ErrorLibraryProviderFactory.java

/*******************************************************************************
 * Copyright (c) 2006-2010 eBay Inc. All Rights Reserved.
 * Licensed 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
 *******************************************************************************/
/**
 * 
 */
package org.ebayopensource.turmeric.eclipse.errorlibrary.providers;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.ebayopensource.turmeric.eclipse.core.logging.SOALogger;
import org.ebayopensource.turmeric.eclipse.errorlibrary.ErrorLibraryActivator;
import org.ebayopensource.turmeric.eclipse.errorlibrary.resources.SOAMessages;
import org.ebayopensource.turmeric.eclipse.exception.resources.SOAGetErrorLibraryProviderFailedException;
import org.ebayopensource.turmeric.eclipse.utils.collections.ListUtil;
import org.ebayopensource.turmeric.eclipse.utils.ui.UIUtil;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtension;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jface.viewers.ILabelProvider;
import org.eclipse.jface.viewers.ILabelProviderListener;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.window.Window;
import org.eclipse.swt.graphics.Image;
import org.eclipse.ui.dialogs.ListDialog;


/**
 * A factory for creating ErrorLibraryProvider objects.
 *
 * @author yayu
 * @since 1.0.0
 */
public final class ErrorLibraryProviderFactory {

	private static String preferredProviderID = null;
	private static Map<String, IErrorLibraryProvider> errorProviders = 
		new LinkedHashMap<String, IErrorLibraryProvider>();
	private static final SOALogger logger = SOALogger.getLogger();

	/** The Constant PROP_KEY_PROVIDER_ID. */
	public static final String PROP_KEY_PROVIDER_ID = "providerID";
	
	/** The Constant PROP_KEY_PROVIDER_IMPLEMENTATION. */
	public static final String PROP_KEY_PROVIDER_IMPLEMENTATION = "providerImplementation";
	
	private static ErrorLibraryProviderFactory factory = new ErrorLibraryProviderFactory();

	/**
	 * 
	 */
	private ErrorLibraryProviderFactory() {
		super();
	}
	
	/**
	 * Gets the single instance of ErrorLibraryProviderFactory.
	 *
	 * @return single instance of ErrorLibraryProviderFactory
	 */
	public static ErrorLibraryProviderFactory getInstance() {
		return factory;
	}
	
	
	/**
	 * Gets the error library providers.
	 *
	 * @return the error library providers
	 * @throws SOAGetErrorLibraryProviderFailedException the sOA get error library provider failed exception
	 */
	public List<IErrorLibraryProvider> getErrorLibraryProviders() 
	throws SOAGetErrorLibraryProviderFailedException{
		if (errorProviders.isEmpty() == true) {
			try {
				final IExtensionRegistry registry = Platform.getExtensionRegistry();
				final IExtensionPoint extensionPoint = registry
						.getExtensionPoint(ErrorLibraryActivator.PLUGIN_ID
								+ ".soaErrorLibProvider");

				if (extensionPoint != null) {
					IExtension[] extensions = extensionPoint.getExtensions();
					final Map<String, IConfigurationElement> providers = new LinkedHashMap<String, IConfigurationElement>();
					for (final IExtension extension : extensions) {
						for (final IConfigurationElement element : extension
								.getConfigurationElements()) {
							final String providerID = element
									.getAttribute(PROP_KEY_PROVIDER_ID);
							
							providers.put(providerID, element);
							errorProviders.put(providerID, (IErrorLibraryProvider)
									element.createExecutableExtension(PROP_KEY_PROVIDER_IMPLEMENTATION));
						}
					}
				}
			} catch (Exception e) {
				throw new SOAGetErrorLibraryProviderFailedException(
						SOAMessages.CONTENT_PROVIDER_NOT_FOUND, e);
			}
		}
		return ListUtil.arrayList(errorProviders.values());
	}
	
	/**
	 * Sets the preferred error library provider id.
	 *
	 * @param providerId the new preferred error library provider id
	 */
	public void setPreferredErrorLibraryProviderId(String providerId) {
		preferredProviderID = providerId;
	}

	/**
	 * Gets the preferred provider.
	 *
	 * @return The preferred error library content provider
	 * @throws SOAGetErrorLibraryProviderFailedException the sOA get error library provider failed exception
	 */
	public IErrorLibraryProvider getPreferredProvider()
			throws SOAGetErrorLibraryProviderFailedException {
		IErrorLibraryProvider preferredProvider = null;
		if (preferredProviderID == null) {
			try {
				final List<IErrorLibraryProvider> providers = getErrorLibraryProviders();
				if (providers.size() == 1) {
					preferredProviderID = providers.get(0).getProviderID();
					logger.info(SOAMessages.PREF_CONTENT_PROVIDER, preferredProviderID);
				} else {
					showDialogAndSelectProvider();
				}
			} catch (Exception e) {
				throw new SOAGetErrorLibraryProviderFailedException(
						SOAMessages.CONTENT_PROVIDER_NOT_FOUND, e);
			}
		}
		
		if (errorProviders.isEmpty() == true) {
			getErrorLibraryProviders();
		}
		preferredProvider = errorProviders.get(preferredProviderID);
		
		if (preferredProvider == null) {
			// no error providers found. bad bad. throw an exception
			throw new SOAGetErrorLibraryProviderFailedException(
					SOAMessages.CONTENT_PROVIDER_NOT_FOUND);

		}
		
		return preferredProvider;
	}

	private void showDialogAndSelectProvider() {
		IStructuredContentProvider contentProvider = new ErrorLibraryStructuredContentProvider(); 
		ILabelProvider labelProvider = new ErrorLibraryLabelProvider();
				
		ListDialog dialog = new ListDialog(
				UIUtil.getActiveShell());
		dialog.setContentProvider(contentProvider);
		dialog.setLabelProvider(labelProvider);
		dialog.setInput(new Object());
		dialog.setMessage("Please select a preferred error library provider to use, " +
		"\nthe selected provider will be used as the default provider.");

		if (dialog.open() == Window.OK) {
			Object[] objects = dialog.getResult();
			if (objects != null && objects.length > 0) {
				preferredProviderID = ((IErrorLibraryProvider)objects[0]).getProviderID();
				logger.info(SOAMessages.PREF_CONTENT_PROVIDER, preferredProviderID);
			}

		}
	}
	
	private class ErrorLibraryStructuredContentProvider implements IStructuredContentProvider {

		@Override
		public void dispose() {
			
		}

		@Override
		public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
			
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public Object[] getElements(Object inputElement) {
			try {
				return getErrorLibraryProviders().toArray();
			} catch (SOAGetErrorLibraryProviderFailedException e) {
				return Collections.EMPTY_LIST.toArray();
			}
		}
		
	}
	
	private static class ErrorLibraryLabelProvider implements ILabelProvider {

		@Override
		public Image getImage(Object element) {
			return null;
		}

		@Override
		public String getText(Object element) {
			if (element instanceof IErrorLibraryProvider) {
				return ((IErrorLibraryProvider)element).getProviderID();
			}
			return "";
		}

		@Override
		public void addListener(ILabelProviderListener listener) {
			
		}

		@Override
		public void dispose() {
			
		}

		@Override
		public boolean isLabelProperty(Object element, String property) {
			return false;
		}

		@Override
		public void removeListener(ILabelProviderListener listener) {
			
		}
		
	}

}