/*
 * Copyright (c) 2002,2009 Declarative Engineering LLC.
 * All rights reserved.  This program and the accompanying materials
 * are made available under the terms of the Declarative Engineering LLC
 * verson 1 which accompanies this distribution, and is available at
 * http://declarativeengineering.com/legal/DE_Developer_License_v1.txt
 */
package com.foundation.tcv.swt.server;

import com.common.util.*;
import com.common.debug.*;
import com.foundation.view.*;
import com.foundation.controller.IController;
import com.foundation.event.*;

/*
 * Encapsulates an object reference used by the view system at runtime, and the class of the runtime reference to allow design type automation.
 */
public class ValueHolder extends Component implements IValueHolder {
	/** The class of value held by this value holder. */
	private Class heldType = null;
	/** The current value held by this value holder. */
	private IEventEmitter value = null;
	/** The collection of listeners listening for held value events. */
	private LiteHashSet eventListeners = new LiteHashSet(5);
	/** The collection of listeners listening for held value events. */
	private LiteHashSet valueHolderListeners = new LiteHashSet(5, LiteHashSet.DEFAULT_LOAD_FACTOR, LiteHashSet.DEFAULT_COMPARATOR, LiteHashSet.STYLE_COUNT_DUPLICATES);
	/** The event support used by value holder related associations to listen for held value events. */
	private EventSupport eventSupport = null;
	/** The parent resource from which this holder's value is derived. */
	private SingleResourceAssociation parent = new SingleResourceAssociation(this, this, getViewContext(), SingleResourceAssociation.TYPE_OBJECT, false, null);
	/** Whether the value holder gets its value from a parent. */
	private boolean hasParent = false;
	/** Whether to not warn when an attempt is made to place a value that is not of the correct type. */
	private boolean ignoreWarnings = false;
/**
 * ValueHolder constructor.
 * @param parent The parent container.
 * @param name The view unqiue name of the component.
 * @param heldType The type of object to be held by the value holder.
 */
public ValueHolder(IAbstractContainer parent, String name, Class heldType) {
	super(parent, name, 0);
	
	this.heldType = heldType;
}//ValueHolder()//
/**
 * Sets whether the holder supresses warnings relating to attempts at setting the value to an invalid object type.
 * @param ignoreWarnings Whether to not warn when an attempt is made to place a value that is not of the correct type.
 */
public void ignoreWarnings(boolean ignoreWarnings) {
	this.ignoreWarnings = ignoreWarnings;
}//ignoreWarnings()//
/**
 * Sets the association container used to access the parent value holder.
 * @param container The parent association metadata.
 */
public void setParentAssociation(SingleAssociationContainer	container) {
	verifyThread();
	this.parent.setAssociations(container);
	this.hasParent = true;
}//setParentAssociation()//
/**
 * Gets the support object that provides event listening functionality.
 * @return Will be used to listen for events from IEventEmitter objects.
 */
protected EventSupport getEventSupport() {
	if(eventSupport == null) {
		eventSupport = new EventSupport(null);
	}//if//

	return eventSupport;
}//getEventSupport()//
/**
 * Gets the value being held by this holder.
 * @return The currently held value.
 */
public IEventEmitter getValue() {
	return value;
}//getValue()//
/**
 * Gets the class for the values held by this value holder.
 * @return The held value type.
 */
public Class getHeldType() {
	return heldType;
}//getHeldType()//
/* (non-Javadoc)
 * @see com.foundation.view.IValueHolder#registerListener(com.foundation.view.IEventCapableAssociation)
 */
public void registerListener(IEventCapableAssociation eventAssociation) {
	IEventEmitter value = getValue();
	
	if((value != null) && (eventAssociation.getEventNumber() != -1) && ((eventAssociation.getValueHolderHeldType() == null) || (eventAssociation.getValueHolderHeldType().isAssignableFrom(value.getClass())))) {
		getEventSupport().register(value, eventAssociation.getEventNumber(), eventAssociation, true);
	}//if//
	
	eventListeners.add(eventAssociation);
}//registerListener()//
/* (non-Javadoc)
 * @see com.foundation.view.IValueHolder#unregisterListener(com.foundation.view.IEventCapableAssociation)
 */
public void unregisterListener(IEventCapableAssociation eventAssociation) {
	IEventEmitter value = getValue();
	
	if((value != null) && (eventAssociation.getEventNumber() != -1) && ((eventAssociation.getValueHolderHeldType() == null) || (eventAssociation.getValueHolderHeldType().isAssignableFrom(value.getClass())))) {
		getEventSupport().unregister(value, eventAssociation.getEventNumber(), eventAssociation);
	}//if//
	
	eventListeners.remove(eventAssociation);
}//unregisterListener()//
/* (non-Javadoc)
 * @see com.foundation.view.IValueHolder#registerListener(com.foundation.view.IValueHolderListener)
 */
public void registerListener(IValueHolderListener listener) {
	valueHolderListeners.add(listener);
}//registerListener()//
/* (non-Javadoc)
 * @see com.foundation.view.IValueHolder#unregisterListener(com.foundation.view.IValueHolderListener)
 */
public void unregisterListener(IValueHolderListener listener) {
	valueHolderListeners.remove(listener);
}//unregisterListener()//
/**
 * Updates the registered listeners so that they are registered with the new held value and are notified that their attributes may have changed.
 * @param oldHeldValue The old value held by this value holder.
 * @param newHeldValue The new value held by this value holder.
 */
public synchronized void updateRegisteredListeners(IEventEmitter oldHeldValue, IEventEmitter newHeldValue) {
	IIterator iterator = new LiteHashSet(eventListeners).iterator();
	
	//Unregister and reregister handlers.//
	while(iterator.hasNext()) {
		IEventCapableAssociation eventAssociation = (IEventCapableAssociation) iterator.next();
		
		if((oldHeldValue != null) && ((eventAssociation.getValueHolderHeldType() == null) || (eventAssociation.getValueHolderHeldType().isAssignableFrom(value.getClass())))) {
			getEventSupport().unregister(oldHeldValue, eventAssociation.getEventNumber(), eventAssociation);
		}//if//
		
		if((newHeldValue != null) && ((eventAssociation.getValueHolderHeldType() == null) || (eventAssociation.getValueHolderHeldType().isAssignableFrom(value.getClass())))) {
			getEventSupport().register(newHeldValue, eventAssociation.getEventNumber(), eventAssociation, true);
		}//if//
	}//while//
	
	iterator.resetToFront();
	
	while(iterator.hasNext()) {
		IEventCapableAssociation eventAssociation = (IEventCapableAssociation) iterator.next();
		
		eventAssociation.evaluate(eventAssociation.getEventNumber(), null, 0);
	}//while//
	
	//Notify the listeners so their user can update.//
	if(valueHolderListeners.getSize() > 0) {
		Object[] listeners = valueHolderListeners.toArray();
		
		for(int index = 0; index < listeners.length; index++) {
			IValueHolderListener listener = (IValueHolderListener) listeners[index];
			
			listener.heldValueChanged();
		}//while//
	}//if//
}//updateRegisteredListeners()//
/**
 * Sets the value being held.
 * @param value The held value.
 */
protected void setValue(IEventEmitter value) {
	if(value != this.value) {
		IEventEmitter oldValue = this.value;
	
		this.value = value;
		updateRegisteredListeners(oldValue, value);
	}//if//
}//setValue()//
/* (non-Javadoc)
 * @see com.foundation.tcv.swt.server.AbstractComponent#internalViewInitialize()
 */
protected void internalViewInitialize() {
	parent.initialize();
	isInitialized(true);
}//internalViewInitialize()//
/* (non-Javadoc)
 * @see com.foundation.tcv.swt.server.AbstractComponent#internalViewRelease()
 */
public void internalViewRelease() {
	parent.release();
	
	if(getContainer() != null) {
		getContainer().getComponents().remove(this);
	}//if//
}//internalViewRelease()//
/* (non-Javadoc)
 * @see com.foundation.tcv.swt.server.AbstractComponent#internalViewRefresh()
 */
protected void internalViewRefresh() {
	if(isInitialized()) {
		if(hasParent) {
			if(parent.refresh()) {
				Object value = parent.getValue();
				
				if((value == null) || (value instanceof IEventEmitter) && (heldType.isAssignableFrom(value.getClass()))) {
					setValue((IEventEmitter) value);
				}//if//
				else if(!ignoreWarnings) {
					if(value instanceof IEventEmitter) {
						Debug.log("Invalid held object.  Received a " + value.getClass().getName() + " and was expecting a " + heldType.getName() + " in the ValueHolder named " + getName() + ".");
					}//if//
					else {
						Debug.log("Invalid held object.  The class " + value.getClass().getName() + " does not implement " + IEventEmitter.class.getName() + " in the ValueHolder named " + getName() + ".");
					}//else//
				}//else if//
			}//if//
		}//if//
		else {
			IAbstractContainer parent = getContainer();
			IController controller = null;
	
			while((parent != null) && (controller == null)) {
				if(parent instanceof IView) {
					controller = ((IView) parent).getController();
				}//if//
				else {
					parent = parent.getContainer();
				}//else//
			}//while//
	
			if((controller != null) && (controller.getClass().isAssignableFrom(heldType))) {
				setValue((IEventEmitter) controller);
			}//if//
			else if(!controller.getClass().isAssignableFrom(heldType)) {
				Debug.log("Invalid controller object.  Received a " + controller.getClass().getName() + " and was expecting a " + heldType.getName() + " in the ValueHolder named " + getName() + ".");
			}//else if//
		}//else//
	}//if//
}//internalViewRefresh()//
/* (non-Javadoc)
 * @see com.foundation.tcv.swt.server.AbstractComponent#internalOnValueChanged(com.foundation.view.SingleResourceAssociation)
 */
protected void internalOnValueChanged(SingleResourceAssociation resourceAssociation, int flags) {
	if(isInitialized()) {
		internalViewRefresh();
	}//if//
}//internalOnValueChanged()//
/* (non-Javadoc)
 * @see com.foundation.tcv.swt.server.AbstractComponent#getClientClassName()
 */
protected String getClientClassName() {
	return StringSupport.EMPTY_STRING;
}//getClientClassName()//
}//ValueHolder//