package wek3;

import wek1.EmptyCollectionException;
import wek1.LinearNode;

public class LinkedQueue<T> implements QueueADT<T>
    {
        private int count;
        private LinearNode<T> head, tail;

        /**
         * Creates an empty queue.
         */
        public LinkedQueue()
        {
            count = 0;
            head = tail = null;
        }


        @Override
        public void enqueue(T element)
        {
            LinearNode<T> node = new LinearNode<T>(element);

            if (isEmpty()) {
                head = node;
            } else {
                tail.setNext(node);
            }

            tail = node;
            count++;
        }


        @Override
        public T dequeue() throws EmptyCollectionException
        {
            if (isEmpty()) {
                throw new EmptyCollectionException("queue");
            }
            T result = head.getElement();
            head = head.getNext();
            count--;

            if (isEmpty()) {
                tail = null;
            }
            return result;
        }


        @Override
        public T first() throws EmptyCollectionException
        {
            if (isEmpty()) {
                throw new EmptyCollectionException("wrong");
            }
            T result = head.getElement();

            return result;
        }


        @Override
        public boolean isEmpty()
        {
            if (size() == 0) {
                return true;
            } else {
                return false;
            }
        }


        @Override
        public int size()
        {
            return count;
        }

        @Override
        public String toString()
        {
            LinearNode node;
            String result="";
            node = head;
            for(int a=0;a<count ;a++){
                result += node.getElement()+ " ";
                node = node.getNext();
            }
            return result;
        }
    }