/*
	Queue a.k.a. FIFO

	http://en.wikipedia.org/wiki/Queue

	(c) BruXy -- http://bruxy.regnet.cz/fel/

   */

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

/*********************
 * Globalni promenne *
 *********************/

typedef struct stack{
	int data;
	struct stack *odkaz;
} STACK;

/*********************
 *     Funkce        *
 *********************/

STACK *create(void){
	STACK *test;

	test = ( (STACK *) malloc(sizeof(STACK)) );
	if(test==NULL){
		printf("Malo pameti!\n");
		return NULL;
	}
	test->odkaz=NULL;

	return test;
}

/* Vrazi cislo do zasobniku a zvetsi ho o jeden prvek */

short int qprazdna(STACK *queue_top)
{
	if(queue_top == NULL){
		printf("Fronta je prazdna!\n");
		return 0;
	}
	else
		return 1;
}


STACK *push(int cislo)
{
	STACK *queue_new; 
	
	/* Vytvori novy konec */
	queue_new = create(); 

	/* Do minuleho konce zapise */
	queue_new->data = cislo;

	return queue_new;
}

/* Vymaze prvni cislo ve fronte a nastavi novou adresu cela fronty */

STACK *pop(STACK *queue_top)
{
	STACK *queue_delete;

	if(qprazdna(queue_top) != 0){
		queue_delete = queue_top;
		free(queue_delete);
		return queue_top->odkaz;
	}
	else
	{
		return NULL;
	}
}

void print_data(STACK *queue_top){

		while(queue_top != NULL) 
		{
			printf(" %6d -> %p \n", queue_top->data, (void *) queue_top->odkaz);
			queue_top = queue_top->odkaz;	
		}
}

void free_data(STACK *queue_top){
	while(queue_top != NULL) 
	{
		queue_top = pop(queue_top);
	}
}

/*********************
 *       Main        *
 *********************/

int main(){
	int cislo, size;
	int citac = 0;

	STACK *s_start, *s_current, *s_temp;

	printf("Kolik prvku ma obsahovat fronta?: ");
	scanf("%d", &size);
	
	/* Ukazatel na zacatek */
	s_start = NULL;

	for(;;)
	{
		if(citac == size){
			break;
		}

		printf("Zadej cislo %d. : ", citac+1);
		scanf("%d", &cislo);
		printf("Ukladam %d na adresu %p.\n", cislo, (void *) s_current);

		s_temp = push(cislo);
		if(!citac){
			s_start = s_current = s_temp;
		}
		else{
			s_current->odkaz=s_temp;
			s_current = s_temp;
		}	
		
		printf("Addr -> %p.\n", (void *) s_current);
		putchar('\n');
		citac++;
	}

	/* Vypsani obsahu cele fronty  */
	printf("Vypis naplnenych dat, od adresy: %p\n", (void *) s_start);

	print_data(s_start);

	printf("\nKolik mam vymazat prvku?:");
	scanf("%d", &cislo);
	citac = 0;

	for(;;)
	{
		if(citac == cislo) break;

		s_start = pop(s_start);
		if(s_start == NULL)
			break;
		

		citac++;	
	}

	print_data(s_start);

	/* Na zaver po sobe uklidime */
	free_data(s_start); 

	return 0;
}