package Queue;

public class Queue<T extends Comparable<T>> {

	private Node<T> firstNode;
	private Node<T> lastNode;
	private int count;
	
	public boolean isEmpty(){
		return this.firstNode == null;
	}
	
	public int size(){
		return this.count;
	}
	
	// O(1)
	public void enqueue(T newData){
		
		this.count++;
		
		Node<T> oldLastNode = this.lastNode;
		this.lastNode = new Node<>(newData);
		this.lastNode.setNextNode(null);
		
		if( isEmpty() ){
			this.firstNode = this.lastNode;
		}else{
			oldLastNode.setNextNode(this.lastNode);
		}
		
	}
	
	// O(1)
	public T dequeue(){
		
		this.count--;
		
		T dataToDequeue = this.firstNode.getData();
		this.firstNode=this.firstNode.getNextNode();
		
		if( isEmpty() ){
			this.lastNode = null;
		}
		
		return dataToDequeue;
	}
}