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

t_stack *stack_create()
{
	t_stack *result = (t_stack *)malloc(sizeof(*result));
	result->items = NULL;
	result->count = 0;
	return result;
}

t_stack *stack_copy(const t_stack *t)
{
	t_stack *result = (t_stack *)malloc(sizeof(*result));
	struct s_stackitem *aitem, *bitem;
	size_t i;

	result->items = NULL;
	result->count = t->count;
	if (result->count)
	{
		aitem = malloc(sizeof(*aitem));
		bitem = t->items;

		aitem->value = bitem->value;
		result->items = aitem;
		for (i =1; i < t->count; ++i)
		{
			aitem->prev = malloc(sizeof(*aitem));
			aitem = aitem->prev;
			bitem = bitem->prev;
			aitem->prev = NULL;
			aitem->value = bitem->value;
		}
	}
	return result;
}

int stack_pop(t_stack *s)
{
	int r;
	struct s_stackitem *oldNode = s->items;

	if (!s->count)
		return -1;
	oldNode = s->items;
	r = oldNode->value;
	s->items = oldNode->prev;
	s->count--;
	free(oldNode);
	return r;
}

size_t stack_length(const t_stack *s)
{
	return s->count;
}

int stack_value(const t_stack *s)
{
	if (!s->count)
		return -1;
	return s->items->value;
}

void stack_destroy(t_stack *stack)
{
	if (!stack)
		return;
	while (stack->count)
		stack_pop(stack);
	free(stack);
}

void stack_push(t_stack *st, int v)
{
	struct s_stackitem *s = (struct s_stackitem *) malloc(sizeof(*s));
	s->prev = st->count ? st->items : NULL;
	s->value = v;
	st->items = s;
	st->count++;
}