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

struct snake* add_snake(struct snake* snake,int x,int y){
	struct snake* novyZaciatok = calloc(1, sizeof(struct snake));	//alokujem pamäť smerníka
	novyZaciatok->x = x;	//nastavím súradnice hada
	novyZaciatok->y = y;
	
	if (snake != NULL) {	//ak má had telo,
		novyZaciatok->next = snake;		//tak mu iba pridám hlavu
	} else {
		novyZaciatok->next = NULL;		//inak musím vytvoriť nové telo
	}
	
    return novyZaciatok;
}

struct snake* remove_snake(struct snake* snake){
	if (snake == NULL) return NULL;		//ak nezadám ako vstup hada, tak okamžite vrátim NULL
	
	else if (snake->next == NULL) {		//ak had nemá pokračovanie,
		free(snake);	//tak ho zruším
		return NULL;	//a vrátim NULL
	}
	
	else {	//inak prebehnem celého hada od začiatku
		struct snake* medzipamat = calloc(1, sizeof(struct snake));		//alokujem medzipamäť
		medzipamat = snake;		//adresu hlavy hada uložím do medzipamäte
		
		while (snake->next->next != NULL) snake = snake->next;	//hada budem prezerať dovtedy, kým nenájdem jeho koniec
		
		free(snake->next);	//koniec hada zmažem
		
		snake->next = NULL;		// nastavím nový koniec hada
		return medzipamat;	//vrátim hlavu hada
	}
}

void free_snake(struct snake* sn){	//funkcia odstráni hada z hry
	struct snake* medzipamat = calloc(1, sizeof(struct snake));		//alokujem medzipamäť
	
	while (sn != NULL) {	//v cykle vymažem každý jeden prvok hada
		medzipamat = sn->next;	//hlavu hada uložím do medzipamäte
		free(sn);	//ak odstránim ju
		sn = medzipamat;	//nastavím novú hlavu hada
	}
	
	free(medzipamat);	//nakoniec vyčistím aj medzipamäť
}

int is_snake(struct snake* snake,int x,int y){
	if (snake == NULL) return 0;
	
    while (snake != NULL) {
    	if (snake->x == x || snake->y == y) return 1;
    	snake = snake->next;
	}
	
	return 0;
}

int step_state(struct state* st){
	int nx = (st->snake->x + st->sx);
    int ny = (st->snake->y + st->sy);
    int i, pocetJedal = FOOD_COUNT;
    
    struct snake* had = calloc(1, sizeof(struct snake));
    struct snake* hlava = calloc(1, sizeof(struct snake));
    
    had = st->snake;
    hlava = st->snake;
    
    while (had != NULL) {
    	if (had->x == nx || had->y == ny) return END_SNAKE;
    	
    	for (i = 0; i < FOOD_COUNT; i++) {
    		if (st->foodx[i] == had->x) {
    			if (st->foody[i] == had->y) {
    				had = add_snake(had, st->foodx[i], st->foody[i]);
    				
					st->foodx[i] = -1;
					st->foody[i] = -1;
					pocetJedal--;
				}
			}
		}
		
		if (pocetJedal == 0) return END_FOOD;
		
		had = had->next;
	}
	
	had = hlava;
	free(hlava);
	
	if (nx > 0 && nx < st->width) {
		if (ny > 0 && ny < st->height) {
			had = add_snake(had, nx, ny);
			had = remove_snake(had);
		}
	}
	
    return END_CONTINUE;
}