/*******************************************************************************
 *Copyright (c) 2008 Standards for Technology in Automotive Retail 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:
 *    David Carver (STAR) - bug 244978 - initial API and implementation
 *******************************************************************************/
package org.eclipse.wst.xsl.ui.internal.contentassist;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Vector;

import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.swt.graphics.Image;
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.util.Debug;
import org.eclipse.wst.sse.ui.internal.contentassist.CustomCompletionProposal;
import org.eclipse.wst.xml.core.internal.contentmodel.CMElementDeclaration;
import org.eclipse.wst.xml.core.internal.contentmodel.CMNode;
import org.eclipse.wst.xml.core.internal.contentmodel.modelquery.ModelQuery;
import org.eclipse.wst.xml.core.internal.contentmodel.modelquery.ModelQueryAction;
import org.eclipse.wst.xml.core.internal.modelquery.ModelQueryUtil;
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.contentassist.XMLRelevanceConstants;
import org.eclipse.wst.xml.ui.internal.editor.CMImageUtil;
import org.eclipse.wst.xml.ui.internal.editor.XMLEditorPluginImageHelper;
import org.eclipse.wst.xml.ui.internal.editor.XMLEditorPluginImages;
import org.eclipse.wst.xml.ui.internal.taginfo.MarkupTagInfoProvider;
import org.eclipse.wst.xml.xpath.core.util.XSLTXPathHelper;
import org.eclipse.wst.xsl.ui.internal.contentassist.contentmodel.XSLContentModelGenerator;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * This class provides content assistance proposals outside of the XSL namespace.  Normal
 * XML editor content assistance only provides proposals for items within the same namespace
 * or if an element has children elements.   This class extends this functionality by checking
 * for the first XSL ancestor and uses that to determine what proposals should be
 * provided in the way of xsl elements.
 * 
 * @author David Carver
 * @since 1.0
 */
public class ElementContentAssistRequest extends
		AbstractXSLContentAssistRequest {

	private XSLContentModelGenerator contentModel;
	private static final String XPATH_FIRST_XSLANCESTOR_NODE = "ancestor::xsl:*[1]";
	private MarkupTagInfoProvider infoProvider = null;

	/**
	 * @param node
	 * @param parent
	 * @param documentRegion
	 * @param completionRegion
	 * @param begin
	 * @param length
	 * @param filter
	 * @param textViewer
	 */
	public ElementContentAssistRequest(Node node,
			IStructuredDocumentRegion documentRegion,
			ITextRegion completionRegion, int begin, int length, String filter,
			ITextViewer textViewer) {
		super(node, documentRegion, completionRegion, begin, length,
				filter, textViewer);
		contentModel = new XSLContentModelGenerator();
	}

	/**
	 * Provides a list of possible proposals for the XSL Elements within the current
	 * scope.
	 */
	@Override
	public ArrayList<ICompletionProposal> getCompletionProposals() {

		if (region.getType() == DOMRegionContext.XML_TAG_OPEN) {
			computeTagOpenProposals();
		} else if (region.getType() == DOMRegionContext.XML_TAG_NAME) {
			computeTagNameProposals();
		}
		return getAllCompletionProposals();
	}

	/**
	 * Calculate proposals for open content regions.
	 */
	protected void computeTagOpenProposals() {

		if (replacementBeginPosition == documentRegion.getStartOffset(region)) {
			if (node.getNodeType() == Node.ELEMENT_NODE) {
				// at the start of an existing tag, right before the '<'
				computeTagNameProposals();
			}
		} else {
			// within the white space
			ITextRegion name = getNameRegion(((IDOMNode) node)
					.getStartStructuredDocumentRegion());
			if ((name != null)
					&& ((documentRegion.getStartOffset(name) <= replacementBeginPosition) && (documentRegion
							.getEndOffset(name) >= replacementBeginPosition))) {
				// replace the existing name
				replacementBeginPosition = documentRegion.getStartOffset(name);
				replacementLength = name.getTextLength();
			} else {
				// insert a valid new name, or possibly an end tag
				// addEndTagProposals(contentAssistRequest);
				setReplacementLength(0);
			}
			addTagNameProposals(getElementPosition(node));
		}
	}

	/**
	 * Calculates the proposals for the XML Tag Name Region.
	 */
	protected void computeTagNameProposals() {
		// completing the *first* tag in "<tagname1 |<tagname2"
		
		// Ignore attributes
		if (inAttributeRegion()) {
			return;
		}
		
		IDOMNode actualNode = (IDOMNode) node;
		addTagNameProposals(this.getElementPosition(node));
		// addEndTagNameProposals();

	}

	/**
	 * Check to see if the current position is in an Attribute Region if so,
	 * return true otherwise false
	 * @return True if in attribute region, false otherwise.
	 */
	protected boolean inAttributeRegion() {
		return replacementBeginPosition > documentRegion.getStartOffset(region) + region.getLength();
	}

	/**
	 * Adds proposals for the XML_TAG_NAME region.
	 * @param position
	 */
	protected void addTagNameProposals(int position) {

		Node ancestorNode = null;
		try {
			ancestorNode = XSLTXPathHelper.selectSingleNode(getNode(),
					XPATH_FIRST_XSLANCESTOR_NODE);
		} catch (Exception ex) {
			return;
		}

		List<CMNode> cmnodes = null;

		if (ancestorNode.getNodeType() == Node.ELEMENT_NODE) {
			cmnodes = getAvailableChildElementDeclarations(
					(Element) ancestorNode, 0);
			Iterator<CMNode> nodeIterator = cmnodes.iterator();
			// chop off any leading <'s and whitespace from the matchstring
			while ((matchString.length() > 0)
					&& (Character.isWhitespace(matchString.charAt(0)) || beginsWith(
							matchString, "<"))) {
				//$NON-NLS-1$
				matchString = matchString.substring(1);
			}
			if (!nodeIterator.hasNext()) {
				return;
			}
			while (nodeIterator.hasNext()) {
				CMNode elementDecl = (CMNode) nodeIterator.next();
				if (elementDecl != null) {
					// only add proposals for the child element's that begin
					// with the matchstring
					String proposedText = null;

					proposedText = contentModel.getRequiredName(ancestorNode,
							elementDecl);
					int cursorAdjustment = proposedText.length();

					if (elementDecl instanceof CMElementDeclaration) {
						CMElementDeclaration ed = (CMElementDeclaration) elementDecl;
						if (ed.getContentType() == CMElementDeclaration.EMPTY) {
							proposedText += contentModel.getStartTagClose(
									ancestorNode, ed);
							cursorAdjustment = proposedText.length();
						} else {
							StringBuffer sb = new StringBuffer();
							contentModel.generateTag(ancestorNode, ed, sb);
							// since it's a name proposal, assume '<' is
							// already there
							// only return the rest of the tag
							proposedText = sb.toString().substring(1);
							cursorAdjustment = getCursorPositionForProposedText(proposedText);

						}
					}
					if (beginsWith(proposedText, matchString)) {
						Image image = CMImageUtil.getImage(elementDecl);
						if (image == null) {
							image = XMLEditorPluginImageHelper
									.getInstance()
									.getImage(
											XMLEditorPluginImages.IMG_OBJ_TAG_GENERIC);
						}
						String proposedInfo = getAdditionalInfo(
								getCMElementDeclaration(getParent()), elementDecl);
						CustomCompletionProposal proposal = new CustomCompletionProposal(
								proposedText, getReplacementBeginPosition(),
								getReplacementLength(), cursorAdjustment,
								image, contentModel.getRequiredName(getParent(),
										elementDecl), null, proposedInfo,
								XMLRelevanceConstants.R_TAG_NAME);
						addProposal(proposal);
					}
				}
			}
		}

	}


	/** Returns a list of CMNodes that are available within this parent context
	 * Given the grammar shown below and a snippet of XML code (where the '|'
	 * indicated the cursor position)
	 * the list would return all of the element declarations that are
	 * potential child elements of Foo.
	 *
	 * grammar : Foo -> (A, B, C)
	 * snippet : <Foo><A>|
	 * result : {A, B, C}
	 * 
	 * @param parent
	 * @param childPosition
	 * @return
	 */
	protected List<CMNode> getAvailableChildElementDeclarations(Element parent,
			int childPosition) {
		List modelQueryActions = getAvailableChildrenAtIndex(parent,
				childPosition, ModelQuery.VALIDITY_NONE);
		Iterator iterator = modelQueryActions.iterator();
		List<CMNode> cmnodes = new Vector();
		while (iterator.hasNext()) {
			ModelQueryAction action = (ModelQueryAction) iterator.next();
			if ((childPosition < 0)
					|| (((action.getStartIndex() <= childPosition) && (childPosition <= action
							.getEndIndex())))) {
				CMNode actionCMNode = action.getCMNode();
				if ((actionCMNode != null) && !cmnodes.contains(actionCMNode)) {
					cmnodes.add(actionCMNode);
				}
			}
		}
		return cmnodes;
	}

	// returns a list of ModelQueryActions
	protected List getAvailableChildrenAtIndex(Element parent, int index,
			int validityChecking) {
		List list = new ArrayList();
		CMElementDeclaration parentDecl = getCMElementDeclaration(parent);
		if (parentDecl != null) {
			ModelQuery modelQuery = ModelQueryUtil.getModelQuery(parent
					.getOwnerDocument());
			// taken from ActionManagers
			// int editMode = modelQuery.getEditMode();
			int editMode = ModelQuery.EDIT_MODE_UNCONSTRAINED;
			int ic = (editMode == ModelQuery.EDIT_MODE_CONSTRAINED_STRICT) ? ModelQuery.INCLUDE_CHILD_NODES
					| ModelQuery.INCLUDE_SEQUENCE_GROUPS
					: ModelQuery.INCLUDE_CHILD_NODES;
			modelQuery.getInsertActions(parent, parentDecl, index, ic,
					validityChecking, list);
		}
		return list;
	}

	protected CMElementDeclaration getCMElementDeclaration(Node node) {
		CMElementDeclaration result = null;
		if (node.getNodeType() == Node.ELEMENT_NODE) {
			ModelQuery modelQuery = ModelQueryUtil.getModelQuery(node
					.getOwnerDocument());
			if (modelQuery != null) {
				result = modelQuery.getCMElementDeclaration((Element) node);
			}
		}
		return result;
	}

	protected int getElementPosition(Node child) {
		Node parent = child.getParentNode();
		if (parent == null) {
			return 0;
		}

		NodeList children = parent.getChildNodes();
		if (children == null) {
			return 0;
		}
		int count = 0;

		for (int i = 0; i < children.getLength(); i++) {
			if (children.item(i) == child) {
				return count;
			} else {
				// if (children.item(i).getNodeType() == Node.ELEMENT_NODE)
				count++;
			}
		}
		return 0;
	}

	/**
	 * Retreives cmnode's documentation to display in the completion proposal's
	 * additional info. If no documentation exists for cmnode, try displaying
	 * parentOrOwner's documentation
	 * 
	 * String any documentation information to display for cmnode.
	 * <code>null</code> if there is nothing to display.
	 */
	protected String getAdditionalInfo(CMNode parentOrOwner, CMNode cmnode) {
		String addlInfo = null;

		if (cmnode == null) {
			if (Debug.displayWarnings) {
				new IllegalArgumentException("Null declaration!").printStackTrace(); //$NON-NLS-1$
			}
			return null;
		}

		addlInfo = getInfoProvider().getInfo(cmnode);
		if ((addlInfo == null) && (parentOrOwner != null)) {
			addlInfo = getInfoProvider().getInfo(parentOrOwner);
		}
		return addlInfo;
	}

	/**
	 * Gets the infoProvider.
	 * 
	 * fInfoProvider and if fInfoProvider was <code>null</code> create a new
	 * instance
	 */
	public MarkupTagInfoProvider getInfoProvider() {
		if (infoProvider == null) {
			infoProvider = new MarkupTagInfoProvider();
		}
		return infoProvider;
	}

	protected boolean beginsWith(String aString, String prefix) {
		if ((aString == null) || (prefix == null)) {
			return true;
		}
		return aString.toLowerCase().startsWith(prefix.toLowerCase());
	}

	/**
	 * This is the position the cursor should be in after the proposal is
	 * applied
	 * 
	 * @param proposedText
	 * @return the position the cursor should be in after the proposal is
	 *         applied
	 */
	private int getCursorPositionForProposedText(String proposedText) {
		int cursorAdjustment;
		cursorAdjustment = proposedText.indexOf("\"\"") + 1; //$NON-NLS-1$
		// otherwise, after the first tag
		if (cursorAdjustment == 0) {
			cursorAdjustment = proposedText.indexOf('>') + 1;
		}
		if (cursorAdjustment == 0) {
			cursorAdjustment = proposedText.length() + 1;
		}

		return cursorAdjustment;
	}

	protected ITextRegion getNameRegion(IStructuredDocumentRegion flatNode) {
		if (flatNode == null) {
			return null;
		}
		Iterator regionList = flatNode.getRegions().iterator();
		while (regionList.hasNext()) {
			ITextRegion region = (ITextRegion) regionList.next();
			if (isNameRegion(region)) {
				return region;
			}
		}
		return null;
	}

	/**
	 * Checks to the see if the element is in the correct region.
	 * @param region
	 * @return
	 */
	protected boolean isNameRegion(ITextRegion region) {
		String type = region.getType();
		return ((type == DOMRegionContext.XML_TAG_NAME)
				|| (type == DOMRegionContext.XML_ELEMENT_DECL_NAME)
				|| (type == DOMRegionContext.XML_DOCTYPE_NAME) || (type == DOMRegionContext.XML_ATTLIST_DECL_NAME));
	}

}