MarkupValidatorCopy

package org.argeo.cms.ui.forms;

import java.io.StringReader;
import java.text.MessageFormat;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.eclipse.rap.rwt.SingletonUtil;
import org.eclipse.swt.widgets.Widget;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.helpers.DefaultHandler;

/**
 * Copy of RAP v2.3 since it is in an internal package.
 */
class MarkupValidatorCopy {

	// Used by Eclipse Scout project
	public static final String MARKUP_VALIDATION_DISABLED = "org.eclipse.rap.rwt.markupValidationDisabled";

	private static final String DTD = createDTD();
	private static final Map<String, String[]> SUPPORTED_ELEMENTS = createSupportedElementsMap();
	private final SAXParser saxParser;

	public static MarkupValidatorCopy getInstance() {
		return SingletonUtil.getSessionInstance(MarkupValidatorCopy.class);
	}

	public MarkupValidatorCopy() {
		saxParser = createSAXParser();
	}

	public void validate(String text) {
		StringBuilder markup = new StringBuilder();
		markup.append(DTD);
		markup.append("<html>");
		markup.append(text);
		markup.append("</html>");
		InputSource inputSource = new InputSource(new StringReader(markup.toString()));
		try {
			saxParser.parse(inputSource, new MarkupHandler());
		} catch (RuntimeException exception) {
			throw exception;
		} catch (Exception exception) {
			throw new IllegalArgumentException("Failed to parse markup text", exception);
		}
	}

	public static boolean isValidationDisabledFor(Widget widget) {
		return Boolean.TRUE.equals(widget.getData(MARKUP_VALIDATION_DISABLED));
	}

	private static SAXParser createSAXParser() {
		SAXParser result = null;
		SAXParserFactory parserFactory = SAXParserFactory.newInstance();
		try {
			result = parserFactory.newSAXParser();
		} catch (Exception exception) {
			throw new RuntimeException("Failed to create SAX parser", exception);
		}
		return result;
	}

	private static String createDTD() {
		StringBuilder result = new StringBuilder();
		result.append("<!DOCTYPE html [");
		result.append("<!ENTITY quot \"&#34;\">");
		result.append("<!ENTITY amp \"&#38;\">");
		result.append("<!ENTITY apos \"&#39;\">");
		result.append("<!ENTITY lt \"&#60;\">");
		result.append("<!ENTITY gt \"&#62;\">");
		result.append("<!ENTITY nbsp \"&#160;\">");
		result.append("<!ENTITY ensp \"&#8194;\">");
		result.append("<!ENTITY emsp \"&#8195;\">");
		result.append("<!ENTITY ndash \"&#8211;\">");
		result.append("<!ENTITY mdash \"&#8212;\">");
		result.append("]>");
		return result.toString();
	}

	private static Map<String, String[]> createSupportedElementsMap() {
		Map<String, String[]> result = new HashMap<String, String[]>();
		result.put("html", new String[0]);
		result.put("br", new String[0]);
		result.put("b", new String[] { "style" });
		result.put("strong", new String[] { "style" });
		result.put("i", new String[] { "style" });
		result.put("em", new String[] { "style" });
		result.put("sub", new String[] { "style" });
		result.put("sup", new String[] { "style" });
		result.put("big", new String[] { "style" });
		result.put("small", new String[] { "style" });
		result.put("del", new String[] { "style" });
		result.put("ins", new String[] { "style" });
		result.put("code", new String[] { "style" });
		result.put("samp", new String[] { "style" });
		result.put("kbd", new String[] { "style" });
		result.put("var", new String[] { "style" });
		result.put("cite", new String[] { "style" });
		result.put("dfn", new String[] { "style" });
		result.put("q", new String[] { "style" });
		result.put("abbr", new String[] { "style", "title" });
		result.put("span", new String[] { "style" });
		result.put("img", new String[] { "style", "src", "width", "height", "title", "alt" });
		result.put("a", new String[] { "style", "href", "target", "title" });
		return result;
	}

	private static class MarkupHandler extends DefaultHandler {

		@Override
		public void startElement(String uri, String localName, String name, Attributes attributes) {
			checkSupportedElements(name, attributes);
			checkSupportedAttributes(name, attributes);
			checkMandatoryAttributes(name, attributes);
		}

		private static void checkSupportedElements(String elementName, Attributes attributes) {
			if (!SUPPORTED_ELEMENTS.containsKey(elementName)) {
				throw new IllegalArgumentException("Unsupported element in markup text: " + elementName);
			}
		}

		private static void checkSupportedAttributes(String elementName, Attributes attributes) {
			if (attributes.getLength() > 0) {
				List<String> supportedAttributes = Arrays.asList(SUPPORTED_ELEMENTS.get(elementName));
				int index = 0;
				String attributeName = attributes.getQName(index);
				while (attributeName != null) {
					if (!supportedAttributes.contains(attributeName)) {
						String message = "Unsupported attribute \"{0}\" for element \"{1}\" in markup text";
						message = MessageFormat.format(message, new Object[] { attributeName, elementName });
						throw new IllegalArgumentException(message);
					}
					index++;
					attributeName = attributes.getQName(index);
				}
			}
		}

		private static void checkMandatoryAttributes(String elementName, Attributes attributes) {
			checkIntAttribute(elementName, attributes, "img", "width");
			checkIntAttribute(elementName, attributes, "img", "height");
		}

		private static void checkIntAttribute(String elementName, Attributes attributes, String checkedElementName,
				String checkedAttributeName) {
			if (checkedElementName.equals(elementName)) {
				String attribute = attributes.getValue(checkedAttributeName);
				try {
					Integer.parseInt(attribute);
				} catch (NumberFormatException exception) {
					String message = "Mandatory attribute \"{0}\" for element \"{1}\" is missing or not a valid integer";
					Object[] arguments = new Object[] { checkedAttributeName, checkedElementName };
					message = MessageFormat.format(message, arguments);
					throw new IllegalArgumentException(message);
				}
			}
		}

	}

}