/******************************************************************************* 
 * Copyright (c) 2010 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.contentassist;

import java.io.Reader;
import java.io.StringReader;

import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IMember;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.text.javadoc.JavadocContentAccess2;
import org.eclipse.jdt.internal.ui.viewsupport.JavaElementLinks;
import org.eclipse.jdt.ui.JavaElementLabels;
import org.eclipse.jface.internal.text.html.HTMLPrinter;
import org.eclipse.jface.text.contentassist.IContextInformation;
import org.eclipse.swt.graphics.Image;

/**
 * Class to provide EL proposals to Content Assistant.
 * The main purpose is to provide correct additional proposal information based on 
 * IJavaElement objects collected for the proposal.
 *  
 * @author Victor Rubezhny
 */
@SuppressWarnings("restriction")
public class AutoELContentAssistantProposal extends AutoContentAssistantProposal {
	private IJavaElement[] fJavaElements;
	private String fAdditionalProposalInfo;

	/**
	 * Constructs the proposal object
	 * 
	 * @param replacementString
	 * @param replacementOffset
	 * @param replacementLength
	 * @param cursorPosition
	 * @param image
	 * @param displayString
	 * @param contextInformation
	 * @param elements
	 * @param relevance
	 */
	public AutoELContentAssistantProposal(String replacementString, int replacementOffset, int replacementLength, int cursorPosition, Image image, String displayString, IContextInformation contextInformation, IJavaElement[] elements, int relevance) {
	    super(replacementString, replacementOffset, replacementLength, cursorPosition, image, displayString, contextInformation, null, relevance);
	    this.fJavaElements = elements;
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.wst.sse.ui.internal.contentassist.CustomCompletionProposal#getAdditionalProposalInfo()
	 */
	public String getAdditionalProposalInfo() {
		if (fAdditionalProposalInfo == null) {
			if (this.fJavaElements != null && this.fJavaElements.length > 0) {
				this.fAdditionalProposalInfo = extractProposalContextInfo(fJavaElements);
			}
		}
		return fAdditionalProposalInfo;
	}

	/*
	 * Extracts the additional proposal information based on Javadoc for the stored IJavaElement objects
	 */
	private String extractProposalContextInfo(IJavaElement[] elements) {
		int nResults= elements.length;
		StringBuffer buffer= new StringBuffer();
		boolean hasContents= false;
		IJavaElement element= null;

		if (nResults > 1) {
			for (int i= 0; i < elements.length; i++) {
				if (elements[i] == null) continue;
				if (elements[i] instanceof IMember || 
						elements[i].getElementType() == IJavaElement.LOCAL_VARIABLE || 
						elements[i].getElementType() == IJavaElement.TYPE_PARAMETER) {
					buffer.append('•').append(' ').append(getInfoText(elements[i]));
					hasContents= true;
				}
				buffer.append("<br/>"); //$NON-NLS-1$
			}

			for (int i=0; i < elements.length; i++) {
				if (elements[i] == null) continue;
				if (elements[i] instanceof IMember || 
						elements[i].getElementType() == IJavaElement.LOCAL_VARIABLE || 
						elements[i].getElementType() == IJavaElement.TYPE_PARAMETER) {
					buffer.append("<br/>"); //$NON-NLS-1$
					addFullInfo(buffer, elements[i]);
					hasContents = true;
				}
			}
		} else {
			element= elements[0];
			if (element instanceof IMember ||
					element.getElementType() == IJavaElement.LOCAL_VARIABLE || 
					element.getElementType() == IJavaElement.TYPE_PARAMETER) {
				addFullInfo(buffer, element);
				hasContents= true;
			}
		}

		if (!hasContents)
			return null;

		if (buffer.length() > 0) {
			HTMLPrinter.insertPageProlog(buffer, 0, (String)null);
			HTMLPrinter.addPageEpilog(buffer);
			return buffer.toString();
		}

		return null;
	}

	private static final long LABEL_FLAGS=  JavaElementLabels.ALL_FULLY_QUALIFIED
			| JavaElementLabels.M_PRE_RETURNTYPE | JavaElementLabels.M_PARAMETER_TYPES | JavaElementLabels.M_PARAMETER_NAMES | JavaElementLabels.M_EXCEPTIONS
			| JavaElementLabels.F_PRE_TYPE_SIGNATURE | JavaElementLabels.M_PRE_TYPE_PARAMETERS | JavaElementLabels.T_TYPE_PARAMETERS
			| JavaElementLabels.USE_RESOLVED;
	private static final long LOCAL_VARIABLE_FLAGS= LABEL_FLAGS & ~JavaElementLabels.F_FULLY_QUALIFIED | JavaElementLabels.F_POST_QUALIFIED;
	private static final long TYPE_PARAMETER_FLAGS= LABEL_FLAGS | JavaElementLabels.TP_POST_QUALIFIED;

	/* 
	 * Returns the label for the IJavaElement objects
	 */
	private String getInfoText(IJavaElement element) {
		long flags;
		switch (element.getElementType()) {
			case IJavaElement.LOCAL_VARIABLE:
				flags= LOCAL_VARIABLE_FLAGS;
				break;
			case IJavaElement.TYPE_PARAMETER:
				flags= TYPE_PARAMETER_FLAGS;
				break;
			default:
				flags= LABEL_FLAGS;
				break;
		}
		StringBuffer label= new StringBuffer(JavaElementLinks.getElementLabel(element, flags));
		
		StringBuffer buf= new StringBuffer();
		buf.append("<span style='word-wrap:break-word;'>"); //$NON-NLS-1$
		buf.append(label);
		buf.append("</span>"); //$NON-NLS-1$

		return buf.toString();
	}

	/*
	 * Adds full information to the additional proposal information
	 * 
	 * @param buffer
	 * @param element
	 * @return
	 */
	private void addFullInfo(StringBuffer buffer, IJavaElement element) {
		if (element instanceof IMember) {
			IMember member= (IMember) element;
			HTMLPrinter.addSmallHeader(buffer, getInfoText(member));
			Reader reader = null;
			try {
				String content= JavadocContentAccess2.getHTMLContent(member, true);
				reader= content == null ? null : new StringReader(content);
			} catch (JavaModelException ex) {
				JavaPlugin.log(ex);
			}

			if (reader != null) {
				HTMLPrinter.addParagraph(buffer, reader);
			}

		} else if (element.getElementType() == IJavaElement.LOCAL_VARIABLE || element.getElementType() == IJavaElement.TYPE_PARAMETER) {
			HTMLPrinter.addSmallHeader(buffer, getInfoText(element));
		}
	}
}
