
    for(int i = 0;i < FOOD_COUNT; i++){
        if(nx==st->foodx[i]&&ny==st->foody[i]){
            st->foody[i]=-1;
            st->foodx[i]=-1;
            
            add_snake(st->snake, nx, ny);
        }
    }
    
    int is_all_eaten=1;
    for(int i = 0;i < FOOD_COUNT; i++){
        if(st->foodx[i]>=0){
            is_all_eaten = 0;
            break;
        }
    }
    
    if(is_all_eaten)
        return END_FOOD;
// 
    
    if(nx<0||ny<0||nx>=st->width||ny>=st->height)
        return END_WALL;
//

    if(st->snake->x != nx && st->snake->y != ny){
        remove_snake(st->snake);
        add_snake(st->snake, nx, ny);
    }

    return END_CONTINUE;
}