/******************************************************************************* 
 * Copyright (c) 2010-2012 Red Hat, Inc. 
 * Distributed under license by Red Hat, Inc. All rights reserved. 
 * This program is 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: 
 * Red Hat, Inc. - initial API and implementation 
 ******************************************************************************/
package org.jboss.tools.jst.jsp.jspeditor.info;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.List;
import java.util.Map;

import org.eclipse.core.filebuffers.FileBuffers;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jface.text.DefaultInformationControl;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IInformationControl;
import org.eclipse.jface.text.IInformationControlCreator;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextPresentation;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.wst.sse.core.StructuredModelManager;
import org.eclipse.wst.sse.core.internal.provisional.IStructuredModel;
import org.eclipse.wst.sse.core.internal.provisional.IndexedRegion;
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.ui.internal.contentassist.ContentAssistUtils;
import org.eclipse.wst.sse.ui.internal.derived.HTML2TextReader;
import org.eclipse.wst.sse.ui.internal.derived.HTMLTextPresenter;
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.taginfo.XMLTagInfoHoverProcessor;
import org.jboss.tools.common.el.core.model.ELInstance;
import org.jboss.tools.common.el.core.model.ELInvocationExpression;
import org.jboss.tools.common.el.core.model.ELModel;
import org.jboss.tools.common.el.core.model.ELUtil;
import org.jboss.tools.common.el.core.parser.ELParser;
import org.jboss.tools.common.el.core.parser.ELParserUtil;
import org.jboss.tools.common.el.core.resolver.ELContext;
import org.jboss.tools.common.el.core.resolver.ELResolution;
import org.jboss.tools.common.el.core.resolver.ELResolver;
import org.jboss.tools.common.el.core.resolver.ELSegment;
import org.jboss.tools.common.el.core.resolver.JavaMemberELSegmentImpl;
import org.jboss.tools.common.el.ui.ca.ELProposalProcessor;
import org.jboss.tools.common.model.XModelObject;
import org.jboss.tools.common.text.TextProposal;
import org.jboss.tools.common.util.StringUtil;
import org.jboss.tools.jst.jsp.contentassist.Utils;
import org.jboss.tools.jst.jsp.contentassist.computers.AbstractXmlCompletionProposalComputer.TextRegion;
import org.jboss.tools.jst.web.kb.IPageContext;
import org.jboss.tools.jst.web.kb.KbQuery;
import org.jboss.tools.jst.web.kb.KbQuery.Type;
import org.jboss.tools.jst.web.kb.PageContextFactory;
import org.jboss.tools.jst.web.kb.PageProcessor;
import org.jboss.tools.jst.web.kb.el.MessagePropertyELSegmentImpl;
import org.jboss.tools.jst.web.kb.taglib.INameSpace;
import org.w3c.dom.Node;

/**
 * 
 * @author Victor Rubezhny
 *
 */
@SuppressWarnings("restriction")
public class FaceletTagInfoHoverProcessor extends XMLTagInfoHoverProcessor {
	private ELContext fContext;
	private int fDocumentPosition;

	public FaceletTagInfoHoverProcessor() {
		super();
	}

	@Override
	protected String computeHoverHelp(ITextViewer textViewer,
			int documentPosition) {
		this.fDocumentPosition = documentPosition;
		this.fContext = null;
		
		fContext = PageContextFactory.createPageContext(textViewer.getDocument());
		if (fContext == null)
			return null;
		
		IStructuredDocumentRegion flatNode = ((IStructuredDocument) textViewer.getDocument()).getRegionAtCharacterOffset(fDocumentPosition);
		ITextRegion region = null;

		if (flatNode != null) {
			region = flatNode.getRegionAtCharacterOffset(fDocumentPosition);
		}
		
		String hoverHelp = null;
		if (region != null) {
			TextRegion elPrefix = getELPrefix(flatNode, region, fDocumentPosition);
			ELInvocationExpression elOperand = getELExpression(flatNode, region, fDocumentPosition);
			if (elPrefix != null && elPrefix.isELStarted() && elOperand != null) {
				IndexedRegion treeNode = ContentAssistUtils.getNodeAt(textViewer, fDocumentPosition);
				if (treeNode == null) {
					return null;
				}
				Node node = (Node) treeNode;

				while ((node != null) && (node.getNodeType() == Node.TEXT_NODE) && (node.getParentNode() != null)) {
					node = node.getParentNode();
				}
				return  computeELHelp((IDOMNode) treeNode, (IDOMNode) node, flatNode, region, elOperand);
			}
		}
		return hoverHelp != null ? hoverHelp : super.computeHoverHelp(textViewer, documentPosition);
	}

	@Override
	protected String computeTagAttNameHelp(IDOMNode xmlnode,
			IDOMNode parentNode, IStructuredDocumentRegion flatNode,
			ITextRegion region) {
		if (fContext == null)
			return null;

		String tagName = Utils.getTagName(xmlnode, true);
		String query = flatNode.getText(region);
		String prefix = getPrefix(tagName);
		String uri = getUri(prefix);
		String[] parentTags = Utils.getParentTags(xmlnode, true, true);
		String parent = Utils.getParent(xmlnode, true, true, true);
		
		KbQuery kbQuery = Utils.createKbQuery(Type.ATTRIBUTE_NAME, fDocumentPosition, query, query,
				prefix, uri, parentTags, parent, false);

		TextProposal[] proposals = PageProcessor.getInstance().getProposals(kbQuery, fContext);
		if (proposals == null)
			return null;
		
		for(TextProposal proposal : proposals) {
			if (proposal != null && proposal.getContextInfo() != null &&
				proposal.getContextInfo().trim().length() > 0) {
				return proposal.getContextInfo();
			}
		}

		return null;
	}

	@Override
	protected String computeTagAttValueHelp(IDOMNode xmlnode,
			IDOMNode parentNode, IStructuredDocumentRegion flatNode,
			ITextRegion region) {
		return null;
	}

	@Override
	protected String computeTagNameHelp(IDOMNode xmlnode, IDOMNode parentNode,
			IStructuredDocumentRegion flatNode, ITextRegion region) {
		if (fContext == null)
			return null;

		String query = Utils.getTagName(xmlnode, true);
		String prefix = getPrefix(query);
		String uri = getUri(prefix);
		String[] parentTags = Utils.getParentTags(xmlnode, false, true);
		String parent = Utils.getParent(xmlnode, false, false, true);
		
		KbQuery kbQuery = Utils.createKbQuery(Type.TAG_NAME, fDocumentPosition, query, "<" + query,  //$NON-NLS-1$
				prefix, uri, parentTags, parent, false);

		TextProposal[] proposals = PageProcessor.getInstance().getProposals(kbQuery, fContext);
		if (proposals == null)
			return null;
		
		for(TextProposal proposal : proposals) {
			if (proposal != null && proposal.getContextInfo() != null &&
				proposal.getContextInfo().trim().length() > 0) {
				return proposal.getContextInfo();
			}
		}

		return null;
	}
	
	
	protected String computeELHelp(IDOMNode xmlnode, IDOMNode parentNode,
			IStructuredDocumentRegion flatNode, ITextRegion region, ELInvocationExpression elOperand) {
		if (fContext == null)
			return null;

		ELResolver[] resolvers =  fContext.getElResolvers();
		
		for (int i = 0; resolvers != null && i < resolvers.length; i++) {
			ELResolution resolution = resolvers[i] == null ? null : resolvers[i].resolve(fContext, elOperand, fDocumentPosition);
			if (resolution == null || !resolution.isResolved())
				continue;
			
			ELSegment segment = resolution.getLastSegment();
			if(segment instanceof JavaMemberELSegmentImpl) {
				JavaMemberELSegmentImpl jmSegment = (JavaMemberELSegmentImpl)segment;
				
				IJavaElement[] javaElements = jmSegment.getAllJavaElements();
				if (javaElements == null || javaElements.length == 0) {
					if (jmSegment.getJavaElement() == null)
						continue;
					
					javaElements = new IJavaElement[] {jmSegment.getJavaElement()};
				}
				if (javaElements == null || javaElements.length == 0)
					continue;
				
				ELInfoHoverBrowserInformationControlInput hover = JavaStringELInfoHover.getHoverInfo2Internal(javaElements, false);
				return (hover == null ? null : hover.getHtml());
			} else if (segment instanceof MessagePropertyELSegmentImpl) {
				MessagePropertyELSegmentImpl mpSegment = (MessagePropertyELSegmentImpl)segment;
				String baseName = mpSegment.getBaseName();
				String propertyName = mpSegment.isBundle() ? null : StringUtil.trimQuotes(segment.getToken().getText());
				
				return ELProposalProcessor.getELMessagesHoverInternal(baseName, propertyName, (List<XModelObject>)mpSegment.getObjects());
			}
		}
		
		return null;
	}
 
	/**
	 * Returns the region to hover the text over based on the offset.
	 * Overrides the base method enabling the TEXT regions to the supported
	 * 
	 * @param textViewer
	 * @param offset
	 * 
	 * @return IRegion region to hover over if offset is within tag name,
	 *         attribute name, or attribute value and if offset is not over
	 *         invalid whitespace. otherwise, returns <code>null</code>
	 * 
	 * @see org.eclipse.jface.text.ITextHover#getHoverRegion(ITextViewer, int)
	 */
	@Override
	public IRegion getHoverRegion(ITextViewer textViewer, int offset) {
		if ((textViewer == null) || (textViewer.getDocument() == null)) {
			return null;
		}
		
		IStructuredDocumentRegion flatNode = ((IStructuredDocument) textViewer.getDocument()).getRegionAtCharacterOffset(offset);
		ITextRegion region = null;

		if (flatNode != null) {
			region = flatNode.getRegionAtCharacterOffset(offset);
		}
		
		if (region != null) {
			// Supply hoverhelp for text 
			String regionType = region.getType();
			if (DOMRegionContext.XML_CONTENT.equals(regionType) ||
					DOMRegionContext.BLOCK_TEXT.equals(regionType) ||
					DOMRegionContext.XML_TAG_ATTRIBUTE_VALUE.equals(regionType)) {
				TextRegion elPrefix = getELPrefix(flatNode, region, offset);
				if (elPrefix != null && elPrefix.isELStarted()) {
					return new Region(elPrefix.getStartOffset() + elPrefix.getOffset() + elPrefix.getLength(), 0);
				}
			}
		}
		return super.getHoverRegion(textViewer, offset);
	}
	/**
	 * Returns IFile resource of the document
	 * 
	 * @return
	 */
	protected IFile getResource(IDocument document) {
		IStructuredModel sModel = StructuredModelManager.getModelManager().getExistingModelForRead(document);
		try {
			if (sModel != null) {
				String baseLocation = sModel.getBaseLocation();
				IPath location = new Path(baseLocation).makeAbsolute();
				return FileBuffers.getWorkspaceFileAtLocation(location);
			}
		}
		finally {
			if (sModel != null) {
				sModel.releaseFromRead();
			}
		}
		return null;
	}

	
	private String getPrefix(String tagname) {
		String prefix = null;
		
		int index = tagname == null ? -1 : tagname.indexOf(':');
		if (tagname != null && index != -1) {
			prefix = tagname.substring(0, index);
		}
		
		if (prefix != null)
			return prefix;

		String uri = getUri(""); //$NON-NLS-1$
		return uri == null ? null : "";   //$NON-NLS-1$
	}
	
	private String getUri(String prefix) {
		if (prefix == null || fContext == null)
			return null;
		if (!(fContext instanceof IPageContext))
			return null;
		
		Map<String, List<INameSpace>> nameSpaces = ((IPageContext)fContext).getNameSpaces(fDocumentPosition);
		if (nameSpaces == null || nameSpaces.isEmpty())
			return null;
		
		for (List<INameSpace> nameSpace : nameSpaces.values()) {
			for (INameSpace n : nameSpace) {
				if (prefix.equals(n.getPrefix())) {
					return n.getURI();
				}
			}
		}
		return null;
	}
	
	/**
	 * Returns EL Prefix Text Region Information Object
	 * 
	 * @return
	 */
	private TextRegion getELPrefix(IStructuredDocumentRegion sdRegion, ITextRegion region, int offset) {
		if (sdRegion == null || region == null)
			return null;

		String text = sdRegion.getFullText(region);
		int startOffset = sdRegion.getStartOffset() + region.getStart();
		
		boolean isAttributeValue = false;
		boolean hasOpenQuote = false;
		boolean hasCloseQuote = false;
		char quoteChar = (char)0;
		if (DOMRegionContext.XML_TAG_ATTRIBUTE_VALUE.equals(region.getType())) {
			isAttributeValue = true;
			if (text.startsWith("\"") || text.startsWith("'")) {//$NON-NLS-1$ //$NON-NLS-2$
				quoteChar = text.charAt(0);
				hasOpenQuote = true;
			}
			if (hasOpenQuote && text.endsWith(String.valueOf(quoteChar))) {
				hasCloseQuote = true;
			}
		}
		
		int inValueOffset = offset - startOffset;
		if (text != null && text.length() < inValueOffset) { // probably, the attribute value ends before the document position
			return null;
		}
		if (inValueOffset<0) {
			return null;
		}
		
		ELParser p = ELParserUtil.getJbossFactory().createParser();
		ELModel model = p.parse(text);
		
		ELInstance is = ELUtil.findInstance(model, inValueOffset);// ELInstance
		ELInvocationExpression ie = ELUtil.findExpression(model, inValueOffset);// ELExpression
		
		boolean isELStarted = (model != null && is != null && (model.toString().startsWith("#{") ||  //$NON-NLS-1$
				model.toString().startsWith("${"))); //$NON-NLS-1$
		boolean isELClosed = (model != null && is != null && model.toString().endsWith("}")); //$NON-NLS-1$
		
		TextRegion tr = new TextRegion(startOffset,  ie == null ? inValueOffset : ie.getStartPosition(), 
				ie == null ? 0 : ie.getLength(), ie == null ? "" : ie.getText(),  //$NON-NLS-1$ 
				isELStarted, isELClosed,
				isAttributeValue, hasOpenQuote, hasCloseQuote, quoteChar);
		
		return tr;
	}

	/**
	 * Returns EL Prefix Text Region Information Object
	 * 
	 * @return
	 */
	private ELInvocationExpression getELExpression(IStructuredDocumentRegion sdRegion, ITextRegion region, int offset) {
		if (sdRegion == null || region == null)
			return null;

		String text = sdRegion.getFullText(region);
		int startOffset = sdRegion.getStartOffset() + region.getStart();
		
		int inValueOffset = offset - startOffset;
		if (text != null && text.length() < inValueOffset) { // probably, the attribute value ends before the document position
			return null;
		}
		if (inValueOffset<0) {
			return null;
		}
		
		ELParser p = ELParserUtil.getJbossFactory().createParser();
		ELModel model = p.parse(text);
		
		ELInvocationExpression ie = ELUtil.findExpression(model, inValueOffset);// ELExpression
		
		return ie;
	}
	
	private static final String EMPTY_STRING= ""; //$NON-NLS-1$

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.ITextHoverExtension#getHoverControlCreator()
	 */
	public IInformationControlCreator getHoverControlCreator() {
		return new IInformationControlCreator() {
			public IInformationControl createInformationControl(Shell parent) {
				return new DefaultInformationControl(parent, new HTMLTextPresenter(true) {

					@Override
					protected Reader createReader(String hoverInfo,
							TextPresentation presentation) {
						return new HTML2TextReader(new StringReader(hoverInfo), presentation) {
							/*
							 * @see org.eclipse.jdt.internal.ui.text.SubstitutionTextReader#computeSubstitution(int)
							 */
							protected String computeSubstitution(int c) throws IOException {
								String substitution = super.computeSubstitution(c);
								if (substitution != null && substitution.length() > 0) {
									// This cuts off all The tags from the text
									if (substitution.startsWith("<") && substitution.endsWith(">")) { //$NON-NLS-1$ //$NON-NLS-2$
										return EMPTY_STRING;
									}
								}
								return substitution;
							}
						};
					}
				});
			}
		};
	}
}
