/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.wicket.devutils.debugbar;

import java.util.ArrayList;
import java.util.List;

import org.apache.wicket.Application;
import org.apache.wicket.AttributeModifier;
import org.apache.wicket.Component;
import org.apache.wicket.MetaDataKey;
import org.apache.wicket.devutils.DevUtilsPanel;
import org.apache.wicket.markup.head.CssHeaderItem;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.markup.head.JavaScriptHeaderItem;
import org.apache.wicket.markup.head.OnDomReadyHeaderItem;
import org.apache.wicket.markup.html.WebMarkupContainer;
import org.apache.wicket.markup.html.image.Image;
import org.apache.wicket.markup.html.list.ListItem;
import org.apache.wicket.markup.html.list.ListView;
import org.apache.wicket.model.AbstractReadOnlyModel;
import org.apache.wicket.request.resource.CssResourceReference;
import org.apache.wicket.request.resource.JavaScriptResourceReference;
import org.apache.wicket.request.resource.PackageResourceReference;
import org.apache.wicket.util.lang.Args;

/**
 * The debug bar is for use during development. It allows contributors to add useful functions or
 * data, making them readily accessible to the developer.<br />
 * <br />
 * To use it, simply add it to your base page so that all of your pages automatically have it.<br />
 * 
 * <br />
 * <code>
 * Java:
 * add(new DebugBar("debug"));
 * 
 * HTML:
 * &lt;div wicket:id="debug"&gt;&lt;/div&gt;
 * </code>
 * 
 * <br />
 * You can also add your own information to the bar by creating a {@link IDebugBarContributor} and
 * registering it with the debug bar.
 *
 * <p>The debug bar uses CSS absolute positioning to appear in the top-right corner of the page.
 * <strong>Important</strong>: if there is an element with a z-index in this part of your page, the DebugBar will need a higher
 * "z-index" style value to show up. Or you can use different position for it. See wicket-debugbar.css.</p>
 *
 * @author Jeremy Thomerson <jthomerson@apache.org>
 * @see IDebugBarContributor
 */
public class DebugBar extends DevUtilsPanel
{
	private static final long serialVersionUID = 1L;

	private static final MetaDataKey<List<IDebugBarContributor>> CONTRIBS_META_KEY = new MetaDataKey<List<IDebugBarContributor>>()
	{
		private static final long serialVersionUID = 1L;
	};

	
	/**
	 * Construct.
	 * <p/>
	 * Create debug bar (initially expanded)
	 * 
	 * @param id
	 *         component id
	 *         
	 * @see #DebugBar(String, boolean) 
	 */
	public DebugBar(final String id)
	{
		this(id, true);
	}
	
	/**
	 * Construct.
	 * 
	 * @param id
	 *         component id
	 * @param initiallyExpanded
	 *         {@code true} to show debug bar initially expanded
	 *         
	 * @see #DebugBar(String) 
	 */
	public DebugBar(final String id, boolean initiallyExpanded)
	{
		super(id);
		setMarkupId("wicketDebugBar");
		setOutputMarkupId(true);
		add(AttributeModifier.replace("class", new AbstractReadOnlyModel<String>()
		{
			private static final long serialVersionUID = 1L;

			@Override
			public String getObject()
			{
				return "wicketDebugBar" + (DebugBar.this.hasErrorMessage() ? "Error" : "");
			}
		}));

		add(new Image("logo", new PackageResourceReference(DebugBar.class, "wicket.png")));
		
		add(contentSection("content", initiallyExpanded));
	}


	/**
	 * Positions the DebugBar at the bottom of the page
	 * @return
	 */
	public DebugBar positionBottom()
	{
		add(AttributeModifier.append("class", "bottom"));
		return this;
	}

	private Component contentSection(final String id, boolean initiallyExpanded)
	{
		WebMarkupContainer section = new WebMarkupContainer(id);
		if (!initiallyExpanded)
		{
			section.add(AttributeModifier.append("style", "display:none").setSeparator(";"));
		}

		List<IDebugBarContributor> contributors = getContributors(getApplication());

		section.add(new ListView<IDebugBarContributor>("contributors", contributors)
		{
			private static final long serialVersionUID = 1L;

			@Override
			protected void populateItem(final ListItem<IDebugBarContributor> item)
			{
				IDebugBarContributor contrib = item.getModelObject();
				Component comp = contrib.createComponent("contrib", DebugBar.this);
				if (comp == null)
				{
					// some contributors only add information to the debug bar
					// and don't actually create a contributed component
					item.setVisibilityAllowed(false);
				}
				else
				{
					item.add(comp);
				}
			}
		});

		section.add(new Image("removeImg", new PackageResourceReference(DebugBar.class, "remove.png")));

		return section;
	}

	@Override
	public boolean isVisible()
	{
		return getApplication().getDebugSettings().isDevelopmentUtilitiesEnabled();
	}

	@Override
	public void renderHead(final IHeaderResponse response)
	{
		response.render(CssHeaderItem.forReference(new CssResourceReference(DebugBar.class,
			"wicket-debugbar.css")));
		response.render(JavaScriptHeaderItem.forReference(new JavaScriptResourceReference(
			DebugBar.class, "wicket-debugbar.js")));
		response.render(OnDomReadyHeaderItem.forScript("wicketDebugBarCheckState()"));
	}

	/**
	 * Register your own custom contributor that will be part of the debug bar. You must have the
	 * context of an application for this thread at the time of calling this method.
	 * 
	 * @param contrib
	 *            custom contributor - can not be null
	 */
	public static void registerContributor(final IDebugBarContributor contrib)
	{
		registerContributor(contrib, Application.get());
	}

	/**
	 * Register your own custom contributor that will be part of the debug bar. You must have the
	 * context of an application for this thread at the time of calling this method.
	 * 
	 * @param application
	 * @param contrib
	 *            custom contributor - can not be null
	 */
	public static void registerContributor(final IDebugBarContributor contrib,
		final Application application)
	{
		Args.notNull(contrib, "contrib");

		List<IDebugBarContributor> contributors = getContributors(application);
		contributors.add(contrib);
		setContributors(contributors, application);
	}

	public static List<IDebugBarContributor> getContributors(final Application application)
	{
		List<IDebugBarContributor> list = application.getMetaData(CONTRIBS_META_KEY);
		return list == null ? new ArrayList<IDebugBarContributor>() : list;
	}

	public static void setContributors(List<IDebugBarContributor> contributors, Application application)
	{
		Args.notNull(application, "application");

		application.setMetaData(CONTRIBS_META_KEY, contributors);
	}
}
