/*******************************************************************************
 * Copyright (c) 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
 *******************************************************************************/
package org.eclipse.jst.jsp.ui.internal.contentassist;


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

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPluginRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
import org.eclipse.jst.jsp.core.internal.java.IJSPTranslation;
import org.eclipse.jst.jsp.core.internal.java.JSPTranslation;
import org.eclipse.jst.jsp.core.internal.java.JSPTranslationAdapter;
import org.eclipse.jst.jsp.ui.internal.Logger;
import org.eclipse.wst.sse.core.IModelManager;
import org.eclipse.wst.sse.core.IModelManagerPlugin;
import org.eclipse.wst.sse.core.text.IStructuredDocumentRegion;
import org.eclipse.wst.sse.ui.IReleasable;
import org.eclipse.wst.sse.ui.StructuredTextViewer;
import org.eclipse.wst.sse.ui.contentassist.IResourceDependentProcessor;
import org.eclipse.wst.sse.ui.nls.ResourceHandler;
import org.eclipse.wst.xml.core.document.XMLDocument;
import org.eclipse.wst.xml.core.document.XMLModel;
import org.eclipse.wst.xml.core.document.XMLNode;
import org.eclipse.wst.xml.core.jsp.model.parser.temp.XMLJSPRegionContexts;

/**
 * @author pavery
 */
public class JSPCompletionProcessor implements IContentAssistProcessor, IReleasable, IResourceDependentProcessor {
	// for debugging
	private static final boolean DEBUG;
	static {
		String value= Platform.getDebugOption("com.ibm.sse.model.jsp/debug/jsptranslation"); //$NON-NLS-1$
		DEBUG= value != null && value.equalsIgnoreCase("true"); //$NON-NLS-1$
	}
	
	private static final String JDT_CORE_PLUGIN_ID = "org.eclipse.jdt.core"; //$NON-NLS-1$
//	private static final String SSE_MODEL_ID = IModelManagerPlugin.ID; //$NON-NLS-1$
	protected int fJspSourcePosition, fJavaPosition;
	protected IResource fResource;
	protected JSPResultCollector fCollector;
	protected String fErrorMessage = null;
	protected StructuredTextViewer fViewer = null;
	private JSPTranslationAdapter fTranslationAdapter = null;

	public JSPCompletionProcessor(IResource resource) {
		fResource = resource;
	}

	private IModelManager getModelManager() {

		IModelManagerPlugin plugin = (IModelManagerPlugin) Platform.getPlugin(IModelManagerPlugin.ID);
		return plugin.getModelManager();
	}

	/**
	 * Returns a list of completion proposals based on the
	 * specified location within the document that corresponds
	 * to the current cursor position within the text viewer.
	 *
	 * @param viewer the viewer whose document is used to compute the proposals
	 * @param documentPosition an offset within the document for which completions should be computed
	 * @return an array of completion proposals or <code>null</code> if no proposals are possible
	 */
	public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int pos) {
		initialize(pos);
		try {
			if (viewer instanceof StructuredTextViewer)
				fViewer = (StructuredTextViewer) viewer;

			XMLModel xmlModel = (XMLModel) getModelManager().getExistingModelForRead(fViewer.getDocument());
			XMLDocument xmlDoc = xmlModel.getDocument();
			xmlModel.releaseFromRead();
			if (fTranslationAdapter == null)
				fTranslationAdapter = (JSPTranslationAdapter) xmlDoc.getAdapterFor(IJSPTranslation.class);
			if (fTranslationAdapter != null) {
				
				JSPTranslation translation = fTranslationAdapter.getJSPTranslation();
				fJavaPosition = translation.getJavaOffset(getDocumentPosition());
				fCollector.setJavaToJSPOffset(fJspSourcePosition - fJavaPosition);
				fCollector.doFilter = cursorInExpression();

				if (DEBUG)
					System.out.println(debug(translation));

				try {
					fCollector.reset(fJavaPosition, translation.getJavaProject(), null); // need to "reset" collector for proposalInfo to show up			
					ICompilationUnit cu = translation.getCompilationUnit();

					// can't get java proposals w/out a compilation unit
					if (cu == null)
						return new ICompletionProposal[0];

					synchronized (cu) {
						cu.codeComplete(fJavaPosition, fCollector, null);
					}
				}
				catch (CoreException coreEx) {
					// a possible Java Model Exception due to not being a Web (Java) Project
					coreEx.printStackTrace();
				}
			}
		}
		catch (Exception exc) {
			exc.printStackTrace();
			// throw out exceptions on code assist.
		}
		ICompletionProposal[] results = fCollector.getResults();
		if (results == null || results.length < 1)
			fErrorMessage = ResourceHandler.getString("Java_Content_Assist_is_not_UI_"); //$NON-NLS-1$ = "Java Content Assist is not available for the current cursor location"

		return results;
	}

	/**
	 * For debugging translation mapping only.
	 * @param translation
	 */
	private String debug(JSPTranslation translation) {
		StringBuffer debugString = new StringBuffer();
		HashMap jsp2java = translation.getJsp2JavaMap();
		String javaText = translation.getJavaText();
		String jspText = fViewer.getDocument().get();
		debugString.append("[jsp2JavaMap in JSPCompletionProcessor]\r\n"); //$NON-NLS-1$
		debugString.append("jsp cursor position >> " + fViewer.getTextWidget().getCaretOffset() + "\n"); //$NON-NLS-1$ //$NON-NLS-2$
		Iterator it = jsp2java.keySet().iterator();
		while (it.hasNext()) {
			try {
				Position jspPos = (Position) it.next();
				Position javaPos = (Position) jsp2java.get(jspPos);
				debugString.append("jsp > " + jspPos.offset + ":" + jspPos.length + ":" + jspText.substring(jspPos.offset, jspPos.offset + jspPos.length) + ":\n"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
				debugString.append("java > " + javaPos.offset + ":" + javaPos.length + ":" + javaText.substring(javaPos.offset, javaPos.offset + javaPos.length) + ":\n"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
				debugString.append("-------------------------------------------------\n"); //$NON-NLS-1$
			}
			catch (Exception e) {
				// eat exceptions, it's only for debug
			}
		}
		return debugString.toString();
	}

	/**
	 * @return whether the source cursor is in an expression
	 */
	private boolean cursorInExpression() {
		boolean inExpression = false;
		IStructuredDocumentRegion sdRegion = null;
		XMLModel xmlModel = (XMLModel) getModelManager().getExistingModelForRead(fViewer.getDocument());
		XMLNode xmlNode = null;
		xmlModel.releaseFromRead();

		xmlNode = (XMLNode) xmlModel.getIndexedRegion(fJspSourcePosition);
		// possible end of document (if there's no XMLNode)
		if (xmlNode == null && fJspSourcePosition > 0)
			xmlNode = (XMLNode) xmlModel.getIndexedRegion(fJspSourcePosition - 1);
		if (xmlNode != null) {
			sdRegion = xmlNode.getFirstStructuredDocumentRegion();
			inExpression = sdRegion != null && (sdRegion.getType() == XMLJSPRegionContexts.JSP_EXPRESSION_OPEN || sdRegion.getType() == XMLJSPRegionContexts.JSP_SCRIPTLET_OPEN);
		}
		return inExpression;
	}

	/**
	 * Returns information about possible contexts based on the
	 * specified location within the document that corresponds
	 * to the current cursor position within the text viewer.
	 *
	 * @param viewer the viewer whose document is used to compute the possible contexts
	 * @param documentPosition an offset within the document for which context information should be computed
	 * @return an array of context information objects or <code>null</code> if no context could be found
	 */
	public org.eclipse.jface.text.contentassist.IContextInformation[] computeContextInformation(org.eclipse.jface.text.ITextViewer viewer, int documentOffset) {
		//System.out.println("requested context information at " + documentOffset); //$NON-NLS-1$
		return null;
	}

	/**
	 * Returns a string of characters which when pressed should
	 * automatically display content-assist proposals.
	 *
	 * @return string of characters
	 */
	public java.lang.String getAutoProposalInvocationCharacters() {
		return null;
	}

	/**
	 * Returns a string of characters which when pressed should
	 * automatically display a content-assist tip.
	 *
	 * @return string of characters
	 */
	public java.lang.String getAutoTipInvocationCharacters() {
		return null;
	}

	/**
	 * Returns the characters which when entered by the user should
	 * automatically trigger the presentation of possible completions.
	 *
	 * @return the auto activation characters for completion proposal or <code>null</code>
	 *		if no auto activation is desired
	 */
	public char[] getCompletionProposalAutoActivationCharacters() {
		return null;
	}

	/**
	 * Returns the characters which when entered by the user should
	 * automatically trigger the presentation of context information.
	 *
	 * @return the auto activation characters for presenting context information
	 *		or <code>null</code> if no auto activation is desired
	 */
	public char[] getContextInformationAutoActivationCharacters() {
		return null;
	}

	/**
	 * Returns a validator used to determine when displayed context information
	 * should be dismissed. May only return <code>null</code> if the processor is
	 * incapable of computing context information.
	 *
	 * @return a context information validator, or <code>null</code> if the processor
	 * 			is incapable of computing context information
	 */
	public org.eclipse.jface.text.contentassist.IContextInformationValidator getContextInformationValidator() {
		return null;
	}

	protected int getDocumentPosition() {
		return fJspSourcePosition;
	}

	public String getErrorMessage() {
		if (fCollector.getErrorMessage() != null && fCollector.getErrorMessage().length() > 0)
			return fCollector.getErrorMessage();
		return fErrorMessage;
	}

	/**
	 * Return the Java project for the to create completions within
	 */
	protected IJavaProject getJavaProject() {
		if (fResource == null)
			return null;
		IProject proj = (fResource.getType() == IResource.PROJECT) ? (IProject) fResource : fResource.getProject();
		IJavaProject javaProj = JavaCore.create(proj);
		return javaProj;
	}

	/**
	 * Initialize the code assist processor.
	 */
	protected void initialize(int pos) {
		initializeJavaPlugins();

		fCollector = new JSPResultCollector();
		fJspSourcePosition = pos;
		fErrorMessage = null;
	}

	/**
	 * Initialize the Java Plugins that the JSP processor requires.
	 */
	protected void initializeJavaPlugins() {
		IPluginRegistry pluginReg = Platform.getPluginRegistry();
		try {
			pluginReg.getPluginDescriptor(JDT_CORE_PLUGIN_ID).getPlugin();//$NON-NLS-1$
		}
		catch (CoreException exc) {
			Logger.logException("Could not initialize the JDT Plugins", exc);//$NON-NLS-1$
		}
	}

	/* (non-Javadoc)
	 * @see com.ibm.sse.editor.IReleasable#release()
	 */
	public void release() {
		fTranslationAdapter = null;
	}

	/*
	 * @see com.ibm.sse.editor.contentassist.IResourceDependent#initialize(org.eclipse.core.resources.IResource)
	 */
	public void initialize(IResource resource) {
		fResource = resource;
	}
}