AjaxSelectCallback.java

package com.googlecode.wicketwebbeans.datepicker;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.wicket.Component;
import org.apache.wicket.Request;
import org.apache.wicket.RequestCycle;
import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.ajax.IAjaxCallDecorator;
import org.apache.wicket.ajax.calldecorator.AjaxCallDecorator;
import org.apache.wicket.util.string.AppendingStringBuffer;
import org.apache.wicket.util.string.Strings;

/**
 * AJAX based {@link ISelectCallback}, which executes an AJAX event when the
 * user selects something in the date picker.
 * 
 * @author Frank Bille Jensen
 */
public abstract class AjaxSelectCallback implements ISelectCallback
{

    private static final Pattern ajaxScriptPattern =
        Pattern.compile("^var wcall=wicketAjaxGet\\('([^']+)'.*$");

    private static final SimpleDateFormat dateParamFormat =
        new SimpleDateFormat("yyyy-M-d-H-m");

    private abstract class SelectCallbackBehavior extends AbstractDefaultAjaxBehavior
    {
        @Override
        public CharSequence getCallbackScript()
        {
            return super.getCallbackScript();
        }
    }

    private SelectCallbackBehavior eventBehavior;

    public final void bind(Component component)
    {
        eventBehavior = new SelectCallbackBehavior()
        {
            private static final long serialVersionUID = 1L;

            protected void respond(AjaxRequestTarget target)
            {
                Request request = RequestCycle.get().getRequest();

                String dateParam = request.getParameter("dateParam");
                Date date = null;

                try
                {
                    date = dateParamFormat.parse(dateParam);
                }
                catch (ParseException e)
                {
                    throw new WicketRuntimeException(e);
                }

                onEvent(target, date);
            }

            @Override
            protected IAjaxCallDecorator getAjaxCallDecorator()
            {
                return new AjaxCallDecorator()
                {
                    private static final long serialVersionUID = 1L;

                    @Override
                    public CharSequence decorateScript(Component component, CharSequence script)
                    {
                        AppendingStringBuffer b = new AppendingStringBuffer();

                        Matcher mat = ajaxScriptPattern.matcher(script);
                        if (mat.matches())
                        {
                            String url = mat.group(1);
                            String newUrl = url + "&dateParam='+dateParam+'";
                            b.append(Strings.replaceAll(script, url, newUrl));
                        }
                        else
                        {
                            throw new WicketRuntimeException("Internal error in Wicket");
                        }

                        return b;
                    }

                };
            }
        };

        component.add(eventBehavior);
    }

    public final CharSequence handleCallback()
    {
        return eventBehavior.getCallbackScript();
    }

    protected abstract void onEvent(AjaxRequestTarget target, Date date);

}