/*******************************************************************************
 * Copyright (c) 2006, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.wst.jsdt.internal.ui.javaeditor.saveparticipant;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.ProjectScope;
import org.eclipse.core.runtime.preferences.IScopeContext;
import org.eclipse.wst.jsdt.internal.corext.fix.CleanUpPostSaveListener;
import org.eclipse.wst.jsdt.internal.ui.fix.CleanUpSaveParticipantPreferenceConfiguration;

/**
 * A registry for save participants. This registry manages
 * {@link SaveParticipantDescriptor}s and keeps track of enabled save
 * participants.
 * <p>
 * Save participants can be enabled and disabled on the Java > Editor >
 * Save Participants preference page. Enabled save participants are notified
 * through a call to
 * {@link IPostSaveListener#saved(org.eclipse.wst.jsdt.core.IJavaScriptUnit, org.eclipse.core.runtime.IProgressMonitor)}
 * whenever the {@link org.eclipse.wst.jsdt.internal.ui.javaeditor.CompilationUnitDocumentProvider} saves a compilation unit
 * that is in the workspace.</p>
 * <p>
 * An instance of this registry can be received through a call to {@link org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin#getSaveParticipantRegistry()}.</p>
 * 
 * 
 */
public final class SaveParticipantRegistry {

	private static final IPostSaveListener[] EMPTY_ARRAY= new IPostSaveListener[0];
    
	/** The map of descriptors, indexed by their identifiers. */
	private Map fDescriptors;

	/**
	 * Creates a new instance.
	 */
	public SaveParticipantRegistry() {
	}

	/**
	 * Returns an array of <code>SaveParticipantDescriptor</code> describing
	 * all registered save participants.
	 *
	 * @return the array of registered save participant descriptors
	 */
	public synchronized SaveParticipantDescriptor[] getSaveParticipantDescriptors() {
		ensureRegistered();
		return (SaveParticipantDescriptor[]) fDescriptors.values().toArray(new SaveParticipantDescriptor[fDescriptors.size()]);
	}

	/**
	 * Returns the save participant descriptor for the given <code>id</code> or
	 * <code>null</code> if no such listener is registered.
	 *
	 * @param id the identifier of the requested save participant
	 * @return the corresponding descriptor, or <code>null</code> if none can be found
	 */
	public synchronized SaveParticipantDescriptor getSaveParticipantDescriptor(String id) {
		ensureRegistered();
		return (SaveParticipantDescriptor) fDescriptors.get(id);
	}

	/**
	 * Ensures that all descriptors are created and stored in
	 * <code>fDescriptors</code>.
	 */
	private void ensureRegistered() {
		if (fDescriptors == null)
			reloadDescriptors();
	}

	/**
	 * Loads the save participants.
	 * <p>
	 * This method can be called more than once in
	 * order to reload from a changed extension registry.
	 * </p>
	 */
	private void reloadDescriptors() {
		Map map= new HashMap();
		SaveParticipantDescriptor desc= new SaveParticipantDescriptor(new CleanUpPostSaveListener()) {
			/**
			 * {@inheritDoc}
			 */
			public ISaveParticipantPreferenceConfiguration createPreferenceConfiguration() {
				return new CleanUpSaveParticipantPreferenceConfiguration();
			}
		};	
		map.put(desc.getId(), desc);
				
		fDescriptors= map;
	}

	public void dispose() {
	}

	/**
	 * Checks weather there are enabled or disabled post save listener in the given context.
	 * 
	 * @param context to context to check, not null
	 * @return true if there are settings in context
	 */
	public synchronized boolean hasSettingsInScope(IScopeContext context) {		
		ensureRegistered();
	
    	for (Iterator iterator= fDescriptors.values().iterator(); iterator.hasNext();) {
	        SaveParticipantDescriptor descriptor= (SaveParticipantDescriptor)iterator.next();
	        if (descriptor.getPreferenceConfiguration().hasSettingsInScope(context))
	        	return true;
    	}
    	
    	return false;
    }
	
	public IPostSaveListener[] getEnabledPostSaveListeners(IProject project) {
	    return getEnabledPostSaveListeners(new ProjectScope(project));
    }

	/**
	 * Returns an array of <code>IPostSaveListener</code> which are 
	 * enabled in the given context.
	 *
	 * @param context the context from which to retrive the settings from, not null
	 * @return the current enabled post save listeners according to the preferences
	 */
	public synchronized IPostSaveListener[] getEnabledPostSaveListeners(IScopeContext context) {
		ensureRegistered();
		
		ArrayList result= null;
		for (Iterator iterator= fDescriptors.values().iterator(); iterator.hasNext();) {
			SaveParticipantDescriptor descriptor= (SaveParticipantDescriptor)iterator.next();
			if (descriptor.getPreferenceConfiguration().isEnabled(context)) {
				if (result == null) {
					result= new ArrayList();
				}
				result.add(descriptor.getPostSaveListener());
			}
		}
		
		if (result == null) {
			return EMPTY_ARRAY;
		} else {
			return (IPostSaveListener[])result.toArray(new IPostSaveListener[result.size()]);
		}
	}
	
}