class DoubleEndedQueue

class DoubleEndedQueue extends Queue implements DoubleEndedQueueInterface {
    
    /**
     * Constructs a double-ended queue (dequeue) object of the specified type,
     * optionally with the specified data.
     *
     * @param string $queueType The type or class name associated with this dequeue.
     * @param array<array-key, T> $data The initial items to store in the dequeue.
     */
    public function __construct(string $queueType, array $data = []) {
        parent::__construct($this->queueType, $data);
    }
    
    /**
     * @throws InvalidArgumentException if $element is of the wrong type
     */
    public function addFirst(mixed $element) : bool {
        if ($this->checkType($this->getType(), $element) === false) {
            throw new InvalidArgumentException('Value must be of type ' . $this->getType() . '; value is ' . $this->toolValueToString($element));
        }
        array_unshift($this->data, $element);
        return true;
    }
    
    /**
     * @throws InvalidArgumentException if $element is of the wrong type
     */
    public function addLast(mixed $element) : bool {
        return $this->add($element);
    }
    public function offerFirst(mixed $element) : bool {
        try {
            return $this->addFirst($element);
        } catch (InvalidArgumentException) {
            return false;
        }
    }
    public function offerLast(mixed $element) : bool {
        return $this->offer($element);
    }
    
    /**
     * @return T the first element in this queue.
     *
     * @throws NoSuchElementException if the queue is empty
     */
    public function removeFirst() : mixed {
        return $this->remove();
    }
    
    /**
     * @return T the last element in this queue.
     *
     * @throws NoSuchElementException if this queue is empty.
     */
    public function removeLast() : mixed {
        return $this->pollLast() ?? throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
    }
    
    /**
     * @return T | null the head of this queue, or `null` if this queue is empty.
     */
    public function pollFirst() : mixed {
        return $this->poll();
    }
    
    /**
     * @return T | null the tail of this queue, or `null` if this queue is empty.
     */
    public function pollLast() : mixed {
        return array_pop($this->data);
    }
    
    /**
     * @return T the head of this queue.
     *
     * @throws NoSuchElementException if this queue is empty.
     */
    public function firstElement() : mixed {
        return $this->element();
    }
    
    /**
     * @return T the tail of this queue.
     *
     * @throws NoSuchElementException if this queue is empty.
     */
    public function lastElement() : mixed {
        return $this->peekLast() ?? throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
    }
    
    /**
     * @return T | null the head of this queue, or `null` if this queue is empty.
     */
    public function peekFirst() : mixed {
        return $this->peek();
    }
    
    /**
     * @return T | null the tail of this queue, or `null` if this queue is empty.
     */
    public function peekLast() : mixed {
        $lastIndex = array_key_last($this->data);
        if ($lastIndex === null) {
            return null;
        }
        return $this->data[$lastIndex];
    }

}