/*******************************************************************************
 * Copyright (c) 2010 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.sse.ui.internal.comment;

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

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.InvalidRegistryObjectException;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.content.IContentType;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.wst.sse.ui.internal.Logger;
import org.eclipse.wst.sse.ui.internal.SSEUIPlugin;

/**
 * <p>The registry of {@link CommentingStrategy}s defined by the <code>org.eclipse.wst.sse.ui.commentinStrategy</code>
 * extension point.</p>
 */
public class CommentingStrategyRegistry {
	/** The extension schema name of the extension point */
	private static final String EXTENSION_POINT = "commentingStrategy"; //$NON-NLS-1$
	
	/** The extension schema name of proposal block comment child elements. */
	private static final String ELEM_PROPOSAL_BLOCK_COMMENTING_STRATEGY = "blockCommentingStrategy"; //$NON-NLS-1$
	
	/** The extension schema name of proposal line comment child elements. */
	private static final String ELEM_PROPOSAL_LINE_COMMENTING_STRATEGY = "lineCommentingStrategy"; //$NON-NLS-1$
	
	/** The extension schema name of the content type child elements. */
	private static final String ELEM_CONTENT_TYPE = "contentType"; //$NON-NLS-1$
	
	/** The extension schema name of the required partition types child elements */
	private static final String ELEM_REQUIRED_PARTITION_TYPES= "requiredPartitionTypes"; //$NON-NLS-1$
	
	/** The extension schema name of the allowable partition types child elements */
	private static final String ELEM_ALLOWABLE_PARTITION_TYPES= "allowablePartitionTypes"; //$NON-NLS-1$
	
	/** The extension schema name of partition type child elements */
	private static final String ELEM_PARTITION_TYPE= "partitionType"; //$NON-NLS-1$
	
	/** The extension schema name of the prefix attribute */
	private static final String ATTR_PREFIX = "prefix"; //$NON-NLS-1$
	
	/** The extension schema name of the suffix attribute */
	private static final String ATTR_SUFFIX = "suffix"; //$NON-NLS-1$
	
	/** The extension schema name of the associatedCommentPartitionTypeID attribute */
	private static final String ATTR_ASSOCIATED_COMMENT_PARTITION_TPYPE_ID = "associatedCommentPartitionTypeID"; //$NON-NLS-1$
	
	/** The extension schema name of the anyPartitionType attribute */
	private static final String ATTR_ANY_PARTITION_TYPE = "anyPartitionType";  //$NON-NLS-1$
	
	/** The extension schema name for ID attribute */
	private static final String ATTR_ID= "id"; //$NON-NLS-1$
	
	/** the singleton instance of the registry */
	private static CommentingStrategyRegistry fSingleton = null;
	
	/** <code>true</code> if this registry has been loaded. */
	private boolean fLoaded;
	
	/**
	 * <p>Registry of content type IDs to {@link BlockCommentingStrategy}s</p>
	 * 
	 * <code>{@link Map}&lt{@link String}, {@link List}&lt{@link BlockContentType}&gt&gt</code>
	 * <ul>
	 * <li><b>key:</b> content type ID</li>
	 * <li><b>value:</b> {@link List} of associated {@link BlockContentType}s</li>
	 * <ul>
	 */
	private Map fBlockCommentTypes;
	
	/**
	 * <p>Registry of content type IDs to {@link LineCommentingStrategy}s</p>
	 *
	 * <code>{@link Map}&lt{@link String}, {@link List}&lt{@link LineContentType}&gt&gt</code>
	 * <ul>
	 * <li><b>key:</b> content type ID</li>
	 * <li><b>value:</b> {@link List} of associated {@link LineContentType}s</li>
	 * <ul>
	 */
	private Map fLineCommentTypes;
	
	/**
	 * @return the single instance of the {@link CommentingStrategyRegistry}
	 */
	public static synchronized CommentingStrategyRegistry getDefault() {
		if(fSingleton == null) {
			fSingleton = new CommentingStrategyRegistry();
		}
		
		return fSingleton;
	}
	
	/**
	 * Singleton constructor for the registry
	 */
	private CommentingStrategyRegistry() {
		this.fLoaded = false;
		this.fBlockCommentTypes = new HashMap();
		this.fLineCommentTypes = new HashMap();
	}
	
	/**
	 * @param contentTypeID get only {@link BlockCommentingStrategy}s associated with this content type
	 * @param regions get only {@link BlockCommentingStrategy}s associated with these types of regions
	 * @return all the {@link BlockCommentingStrategy}s associated with the given content type and regions
	 */
	public CommentingStrategy getBlockCommentingStrategy(String contentTypeID, ITypedRegion[] regions) {
		return getCommentingStrategy(contentTypeID, regions, this.fBlockCommentTypes);
	}
	
	/**
	 * @param contentTypeID get only {@link LineCommentingStrategy}s associated with this content type
	 * @param regions get only {@link LineCommentingStrategy}s associated with these types of regions
	 * @return all the {@link LineCommentingStrategy}s associated with the given content type and regions
	 */
	public CommentingStrategy getLineCommentingStrategy(String contentTypeID, ITypedRegion[] regions) {
		return getCommentingStrategy(contentTypeID, regions, this.fLineCommentTypes);
	}
	
	/**
	 * <p>get all the {@link CommentingStrategy}s associated with the given content type and regions
	 * from the given registry</p>
	 * 
	 * @param contentTypeID  get only {@link CommentingStrategy}s associated with this content type
	 * @param regions get only {@link CommentingStrategy}s associated with these types of regions
	 * @param registry get the {@link CommentingStrategy}s from this registry
	 * @return all the {@link CommentingStrategy}s associated with the given content type and regions
	 * from the given registry
	 */
	private CommentingStrategy getCommentingStrategy(String contentTypeID, ITypedRegion[] regions, Map registry) {
		ensureExtensionPointRead();
		
		CommentingStrategy match = null;
		IContentType contentType = Platform.getContentTypeManager().getContentType(contentTypeID);
		
		/* get all the commenting strategies for the given content type id,
		 * including those registered for parent content types
		 */
		List possibleCommentingStrategies = new ArrayList();
		while(contentType != null) {
			List contentTypeCommentingStrategies = (List)registry.get(contentType.getId());
			if(contentTypeCommentingStrategies != null && contentTypeCommentingStrategies.size() > 0) {
				possibleCommentingStrategies.addAll(contentTypeCommentingStrategies);
			}
			contentType = contentType.getBaseType();
		}
		
		/* find the commenting strategy applicable for the given regions,
		 * because strategies were added starting from the most specific
		 * content type first, the most specific strategy will always be chosen
		 */
		for(int i = 0; i < possibleCommentingStrategies.size() && match == null; ++i) {
			CommentingStrategy commentType = (CommentingStrategy)possibleCommentingStrategies.get(i);
			if(commentType.isApplicableFor(regions)) {
				match = commentType;
			}
		}
		
		return match;
	}
	
	/**
	 * <p>Ensures that the extensions are read and this registry is built</p>
	 */
	private void ensureExtensionPointRead() {
		if(!fLoaded) {
			load();
			fLoaded = true;
		}
	}
	
	/**
	 * <p>Load the extension points into the registry</p>
	 */
	private void load() {
		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();
		List extensionElements = new ArrayList(Arrays.asList(extensionRegistry.getConfigurationElementsFor(SSEUIPlugin.ID, EXTENSION_POINT)));
	
		//for each extension
		for (Iterator iter= extensionElements.iterator(); iter.hasNext();) {
			IConfigurationElement element = (IConfigurationElement) iter.next();
			try {
				CommentingStrategy newCommentingStrategy = null;
				Map commentingStrategyRegistry = null;
				//either a block or line commenting strategy
				if(element.getName().equals(ELEM_PROPOSAL_BLOCK_COMMENTING_STRATEGY)) {
					String prefix = element.getAttribute(ATTR_PREFIX);
					checkExtensionAttributeNotNull(prefix, ATTR_PREFIX, element);
					
					String suffix = element.getAttribute(ATTR_SUFFIX);
					checkExtensionAttributeNotNull(suffix, ATTR_SUFFIX, element);
					
					if(prefix != null && suffix != null) {
						newCommentingStrategy = new BlockCommentingStrategy(prefix, suffix);
						commentingStrategyRegistry = this.fBlockCommentTypes;
					}
				} else if(element.getName().equals(ELEM_PROPOSAL_LINE_COMMENTING_STRATEGY)) {
					String prefix = element.getAttribute(ATTR_PREFIX);
					checkExtensionAttributeNotNull(prefix, ATTR_PREFIX, element);
					
					if(prefix != null) {
						newCommentingStrategy = new LineCommentingStrategy(prefix);
						commentingStrategyRegistry = this.fLineCommentTypes;
					}
				}
				
				//add the new strategy to the registry
				if(commentingStrategyRegistry != null && newCommentingStrategy != null) {
					addCommentingStrategyToRegistry(element, commentingStrategyRegistry, newCommentingStrategy);
				} else {
					Logger.log(Logger.WARNING, "Invalid CommentingStrategy extension: " + element); //$NON-NLS-1$
				}
			} catch (CoreException e) {
				Logger.logException(e);
			} catch (InvalidRegistryObjectException x) {
				/* Element is not valid any longer as the contributing plug-in was unloaded or for
				 * some other reason. Do not include the extension in the list and log it
				 */
				String message = "The extension ''" + element.toString() + "'' is invalid."; //$NON-NLS-1$ //$NON-NLS-2$
				IStatus status= new Status(IStatus.WARNING, SSEUIPlugin.ID, IStatus.WARNING, message, x);
				Logger.log(status);
			}
		}
	}
	
	/**
	 * <p>Checks that the given attribute value is not <code>null</code>.</p>
	 *
	 * @param value the object to check if not null
	 * @param attribute the attribute
	 * 
	 * @throws InvalidRegistryObjectException if the registry element is no longer valid
	 * @throws CoreException if <code>value</code> is <code>null</code>
	 */
	private static void checkExtensionAttributeNotNull(Object value, String attribute,
			IConfigurationElement element) throws InvalidRegistryObjectException, CoreException {
		
		if (value == null) {
			String message = "The extension \"" + element.getDeclaringExtension().getUniqueIdentifier() + //$NON-NLS-1$
				"\" from plug-in \"" + element.getContributor().getName() + //$NON-NLS-1$
				"\" did not specify a value for the required \"" + attribute + //$NON-NLS-1$
				"\" attribute for the element \"" + element.getName() + "\". Disabling the extension."; //$NON-NLS-1$ //$NON-NLS-2$
			IStatus status= new Status(IStatus.WARNING, SSEUIPlugin.ID, IStatus.OK, message, null);
			throw new CoreException(status);
		}
	}
	
	/**
	 * <p>Using the content type element children of the given element add a copy of the given
	 * base commenting strategy to the given registry</p>
	 * 
	 * @param element a {@link IConfigurationElement} with contentType element children
	 * @param commentingStrategyRegistry {@link Map} of content type ids to {@link CommentingStrategy}s to register
	 * the given {@link CommentingStrategy} with based on the <code>element</code>
	 * @param baseCommentingStrategy {@link CommentingStrategy} that will be cloned and configured for each
	 * content type in the given <code>element</code>
	 */
	private static void addCommentingStrategyToRegistry(IConfigurationElement element,
			Map commentingStrategyRegistry, CommentingStrategy baseCommentingStrategy) {
		
		//get all the content type elements
		IConfigurationElement[] contentTypeElements = element.getChildren(ELEM_CONTENT_TYPE);
		if(contentTypeElements.length > 0) {
			for(int contentTypeIndex = 0; contentTypeIndex < contentTypeElements.length; ++contentTypeIndex) {
				try {
					String contentTypeID = contentTypeElements[contentTypeIndex].getAttribute(ATTR_ID);
					checkExtensionAttributeNotNull(contentTypeID, ATTR_ID, contentTypeElements[contentTypeIndex]);
					
					List commentTypes = (List)commentingStrategyRegistry.get(contentTypeID);
					if(commentTypes == null) {
						commentTypes = new ArrayList();
						commentingStrategyRegistry.put(contentTypeID, commentTypes);
					}
					
					//this element is required
					List allowablePartitionTypeIDs = new ArrayList();
					IConfigurationElement[] allowablePartitionTypes =
						contentTypeElements[contentTypeIndex].getChildren(ELEM_ALLOWABLE_PARTITION_TYPES);
					boolean anyPartitionType = false;
					//determine anyPartitionType attribute value
					String anyPartitionTypeValue = allowablePartitionTypes[0].getAttribute(ATTR_ANY_PARTITION_TYPE);
					if(anyPartitionTypeValue != null) {
						anyPartitionType = Boolean.valueOf(anyPartitionTypeValue).booleanValue();
					}
					
					//get the optional partition types
					allowablePartitionTypes = allowablePartitionTypes[0].getChildren(ELEM_PARTITION_TYPE);
					if(allowablePartitionTypes.length > 0) {
						for (int partitionTypeIndex = 0; partitionTypeIndex < allowablePartitionTypes.length; ++partitionTypeIndex) {
							String partitionTypeID = allowablePartitionTypes[partitionTypeIndex].getAttribute(ATTR_ID);
							checkExtensionAttributeNotNull(partitionTypeID, ATTR_ID, allowablePartitionTypes[partitionTypeIndex]);
							
							allowablePartitionTypeIDs.add(partitionTypeID);
						}
					}
					
					//this element is optional
					List requiredPartitionTypeIDs = new ArrayList();
					IConfigurationElement[] requiredPartitionTypes =
						contentTypeElements[contentTypeIndex].getChildren(ELEM_REQUIRED_PARTITION_TYPES);
					if(requiredPartitionTypes.length > 0) {
						//get the required partition types
						requiredPartitionTypes = requiredPartitionTypes[0].getChildren(ELEM_PARTITION_TYPE);
						if(requiredPartitionTypes.length > 0) {
							for (int partitionTypeIndex = 0; partitionTypeIndex < requiredPartitionTypes.length; ++partitionTypeIndex) {
								String partitionTypeID = requiredPartitionTypes[partitionTypeIndex].getAttribute(ATTR_ID);
								checkExtensionAttributeNotNull(partitionTypeID, ATTR_ID, requiredPartitionTypes[partitionTypeIndex]);
								
								requiredPartitionTypeIDs.add(partitionTypeID);
							}
						}
					}
					
					//get the optional associated comment partition type ID
					String associatedCommentPartitionTypeID =
						contentTypeElements[contentTypeIndex].getAttribute(ATTR_ASSOCIATED_COMMENT_PARTITION_TPYPE_ID);
					
					//register the strategy
					CommentingStrategy newCommentingStrategy = (CommentingStrategy)baseCommentingStrategy.clone();
					newCommentingStrategy.setPartitionInformation(allowablePartitionTypeIDs, anyPartitionType,
							requiredPartitionTypeIDs, associatedCommentPartitionTypeID);
					commentTypes.add(newCommentingStrategy);
				} catch(CoreException e) {
					Logger.logException(e);
				}
			}
		} else {
			Logger.log(Logger.WARNING, "The commmenting strategy element: " + element +//$NON-NLS-1$
					" does not contain any required " + ELEM_CONTENT_TYPE + "s"); //$NON-NLS-1$ //$NON-NLS-2$
		}
	}
}