/**
 * Copyright 2010 JBoss Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.drools.eclipse.flow.ruleflow.view.property.constraint;

/*
 * Copyright 2005 JBoss Inc
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;

import org.drools.eclipse.DroolsEclipsePlugin;
import org.drools.eclipse.editors.completion.CompletionUtil;
import org.drools.eclipse.editors.completion.DefaultCompletionProcessor;
import org.drools.eclipse.editors.completion.RuleCompletionProcessor;
import org.drools.eclipse.editors.completion.RuleCompletionProposal;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IFileEditorInput;
import org.eclipse.ui.IWorkbench;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PlatformUI;

/**
 * Completion for ruleflow constraints. 
 * 
 * @author <a href="mailto:kris_verlaenen@hotmail.com">Kris Verlaenen</a>
 */
public class ImportCompletionProcessor extends DefaultCompletionProcessor {

	public ImportCompletionProcessor() {
		super(null);
	}
	
	public IEditorPart getEditor() {
		IWorkbench workbench = PlatformUI.getWorkbench();
		if (workbench != null) { 
			IWorkbenchWindow workbenchWindow = workbench.getActiveWorkbenchWindow();
			if (workbenchWindow != null) {
				IWorkbenchPage workbenchPage = workbenchWindow.getActivePage(); 
				if (workbenchPage != null) {
					return workbenchPage.getActiveEditor();
				}
			}
		}
		return null;
	}

    protected List getCompletionProposals(ITextViewer viewer,
            int documentOffset) {
		try {
			IDocument doc = viewer.getDocument();
			String backText = readBackwards(documentOffset, doc);

			String prefix = CompletionUtil.stripLastWord(backText);

			List props = null;
			Matcher matcher = IMPORT_PATTERN.matcher(backText);
			if (matcher.matches()) {
				String classNameStart = backText.substring(backText
						.lastIndexOf("import") + 7);
				props = getAllClassProposals(classNameStart, documentOffset,
						prefix);
			} else {
				props = getPossibleProposals(viewer, documentOffset, backText, prefix);
			}
			return props;
		} catch (Throwable t) {
			DroolsEclipsePlugin.log(t);
		}
		return null;
	}

    
    public List getImports() {
    	return Collections.EMPTY_LIST;
    }
    
    public List getGlobals() {
    	return Collections.EMPTY_LIST;
    }
    
    protected IJavaProject getCurrentJavaProject() {
    	IEditorPart editor = getEditor();
    	if (editor != null && editor.getEditorInput() instanceof IFileEditorInput) {
			IFile file = ((IFileEditorInput) editor.getEditorInput()).getFile();
	    	try {
	    		if (file.getProject().getNature("org.eclipse.jdt.core.javanature") != null) {
	    			return JavaCore.create(file.getProject());
	    		}
	    	} catch (CoreException e) {
	    		// do nothing
	    	}
		}
    	return null;
    }
    
    protected List getPossibleProposals(ITextViewer viewer,
            int documentOffset,
            String backText,
            final String prefix) {
		List list = new ArrayList();
		list.add(new RuleCompletionProposal(documentOffset - prefix.length(), prefix.length(), "import", "import "));
		DefaultCompletionProcessor.filterProposalsOnPrefix(prefix, list);
		return list;
	}

    /**
     * @return a list of "MVELified" RuleCompletionProposal. That list contains only unique proposal based on
     * the overrriden equals in {@link RuleCompletionProposal} to avoid the situation when several
     * accessors can exist for one property. for that case we want to keep only one proposal.
     */
    protected Collection getJavaMvelCompletionProposals(final int documentOffset,
                                                     final String javaText,
                                                     final String prefix,
                                                     Map params) {
                                                        final List list = new ArrayList();
                                                        requestJavaCompletionProposals( javaText,
                                                                                        prefix,
                                                                                        documentOffset,
                                                                                        params,
                                                                                        list );
                                                    
                                                        Collection mvelList = RuleCompletionProcessor.mvelifyProposals( list, false );
                                                        return mvelList;
                                                    }
}