Tapestry HashChange mixin

HashChange.java

package my.package.mixins;

import org.apache.commons.lang3.StringUtils;
import org.apache.tapestry5.*;
import org.apache.tapestry5.annotations.Environmental;
import org.apache.tapestry5.annotations.Import;
import org.apache.tapestry5.annotations.InjectContainer;
import org.apache.tapestry5.annotations.Parameter;
import org.apache.tapestry5.corelib.base.AbstractComponentEventLink;
import org.apache.tapestry5.corelib.components.ActionLink;
import org.apache.tapestry5.corelib.components.EventLink;
import org.apache.tapestry5.internal.InternalComponentResources;
import org.apache.tapestry5.ioc.annotations.Inject;
import org.apache.tapestry5.ioc.services.TypeCoercer;
import org.apache.tapestry5.json.JSONObject;
import org.apache.tapestry5.services.Request;
import org.apache.tapestry5.services.javascript.InitializationPriority;
import org.apache.tapestry5.services.javascript.JavaScriptSupport;
import org.slf4j.Logger;

@Import(library={"context:js/jquery.ba-hashchange.js","hashchange.js"})
public class HashChange {
    @Parameter(defaultPrefix=BindingConstants.LITERAL)
    private String zone;

    @Inject
    private Logger logger;
    
    @Inject
    private ComponentResources resources;
    
    @Inject
    private Request request;
    
    @Inject
    private TypeCoercer typeCoercer;
    
    @InjectContainer 
    private AbstractComponentEventLink link;
    
    @Environmental
    private JavaScriptSupport jsSupport;

    void afterRender ( MarkupWriter writer ) {
        InternalComponentResources internalResources = 
                (InternalComponentResources) resources.getContainerResources ();
        
        String path = null;
        
        if ( link instanceof EventLink ) {
            Binding eventBinding = internalResources.getBinding ( "event" );
            path = eventBinding.get ().toString ();
        }
        
        if ( link instanceof ActionLink ) {
            Binding contextBinding = internalResources.getBinding ( "context" );
            if ( contextBinding == null )
                path = link.getClientId ();
            else
                path = typeCoercer.coerce ( contextBinding.get (), String.class );
        }
        
        if ( path == null )
            throw new IllegalArgumentException ( "cannot determine hash path" );
        
        if ( internalResources.getBinding ( "zone" ) != null ) {
            Binding zoneBinding = internalResources.getBinding ( "zone" );
            if ( StringUtils.isNotBlank ( zoneBinding.get ().toString () ) ) {
                JSONObject params = new JSONObject ();
                params.put ( "linkId", link.getClientId () );
                params.put ( "zoneId", zoneBinding.get ().toString () );
                params.put ( "token", path );
                params.put ( "ajax", request.isXHR () );
                jsSupport.addInitializerCall ( InitializationPriority.LATE, "hashchange", params );
            }
        }
    }
}

hashchange.js

var hashchangeHandlers = {};
var hashchangeInstalled = false;

Tapestry.Initializer.hashchange = function(spec) {
	var token 	= spec.token;
	var linkId 	= spec.linkId;
	var zoneId	= spec.zoneId;
	
	var el 			= jQuery('#'+linkId);
	var zoneElement = jQuery('#'+zoneId);
	var url 		= jQuery(el).attr('href');
	
	Tapestry.onDOMLoaded(function() {
		var setupHandlers = function() {
			// unbind default click handler
			el.unbind('click');
			
			// perform hash change
			el.bind('click', function(event) {
				location.hash = '#'+token;
				return false;
			});
		};
		
		hashchangeHandlers['#'+token] = function() {
			el.trigger(Tapestry.TRIGGER_ZONE_UPDATE_EVENT);
		};
		
		setupHandlers();
		
		jQuery(document.body).unbind(Tapestry.ZONE_UPDATED_EVENT + "." + token);
	    jQuery(document.body).bind(Tapestry.ZONE_UPDATED_EVENT + "." + token, function(){
			setupHandlers();
		});

		if (!hashchangeInstalled) {
			jQuery(window).hashchange(function() {
				if (hashchangeHandlers[location.hash] != null) {
					var hashchangeHandler = hashchangeHandlers[location.hash];
					hashchangeHandler();
				}
			});
			hashchangeInstalled = true;
		}
		
		if (!spec.ajax && (location.hash == ('#'+token)))
			el.trigger(Tapestry.TRIGGER_ZONE_UPDATE_EVENT);
	});
};