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

#include "stack.h"

struct Stack {
	void** data;
	int top_index;
	int capacity;
	int curr_size;
};

Stack* new_stack(int stack_size) {
	assert(stack_size > 0);
	Stack* my_stack = malloc(sizeof(Stack));
	my_stack->capacity = stack_size;
	my_stack->data = malloc(stack_size);
	my_stack->top_index = 0;
	my_stack->curr_size = 0;
	return my_stack;
}

void stack_push(Stack* stack,void* element) {
	if (stack->curr_size >= stack->capacity-1) {
		stack->data = realloc(stack->data, stack->capacity*2);
		stack->capacity *= 2;
	}
	*(stack->data + stack->top_index) = element;
	stack->top_index++;
	stack->curr_size++;
	return;
}

void* stack_pop(Stack* stack) {
	assert( !(stack_isEmpty(stack)) );
//	free(stack->data + stack->top_index);
	stack->top_index--;
	void* to_return = *(stack->data + stack->top_index);
	*(stack->data + stack->top_index) = NULL;

	stack->curr_size--;

	return to_return;
}

void* stack_peek(Stack* stack) {
	void* to_return = *(stack->data + stack->top_index - 1);
	return to_return;
}

int stack_size(Stack* stack) {
	return (stack->curr_size);
}

bool stack_isEmpty(Stack* stack) {
	if (stack_size(stack) == 0) {
		return true;
	}
	return false;
}