content: /*******************************************************************************
   * Copyright (c) 2000, 2015 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.java.hover;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.net.URL;
  
  import org.eclipse.core.runtime.FileLocator;
  import org.eclipse.core.runtime.Platform;
  import org.eclipse.wst.jsdt.internal.ui.text.html.HTMLPrinter;
  import org.eclipse.wst.jsdt.internal.ui.text.html.HTMLTextPresenter;
  import org.eclipse.jface.resource.JFaceResources;
  import org.eclipse.jface.text.DefaultInformationControl;
  import org.eclipse.jface.text.IInformationControl;
  import org.eclipse.jface.text.IInformationControlCreator;
  import org.eclipse.jface.text.IRegion;
  import org.eclipse.jface.text.ITextHoverExtension;
  import org.eclipse.jface.text.ITextViewer;
  import org.eclipse.swt.SWT;
  import org.eclipse.swt.graphics.FontData;
  import org.eclipse.swt.widgets.Shell;
  import org.eclipse.ui.IEditorInput;
  import org.eclipse.ui.IEditorPart;
  import org.eclipse.ui.editors.text.EditorsUI;
  import org.eclipse.wst.jsdt.core.ICodeAssist;
  import org.eclipse.wst.jsdt.core.IJavaScriptElement;
  import org.eclipse.wst.jsdt.core.JavaScriptModelException;
  import org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin;
  import org.eclipse.wst.jsdt.internal.ui.javaeditor.IClassFileEditorInput;
  import org.eclipse.wst.jsdt.internal.ui.javaeditor.WorkingCopyManager;
  import org.eclipse.wst.jsdt.internal.ui.text.JavaWordFinder;
  import org.eclipse.wst.jsdt.ui.PreferenceConstants;
  import org.eclipse.wst.jsdt.ui.text.java.hover.IJavaEditorTextHover;
  import org.osgi.framework.Bundle;
  
  /**
   * Abstract class for providing hover information for Java elements.
   *
   * 
   */
  public abstract class AbstractJavaEditorTextHover implements IJavaEditorTextHover, ITextHoverExtension {
  	/**
  	 * The style sheet (css).
  	 * 
  	 */
  	private static String fgStyleSheet;
  	private IEditorPart fEditor;
  
  	/*
  	 * @see IJavaEditorTextHover#setEditor(IEditorPart)
  	 */
  	public void setEditor(IEditorPart editor) {
  		fEditor= editor;
  	}
  
  	protected IEditorPart getEditor() {
  		return fEditor;
  	}
  
  	protected ICodeAssist getCodeAssist() {
  		if (fEditor != null) {
  			IEditorInput input= fEditor.getEditorInput();
  			if (input instanceof IClassFileEditorInput) {
  				IClassFileEditorInput cfeInput= (IClassFileEditorInput) input;
  				return cfeInput.getClassFile();
  			}
  
  			WorkingCopyManager manager= JavaScriptPlugin.getDefault().getWorkingCopyManager();
  			return manager.getWorkingCopy(input, false);
  		}
  
  		return null;
  	}
  
  	/*
  	 * @see ITextHover#getHoverRegion(ITextViewer, int)
  	 */
  	public IRegion getHoverRegion(ITextViewer textViewer, int offset) {
  		return JavaWordFinder.findWord(textViewer.getDocument(), offset);
  	}
  
  	/*
  	 * @see ITextHover#getHoverInfo(ITextViewer, IRegion)
  	 */
  	public String getHoverInfo(ITextViewer textViewer, IRegion hoverRegion) {
  		
  		/*
  		 * The region should be a word region an not of length 0.
  		 * This check is needed because codeSelect(...) also finds
  		 * the Java element if the offset is behind the word.
  		 */
  		if (hoverRegion.getLength() == 0)
  			return null;
  		
  		ICodeAssist resolve= getCodeAssist();
  		if (resolve != null) {
  			try {
  				IJavaScriptElement[] result= resolve.codeSelect(hoverRegion.getOffset(), hoverRegion.getLength());
  				if (result == null)
  					return null;
  
  				int nResults= result.length;
  				if (nResults == 0)
  					return null;
  
  				return getHoverInfo(result);
  
  			} catch (JavaScriptModelException x) {
  				return null;
  			}
  		}
  		return null;
  	}
  
  	/**
  	 * Provides hover information for the given Java elements.
  	 *
  	 * @param javaElements the Java elements for which to provide hover information
  	 * @return the hover information string
  	 * 
  	 */
  	protected String getHoverInfo(IJavaScriptElement[] javaElements) {
  		return null;
  	}
  
  	/*
  	 * @see ITextHoverExtension#getHoverControlCreator()
  	 * 
  	 */
  	public IInformationControlCreator getHoverControlCreator() {
  		return new IInformationControlCreator() {
  			public IInformationControl createInformationControl(Shell parent) {
  				return new DefaultInformationControl(parent, SWT.NONE, new HTMLTextPresenter(true), EditorsUI.getTooltipAffordanceString());
  			}
  		};
  	}
  
  	protected static String getStyleSheet() {
  		if (fgStyleSheet == null)
  			fgStyleSheet= loadStyleSheet();
  		String css= fgStyleSheet;
  		if (css != null) {
  			FontData fontData= JFaceResources.getFontRegistry().getFontData(PreferenceConstants.APPEARANCE_JAVADOC_FONT)[0];
  			css= HTMLPrinter.convertTopLevelFont(css, fontData);
  		}
  
  		return css;
  	}
  	
  	private static String loadStyleSheet() {
  		Bundle bundle= Platform.getBundle(JavaScriptPlugin.getPluginId());
  		URL styleSheetURL= bundle.getEntry("/JavadocHoverStyleSheet.css"); //$NON-NLS-1$
  		if (styleSheetURL != null) {
  			try {
  				styleSheetURL= FileLocator.toFileURL(styleSheetURL);
  				StringBuffer buffer= new StringBuffer(200);
  				BufferedReader reader= new BufferedReader(new InputStreamReader(styleSheetURL.openStream()));
  				try {
  					String line= reader.readLine();
  					while (line != null) {
  						buffer.append(line);
  						buffer.append('\n');
  						line= reader.readLine();
  					}
  				} finally {
  					reader.close();
  				}
  				return buffer.toString();
  			} catch (IOException ex) {
  				JavaScriptPlugin.log(ex);
  				return ""; //$NON-NLS-1$
  			}
  		}
  		return null;
  	}
  }
  