package org.madore.damlengine;

import java.util.Collection;
import java.util.LinkedList;

public final class TodoDeque {

    protected final LinkedList<TodoItem> deque;

    public TodoDeque() {
	deque = new LinkedList<TodoItem>();
    }

    public void registerAtEnd(TodoItem it) {
	it.setOwnerDeque(this);
	deque.addLast(it);
    }

    public void registerAtEnd(Collection<? extends TodoItem> them) {
	for ( TodoItem it : them )
	    it.setOwnerDeque(this);
	deque.addAll(them);
    }

    public void registerAtStart(TodoItem it) {
	it.setOwnerDeque(this);
	deque.addFirst(it);
    }

    public void registerAtStart(Collection<? extends TodoItem> them) {
	for ( TodoItem it : them )
	    it.setOwnerDeque(this);
	deque.addAll(0, them);
    }

    public TodoItem removeNext() {
	return deque.poll();
    }

    public boolean dispatchOne() {
	TodoItem it = removeNext();
	if ( it != null ) {
	    assert(it.getOwnerDeque() == this);
	    it.handle();
	    return true;
	} else
	    return false;
    }

    public void dispatchLoop() {
	while ( dispatchOne() )
	    ;
    }

}