/*******************************************************************************
 * Copyright (c) 2001, 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
 *     Jens Lukowski/Innoopract - initial renaming/restructuring
 *     
 *******************************************************************************/
package org.eclipse.wst.sse.ui.internal.taginfo;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jface.preference.IPreferenceStore;
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.source.Annotation;
import org.eclipse.jface.text.source.IAnnotationModel;
import org.eclipse.jface.text.source.SourceViewer;
import org.eclipse.ui.editors.text.EditorsUI;
import org.eclipse.ui.texteditor.AnnotationPreference;
import org.eclipse.ui.texteditor.ChainedPreferenceStore;
import org.eclipse.wst.sse.core.utils.StringUtils;
import org.eclipse.wst.sse.ui.internal.SSEUIMessages;
import org.eclipse.wst.sse.ui.internal.SSEUIPlugin;

/**
 * Hover help that displays annotations shown in text of editor. Currently,
 * this text hover is used in conjunction with AbstractTextHoverProcessor.
 * 
 * @author amywu
 */
public class AnnotationHoverProcessor extends AbstractHoverProcessor {
	private final static String LIST_BEGIN = "<ul>"; //$NON-NLS-1$
	private final static String LIST_ELEMENT = "<li>"; //$NON-NLS-1$
	private final static String PARAGRAPH_END = "</p>"; //$NON-NLS-1$
	private final static String PARAGRAPH_START = "<p>"; //$NON-NLS-1$

	private IPreferenceStore fPreferenceStore = null;

	/**
	 * 
	 */
	public AnnotationHoverProcessor() {
		super();
	}

	/**
	 * Formats a msg to a proper html message
	 * 
	 * @param msg -
	 *            assumes msg is neither null nor empty string
	 * @return
	 */
	private String formatMessage(String msg) {
		StringBuffer buf = new StringBuffer();
		buf.append(PARAGRAPH_START);
		buf.append(StringUtils.convertToHTMLContent(msg));
		buf.append(PARAGRAPH_END);
		return buf.toString();
	}

	/**
	 * Formats multiple messages into proper html message
	 * 
	 * @param messages
	 * @return
	 */
	private String formatMessages(List messages) {
		StringBuffer buffer = new StringBuffer();
		buffer.append(PARAGRAPH_START);
		buffer.append(SSEUIMessages.Multiple_errors); //$NON-NLS-1$
		buffer.append(LIST_BEGIN);

		Iterator e = messages.iterator();
		while (e.hasNext()) {
			buffer.append(LIST_ELEMENT);
			buffer.append(StringUtils.convertToHTMLContent((String) e.next()));
		}
		buffer.append(PARAGRAPH_END);
		return buffer.toString();
	}

	/**
	 * Returns the annotation preference for the given annotation. (copied
	 * from org.eclipse.jdt.internal.ui.text.java.hover.AnnotationHover)
	 * 
	 * @param annotation
	 *            the annotation
	 * @return the annotation preference or <code>null</code> if none
	 */
	private AnnotationPreference getAnnotationPreference(Annotation annotation) {

		if (annotation.isMarkedDeleted())
			return null;
		return EditorsUI.getAnnotationPreferenceLookup().getAnnotationPreference(annotation);
	}

	public String getHoverInfo(ITextViewer viewer, IRegion hoverRegion) {
		IAnnotationModel model = ((SourceViewer) viewer).getAnnotationModel();
		if (model != null) {
			List messages = new ArrayList();
			Iterator e = model.getAnnotationIterator();
			while (e.hasNext()) {
				Annotation a = (Annotation) e.next();
				if (!isAnnotationValid(a))
					continue;

				Position p = model.getPosition(a);
				/*
				 * Check if this is an Annotation in the region we are
				 * concerned with
				 */
				if (p.overlapsWith(hoverRegion.getOffset(), hoverRegion.getLength())) {
					String msg = a.getText();
					if ((msg != null) && msg.trim().length() > 0) {
						/*
						 * It is possible for temporary annotations to
						 * duplicate other annotations so make sure not to add
						 * duplicates.
						 */
						boolean duplicated = false;
						int j = 0;
						while (j < messages.size() && !duplicated) {
							duplicated = messages.get(j).equals(msg);
							++j;
						}
						if (!duplicated) {
							messages.add(msg);
						}
					}
				}
			}
			if (messages.size() > 1) {
				return formatMessages(messages);
			}
			else if (messages.size() > 0) {
				return formatMessage(messages.get(0).toString());
			}
		}
		return null;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.ITextHover#getHoverRegion(org.eclipse.jface.text.ITextViewer,
	 *      int)
	 */
	public IRegion getHoverRegion(ITextViewer textViewer, int offset) {
		IAnnotationModel model = ((SourceViewer) textViewer).getAnnotationModel();
		Region hoverRegion = null;

		if (model != null) {
			Iterator e = model.getAnnotationIterator();
			while (e.hasNext()) {
				Annotation a = (Annotation) e.next();
				if (!isAnnotationValid(a))
					continue;
				Position p = model.getPosition(a);
				if (p.includes(offset)) {
					// find the smallest region containing offset
					if ((hoverRegion == null) || (hoverRegion.getLength() > p.getLength())) {
						hoverRegion = new Region(p.getOffset(), p.getLength());
					}
				}
			}
		}
		return hoverRegion;
	}

	/**
	 * Retreives the preference store If no preference store is currently
	 * stored, retreive the appropriate preference store
	 */
	private IPreferenceStore getPreferenceStore() {
		if (fPreferenceStore == null) {
			IPreferenceStore sseEditorPrefs = SSEUIPlugin.getDefault().getPreferenceStore();
			IPreferenceStore baseEditorPrefs = EditorsUI.getPreferenceStore();
			fPreferenceStore = new ChainedPreferenceStore(new IPreferenceStore[]{sseEditorPrefs, baseEditorPrefs});
		}
		return fPreferenceStore;
	}

	boolean isAnnotationValid(Annotation a) {
		AnnotationPreference preference = getAnnotationPreference(a);
		if (preference == null)
			return false;
		String textPreferenceKey = preference.getTextPreferenceKey();
		String highlightPreferenceKey = preference.getHighlightPreferenceKey();
		if (textPreferenceKey == null || !(getPreferenceStore().getBoolean(textPreferenceKey)) || highlightPreferenceKey == null || getPreferenceStore().getBoolean(highlightPreferenceKey))
			return false;
		return true;
	}
}