/*******************************************************************************
 * Copyright (c) 2010, 2011 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.css.ui.internal.editor;

import java.util.HashSet;
import java.util.Set;

import org.eclipse.core.runtime.IAdapterFactory;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.wst.css.core.internal.document.CSSNodeImpl;
import org.eclipse.wst.css.core.internal.provisional.document.ICSSModel;
import org.eclipse.wst.css.core.internal.provisional.document.ICSSNode;
import org.eclipse.wst.css.core.internal.provisional.document.ICSSStyleSheet;
import org.eclipse.wst.css.ui.internal.Logger;
import org.eclipse.wst.sse.core.internal.provisional.IStructuredModel;
import org.eclipse.wst.sse.core.internal.provisional.IndexedRegion;
import org.eclipse.wst.sse.ui.internal.editor.SelectionConvertor;

/**
 * <p>Factory to adapt from {@link ICSSModel} to {@link SelectionConvertor}</p>
 */
public class CSSSelectionConverterFactory implements IAdapterFactory {

	/** the list of classes this factory can adapt to */
	private static final Class[] ADAPTER_LIST = new Class[]{SelectionConvertor.class};
	
	/** the adapted class */
	private static final Object selectionConvertor = new CSSSelectionConverter();
	
	/**
	 * <p>Default constructor</p>
	 */
	public CSSSelectionConverterFactory() {
	}
	
	/**
	 * <p>Adapts {@link ICSSModel} to {@link SelectionConvertor}</p>
	 * 
	 * @see org.eclipse.core.runtime.IAdapterFactory#getAdapter(java.lang.Object, java.lang.Class)
	 */
	public Object getAdapter(Object adaptableObject, Class adapterType) {
		Object adapter = null;
		if (adaptableObject instanceof ICSSModel && SelectionConvertor.class.equals(adapterType)) {
			adapter = selectionConvertor;
		}
		return adapter;
	}

	/**
	 * <p>Adapts to {@link SelectionConvertor}</p>
	 * 
	 * @see org.eclipse.core.runtime.IAdapterFactory#getAdapterList()
	 */
	public Class[] getAdapterList() {
		return ADAPTER_LIST;
	}
	
	/**
	 * <p>{@link SelectionConvertor} specific to CSS</p>
	 */
	private static class CSSSelectionConverter extends SelectionConvertor {
		/**
		 * <p>Default constructor</p>
		 */
		public CSSSelectionConverter() {
		}
		
		/**
		 * @see org.eclipse.wst.sse.ui.internal.editor.SelectionConvertor#getElements(org.eclipse.wst.sse.core.internal.provisional.IStructuredModel, int, int)
		 */
		public Object[] getElements(IStructuredModel model, int start, int end) {
			Object[] localSelectedStructures = null;
			if (model != null) {
				IndexedRegion region = model.getIndexedRegion(start);
				
				/* in CSS docs whitespace is owned by the style sheet
				 * this is to find the first none whitespace region
				 */
				if(region instanceof ICSSStyleSheet) {
					try {
						String selection = model.getStructuredDocument().get(start, end);
						int whitespaceLength = beginingWhitespaceLength(selection);
						region = model.getIndexedRegion(start+whitespaceLength+1);
					} catch(BadLocationException e) {
						//should never be able to happen
						Logger.logException("Bad location on selection, this should never happen", e);
					}
				}

				if (region != null) {
					// if single selection spans selected region
					// else multiple selection
					if (end <= region.getEndOffset()) {
						// single selection
						localSelectedStructures = new Object[1];
						localSelectedStructures[0] = region;
					}
					else {
						int maxLength = model.getStructuredDocument().getLength();
						Set structures = new HashSet();
						while (region != null && region.getEndOffset() <= end && region.getEndOffset() <= maxLength && !structures.contains(region)) {
							structures.add(region);

							//use the CSS model to find the next sibling
							boolean foundNextSibling = false;
							if(region instanceof CSSNodeImpl ) {
								ICSSNode node = ((ICSSNode)region).getNextSibling();
								if(node instanceof IndexedRegion) {
									region = (IndexedRegion)node;
									foundNextSibling = true;
								}
							}
							
							if(!foundNextSibling) {
								region = model.getIndexedRegion(region.getEndOffset() + 1);
							}
						}
						localSelectedStructures = structures.toArray();
					}
				}
			}
			if (localSelectedStructures == null) {
				localSelectedStructures = new Object[0];
			}
			return localSelectedStructures;
		}

	}
	
	/**
	 * @param s find the length of the whitespace preceding this {@link String}
	 * @return the length of the whitespace preceding the given {@link String}
	 */
	private static int beginingWhitespaceLength(String s) {
		int length = 0;
		
		for (int i = 0; i < s.length() && length == 0; ++i) {
			if (!Character.isWhitespace(s.charAt(i))) {
				length = i;
			}
		}
		
		return length;
	}
}