/**********************************************
    * Copyright (C) 2010 Lukas Laag
    * This file is part of lib-gwt-svg.
    * 
    * libgwtsvg is free software: you can redistribute it and/or modify
    * it under the terms of the GNU Lesser General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    * 
   * libgwtsvg 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 Lesser General Public License for more details.
   * 
   * You should have received a copy of the GNU Lesser General Public License
   * along with libgwtsvg.  If not, see http://www.gnu.org/licenses/
   **********************************************/
  package org.vectomatic.dom.svg.impl;
  
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  
  import org.vectomatic.dom.svg.OMSVGScriptElement;
  import org.vectomatic.dom.svg.utils.DOMHelper;
  import org.vectomatic.dom.svg.utils.ParserException;
  import org.vectomatic.dom.svg.utils.SVGPrefixResolver;
  
  import com.google.gwt.core.client.JavaScriptException;
  import com.google.gwt.core.client.JavaScriptObject;
  import com.google.gwt.dom.client.Document;
  import com.google.gwt.dom.client.Element;
  import com.google.gwt.dom.client.Node;
  import com.google.gwt.dom.client.Text;
  
  public class SVGParserImpl {
  	@SuppressWarnings("unused")
  	private final JavaScriptObject domParser = createDOMParser();
  	
  	private native JavaScriptObject createDOMParser() /*-{
  	  return new DOMParser();
  	}-*/;
  
  	public final native Document parseFromString(String rawText, String contentType) /*-{
        return this.@org.vectomatic.dom.svg.impl.SVGParserImpl::domParser.parseFromString(rawText, contentType);
  	}-*/;
  
  	/**
  	 * Parses the supplied SVG text into a document
  	 * @param rawSvg
  	 * raw xml to be parsed
  	 * @param enableScripts
  	 * true to enable embedded scripts, false otherwise
  	 * @return
  	 * the document resulting from the parse
  	 */
  	public SVGSVGElement parse(String rawSvg, boolean enableScripts) throws ParserException {
  		if (isIE()) {
  			return parseIE(rawSvg, enableScripts);
  		}
  		SVGDocument doc = parseFromString(rawSvg, "text/xml").cast();
  		Element elt = doc.getDocumentElement();
  		if ("parsererror".equals(DOMHelper.getLocalName(elt))) {
  			String message = "Parsing error";
  			if (elt.getFirstChild() != null) {
  				message = elt.getFirstChild().<Text>cast().getData();
  			}
  			throw new ParserException(ParserException.Type.NotWellFormed, message);
  		}
  		SVGSVGElement svg = DOMHelper.importNode(DOMHelper.getCurrentDocument(), elt, true).<SVGSVGElement>cast();
  		return enableScripts ? enableScriptElements(svg) : svg;
  	}
  
  	/**
  	 * Re-enables scripts disabled by the DOMParser.parseFromString method.
  	 * @param svg
  	 * The svg for which scripts are to be re-enabled.
  	 * @return
  	 * The svg with re-enabled scripts.
  	 */
  	protected static SVGSVGElement enableScriptElements(SVGSVGElement svg) {
  		// Put all scripts in a list (XPath result sets cannot be modified during traversal).
  		List<SVGScriptElement> scripts = new ArrayList<SVGScriptElement>();
  		Iterator<Node> iterator = DOMHelper.evaluateNodeListXPath(svg, "//svg:script", SVGPrefixResolver.INSTANCE);
  		while (iterator.hasNext()) {
  			scripts.add(iterator.next().<SVGScriptElement>cast());
  		}
  		for (SVGScriptElement script : scripts) {
  			// Reparent the script subtree under a fresh script node
  			SVGScriptElement newScript = new OMSVGScriptElement().getElement().<SVGScriptElement>cast();
  			Node node;
  			while((node = script.getFirstChild()) != null) {
  				newScript.appendChild(script.removeChild(node));
  			}
  			script.getParentNode().replaceChild(newScript, script);
  		}
  		return svg;
  	}
  	
 	public static native boolean isIE() /*-{
 		return typeof document.documentMode === 'number';
 	}-*/;
 	
 	public final SVGSVGElement parseIE(String rawSvg, boolean enableScripts) throws ParserException {
 		SVGDocument doc = null;
 		try {
 			doc = parseFromString(rawSvg, "text/xml").cast();
 			
 		} catch(JavaScriptException e) {
 			throw new ParserException(ParserException.Type.NotWellFormed, e.getMessage());
 		}
 		Element elt = doc.getDocumentElement();
 		if ("parsererror".equals(DOMHelper.getLocalName(elt))) {
 			String message = "Parsing error";
 			if (elt.getFirstChild() != null) {
 				message = elt.getFirstChild().<Text>cast().getData();
 			}
 			throw new ParserException(ParserException.Type.NotWellFormed, message);
 		}
 		SVGSVGElement svg = DOMHelper.importNode(DOMHelper.getCurrentDocument(), elt, true).cast();
 		// IE9 bug workaround: update all SVG style elements by
 		// adding a trailing whitespace char, otherwise IE9 will
 		// ignore them
 		Iterator<Text> iterator = DOMHelper.evaluateNodeListXPath(svg, ".//svg:style/text()", SVGPrefixResolver.INSTANCE);
 		List<Text> styleTexts = new ArrayList<Text>();
 		while(iterator.hasNext()) {
 			Text styleText = iterator.next();
 			styleTexts.add(styleText);
 		}
 		for (Text styleText : styleTexts) {
 			styleText.<Text>cast().setData(styleText.<Text>cast().getData() + " ");
 		}
 		
 		return enableScripts ? enableScriptElements(svg) : svg;
 	}
 
 }