package org.eclipse.wst.jsdt.web.ui.internal.contentassist;

import java.util.HashMap;
import java.util.Iterator;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.wst.jsdt.core.ICompilationUnit;
import org.eclipse.wst.jsdt.web.core.internal.java.IJSPTranslation;
import org.eclipse.wst.jsdt.web.core.internal.java.JSPTranslation;
import org.eclipse.wst.jsdt.web.core.internal.java.JSPTranslationAdapter;
import org.eclipse.wst.jsdt.web.ui.internal.JSPUIMessages;
import org.eclipse.wst.sse.core.StructuredModelManager;
import org.eclipse.wst.sse.ui.internal.StructuredTextViewer;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMDocument;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMModel;
import org.eclipse.wst.xml.ui.internal.contentassist.AbstractContentAssistProcessor;
import org.osgi.framework.Bundle;

public class JSDTContentAssistantProcessor extends AbstractContentAssistProcessor {
    
    public JSDTContentAssistantProcessor() {
        super();
    }
    
    private static final boolean   DEBUG;
    private JSDTProposalCollector fProposalCollector;
    
    static {
        String value = Platform.getDebugOption("org.eclipse.wst.jsdt.web.core/debug/jsptranslation"); //$NON-NLS-1$
        DEBUG = value != null && value.equalsIgnoreCase("true"); //$NON-NLS-1$
    }
    
    private static final String    JSDT_CORE_PLUGIN_ID = "org.eclipse.wst.jsdt.core"; //$NON-NLS-1$
                                                                                      
    protected int                  fJspSourcePosition, fJavaPosition;
    protected String               fErrorMessage       = null;
    protected StructuredTextViewer fViewer             = null;
    private JSPTranslationAdapter  fTranslationAdapter = null;
    
    /**
     * Returns a list of completion proposals based on the specified location
     * within the document that corresponds to the current cursor position
     * within the text viewer.
     * 
     * @param viewer
     *            the viewer whose document is used to compute the proposals
     * @param documentPosition
     *            an offset within the document for which completions should be
     *            computed
     * @return an array of completion proposals or <code>null</code> if no
     *         proposals are possible
     */
    public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int pos) {
        initialize(pos);
        
        JSDTProposalCollector collector = null;
        
        IDOMModel xmlModel = null;
        try {
            if (viewer instanceof StructuredTextViewer) {
                fViewer = (StructuredTextViewer) viewer;
            }
            
            xmlModel = (IDOMModel) StructuredModelManager.getModelManager().getExistingModelForRead(fViewer.getDocument());
            
            IDOMDocument xmlDoc = xmlModel.getDocument();
            if (fTranslationAdapter == null) {
                fTranslationAdapter = (JSPTranslationAdapter) xmlDoc.getAdapterFor(IJSPTranslation.class);
            }
            if (fTranslationAdapter != null) {
                
                JSPTranslation translation = fTranslationAdapter.getJSPTranslation();
                fJavaPosition = translation.getJavaOffset(getDocumentPosition());
                
                if (DEBUG) {
                    System.out.println("Cursor Location in Java Offset:" + fJavaPosition);
                    System.out.println(debug(translation));
                }
               
                
                try {
                    
                    ICompilationUnit cu = translation.getCompilationUnit();
                    
                    // can't get java proposals w/out a compilation unit
                    // or without a valid position
                    if (cu == null || -1 == fJavaPosition) {
                        return new ICompletionProposal[0];
                    }
                    
                    collector = getProposalCollector();
                    synchronized (cu) {
                        cu.codeComplete(fJavaPosition, collector, null);
                    }
                } catch (CoreException coreEx) {
                    // a possible Java Model Exception due to not being a Web
                    // (Java) Project
                    coreEx.printStackTrace();
                }
            }
        } catch (Exception exc) {
            exc.printStackTrace();
            // throw out exceptions on code assist.
        } finally {
            if (xmlModel != null) {
                xmlModel.releaseFromRead();
            }
        }
        ICompletionProposal[] results = new ICompletionProposal[0];
        if (collector != null) {
            results = collector.getJSPCompletionProposals();
            if (results == null || results.length < 1) {
                fErrorMessage = JSPUIMessages.Java_Content_Assist_is_not_UI_;
            }
        }
        return results;
    }
    
    protected JSDTProposalCollector getProposalCollector() {
        return fProposalCollector;
       // return new JSPProposalCollector(translation);
    }
    
    public void setProposalCollector(JSDTProposalCollector translation){
        this.fProposalCollector = translation;
    }
    
    /**
     * For debugging translation mapping only.
     * 
     * @param translation
     */
    private String debug(JSPTranslation translation) {
        StringBuffer debugString = new StringBuffer();
        HashMap jsp2java = translation.getJsp2JavaMap();
        String javaText = translation.getJavaText();
        String jspText = fViewer.getDocument().get();
        debugString.append("[jsp2JavaMap in JSPCompletionProcessor]\r\n"); //$NON-NLS-1$
        int jspCursPos = fViewer.getTextWidget().getCaretOffset();
        debugString.append("jsp cursor position >> " + jspCursPos + "\n"); //$NON-NLS-1$ //$NON-NLS-2$
        Iterator it = jsp2java.keySet().iterator();
        while (it.hasNext()) {
            try {
                Position jspPos = (Position) it.next();
                Position javaPos = (Position) jsp2java.get(jspPos);
                debugString.append("jsp > " + jspPos.offset + ":" + jspPos.length + ":" + jspText.substring(jspPos.offset, jspPos.offset + jspPos.length) + ":\n"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
                debugString.append("java > " + javaPos.offset + ":" + javaPos.length + ":" + javaText.substring(javaPos.offset, javaPos.offset + javaPos.length) + ":\n"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
                debugString.append("char at Java pos (-1)>" + javaText.substring(javaPos.offset, javaPos.offset + javaPos.length).charAt(fJavaPosition - 1) + ":\n");
                debugString.append("char at JSP pos (-1)>" + jspText.charAt(jspCursPos - 1) + ":\n");
                
                debugString.append("-------------------------------------------------\n"); //$NON-NLS-1$
            } catch (Exception e) {
                // eat exceptions, it's only for debug
            }
        }
        return debugString.toString();
    }
    
    /**
     * Returns information about possible contexts based on the specified
     * location within the document that corresponds to the current cursor
     * position within the text viewer.
     * 
     * @param viewer
     *            the viewer whose document is used to compute the possible
     *            contexts
     * @param documentPosition
     *            an offset within the document for which context information
     *            should be computed
     * @return an array of context information objects or <code>null</code> if
     *         no context could be found
     */
    public org.eclipse.jface.text.contentassist.IContextInformation[] computeContextInformation(org.eclipse.jface.text.ITextViewer viewer, int documentOffset) {
        return null;
    }
    
    /**
     * Returns a string of characters which when pressed should automatically
     * display content-assist proposals.
     * 
     * @return string of characters
     */
    public java.lang.String getAutoProposalInvocationCharacters() {
        return null;
    }
    
    /**
     * Returns a string of characters which when pressed should automatically
     * display a content-assist tip.
     * 
     * @return string of characters
     */
    public java.lang.String getAutoTipInvocationCharacters() {
        return null;
    }
    
    /**
     * Returns the characters which when entered by the user should
     * automatically trigger the presentation of possible completions.
     * 
     * @return the auto activation characters for completion proposal or
     *         <code>null</code> if no auto activation is desired
     */
    public char[] getCompletionProposalAutoActivationCharacters() {
        return null;
    }
    
    /**
     * Returns the characters which when entered by the user should
     * automatically trigger the presentation of context information.
     * 
     * @return the auto activation characters for presenting context information
     *         or <code>null</code> if no auto activation is desired
     */
    public char[] getContextInformationAutoActivationCharacters() {
        return null;
    }
    
    /**
     * Returns a validator used to determine when displayed context information
     * should be dismissed. May only return <code>null</code> if the processor
     * is incapable of computing context information.
     * 
     * @return a context information validator, or <code>null</code> if the
     *         processor is incapable of computing context information
     */
    public org.eclipse.jface.text.contentassist.IContextInformationValidator getContextInformationValidator() {
        return null;
    }
    
    protected int getDocumentPosition() {
        return fJspSourcePosition;
    }
    
    public String getErrorMessage() {
        // TODO: get appropriate error message
        // if (fCollector.getErrorMessage() != null &&
        // fCollector.getErrorMessage().length() > 0)
        // return fCollector.getErrorMessage();
        return fErrorMessage;
    }
    
    /**
     * Initialize the code assist processor.
     */
    protected void initialize(int pos) {
        initializeJavaPlugins();
        
        fJspSourcePosition = pos;
        fErrorMessage = null;
    }
    
    /**
     * Initialize the Java Plugins that the JSP processor requires. See
     * https://bugs.eclipse.org/bugs/show_bug.cgi?id=143765 We should not call
     * "start", because that will cause that state to be remembered, and
     * re-started automatically during the next boot up sequence.
     * 
     * ISSUE: we may be able to get rid of this all together, in future, since
     * 99% we probably have already used some JDT class by the time we need JDT
     * to be active ... but ... this is the safest fix for this point in 1.5
     * stream. Next release, let's just remove this, re-discover what ever bug
     * this was fixing (if any) and if there is one, then we'll either put back
     * in, as is, or come up with a more appropriate fix.
     * 
     */
    protected void initializeJavaPlugins() {
        try {
            Bundle bundle = Platform.getBundle(JSDT_CORE_PLUGIN_ID);
            bundle.loadClass("dummyClassNameThatShouldNeverExist");
        } catch (ClassNotFoundException e) {
            // this is the expected result, we just want to
            // nudge the bundle to be sure its activated.
        }
    }
    
    public void release() {
        fTranslationAdapter = null;
    }
    
}