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

#define INIT_SIZE  100

struct _Stack {
	int size;
	void** elems;
	StackFreeFunc free;
};

static void free_elem(Stack* stack) {
	if (stack->free) {
		for (int i = 0; i < stack->size; i++)
			stack->free(stack->elems[i]);
	}
	free(stack->elems);
}

static Stack* stack_new_common() {
	Stack* s = malloc(sizeof(Stack));
	s->elems = malloc(sizeof(void*) * INIT_SIZE);
	s->size = 0;
	s->free = NULL;
	return s;
}

Stack* stack_new() {
	return stack_new_common();
}

Stack* stack_new_full(StackFreeFunc free) {
	Stack* s = 	stack_new_common();
	s->free = free;
	return s;
}

void stack_destroy(Stack* stack) {
	free_elem(stack);
	free(stack);
}

void* stack_pop(Stack* stack) {
	if (stack_empty(stack))
		return NULL;
	stack->size -= 1;
	void* elem = stack->elems[stack->size];
	stack->elems[stack->size] = NULL;

	return elem;
}

void stack_push(Stack* stack, void* elem) {
	if (stack == NULL)
		return;

	stack->size += 1;
	if (stack->size == INIT_SIZE) {
		stack->elems = realloc(stack->elems, (INIT_SIZE + stack->size) * sizeof(void*));
	}

	stack->elems[stack->size - 1] = elem;
}

void* stack_peek(Stack* stack) {
	if (stack_empty(stack))
		return NULL;
	return stack->elems[stack->size - 1];
}

bool stack_empty(Stack* stack) {
	return (stack == NULL || stack->size == 0);
}

void stack_clear(Stack* stack) {
	if (stack == NULL)
		return;

	free_elem(stack);
	stack->size = 0;
}

int stack_size(Stack* stack) {
	if (stack_empty(stack))
		return 0;
	return stack->size;
}

/*
typedef struct _Stack {
	void** elems;
	int size;
	StackFreeFunc free;
} Stack;

static void free_elem(Stack* stack) {
	if (stack->free) {
		for (int i = 0; i < stack->size; i++)
			stack->free(stack->elems[i]);
	}
	free(stack->elems);
}

Stack* stack_new() {
	Stack* s = malloc(sizeof(Stack));
	s->size = 0;
	s->elems = NULL;
	s->free = NULL;
	return s;
}

Stack* stack_new_full(StackFreeFunc free) {
	Stack* s = malloc(sizeof(Stack));
	s->size = 0;
	s->elems = NULL;
	s->free = free;
	return s;
}

void stack_destroy(Stack* stack) {
	free_elem(stack);
	free(stack);
}

void* stack_pop(Stack* stack) {
	if (stack_empty(stack))
		return NULL;
	stack->size -= 1;
	void* elem = stack->elems[stack->size];
	stack->elems[stack->size] = NULL;
	stack->elems = realloc(stack->elems, stack->size * sizeof(void*));

	return elem;
}

void stack_push(Stack* stack, void* elem) {
	if (stack == NULL)
		return;

	stack->size += 1;
	stack->elems = realloc(stack->elems, stack->size * sizeof(void*));
	stack->elems[stack->size - 1] = elem;
}

void* stack_peek(Stack* stack) {
	if (stack_empty(stack))
		return NULL;
	return stack->elems[stack->size - 1];
}

bool stack_empty(Stack* stack) {
	return (stack == NULL || stack->size == 0);
}

void stack_clear(Stack* stack) {
	if (stack == NULL)
		return;

	free_elem(stack);
	stack->size = 0;
	stack->elems = NULL;
}

int stack_size(Stack* stack) {
	if (stack_empty(stack))
		return 0;
	return stack->size;
}
*/