/*******************************************************************************
 * Copyright (c) 2001, 2004 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.xml.ui.internal.validation;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.osgi.util.NLS;
import org.eclipse.wst.sse.core.StructuredModelManager;
import org.eclipse.wst.sse.core.internal.provisional.IStructuredModel;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocument;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocumentRegion;
import org.eclipse.wst.sse.core.internal.provisional.text.ITextRegion;
import org.eclipse.wst.sse.core.internal.provisional.text.ITextRegionList;
import org.eclipse.wst.sse.ui.internal.reconcile.AbstractStructuredTextReconcilingStrategy;
import org.eclipse.wst.sse.ui.internal.reconcile.ReconcileAnnotationKey;
import org.eclipse.wst.sse.ui.internal.reconcile.TemporaryAnnotation;
import org.eclipse.wst.sse.ui.internal.reconcile.validator.AnnotationInfo;
import org.eclipse.wst.sse.ui.internal.reconcile.validator.ISourceValidator;
import org.eclipse.wst.sse.ui.internal.reconcile.validator.IncrementalReporter;
import org.eclipse.wst.validation.internal.core.ValidationException;
import org.eclipse.wst.validation.internal.operations.LocalizedMessage;
import org.eclipse.wst.validation.internal.provisional.core.IMessage;
import org.eclipse.wst.validation.internal.provisional.core.IReporter;
import org.eclipse.wst.validation.internal.provisional.core.IValidationContext;
import org.eclipse.wst.validation.internal.provisional.core.IValidator;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMNode;
import org.eclipse.wst.xml.core.internal.regions.DOMRegionContext;
import org.eclipse.wst.xml.ui.internal.Logger;
import org.eclipse.wst.xml.ui.internal.XMLUIMessages;
import org.eclipse.wst.xml.ui.internal.correction.ProblemIDsXML;
import org.w3c.dom.Node;

/**
 * Basic XML syntax checking step.
 * Only used as ISourceValidator at the momment
 * 
 * @author pavery
 */
public class MarkupValidator implements IValidator, ISourceValidator {
	private String DQUOTE = "\""; //$NON-NLS-1$

	protected String SEVERITY_ATTR_MISSING_VALUE = TemporaryAnnotation.ANNOT_ERROR;
	protected String SEVERITY_ATTR_NO_VALUE = TemporaryAnnotation.ANNOT_ERROR;
	// severities for the problems discoverable by this reconciler; possibly
	// user configurable later
	protected String SEVERITY_GENERIC_ILLFORMED_SYNTAX = TemporaryAnnotation.ANNOT_WARNING;
	protected String SEVERITY_STRUCTURE = TemporaryAnnotation.ANNOT_ERROR;
	protected String SEVERITY_SYNTAX_ERROR = TemporaryAnnotation.ANNOT_ERROR;
	// used for attribute quote checking
	private String SQUOTE = "'"; //$NON-NLS-1$

	private IDocument fDocument;

	private void addAttributeError(String messageText, String attributeValueText, int start, int length, int problemId, IStructuredDocumentRegion sdRegion,  IReporter reporter) {
        
        if (sdRegion.isDeleted())
            return;
        
        int lineNo = getLineNumber(start);
        LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
        message.setOffset(start);
        message.setLength(length);
        message.setLineNo(lineNo);
        
        AnnotationInfo info = new AnnotationInfo(message, problemId, attributeValueText);
        ((IncrementalReporter)reporter).addAnnotationInfo(this, info);
	}

	private void checkAttributesInEndTag(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
        
        if(structuredDocumentRegion.isDeleted())
            return;
        
		ITextRegionList textRegions = structuredDocumentRegion.getRegions();
		int errorCount = 0;
		int start = structuredDocumentRegion.getEndOffset();
		int end = structuredDocumentRegion.getEndOffset();
		for (int i = 0; i < textRegions.size() && errorCount < AbstractStructuredTextReconcilingStrategy.ELEMENT_ERROR_LIMIT && !structuredDocumentRegion.isDeleted(); i++) {
			ITextRegion textRegion = textRegions.get(i);
			if (textRegion.getType() == DOMRegionContext.XML_TAG_ATTRIBUTE_NAME || textRegion.getType() == DOMRegionContext.XML_TAG_ATTRIBUTE_EQUALS || textRegion.getType() == DOMRegionContext.XML_TAG_ATTRIBUTE_VALUE) {
				if (start > structuredDocumentRegion.getStartOffset(textRegion))
					start = structuredDocumentRegion.getStartOffset(textRegion);
				end = structuredDocumentRegion.getEndOffset(textRegion);
				errorCount++;
			}
		}
		// create one error for all attributes in the end tag
		if (errorCount > 0) {
			// Position p = new Position(start, end - start);
			String messageText = XMLUIMessages.End_tag_has_attributes;
			LocalizedMessage message = new LocalizedMessage(IMessage.NORMAL_SEVERITY, messageText);
			message.setOffset(start);
			message.setLength(end - start);
			message.setLineNo(getLineNumber(start));
			
			AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.AttrsInEndTag, null);
			((IncrementalReporter)reporter).addAnnotationInfo(this, info);
		}
	}


	private void checkClosingBracket(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
        
        if(structuredDocumentRegion.isDeleted())
            return;
        
		ITextRegionList regions = structuredDocumentRegion.getRegions();
		ITextRegion r = null;
		boolean closed = false;
		for (int i = 0; i < regions.size()  && !structuredDocumentRegion.isDeleted(); i++) {
			r = regions.get(i);
			if (r.getType() == DOMRegionContext.XML_TAG_CLOSE || r.getType() == DOMRegionContext.XML_EMPTY_TAG_CLOSE)
				closed = true;
		}
		if (!closed) {

			String messageText = XMLUIMessages.ReconcileStepForMarkup_6;

			int start = structuredDocumentRegion.getStartOffset();
			int length = structuredDocumentRegion.getText().trim().length();
			int lineNo = getLineNumber(start);
			
			LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
			message.setOffset(start);
			message.setLength(length);
			message.setLineNo(lineNo);
			
			AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.MissingClosingBracket, null);
			((IncrementalReporter)reporter).addAnnotationInfo(this, info);
		}
	}

	private void checkEmptyTag(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
        
        if(structuredDocumentRegion.isDeleted())
            return;
        
		// navigate to name
		ITextRegionList regions = structuredDocumentRegion.getRegions();
		if (regions.size() == 2) {
			// missing name region
			if (regions.get(0).getType() == DOMRegionContext.XML_TAG_OPEN && regions.get(1).getType() == DOMRegionContext.XML_TAG_CLOSE) {
				String messageText = XMLUIMessages.ReconcileStepForMarkup_3;
				int start = structuredDocumentRegion.getStartOffset();
				int length = structuredDocumentRegion.getLength();
				int lineNo = getLineNumber(start);
				
				LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
				message.setOffset(start);
				message.setLength(length);
				message.setLineNo(lineNo);
				
				AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.EmptyTag, null);
				((IncrementalReporter)reporter).addAnnotationInfo(this, info);
			}
		}
	}

	private int getLineNumber(int start) {
		int lineNo = -1;
		try {
			lineNo = getDocument().getLineOfOffset(start);
		}
		catch (BadLocationException e) {
			Logger.logException(e);
		}
		return lineNo;
	}

	private void checkForAttributeValue(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
        
        if(structuredDocumentRegion.isDeleted())
            return;
        
		// check for attributes without a value
		// track the attribute/equals/value sequence using a state of 0, 1 ,2
		// representing the name, =, and value, respectively
		int attrState = 0;
		ITextRegionList textRegions = structuredDocumentRegion.getRegions();
		// ReconcileAnnotationKey key = createKey(structuredDocumentRegion, getScope());
		
		int errorCount = 0;
		for (int i = 0; i < textRegions.size() && errorCount < AbstractStructuredTextReconcilingStrategy.ELEMENT_ERROR_LIMIT; i++) {
			ITextRegion textRegion = textRegions.get(i);
			if (textRegion.getType() == DOMRegionContext.XML_TAG_ATTRIBUTE_NAME || isTagCloseTextRegion(textRegion)) {
				// dangling name and '='
				if (attrState == 2 && i >= 2) {
					// create annotation
					ITextRegion nameRegion = textRegions.get(i - 2);
					Object[] args = {structuredDocumentRegion.getText(nameRegion)};
					String messageText = NLS.bind(XMLUIMessages.Attribute__is_missing_a_value, args);
					
					int start = structuredDocumentRegion.getStartOffset(nameRegion);
					int end = structuredDocumentRegion.getEndOffset();
					int lineNo = getLineNumber(start);
					int textLength = structuredDocumentRegion.getText(nameRegion).trim().length();
					
					LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
					message.setOffset(start);
					message.setLength(textLength);
					message.setLineNo(lineNo);
					
					// quick fix info
					ITextRegion equalsRegion = textRegions.get(i - 2 + 1);
					int insertOffset = structuredDocumentRegion.getTextEndOffset(equalsRegion) - end;
					Object[] additionalFixInfo = {structuredDocumentRegion.getText(nameRegion), new Integer(insertOffset)};
					
					AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.MissingAttrValue, additionalFixInfo);
					
					((IncrementalReporter)reporter).addAnnotationInfo(this, info);
					
					// annotation.setAdditionalFixInfo(additionalFixInfo);
					//results.add(annotation);
					errorCount++;
				}
				// name but no '=' (XML only)
				else if (attrState == 1 && i >= 1) {
					// create annotation
					ITextRegion previousRegion = textRegions.get(i - 1);
					Object[] args = {structuredDocumentRegion.getText(previousRegion)};
					String messageText = NLS.bind(XMLUIMessages.Attribute__has_no_value, args);
					int start = structuredDocumentRegion.getStartOffset(previousRegion);
					int textLength = structuredDocumentRegion.getText(previousRegion).trim().length();
					int lineNo = getLineNumber(start);
					
					LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
					message.setOffset(start);
					message.setLength(textLength);
					message.setLineNo(lineNo);
					
					AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.NoAttrValue, structuredDocumentRegion.getText(previousRegion));
			
					((IncrementalReporter)reporter).addAnnotationInfo(this, info);
					
					errorCount++;
				}
				attrState = 1;
			} else if (textRegion.getType() == DOMRegionContext.XML_TAG_ATTRIBUTE_EQUALS) {
				attrState = 2;
			} else if (textRegion.getType() == DOMRegionContext.XML_TAG_ATTRIBUTE_VALUE) {
				attrState = 0;
			}
		}

	}

	private void checkForSpaceBeforeName(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
        
        if(structuredDocumentRegion.isDeleted())
            return;
        
		String sdRegionText = structuredDocumentRegion.getFullText();
		if (sdRegionText.startsWith(" ")) { //$NON-NLS-1$
			IStructuredDocumentRegion prev = structuredDocumentRegion.getPrevious();
			if (prev != null) {
				// this is possibly the case of "< tag"
				if (prev.getRegions().size() == 1 && isStartTag(prev)) {
					// add the error for preceding space in tag name
					String messageText = XMLUIMessages.ReconcileStepForMarkup_2;
					int start = structuredDocumentRegion.getStartOffset();
					// find length of whitespace
					int length = sdRegionText.trim().equals("") ? sdRegionText.length() : sdRegionText.indexOf(sdRegionText.trim()); //$NON-NLS-1$
					
					LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
					message.setOffset(start);
					message.setLength(length);
					message.setLineNo(getLineNumber(start));
					
					AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.SpacesBeforeTagName, null);
					((IncrementalReporter)reporter).addAnnotationInfo(this, info);
				}
			}
		}
	}

	private void checkNoNamespaceInPI(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
        
        if(structuredDocumentRegion.isDeleted())
            return;
        
		// navigate to name
		ITextRegionList regions = structuredDocumentRegion.getRegions();
		ITextRegion r = null;
		int errorCount = 0;
		for (int i = 0; i < regions.size() && errorCount < AbstractStructuredTextReconcilingStrategy.ELEMENT_ERROR_LIMIT && !structuredDocumentRegion.isDeleted(); i++) {
			r = regions.get(i);
			if (r.getType() == DOMRegionContext.XML_TAG_NAME) {
				String piText = structuredDocumentRegion.getText(r);
				int index = piText.indexOf(":"); //$NON-NLS-1$
				if (index != -1) {
					String messageText = XMLUIMessages.ReconcileStepForMarkup_4;
					int start = structuredDocumentRegion.getStartOffset(r) + index;
					int length = piText.trim().length() - index;
					
					LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
					message.setOffset(start);
					message.setLength(length);
					message.setLineNo(getLineNumber(start));
					
					AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.NamespaceInPI, null);
					((IncrementalReporter)reporter).addAnnotationInfo(this, info);

					errorCount++;
				}
			}
		}
	}

	private void checkQuotesForAttributeValues(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
		ITextRegionList regions = structuredDocumentRegion.getRegions();
		ITextRegion r = null;
		String attrValueText = ""; //$NON-NLS-1$
		int errorCount = 0;
		for (int i = 0; i < regions.size() && errorCount < AbstractStructuredTextReconcilingStrategy.ELEMENT_ERROR_LIMIT; i++) {
			r = regions.get(i);
			if (r.getType() != DOMRegionContext.XML_TAG_ATTRIBUTE_VALUE)
				continue;

			attrValueText = structuredDocumentRegion.getText(r);
			// attribute value includes quotes in the string
			// split up attribute value on quotes
			/*
			 * WORKAROUND till
			 * http://dev.icu-project.org/cgi-bin/icu-bugs/incoming?findid=5207
			 * is fixed. (Also see BUG143628)
			 */

			java.util.StringTokenizer st = new java.util.StringTokenizer(attrValueText, "\"'", true); //$NON-NLS-1$
			int size = st.countTokens();
			// get the pieces of the attribute value
			String one = "", two = ""; //$NON-NLS-1$ //$NON-NLS-2$
			if (size > 0)
				one = st.nextToken();
			if (size > 1)
				two = st.nextToken();
			if (size > 2) {
				// should be handled by parsing...
				// as in we can't have an attribute value like: <element
				// attr="a"b"c"/>
				// and <element attr='a"b"c' /> is legal
				continue;
			}


			if (size == 1) {
				if (one.equals(DQUOTE) || one.equals(SQUOTE)) {
					// missing closing quote
					String message = XMLUIMessages.ReconcileStepForMarkup_0;
					addAttributeError(message, attrValueText, structuredDocumentRegion.getStartOffset(r), attrValueText.trim().length(), ProblemIDsXML.Unclassified, structuredDocumentRegion, reporter);
					errorCount++;
				} else {
					// missing both
					String message = XMLUIMessages.ReconcileStepForMarkup_1;
					addAttributeError(message, attrValueText, structuredDocumentRegion.getStartOffset(r), attrValueText.trim().length(), ProblemIDsXML.AttrValueNotQuoted, structuredDocumentRegion, reporter);
					errorCount++;
				}
			} else if (size == 2) {
				if (one.equals(SQUOTE) && !two.equals(SQUOTE) || one.equals(DQUOTE) && !two.equals(DQUOTE)) {
					// missing closing quote
					String message = XMLUIMessages.ReconcileStepForMarkup_0;
					addAttributeError(message, attrValueText, structuredDocumentRegion.getStartOffset(r), attrValueText.trim().length(), ProblemIDsXML.Unclassified, structuredDocumentRegion, reporter);
					errorCount++;
				}
			}
		}
		// end of region for loop
	}

	private void checkStartEndTagPairs(IStructuredDocumentRegion sdRegion, IReporter reporter) {
        
        if(sdRegion.isDeleted())
            return;
        
		// check start/end tag pairs
		IDOMNode xmlNode = getXMLNode(sdRegion);
        
        if(xmlNode == null)
            return;
        
		boolean selfClosed = false;
		String tagName = null;
		int length = 0;

		if (xmlNode.isContainer()) {
			IStructuredDocumentRegion endRegion = xmlNode.getEndStructuredDocumentRegion();
			if (endRegion == null) {
                IStructuredDocumentRegion startRegion = xmlNode.getStartStructuredDocumentRegion();
                if(!startRegion.isDeleted()) {
    				// analyze the tag (check self closing)
    				ITextRegionList regions = startRegion.getRegions();
    				ITextRegion r = null;
    				for (int i = 0; i < regions.size(); i++) {
    					r = regions.get(i);
    					if (r.getType() == DOMRegionContext.XML_TAG_OPEN || r.getType() == DOMRegionContext.XML_TAG_CLOSE) {
    						length++;
    					} else if (r.getType() == DOMRegionContext.XML_TAG_NAME) {
    						tagName = sdRegion.getText(r);
    						length += tagName.length();
    					} else if (r.getType() == DOMRegionContext.XML_EMPTY_TAG_CLOSE) {
    						selfClosed = true;
    					}
    				}
    
    				if (!selfClosed && tagName != null) {
    					Object[] args = {tagName};
    					String messageText = NLS.bind(XMLUIMessages.Missing_end_tag_, args);
    
    					int start = sdRegion.getStart();
    					int lineNumber = getLineNumber(start);
    					
    					//SEVERITY_STRUCTURE == IMessage.HIGH_SEVERITY
    					IMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
    					message.setOffset(start);
    					message.setLength(length);
    					message.setLineNo(lineNumber);
    					
    					if(reporter instanceof IncrementalReporter) {
    						
        					Object[] additionalFixInfo = getStartEndFixInfo(xmlNode, tagName, r);
        					
        					AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.MissingEndTag, additionalFixInfo);
        					//annotation.setAdditionalFixInfo(additionalFixInfo);
        					((IncrementalReporter)reporter).addAnnotationInfo(this, info);
    					}
    					else {
    						reporter.addMessage(this, message);
    					}
    				}
    			}
            }

		}
	}

	private Object[] getStartEndFixInfo(IDOMNode xmlNode, String tagName, ITextRegion r) {
		// quick fix info
		String tagClose = "/>"; //$NON-NLS-1$
		int tagCloseOffset = xmlNode.getFirstStructuredDocumentRegion().getEndOffset();
		if (r != null && r.getType() == DOMRegionContext.XML_TAG_CLOSE) {
			tagClose = "/"; //$NON-NLS-1$
			tagCloseOffset--;
		}
		IDOMNode firstChild = (IDOMNode) xmlNode.getFirstChild();
		while (firstChild != null && firstChild.getNodeType() == Node.TEXT_NODE) {
			firstChild = (IDOMNode) firstChild.getNextSibling();
		}
		int endOffset = xmlNode.getEndOffset();
		int firstChildStartOffset = firstChild == null ? endOffset : firstChild.getStartOffset();
		Object[] additionalFixInfo = {tagName, tagClose, new Integer(tagCloseOffset), new Integer(xmlNode.getFirstStructuredDocumentRegion().getEndOffset()), // startTagEndOffset
					new Integer(firstChildStartOffset), // firstChildStartOffset
					new Integer(endOffset)}; // endOffset
		return additionalFixInfo;
	}

	private void checkStartingSpaceForPI(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {
        
        if(structuredDocumentRegion.isDeleted())
            return;
        
		IStructuredDocumentRegion prev = structuredDocumentRegion.getPrevious();
		if (prev != null && !prev.isDeleted()) {
			String prevText = prev.getFullText();
			if (prev.getType() == DOMRegionContext.XML_CONTENT && prevText.endsWith(" ")) { //$NON-NLS-1$
				String messageText = XMLUIMessages.ReconcileStepForMarkup_5;
				int start = prev.getStartOffset();
				int length = prev.getLength();
				
				LocalizedMessage message = new LocalizedMessage(IMessage.HIGH_SEVERITY, messageText);
				message.setOffset(start);
				message.setLength(length);
				message.setLineNo(getLineNumber(start));
				
				AnnotationInfo info = new AnnotationInfo(message, ProblemIDsXML.SpacesBeforePI, null);
				((IncrementalReporter)reporter).addAnnotationInfo(this, info);
				
//				Position p = new Position(start, length);
//				
//				ReconcileAnnotationKey key = createKey(structuredDocumentRegion, getScope());
//				TemporaryAnnotation annotation = new TemporaryAnnotation(p, SEVERITY_SYNTAX_ERROR, message, key, ProblemIDsXML.SpacesBeforePI);
//				results.add(annotation);
			}
		}
	}

	public int getScope() {
		return ReconcileAnnotationKey.PARTIAL;
	}

	private IDOMNode getXMLNode(IStructuredDocumentRegion sdRegion) {
        
        if(sdRegion == null)
            return null;
        
		IStructuredModel xModel = null;
		IDOMNode xmlNode = null;
		// get/release models should always be in a try/finally block
		try {
			xModel = StructuredModelManager.getModelManager().getExistingModelForRead(getDocument());
			// xModel is sometime null, when closing editor, for example
			if (xModel != null) {
				xmlNode = (IDOMNode) xModel.getIndexedRegion(sdRegion.getStart());
			}
		} finally {
			if (xModel != null) {
				xModel.releaseFromRead();
			}
		}
		return xmlNode;
	}

	/**
	 * Determines whether the IStructuredDocumentRegion is a XML "end tag"
	 * since they're not allowed to have attribute ITextRegions
	 * 
	 * @param structuredDocumentRegion
	 */
	private boolean isEndTag(IStructuredDocumentRegion structuredDocumentRegion) {
		if (structuredDocumentRegion == null || structuredDocumentRegion.isDeleted())
			return false;
		return structuredDocumentRegion.getFirstRegion().getType() == DOMRegionContext.XML_END_TAG_OPEN;
	}

	/**
	 * Determines if the IStructuredDocumentRegion is an XML Processing
	 * Instruction
	 * 
	 * @param structuredDocumentRegion
	 * 
	 */
	private boolean isPI(IStructuredDocumentRegion structuredDocumentRegion) {
        if (structuredDocumentRegion == null || structuredDocumentRegion.isDeleted())
            return false;
		return structuredDocumentRegion.getFirstRegion().getType() == DOMRegionContext.XML_PI_OPEN;
	}

	/**
	 * Determines whether the IStructuredDocumentRegion is a XML "start tag"
	 * since they need to be checked for proper XML attribute region sequences
	 * 
	 * @param structuredDocumentRegion
	 * 
	 */
	private boolean isStartTag(IStructuredDocumentRegion structuredDocumentRegion) {
		if (structuredDocumentRegion == null || structuredDocumentRegion.isDeleted())
			return false;
		return structuredDocumentRegion.getFirstRegion().getType() == DOMRegionContext.XML_TAG_OPEN;
	}

	// Because we check the "proper" closing separately from attribute
	// sequencing, we need to know what's
	// an appropriate close.
	private boolean isTagCloseTextRegion(ITextRegion textRegion) {
		return textRegion.getType() == DOMRegionContext.XML_TAG_CLOSE || textRegion.getType() == DOMRegionContext.XML_EMPTY_TAG_CLOSE;
	}

	/**
	 * Determines if the IStructuredDocumentRegion is XML Content
	 * 
	 * @param structuredDocumentRegion
	 * 
	 */
	private boolean isXMLContent(IStructuredDocumentRegion structuredDocumentRegion) {
        if(structuredDocumentRegion == null || structuredDocumentRegion.isDeleted())
            return false;
		return structuredDocumentRegion.getFirstRegion().getType() == DOMRegionContext.XML_CONTENT;
	}

	private void setDocument(IDocument doc){
		fDocument = doc;
	}
	private IDocument getDocument() {
		return fDocument;
	}
	
	public void connect(IDocument document) {
		setDocument(document);
	}

	public void disconnect(IDocument document) {
		// nothing to do	
	}

	public void validate(IRegion dirtyRegion, IValidationContext helper, IReporter reporter) {
		if(getDocument() == null)
			return;
		if(!(reporter instanceof IncrementalReporter))
			return;
		if(!(getDocument() instanceof IStructuredDocument))
			return;

		// remove old messages
		reporter.removeAllMessages(this);
		
		IStructuredDocumentRegion[] regions = ((IStructuredDocument)fDocument).getStructuredDocumentRegions(dirtyRegion.getOffset(), dirtyRegion.getLength());
		for (int i = 0; i < regions.length; i++) {
			validate(regions[i], reporter);
		}
	}
	
	public void validate(IStructuredDocumentRegion structuredDocumentRegion, IReporter reporter) {

		if (structuredDocumentRegion == null)
			return;
		
		if (isStartTag(structuredDocumentRegion)) {
			// check for attributes without a value
			checkForAttributeValue(structuredDocumentRegion, reporter);
			// check if started tag is ended
			checkStartEndTagPairs(structuredDocumentRegion, reporter);		
			// check empty tag <>
			checkEmptyTag(structuredDocumentRegion, reporter);
			// check that each attribute has quotes
			checkQuotesForAttributeValues(structuredDocumentRegion, reporter);
			// check that the closing '>' is there
			checkClosingBracket(structuredDocumentRegion, reporter);
		} else if (isEndTag(structuredDocumentRegion)) {
			checkAttributesInEndTag(structuredDocumentRegion, reporter);
			// check that the closing '>' is there
			checkClosingBracket(structuredDocumentRegion, reporter);
		} else if (isPI(structuredDocumentRegion)) {
			// check validity of processing instruction
			checkStartingSpaceForPI(structuredDocumentRegion, reporter);
			checkNoNamespaceInPI(structuredDocumentRegion, reporter);
		} else if (isXMLContent(structuredDocumentRegion)) {
			checkForSpaceBeforeName(structuredDocumentRegion, reporter);
		}
	}

	public void cleanup(IReporter reporter) {
		// TODO Auto-generated method stub
		
	}

	public void validate(IValidationContext helper, IReporter reporter) throws ValidationException {
		// TODO Auto-generated method stub
		
	}
}