/*******************************************************************************
 * 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.xml.ui.internal.contentassist;


import java.util.HashMap;
import java.util.Iterator;

import org.eclipse.core.resources.IResource;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
import org.eclipse.jface.text.contentassist.IContextInformation;
import org.eclipse.jface.text.contentassist.IContextInformationValidator;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocumentRegion;
import org.eclipse.wst.sse.ui.internal.IReleasable;
import org.eclipse.wst.sse.ui.internal.StructuredTextViewer;
import org.eclipse.wst.sse.ui.internal.contentassist.ContentAssistUtils;
import org.eclipse.wst.sse.ui.internal.contentassist.IResourceDependentProcessor;
import org.eclipse.wst.xml.core.internal.provisional.text.IXMLPartitions;
import org.eclipse.wst.xml.core.internal.regions.DOMRegionContext;


/**
 * ContentAssistProcessor to handle special cases in content assist where the
 * partitioner cannot determine a partition type at the current cursor
 * position (usually at EOF).
 * 
 * @author pavery
 */
public class NoRegionContentAssistProcessor implements IContentAssistProcessor, IResourceDependentProcessor, IReleasable {

	protected char completionProposalAutoActivationCharacters[] = null;
	protected char contextInformationAutoActivationCharacters[] = null;

	private final ICompletionProposal[] EMPTY_PROPOSAL_SET = new ICompletionProposal[0];
	protected String fErrorMessage = null;
	protected HashMap fNameToProcessorMap = null;
	protected HashMap fPartitionToProcessorMap = null;
	protected IResource fResource = null;

	public NoRegionContentAssistProcessor() {
		super();
		fPartitionToProcessorMap = new HashMap();
		fNameToProcessorMap = new HashMap();
		initNameToProcessorMap();
		initPartitionToProcessorMap();

	}

	/**
	 * Figures out what the correct ICompletionProposalProcessor is and
	 * computesCompletionProposals on that.
	 * 
	 * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#computeCompletionProposals(org.eclipse.jface.text.ITextViewer,
	 *      int)
	 */
	public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int documentOffset) {
		IContentAssistProcessor p = null;
		ICompletionProposal[] results = EMPTY_PROPOSAL_SET;

		p = guessContentAssistProcessor(viewer, documentOffset);
		if (p != null)
			results = p.computeCompletionProposals(viewer, documentOffset);

		return (results != null) ? results : EMPTY_PROPOSAL_SET;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#computeContextInformation(org.eclipse.jface.text.ITextViewer,
	 *      int)
	 */
	public IContextInformation[] computeContextInformation(ITextViewer viewer, int documentOffset) {
		// get context info from processor that we end up using...
		return null;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getCompletionProposalAutoActivationCharacters()
	 */
	public char[] getCompletionProposalAutoActivationCharacters() {
		return completionProposalAutoActivationCharacters;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getContextInformationAutoActivationCharacters()
	 */
	public char[] getContextInformationAutoActivationCharacters() {
		return contextInformationAutoActivationCharacters;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getContextInformationValidator()
	 */
	public IContextInformationValidator getContextInformationValidator() {
		// return the validator for the content assist processor that we
		// used...
		return null;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getErrorMessage()
	 */
	public String getErrorMessage() {
		return fErrorMessage;
	}

	/**
	 * Gives you the document partition type (String) for the given
	 * StructuredTextViewer and documentPosition.
	 * 
	 * @param viewer
	 * @param documentPosition
	 * @return String
	 */
	protected String getPartitionType(StructuredTextViewer viewer, int documentPosition) {
		IDocument document = viewer.getDocument();
		String partitionType = null;
		ITypedRegion partition = null;
		try {
			partition = document.getPartition(documentPosition);
			partitionType = partition.getType();
		} catch (BadLocationException e) {
			partitionType = null;
		}
		return partitionType;
	}

	/**
	 * Guesses a ContentAssistProcessor based on the TextViewer and
	 * documentOffset.
	 * 
	 * @param viewer
	 * @param documentOffset
	 */
	protected IContentAssistProcessor guessContentAssistProcessor(ITextViewer viewer, int documentOffset) {
		//  mapping logic here...
		// look @ previous region
		// look @ previous doc partition type
		// look @ page language
		IContentAssistProcessor p = null;
		IStructuredDocumentRegion sdRegion = ContentAssistUtils.getStructuredDocumentRegion((StructuredTextViewer) viewer, documentOffset);
		if (sdRegion != null) {
			String currentRegionType = sdRegion.getType();
			//System.out.println("current region type is >> " +
			// currentRegionType);
			if (currentRegionType == DOMRegionContext.UNDEFINED) {
				IStructuredDocumentRegion sdPrev = sdRegion.getPrevious();
				if (sdPrev != null) {
					String prevRegionType = sdPrev.getType();
					//System.out.println("previous region type is >> " +
					// prevRegionType);
				}
			}
		}
		// working w/ viewer & document partition
		if (p == null && viewer.getDocument().getLength() > 0) {
			String prevPartitionType = getPartitionType((StructuredTextViewer) viewer, documentOffset - 1);
			//System.out.println("previous partition type is > " +
			// prevPartitionType);
			p = (IContentAssistProcessor) fPartitionToProcessorMap.get(prevPartitionType);
		}
		return p;
	}

	/**
	 * Necessary for certain content assist processors (such as
	 * JSPJavaContentAssistProcessor). This gets set in
	 * StructuredTextViewerConfiguration.
	 *  
	 */
	public void initialize(IResource resource) {
		fResource = resource;
		setResourceOnProcessors(resource);
	}

	/**
	 * Inits map for extra ContentAssistProcessors (useBean, get/setProperty)
	 */
	protected void initNameToProcessorMap() {
	}

	/**
	 * Adds all relevent ContentAssistProcessors to the partition to processor
	 * map (just XML here)
	 */
	protected void initPartitionToProcessorMap() {
		XMLContentAssistProcessor xmlProcessor = new XMLContentAssistProcessor();
		fPartitionToProcessorMap.put(IXMLPartitions.XML_DEFAULT, xmlProcessor);
	}

	public void release() {
		releasePartitionToProcessorMap();
		releaseNameToProcessorMap();
	}

	protected void releaseMap(HashMap map) {
		if (map != null && !map.isEmpty()) {
			Iterator it = map.keySet().iterator();
			Object key = null;
			while (it.hasNext()) {
				key = it.next();
				if (map.get(key) instanceof IReleasable)
					((IReleasable) map.get(key)).release();
			}
			map.clear();
			map = null;
		}
	}

	protected void releaseNameToProcessorMap() {
		releaseMap(fNameToProcessorMap);
	}

	protected void releasePartitionToProcessorMap() {
		releaseMap(fPartitionToProcessorMap);
	}

	private void setResourceOnMap(IResource resource, HashMap map) {
		if (!map.isEmpty()) {
			Iterator keys = map.keySet().iterator();
			Object o = null;
			while (keys.hasNext()) {
				o = fPartitionToProcessorMap.get(keys.next());
				if (o instanceof IResourceDependentProcessor)
					((IResourceDependentProcessor) o).initialize(resource);
			}
		}
	}

	/**
	 * @param resource
	 */
	private void setResourceOnProcessors(IResource resource) {
		setResourceOnMap(resource, fPartitionToProcessorMap);
		setResourceOnMap(resource, fNameToProcessorMap);
	}

}