/*******************************************************************************
 * Copyright (c) 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.jst.jsp.ui.internal.autoedit;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentCommand;
import org.eclipse.jface.text.IAutoEditStrategy;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jst.jsp.ui.internal.JSPUIPlugin;
import org.eclipse.jst.jsp.ui.internal.Logger;
import org.eclipse.jst.jsp.ui.internal.preferences.JSPUIPreferenceNames;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.texteditor.ITextEditor;
import org.eclipse.ui.texteditor.ITextEditorExtension3;
import org.eclipse.wst.sse.core.StructuredModelManager;
import org.eclipse.wst.sse.core.internal.provisional.IStructuredModel;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocumentRegion;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMNode;

public class StructuredAutoEditStrategyJSPJava implements IAutoEditStrategy {

	public void customizeDocumentCommand(IDocument document, DocumentCommand command) {
		Object textEditor = getActiveTextEditor();
		if (!(textEditor instanceof ITextEditorExtension3 && ((ITextEditorExtension3) textEditor).getInsertMode() == ITextEditorExtension3.SMART_INSERT))
			return;
		
		IStructuredModel model = null;
		try {
			// Auto edit for JSP Comments
			if ("-".equals(command.text) && isPreferenceEnabled(JSPUIPreferenceNames.TYPING_COMPLETE_COMMENTS)) { //$NON-NLS-1$
				if (prefixedWith(document, command.offset, "<%-")) { //$NON-NLS-1$
					
					model = StructuredModelManager.getModelManager().getExistingModelForRead(document);
					if (model != null) {
						IDOMNode node = (IDOMNode) model.getIndexedRegion(command.offset);
						IDOMNode parent = (node != null) ? (IDOMNode) node.getParentNode() : null;
						// Parent is the scriptlet tag
						if (parent != null && !parent.getSource().endsWith("--%>")) { //$NON-NLS-1$
							IStructuredDocumentRegion end = parent.getEndStructuredDocumentRegion();
							if (end != null) {
								try {
									document.replace(end.getStartOffset(), 0, "--"); //$NON-NLS-1$
								} catch (BadLocationException e) {
									Logger.logException(e);
								}
							}
						}
					}
				}
			}
		}
		finally {
			if (model != null)
				model.releaseFromRead();
		}
	}
	
	private boolean isPreferenceEnabled(String key) {
		return (key != null && JSPUIPlugin.getDefault().getPreferenceStore().getBoolean(key));
	}
	
	/**
	 * Return the active text editor if possible, otherwise the active editor
	 * part.
	 * 
	 * @return
	 */
	private Object getActiveTextEditor() {
		IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
		if (window != null) {
			IWorkbenchPage page = window.getActivePage();
			if (page != null) {
				IEditorPart editor = page.getActiveEditor();
				if (editor != null) {
					if (editor instanceof ITextEditor)
						return editor;
					ITextEditor textEditor = (ITextEditor) editor.getAdapter(ITextEditor.class);
					if (textEditor != null)
						return textEditor;
					return editor;
				}
			}
		}
		return null;
	}

	private boolean prefixedWith(IDocument document, int offset, String string) {

		try {
			return document.getLength() >= string.length() && document.get(offset - string.length(), string.length()).equals(string);
		}
		catch (BadLocationException e) {
			Logger.logException(e);
			return false;
		}
	}

}