package com.dragome.forms.bindings.client.command;

import com.dragome.forms.bindings.client.binding.Disposable;
import com.dragome.forms.bindings.client.channel.DefaultChannel;
import com.dragome.forms.bindings.client.channel.Destination;
import com.dragome.forms.bindings.client.util.SubscriptionList;
import com.dragome.forms.bindings.extra.user.client.Command;

/**
 * Created by IntelliJ IDEA.
 * User: andrew
 * Date: Apr 1, 2010
 * Time: 1:38:00 PM
 * To change this template use File | Settings | File Templates.
 */
public abstract class AbstractEvents implements Events
{
	private SubscriptionList<LifeCycleCallback> callbacks= new SubscriptionList<LifeCycleCallback>();
	private DefaultChannel<Void> startChannel= new DefaultChannel<Void>();
	private DefaultChannel<Void> finishedChannel= new DefaultChannel<Void>();

	protected AbstractEvents()
	{
	}

	protected void fireStart()
	{
		startChannel.publish(null);
		visitSubscribers(new SubscriptionList.Visitor<LifeCycleCallback>()
		{
			public void visit(LifeCycleCallback subscriber)
			{
				subscriber.onStart();
			}
		});
	}

	protected void fireFinish()
	{
		finishedChannel.publish(null);
		visitSubscribers(new SubscriptionList.Visitor<LifeCycleCallback>()
		{
			public void visit(LifeCycleCallback subscriber)
			{
				subscriber.onFinish();
			}
		});
	}

	protected void visitSubscribers(SubscriptionList.Visitor<LifeCycleCallback> visitor)
	{
		if (visitor == null)
		{
			throw new NullPointerException("visitor is null");
		}
		callbacks.visitSubscribers(visitor);
	}

	public Disposable onStartInvoke(final Command command)
	{
		if (command == null)
		{
			throw new NullPointerException("command is null");
		}

		return startChannel.sendTo(new Destination<Void>()
		{
			public void receive(Void value)
			{
				command.execute();
			}
		});
	}

	public <T> SendToBuilder<T> onStartSend(final T value)
	{
		return new SendToBuilderImpl<T>(startChannel, value);
	}

	public Disposable onFinishInvoke(final Command command)
	{
		if (command == null)
		{
			throw new NullPointerException("command is null");
		}

		return finishedChannel.sendTo(new Destination<Void>()
		{
			public void receive(Void value)
			{
				command.execute();
			}
		});
	}

	public Disposable sendAllEventsTo(LifeCycleCallback callback)
	{
		if (callback == null)
		{
			throw new NullPointerException("callback is null");
		}

		return callbacks.subscribe(callback);
	}

	public <T> SendToBuilder<T> onFinishSend(final T value)
	{
		return new SendToBuilderImpl<T>(finishedChannel, value);
	}

}