#include "./stack.h"
#include <stdbool.h>
#include <stdlib.h>

bool stack_is_empty(stack *s)
{
	if (!s || s->top == -1) {
		return true;
	}

	return false;
}

stack *new_stack(size_t size)
{
        stack *s = malloc(sizeof(stack));
	if (!s)
		return NULL;

	s->data = malloc(size * sizeof(void *));
	if (!s->data) {
		free(s);
		return NULL;
	}

	s->capacity = size;
	s->top = -1;
	return s;
}

void free_stack(stack *s)
{
	if (!s)
		return;

	free(s->data);
	free(s);
}

void *pop(stack *s)
{
	if (stack_is_empty(s))
		return NULL;
	return s->data[s->top--];
}

void *peek(stack *s)
{
	if (stack_is_empty(s))
		return NULL;
	return s->data[s->top];
}

void *push(stack *s, void *data)
{
	if (!s)
		return NULL;

	if (s->top + 1 >= s->capacity) {
		s->capacity *= 2;
		s->data = realloc(s->data, sizeof(void *) * s->capacity);
	}

	return s->data[++s->top] = data;
}