content: /*******************************************************************************
   * Copyright (c) 2000, 2008 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.jsdt.internal.ui.text.template.contentassist;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.eclipse.core.runtime.Assert;
  import org.eclipse.jface.text.BadLocationException;
  import org.eclipse.jface.text.IDocument;
  import org.eclipse.jface.text.IRegion;
  import org.eclipse.jface.text.ITextViewer;
  import org.eclipse.jface.text.Position;
  import org.eclipse.jface.text.Region;
  import org.eclipse.jface.text.templates.GlobalTemplateVariables;
  import org.eclipse.jface.text.templates.Template;
  import org.eclipse.jface.text.templates.TemplateContextType;
  import org.eclipse.swt.graphics.Point;
  import org.eclipse.wst.jsdt.core.IJavaScriptUnit;
  import org.eclipse.wst.jsdt.internal.corext.template.java.CompilationUnitContext;
  import org.eclipse.wst.jsdt.internal.corext.template.java.CompilationUnitContextType;
  import org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin;
  import org.eclipse.wst.jsdt.internal.ui.JavaPluginImages;
  
  public class TemplateEngine {
  
  	private static final String $_LINE_SELECTION= "${" + GlobalTemplateVariables.LineSelection.NAME + "}"; //$NON-NLS-1$ //$NON-NLS-2$
  	private static final String $_WORD_SELECTION= "${" + GlobalTemplateVariables.WordSelection.NAME + "}"; //$NON-NLS-1$ //$NON-NLS-2$
  
  	/** The context type. */
  	private TemplateContextType fContextType;
  	/** The result proposals. */
  	private ArrayList fProposals= new ArrayList();
  	/** Positions created on the key documents to remove in reset. */
  	private final Map fPositions= new HashMap();
  
  	/**
  	 * Creates the template engine for a particular context type.
  	 * See <code>TemplateContext</code> for supported context types.
  	 */
  	public TemplateEngine(TemplateContextType contextType) {
  		Assert.isNotNull(contextType);
  		fContextType= contextType;
  	}
  
  	/**
  	 * Empties the collector.
  	 */
  	public void reset() {
  		fProposals.clear();
  		for (Iterator it= fPositions.entrySet().iterator(); it.hasNext();) {
  			Entry entry= (Entry) it.next();
  			IDocument doc= (IDocument) entry.getKey();
  			Position position= (Position) entry.getValue();
  			doc.removePosition(position);
  		}
  		fPositions.clear();
  	}
  
  	/**
  	 * Returns the array of matching templates.
  	 */
  	public TemplateProposal[] getResults() {
  		return (TemplateProposal[]) fProposals.toArray(new TemplateProposal[fProposals.size()]);
  	}
  
  	/**
  	 * Inspects the context of the compilation unit around <code>completionPosition</code>
  	 * and feeds the collector with proposals.
  	 * @param viewer the text viewer
  	 * @param completionPosition the context position in the document of the text viewer
  	 * @param compilationUnit the compilation unit (may be <code>null</code>)
  	 */
  	public void complete(ITextViewer viewer, int completionPosition, IJavaScriptUnit compilationUnit) {
  	    IDocument document= viewer.getDocument();
  
  		if (!(fContextType instanceof CompilationUnitContextType))
  			return;
  
  		Point selection= viewer.getSelectedRange();
  		Position position= new Position(completionPosition, selection.y);
  
  		// remember selected text
  		String selectedText= null;
  		if (selection.y != 0) {
  			try {
  				selectedText= document.get(selection.x, selection.y);
  				document.addPosition(position);
  				fPositions.put(document, position);
  			} catch (BadLocationException e) {}
  		}
  
  		CompilationUnitContext context= ((CompilationUnitContextType) fContextType).createContext(document, position, compilationUnit);
  		context.setVariable("selection", selectedText); //$NON-NLS-1$
  		int start= context.getStart();
  		int end= context.getEnd();
  		IRegion region= new Region(start, end - start);
  
  		Template[] templates= JavaScriptPlugin.getDefault().getTemplateStore().getTemplates();
  
  		if (selection.y == 0) {
  			for (int i= 0; i != templates.length; i++)
  				if (context.canEvaluate(templates[i]))
  					fProposals.add(new TemplateProposal(templates[i], context, region, JavaPluginImages.get(JavaPluginImages.IMG_OBJS_TEMPLATE)));
  
  		} else {
  
  			if (context.getKey().length() == 0)
  				context.setForceEvaluation(true);
  
  			boolean multipleLinesSelected= areMultipleLinesSelected(viewer);
  
  			for (int i= 0; i != templates.length; i++) {
  				Template template= templates[i];
  				if (context.canEvaluate(template) &&
  					template.getContextTypeId().equals(context.getContextType().getId()) &&
  					(!multipleLinesSelected && template.getPattern().indexOf($_WORD_SELECTION) != -1 || (multipleLinesSelected && template.getPattern().indexOf($_LINE_SELECTION) != -1)))
  				{
  					fProposals.add(new TemplateProposal(templates[i], context, region, JavaPluginImages.get(JavaPluginImages.IMG_OBJS_TEMPLATE)));
  				}
  			}
  		}
  	}
  
  	/**
  	 * Returns <code>true</code> if one line is completely selected or if multiple lines are selected.
  	 * Being completely selected means that all characters except the new line characters are
  	 * selected.
  	 *
  	 * @return <code>true</code> if one or multiple lines are selected
  	 * 
  	 */
  	private boolean areMultipleLinesSelected(ITextViewer viewer) {
  		if (viewer == null)
  			return false;
  
  		Point s= viewer.getSelectedRange();
  		if (s.y == 0)
  			return false;
  
  		try {
  
  			IDocument document= viewer.getDocument();
  			int startLine= document.getLineOfOffset(s.x);
  			int endLine= document.getLineOfOffset(s.x + s.y);
  			IRegion line= document.getLineInformation(startLine);
  			return startLine != endLine || (s.x == line.getOffset() && s.y == line.getLength());
  
  		} catch (BadLocationException x) {
  			return false;
  		}
  	}
  }
  