/**********************************************
    * Copyright (C) 2010 Lukas Laag
    * This file is part of svgreal.
    * 
    * svgreal is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    * 
   * svgreal is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   * 
   * You should have received a copy of the GNU General Public License
   * along with svgreal.  If not, see http://www.gnu.org/licenses/
   **********************************************/
  package org.vectomatic.svg.edit.client.engine;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import org.vectomatic.dom.svg.OMNode;
  import org.vectomatic.dom.svg.OMSVGElement;
  import org.vectomatic.dom.svg.impl.Attr;
  import org.vectomatic.dom.svg.impl.NamedNodeMap;
  import org.vectomatic.dom.svg.impl.SVGElement;
  import org.vectomatic.dom.svg.itf.ISVGTransformable;
  import org.vectomatic.dom.svg.utils.DOMHelper;
  import org.vectomatic.dom.svg.utils.SVGConstants;
  
  import com.google.gwt.core.client.GWT;
  import com.google.gwt.dom.client.Element;
  import com.google.gwt.dom.client.Node;
  import com.google.gwt.dom.client.NodeList;
  
  /**
   * Class to normalize id and idrefs in an SVG document
   * @author laaglu
   */
  public class SVGProcessor {
  	/*==========================================================
  	 * 
  	 * E L E M E N T   C L A S S I F I C A T I O N
  	 * 
  	 *==========================================================*/
  	/**
  	 * Tag names of definition elements which contain graphical
  	 * elements but are not displayed directly
  	 */
  	protected static Set<String> definitionElementNames;
  	/**
  	 * Tag names of graphical elements
  	 */
  	protected static Set<String> graphicalElementNames;
  	/**
  	 * Tag names of group element
  	 */
  	protected static Set<String> groupElementNames;
  
  	public static boolean isGroupElement(SVGElement element) {
  		if (groupElementNames == null) {
  			groupElementNames = new HashSet<String>(Arrays.asList(new String[] {
  					SVGConstants.SVG_G_TAG,
  					SVGConstants.SVG_DEFS_TAG
  				}));
  		}
  		return groupElementNames.contains(DOMHelper.getLocalName(element));
  	}
  
  	/**
  	 * Returns true if the specified node is a definition element.
  	 * @param element the element to test.
  	 * @return true if the specified node is a definition element.
  	 */
  	public static boolean isDefinitionElement(SVGElement element) {
  		if (definitionElementNames == null) {
  			definitionElementNames = new HashSet<String>(Arrays.asList(new String[] {
  					SVGConstants.SVG_SYMBOL_TAG,
  					SVGConstants.SVG_DEFS_TAG,
  					SVGConstants.SVG_PATTERN_TAG,
  					SVGConstants.SVG_MARKER_TAG,
  					SVGConstants.SVG_CLIP_PATH_TAG,
  					SVGConstants.SVG_MASK_TAG,
  					SVGConstants.SVG_GLYPH_TAG,
  					SVGConstants.SVG_MISSING_GLYPH_TAG
  				}));
  		}
  		return definitionElementNames.contains(DOMHelper.getLocalName(element));
  	}
  	
  	/**
  	 * Returns true if the specified node is a graphical element.
 	 * @param element the element to test.
 	 * @return true if the specified node is a graphical element.
 	 */
 	public static boolean isGraphicalElement(SVGElement element) {
 		if (graphicalElementNames == null) {
 			graphicalElementNames = new HashSet<String>(Arrays.asList(new String[] {
 			SVGConstants.SVG_CIRCLE_TAG,
 			SVGConstants.SVG_ELLIPSE_TAG,
 			SVGConstants.SVG_G_TAG,
 			SVGConstants.SVG_IMAGE_TAG,
 			SVGConstants.SVG_LINE_TAG,
 			SVGConstants.SVG_PATH_TAG,
 			SVGConstants.SVG_POLYLINE_TAG,
 			SVGConstants.SVG_POLYGON_TAG,
 			SVGConstants.SVG_RECT_TAG,
 			SVGConstants.SVG_TEXT_TAG,
 			SVGConstants.SVG_T_REF_TAG,
 			SVGConstants.SVG_T_SPAN_TAG,
 			SVGConstants.SVG_USE_TAG
 			}));	
 		}
 		return graphicalElementNames.contains(DOMHelper.getLocalName(element));
 	}
 	
 	/**
 	 * Returns true if the specified node is an SVG element.
 	 * @param node the node to test.
 	 * @return true if the specified node is an SVG element.
 	 */
 	public static boolean isSvgElement(Node node) {
 		return node.getNodeType() == Node.ELEMENT_NODE 
 			&& SVGConstants.SVG_NAMESPACE_URI.equals(DOMHelper.getNamespaceURI(node));
 	}
 	
 	/**
 	 * Returns true if the specified element is an SVG title or desc element.
 	 * @param element the element to test.
 	 * @return true if the specified element is an SVG title or desc element.
 	 */
 	public static boolean isTitleDescElement(SVGElement element) {
 		String localName = DOMHelper.getLocalName(element);
 		return SVGConstants.SVG_TITLE_TAG.equals(localName) || SVGConstants.SVG_DESC_TAG.equals(localName);
 	}
 
 	/**
 	 * Returns true if the specified element implements ISVGTransformable.
 	 * @param node the node to test.
 	 * @return true if the specified element implements ISVGTransformable.
 	 */
 	public static boolean isTransformable(Node node) {
 		return OMNode.convert(node) instanceof ISVGTransformable;
 	}
 	
 	/*==========================================================
 	 * 
 	 * I D   R E F E R E N C E S   M A N A G E M E N T 
 	 * 
 	 *==========================================================*/
 	
 	static Set<String> IDREF_ATTS = new HashSet<String>(Arrays.asList(
 			new String[] { "clip-path",
 			 "mask",
 			 "marker-start",
 			 "marker-mid",
 			 "marker-end",
 			 "fill",
 			 "stroke",
 			 "filter",
 			 "cursor",
 			 "style"}));
 	static IdRefTokenizer TOKENIZER = GWT.create(IdRefTokenizer.class);
 
 	/**
 	 * Adds the ids of all elements referred to by the specified element
 	 * to the specified collection of referenced ids.
 	 * @param element
 	 * The element to analyze
 	 * @param refs
 	 * A collection of referenced ids.
 	 */
 	public static void getIdReferences(Collection<String> refs, Element element) {
 		NamedNodeMap<Attr> attrs = DOMHelper.getAttributes(element);
 		for (int i = 0, length = attrs.getLength(); i < length; i++) {
 			Attr attr = attrs.item(i);
 			if (IDREF_ATTS.contains(attr.getName())) {
 				TOKENIZER.tokenize(attr.getValue());
 				IdRefTokenizer.IdRefToken token;
 				while ((token = TOKENIZER.nextToken()) != null) {
 					if (token.getKind() == IdRefTokenizer.IdRefToken.IDREF) {
 						refs.add(token.getValue());
 					}
 				}
 			}
 		}
 	}
 
 
 	/*==========================================================
 	 * 
 	 * M U L T I D O C U M E N T   M A N A G E M E N T 
 	 * 
 	 *==========================================================*/
 	
 	static int docId;
 	public static void main(String[] args) {
 		for (int i = 0; i < args.length; i++) {
 			IdRefTokenizer tokenizer = new IdRefTokenizer();
 			StringBuilder builder = new StringBuilder();
 			tokenizer.tokenize(args[i]);
 			IdRefTokenizer.IdRefToken token;
 			while ((token = tokenizer.nextToken()) != null) {
 				String txt = (token.getKind() == IdRefTokenizer.IdRefToken.DATA) ? token.getValue() : ("{" + token.getValue() + "}");
 				builder.append(txt);
 			}
 			System.out.println("\"" + args[i] + "\" ==> \"" + builder.toString() + "\"");
 		}
 	}
 	
 	/**
 	 * Creates a new unique id prefix for id attributes of an svg model.
 	 * The ids have the following structure:
 	 * <pre>{prefix/ext1/...extN}localId</pre>
 	 * where:
 	 * <dl>
 	 * <dt>prefix</dt><dd>is the unique document prefix returned by this method</dd>
 	 * <dt>extK</dt><dd>is a model specific extension used to avoid collisions between virtual hiearchies created in the model (such as element/twin)</dd>
 	 * <dt>localId</dt><dd>is the actual id appearing in the source document</dd>
 	 * </dl>
 	 * @return
 	 */
 	public static String newIdPrefix() {
 		docId++;
 		return "d" + docId;
 	}
 	
 	/**
 	 * Creates a new unique id prefix with the specified extension
 	 * @param base The base prefix
 	 * @param extension The extension to add
 	 * @return The prefix id
 	 */
 	public static String newPrefixExtension(String base, String extension) {
 		return base + "/" + extension;
 	}
 	
 	public static String makeId(String idPrefix, String localId) {
 		return "{" + idPrefix + "}" + localId;
 	}
 	
 	/**
 	 * Transforms all ids and id-refs in the specified source svg to avoid
 	 * collisions with other svgs in other models.
 	 * @param srcSvg The source svg
 	 * @param idPrefix A prefix to apply to avoid collisions
 	 */
 	public static void normalizeIds(OMSVGElement srcSvg, String idPrefix) {
 		// Collect all the original element ids and replace them with a
 		// normalized id
 		int idIndex = 0;
 		Map<String, String> idToNormalizedId = new HashMap<String, String>();
 		List<Element> queue = new ArrayList<Element>();
 		queue.add(srcSvg.getElement());
 		while (queue.size() > 0) {
 			Element element = queue.remove(0);
 			String id = element.getId();
 			if (id != null) {
 				String normalizedId = makeId(idPrefix, Integer.toString(idIndex++));
 				idToNormalizedId.put(id, normalizedId);
 				element.setId(normalizedId);
 			}
 			NodeList<Node> childNodes =  element.getChildNodes();
 			for (int i = 0, length = childNodes.getLength(); i < length; i++) {
 				Node childNode = childNodes.getItem(i);
 				if (childNode.getNodeType() == Node.ELEMENT_NODE) {
 					queue.add((Element)childNode.cast());
 				}
 			}
 		}
 		
 		// Change all the attributes which are URI references
 		queue.add(srcSvg.getElement());
 		while (queue.size() > 0) {
 			Element element = queue.remove(0);
 			if (DOMHelper.hasAttributeNS(element, SVGConstants.XLINK_NAMESPACE_URI, SVGConstants.XLINK_HREF_ATTRIBUTE)) {
 				String idRef = DOMHelper.getAttributeNS(element, SVGConstants.XLINK_NAMESPACE_URI, SVGConstants.XLINK_HREF_ATTRIBUTE);
 				// TODO: Test will probably not work on Opera (where all URLs are made absolute)
 				if (idRef.startsWith("#")) {
 					// Normalize hrefs to internal elements (such as between two gradients),
 					// not hrefs to external elements (such as between an image and its png)
 					String normalizeIdRef = idToNormalizedId.get(idRef.substring(1));
 					DOMHelper.setAttributeNS(element, SVGConstants.XLINK_NAMESPACE_URI, SVGConstants.XLINK_HREF_ATTRIBUTE, "#" + normalizeIdRef);
 				}
 			}
 			NamedNodeMap<Attr> attrs = DOMHelper.getAttributes(element);
 			for (int i = 0, length = attrs.getLength(); i < length; i++) {
 				Attr attr = attrs.item(i);
 				if (IDREF_ATTS.contains(attr.getName())) {
 					StringBuilder builder = new StringBuilder();
 					TOKENIZER.tokenize(attr.getValue());
 					IdRefTokenizer.IdRefToken token;
 					while ((token = TOKENIZER.nextToken()) != null) {
 						String value = token.getValue();
 						if (token.getKind() == IdRefTokenizer.IdRefToken.DATA) {
 							builder.append(value);
 						} else {
 							value = idToNormalizedId.get(value);
 							builder.append(value == null ? token.getValue() : value);
 						}
 					}
 					attr.setValue(builder.toString());
 				}
 			}
 			NodeList<Node> childNodes =  element.getChildNodes();
 			for (int i = 0, length = childNodes.getLength(); i < length; i++) {
 				Node childNode = childNodes.getItem(i);
 				if (childNode.getNodeType() == Node.ELEMENT_NODE) {
 					queue.add((Element)childNode.cast());
 				}
 			}
 		}
 	}
 
 	/**
 	 * Transfers all the children for one element to another element
 	 * @param src the source element
 	 * @param dest the destination element
 	 */
 	public static void reparent(OMSVGElement src, OMSVGElement dest) {
 		Element srcElement = src.getElement();
 		Element destElement = dest.getElement();
 		Node node;
 		while((node = srcElement.getFirstChild()) != null) {
 			destElement.appendChild(srcElement.removeChild(node));
 		}
 	}
 
 }