/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package net.sourceforge.phpeclipse.wiki.editor;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import net.sourceforge.phpeclipse.wiki.editor.model.WikipediaText;

import org.eclipse.jface.viewers.IPostSelectionProvider;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.SelectionChangedEvent;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.source.Annotation;
import org.eclipse.jface.text.source.IAnnotationModel;
import org.eclipse.jface.text.source.ISourceViewer;



class WikiOccurrencesUpdater implements ISelectionChangedListener {
	/**
	 * Annotation fType for recipe occurrences.
	 */
	private static final String ANNOTATION_TYPE= "net.sourceforge.phpeclipse.wiki.editor.highlightannotation";
	/**
	 * The editor we operate on.
	 */
	private final WikiEditor fEditor;
	/**
	 * The set of annotations added in the previous run, always replaced by a
	 * new run.
	 */
	private final List fOldAnnotations= new LinkedList();
	
	/**
	 * Creates a new instance on editor <code>editor</code>.
	 * 
	 * @param editor the editor to mark occurrences on.
	 */
	public WikiOccurrencesUpdater(WikiEditor editor) {
		((IPostSelectionProvider) editor.getSelectionProvider()).addPostSelectionChangedListener(this);
		fEditor= editor;
	}

	/*
	 * @see org.eclipse.jface.viewers.ISelectionChangedListener#selectionChanged(org.eclipse.jface.viewers.SelectionChangedEvent)
	 */
	public void selectionChanged(SelectionChangedEvent event) {
		update((ISourceViewer) event.getSource());
	}

	/**
	 * Updates the drawn annotations.
	 * 
	 * @param viewer the viewer to get the document and annotation model from
	 */
	public void update(ISourceViewer viewer) {
	        if (viewer==null) {  
	          return;
	        }
//		try {
			IDocument document= viewer.getDocument();
			IAnnotationModel model= viewer.getAnnotationModel();
			if (document == null || model == null)
				return;
			
			removeOldAnnotations(model);

//			String word= getWordAtSelection(fEditor.getSelectionProvider().getSelection(), document);
//			if (isIngredient(word)) {
//				createNewAnnotations(word, document, model);
//			}
			
//		} catch (BadLocationException e) {
//			// ignore
//		}
	}

	/**
	 * Removes the previous set of annotations from the annotation model.
	 * 
	 * @param model the annotation model
	 */
	private void removeOldAnnotations(IAnnotationModel model) {
		for (Iterator it= fOldAnnotations.iterator(); it.hasNext();) {
			Annotation annotation= (Annotation) it.next();
			model.removeAnnotation(annotation);
		}
		fOldAnnotations.clear();
	}

	/**
	 * Returns the word at the current selection / caret position.
	 * 
	 * @param selection the selection
	 * @param document the document
	 * @return the currently selected text, or the word at the caret if the
	 *         selection has length 0
	 * @throws BadLocationException if accessing the document fails
	 */
	private String getWordAtSelection(ISelection selection, IDocument document) throws BadLocationException {
		if (selection instanceof ITextSelection) {
			ITextSelection ts= (ITextSelection) selection;
			int offset= ts.getOffset();
			int end= offset + ts.getLength();
			
			// non-empty selections
			if (end != offset)
				return ts.getText();
			
			while (offset > 0 && isIngredientChar(document.getChar(offset - 1)))
				offset--;
			while (end < document.getLength() && isIngredientChar(document.getChar(end)))
				end++;
			
			return document.get(offset, end - offset);
		}
		return "";
	}

	private boolean isIngredientChar(char c) {
		return !Character.isWhitespace(c) && c != ':' && c != ',' && c != '.';
	}

	/**
	 * Adds an annotation for every occurrence of
	 * <code>ingredient</code> in the document. Also stores the created 
	 * annotations in <code>fOldAnnotations</code>.
	 * 
	 * @param ingredient the word to look for
	 * @param document the document
	 * @param model the annotation model
	 */
	private void createNewAnnotations(String ingredient, IDocument document, IAnnotationModel model) {
		String content= document.get();
		int idx= content.indexOf(ingredient);
		while (idx != -1) {
			Annotation annotation= new Annotation(ANNOTATION_TYPE, false, ingredient);
			Position position= new Position(idx, ingredient.length());
			
			model.addAnnotation(annotation, position);
			fOldAnnotations.add(annotation);
			
			idx= content.indexOf(ingredient, idx + 1);
		}
	}
	
	public void dispose() {
		((IPostSelectionProvider) fEditor.getSelectionProvider()).removePostSelectionChangedListener(this);
	}
}