<?php

declare(strict_types=1);

namespace App\Util;

/**
 * Basic stack data structure.
 *
 * @author Adam Pippin <hello@adampippin.ca>
 */
class Stack
{
	/**
	 * Stack data.
	 * @var mixed[]
	 */
	protected $stack;

	/**
	 * Create a new stack.
	 */
	public function __construct()
	{
		$this->stack = [];
	}

	/**
	 * Count how many items this stack contains.
	 *
	 * @return int
	 */
	public function count(): int
	{
		return sizeof($this->stack);
	}

	/**
	 * Get all items in this stack.
	 *
	 * @return mixed[]
	 */
	public function get(): array
	{
		return $this->stack;
	}

	/**
	 * Pop an item off of this stack.
	 *
	 * @param  int   $offset offset from the end to pop if not the last element
	 * @return mixed
	 */
	public function pop(int $offset = 0)
	{
		if (sizeof($this->stack) < $offset + 1)
		{
			throw new \Exception('Stack underflow!');
		}
		return array_splice($this->stack, -1 * ($offset + 1), 1)[0];
	}

	/**
	 * Push an item onto the end of the stack.
	 *
	 * @param  mixed $value
	 * @return void
	 */
	public function push($value): void
	{
		array_push($this->stack, $value);
	}
}