/*******************************************************************************
 * Copyright (c) 2008 Oracle Corporation.
 * 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:
 *    Cameron Bateman - initial API and implementation
 *******************************************************************************/
package org.eclipse.jst.jsf.facelet.core.internal.registry.taglib;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.runtime.ISafeRunnable;
import org.eclipse.core.runtime.SafeRunner;
import org.eclipse.jst.jsf.common.internal.locator.ILocatorProvider;
import org.eclipse.jst.jsf.core.internal.tld.IFaceletConstants;
import org.eclipse.jst.jsf.facelet.core.internal.FaceletCorePlugin;

/**
 * Taglib descriptor for a project.
 * 
 * @author cbateman
 *
 */
public class ProjectTaglibDescriptor implements IProjectTaglibDescriptor
{
    private final AtomicInteger                      _isInitialized = new AtomicInteger(
                                                                            0);
    private final IProject                           _project;
    private final ILocatorProvider<AbstractFaceletTaglibLocator>      _locatorProvider;
    private final MyChangeListener                   _libChangeListener;
    private final Map<String, IFaceletTagRecord>     _tagRecords;
    private final TagRecordFactory _factory;
    private final AtomicBoolean     _isDisposed = new AtomicBoolean(false);
    private final DefaultStandardTaglibLocator _defaultTaglibLocator;

    /**
     * @param project
     * @param factory 
     * @param locatorProvider 
     */
    public ProjectTaglibDescriptor(final IProject project, final TagRecordFactory factory, 
            final ILocatorProvider<AbstractFaceletTaglibLocator> locatorProvider)
    {
        _project = project;
        _tagRecords = new HashMap<String, IFaceletTagRecord>();
        _locatorProvider = locatorProvider;
        _locatorProvider.initialize();
        _factory = factory; 
        _libChangeListener = new MyChangeListener();
        _defaultTaglibLocator = new DefaultStandardTaglibLocator();
        _defaultTaglibLocator.start(project);
    }

    private void initialize()
    {
        if (_isInitialized.addAndGet(1) == 1)
        {
            synchronized (this)
            {
                for (final AbstractFaceletTaglibLocator locator : _locatorProvider.getLocators())
                {
                    SafeRunner.run(new ISafeRunnable()
                    {
                        public void handleException(final Throwable exception)
                        {
                            FaceletCorePlugin
                                    .log(
                                            "While locating facelet libraries on project: " + _project.getName(), new Exception(exception)); //$NON-NLS-1$
                        }
                        public void run() throws Exception
                        {
                            locator.addListener(_libChangeListener);
                            locator.start(_project);
                            _tagRecords.putAll(locator.locate(_project));
                        }
                    });
                }
                // ensure that we add the standard tag libraries if we don't find them 
                // on the classpath.  The spec doesn't require that taglib's are
                // included in a JSF impl for these
                ensureStandardLibraries(_project);
            }
        }
    }

    private void ensureStandardLibraries(final IProject project)
    {
        final Map<String, ? extends IFaceletTagRecord>  defaultRecords = _defaultTaglibLocator.locate(project);
        for (final String uri : IFaceletConstants.ALL_FACELET_TAGLIBS)
        {
            if (!_tagRecords.containsKey(uri))
            {
                IFaceletTagRecord faceletTagRecord = defaultRecords.get(uri);
                if (faceletTagRecord != null)
                {
                    _tagRecords.put(uri, faceletTagRecord);
                }
                else
                {
                    FaceletCorePlugin.log("Could not find taglib for uri: "+uri, new Exception()); //$NON-NLS-1$
                }
            }
        }
    }

    public Collection<? extends IFaceletTagRecord> getTagLibraries()
    {
        initialize();
        return Collections.unmodifiableCollection(_tagRecords.values());
    }

    void maybeLog(final Exception e)
    {
        if (_isInitialized.get() <= 1)
        {
            FaceletCorePlugin.log("Failed initializing taglib descriptor", e); //$NON-NLS-1$
        }
    }

    public IFaceletTagRecord getTagLibrary(final String uri)
    {
        initialize();
        return _tagRecords.get(uri);
    }

    public void addListener(final Listener listener)
    {
        for (final AbstractFaceletTaglibLocator locator : _locatorProvider.getLocators())
        {
            locator.addListener(listener);
        }
    }

    public void removeListener(final Listener listener)
    {
        for (final AbstractFaceletTaglibLocator locator : _locatorProvider.getLocators())
        {
            locator.removeListener(listener);
        }
    }

    public void checkpoint()
    {
        // do nothing
    }

    public void destroy()
    {
        // call dispose;  there is no persistent data to cleanup.
        dispose();
    }

    public void dispose()
    {
        if (_isDisposed.compareAndSet(false, true))
        {
            for (final AbstractFaceletTaglibLocator locator : _locatorProvider.getLocators())
            {
                try
                {
                    locator.stop();
                } catch (Exception e)
                {
                    FaceletCorePlugin.log("Disposing ProjectTaglibDescriptor", e); //$NON-NLS-1$
                }
            }
            _factory.dispose();
        }
    }

    public boolean isDisposed()
    {
        return _isDisposed.get();
    }

    private class MyChangeListener extends Listener
    {
        @Override
        public void changed(final TaglibChangedEvent event)
        {
            switch (event.getChangeType())
            {
                case ADDED:
                    _tagRecords.put(event.getNewValue().getURI(), event
                            .getNewValue());
                break;
                case CHANGED:
                    _tagRecords.put(event.getNewValue().getURI(), event
                            .getNewValue());
                break;
                case REMOVED:
                    _tagRecords.remove(event.getOldValue());
                break;
            }
        }
    }
}