/*******************************************************************************
 * Copyright (c) 2005, 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
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.jface.text.DefaultTextHover;

import dwt.dwthelper.utils;

import java.util.Iterator;

import dwtx.core.runtime.Assert;
import dwtx.jface.text.source.Annotation;
import dwtx.jface.text.source.IAnnotationModel;
import dwtx.jface.text.source.ISourceViewer;
import dwtx.jface.text.source.ISourceViewerExtension2;

/**
 * Standard implementation of {@link dwtx.jface.text.ITextHover}.
 * 
 * @since 3.2
 */
public class DefaultTextHover : ITextHover {

    /** This hover's source viewer */
    private ISourceViewer fSourceViewer;

    /**
     * Creates a new annotation hover.
     * 
     * @param sourceViewer this hover's annotation model
     */
    public DefaultTextHover(ISourceViewer sourceViewer)  {
        Assert.isNotNull(sourceViewer);
        fSourceViewer= sourceViewer;
    }
    
    /*
     * @see dwtx.jface.text.ITextHover#getHoverInfo(dwtx.jface.text.ITextViewer, dwtx.jface.text.IRegion)
     */
    public String getHoverInfo(ITextViewer textViewer, IRegion hoverRegion) {
        IAnnotationModel model= getAnnotationModel(fSourceViewer);
        if (model is null)
            return null;
        
        Iterator e= model.getAnnotationIterator();
        while (e.hasNext()) {
            Annotation a= (Annotation) e.next();
            if (isIncluded(a)) {
                Position p= model.getPosition(a);
                if (p !is null && p.overlapsWith(hoverRegion.getOffset(), hoverRegion.getLength())) {
                    String msg= a.getText();
                    if (msg !is null && msg.trim().length() > 0)
                        return msg;
                }
            }
        }
        
        return null;
    }

    /*
     * @see dwtx.jface.text.ITextHover#getHoverRegion(dwtx.jface.text.ITextViewer, int)
     */
    public IRegion getHoverRegion(ITextViewer textViewer, int offset) {
        return findWord(textViewer.getDocument(), offset);
    }
    
    /**
     * Tells whether the annotation should be included in
     * the computation.
     * 
     * @param annotation the annotation to test
     * @return <code>true</code> if the annotation is included in the computation
     */
    protected bool isIncluded(Annotation annotation) {
        return true;
    }
    
    private IAnnotationModel getAnnotationModel(ISourceViewer viewer) {
        if (viewer instanceof ISourceViewerExtension2) {
            ISourceViewerExtension2 extension= (ISourceViewerExtension2) viewer;
            return extension.getVisualAnnotationModel();
        }
        return viewer.getAnnotationModel();
    }
    
    private IRegion findWord(IDocument document, int offset) {
        int start= -2;
        int end= -1;

        try {

            int pos= offset;
            char c;

            while (pos >= 0) {
                c= document.getChar(pos);
                if (!Character.isUnicodeIdentifierPart(c))
                    break;
                --pos;
            }

            start= pos;

            pos= offset;
            int length= document.getLength();

            while (pos < length) {
                c= document.getChar(pos);
                if (!Character.isUnicodeIdentifierPart(c))
                    break;
                ++pos;
            }

            end= pos;

        } catch (BadLocationException x) {
        }

        if (start >= -1 && end > -1) {
            if (start is offset && end is offset)
                return new Region(offset, 0);
            else if (start is offset)
                return new Region(start, end - start);
            else
                return new Region(start + 1, end - start - 1);
        }

        return null;
    }
}