/*******************************************************************************
 * Copyright (c) 2001, 2004 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
 *     Jens Lukowski/Innoopract - initial renaming/restructuring
 *     
 *******************************************************************************/
package org.eclipse.wst.sse.ui.extension;

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

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.Platform;
import org.eclipse.swt.custom.BusyIndicator;
import org.eclipse.wst.sse.core.util.StringUtils;
import org.eclipse.wst.sse.ui.internal.Logger;
import org.eclipse.wst.sse.ui.internal.SSEUIPlugin;
import org.eclipse.wst.sse.ui.internal.extension.RegistryReader;
import org.osgi.framework.Bundle;


/**
 * Simple generic ID to class to mapping. Loads a specified class defined in a
 * configuration element with the matching type and target ID. Example
 * plugin.xml section:
 * 
 * &lt;extension
 * point=&quot;org.eclipse.wst.sse.ui.extendedconfiguration&quot;&gt;configuration
 * type=&quot;contentoutlineconfiguration&quot;
 * target=&quot;org.eclipse.wst.sse.ui.dtd.StructuredTextEditorDTD&quot;
 * class=&quot;org.eclipse.wst.sse.ui.dtd.views.contentoutline.DTDContentOutlineConfiguration&quot;/&gt;
 * &lt;/extension&gt;
 * 
 * Used in code by getConfiguration(&quot;contentoutlineconfiguration&quot;,
 * &quot;org.eclipse.wst.sse.ui.dtd.StructuredTextEditorDTD&quot;);
 * 
 */
public class ExtendedConfigurationBuilder extends RegistryReader {
	private static final String ATT_CLASS = "class"; //$NON-NLS-1$
	private static final String ATT_TARGET = "target"; //$NON-NLS-1$
	private static final String ATT_TYPE = "type"; //$NON-NLS-1$
	private static final String CONFIGURATION = "configuration"; //$NON-NLS-1$
	private static Map configurationMap = null;
	private final static boolean debugTime = "true".equalsIgnoreCase(Platform.getDebugOption("org.eclipse.wst.sse.ui/extendedconfigurationbuilder/time")); //$NON-NLS-1$  //$NON-NLS-2$
	private static final String DEFINITION = "definition"; //$NON-NLS-1$
	private static final String EP_EXTENDEDCONFIGURATION = "extendedconfiguration"; //$NON-NLS-1$
	private static ExtendedConfigurationBuilder instance = null;
	public static final String VALUE = "value"; //$NON-NLS-1$

	/**
	 * Creates an extension. If the extension plugin has not been loaded a
	 * busy cursor will be activated during the duration of the load.
	 * 
	 * @param element
	 *            the config element defining the extension
	 * @param classAttribute
	 *            the name of the attribute carrying the class
	 * @returns the extension object if successful. If an error occurs when
	 *          createing executable extension, the exception is logged, and
	 *          null returned.
	 */
	static Object createExtension(final IConfigurationElement element, final String classAttribute, final String targetID) {
		final Object[] result = new Object[1];
		String pluginId = element.getDeclaringExtension().getNamespace();
		Bundle bundle = Platform.getBundle(pluginId);
		if (bundle.getState() == Bundle.ACTIVE) {
			try {
				result[0] = element.createExecutableExtension(classAttribute);
			}
			catch (Exception e) {
				// catch and log ANY exception while creating the extension
				Logger.logException("error loading class " + classAttribute + " for " + targetID, e); //$NON-NLS-1$ //$NON-NLS-2$
			}
		}
		else {
			BusyIndicator.showWhile(null, new Runnable() {
				public void run() {
					try {
						result[0] = element.createExecutableExtension(classAttribute);
					}
					catch (Exception e) {
						// catch and log ANY exception from extension point
						Logger.logException("error loading class " + classAttribute + " for " + targetID, e); //$NON-NLS-1$ //$NON-NLS-2$
					}
				}
			});
		}
		if (result[0] != null && result[0] instanceof IExtendedConfiguration) {
			((IExtendedConfiguration) result[0]).setDeclaringID(targetID);
		}
		return result[0];
	}

	public synchronized static ExtendedConfigurationBuilder getInstance() {
		if (instance == null)
			instance = new ExtendedConfigurationBuilder();
		return instance;
	}

	long time0 = 0;

	private ExtendedConfigurationBuilder() {
		super();
	}

	private List createConfigurations(List configurations, String extensionType, String targetID) {
		if (configurations == null)
			return new ArrayList(0);
		List result = new ArrayList(1);
		for (int i = 0; i < configurations.size(); i++) {
			IConfigurationElement element = (IConfigurationElement) configurations.get(i);
			if ((element.getName().equals(extensionType) || (element.getName().equals(CONFIGURATION) && extensionType.equals(element.getAttribute(ATT_TYPE))))) {
				String[] targets = StringUtils.unpack(element.getAttribute(ATT_TARGET));
				for (int j = 0; j < targets.length; j++) {
					if (targetID.equals(targets[j])) {
						Object o = createExtension(element, ATT_CLASS, targetID);
						if (o != null) {
							result.add(o);
						}
					}
				}
			}
		}
		return result;
	}

	private IConfigurationElement[] findConfigurationElements(List configurations, String extensionType, String targetID) {
		if (configurations == null)
			return new IConfigurationElement[0];
		List result = new ArrayList(1);
		for (int i = 0; i < configurations.size(); i++) {
			IConfigurationElement element = (IConfigurationElement) configurations.get(i);
			if ((element.getName().equals(extensionType) || (element.getName().equals(DEFINITION) && extensionType.equals(element.getAttribute(ATT_TYPE)))) && element.getAttribute(ATT_TARGET).equals(targetID)) {
				result.add(element);
			}
		}
		return (IConfigurationElement[]) result.toArray(new IConfigurationElement[0]);
	}

	/**
	 * Returns a configuration for the given extensionType matching the
	 * targetID, if one is available.
	 * 
	 * @param extensionType
	 * @param targetID
	 * @return a configuration object, if one was defined
	 */
	public Object getConfiguration(String extensionType, String targetID) {
		if (targetID == null || targetID.length() == 0)
			return null;
		if (debugTime) {
			time0 = System.currentTimeMillis();
		}
		List configurations = getConfigurations(extensionType, targetID);
		if (configurations.isEmpty())
			return null;
		return configurations.get(0);
	}

	/**
	 * Returns all configurations for the given extensionType matching the
	 * targetID, if any are available.
	 * 
	 * @param extensionType
	 * @param targetID
	 * @return a List of configuration objects, which may or may not be empty
	 */
	public List getConfigurations(String extensionType, String targetID) {
		if (targetID == null || targetID.length() == 0)
			return new ArrayList(0);
		if (configurationMap == null) {
			configurationMap = new HashMap(0);
			synchronized (configurationMap) {
				readRegistry(Platform.getExtensionRegistry(), SSEUIPlugin.ID, EP_EXTENDEDCONFIGURATION);
				if (debugTime) {
					System.out.println(getClass().getName() + "#readRegistry():  " + (System.currentTimeMillis() - time0) + "ms"); //$NON-NLS-1$ //$NON-NLS-2$
					time0 = System.currentTimeMillis();
				}
			}
		}
		List extensions = (List) configurationMap.get(extensionType);
		List configurations = createConfigurations(extensions, extensionType, targetID);
		if (debugTime) {
			if (!configurations.isEmpty())
				System.out.println(getClass().getName() + "#getConfiguration(" + extensionType + ", " + targetID + "): configurations loaded in " + (System.currentTimeMillis() - time0) + "ms"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
			else
				System.out.println(getClass().getName() + "#getConfiguration(" + extensionType + ", " + targetID + "): ran in " + (System.currentTimeMillis() - time0) + "ms"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
		}
		return configurations;
	}

	/**
	 * Returns all declared definitions for the given extensionType matching
	 * the targetID, if any are available.
	 * 
	 * @param extensionType
	 * @param targetID
	 * @return An array containing the definitions, empty if none were
	 *         declared
	 */
	public String[] getDefinitions(String extensionType, String targetID) {
		if (targetID == null || targetID.length() == 0)
			return new String[0];
		if (debugTime) {
			time0 = System.currentTimeMillis();
		}
		if (configurationMap == null) {
			configurationMap = new HashMap(0);
			synchronized (configurationMap) {
				readRegistry(Platform.getExtensionRegistry(), SSEUIPlugin.ID, EP_EXTENDEDCONFIGURATION);
				if (debugTime) {
					System.out.println(getClass().getName() + "#readRegistry():  " + (System.currentTimeMillis() - time0) + "ms"); //$NON-NLS-1$ //$NON-NLS-2$
					time0 = System.currentTimeMillis();
				}
			}
		}
		List definitions = (List) configurationMap.get(extensionType);
		IConfigurationElement[] elements = findConfigurationElements(definitions, extensionType, targetID);
		String[] values = new String[elements.length];
		for (int i = 0; i < values.length; i++) {
			values[i] = elements[i].getAttribute(VALUE);
		}
		if (debugTime) {
			if (values.length > 0)
				System.out.println(getClass().getName() + "#getDefinitions(" + extensionType + ", " + targetID + "): definition loaded in " + (System.currentTimeMillis() - time0) + "ms"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
			else
				System.out.println(getClass().getName() + "#getDefinitions(" + extensionType + ", " + targetID + "): ran in " + (System.currentTimeMillis() - time0) + "ms"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
		}
		return values;
	}

	protected boolean readElement(IConfigurationElement element) {
		String name = element.getName();
		if (name.equals(CONFIGURATION) || name.equals(DEFINITION))
			name = element.getAttribute(ATT_TYPE);
		List configurations = (List) configurationMap.get(name);
		if (configurations == null) {
			configurations = new ArrayList(1);
			configurationMap.put(name, configurations);
		}
		configurations.add(element);
		return true;
	}
}