#include "position_stack.h"
#include "utils.h"
#include <stdio.h>
#include <stdlib.h>

// Error handler for stack errors
void stack_error(int err)
{
	switch (err)
	{
	case STACK_ERR_OVERFLOW:
		printf("Error: Stack overflow\nBe kind and report this problem.");
		break;
	case STACK_ERR_UNDERFLOW:
		printf("Error: Stack underflow\nBe kind and report this problem.");
		break;
	}

	exit(1);
}

// Creates a new stack
PositionStack *pos_stack_create(unsigned int capacity)
{
	PositionStack *pos_stack = malloc_s(sizeof(PositionStack));

	pos_stack->capacity = capacity;
	pos_stack->top = -1;
	pos_stack->items = malloc_s(sizeof(Position) * capacity);

	return pos_stack;
}

void pos_stack_destroy(PositionStack *pos_stack)
{
	free(pos_stack->items);
	free(pos_stack);
}

// Adds a new item to a stack
void pos_stack_push(PositionStack *pos_stack, Position pos)
{
	// Avoid a overflow by checking if the stack is full
	if (pos_stack->top == pos_stack->capacity - 1)
	{
		stack_error(STACK_ERR_OVERFLOW);
	}

	// Add an element and increase the top index
	pos_stack->items[++pos_stack->top] = pos;
}

// Returns the topmost item of a stack
Position pos_stack_peek(PositionStack *pos_stack)
{
	// Avoid a underflow by checking if the stack is empty
	if (pos_stack->top == -1)
	{
		stack_error(STACK_ERR_UNDERFLOW);
	}

	return pos_stack->items[pos_stack->top];
}

// Deletes the topmost item of a stack
Position pos_stack_pop(PositionStack *pos_stack)
{
	// Avoid a underflow by checking if the stack is empty
	if (pos_stack->top == -1)
	{
		stack_error(STACK_ERR_UNDERFLOW);
	}

	// Decrease the stack size by 1 and return the popped element
	return pos_stack->items[pos_stack->top--];
}