org.eclipse.osbp.xtext.basic.ui/src/org/eclipse/osbp/xtext/basic/ui/contentassist/TerminalsProposalProviderWithDescription.java

package org.eclipse.osbp.xtext.basic.ui.contentassist;

import org.eclipse.emf.ecore.EObject;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.osbp.xtext.basic.ui.BasicDSLDocumentationTranslator;
import org.eclipse.xtext.Assignment;
import org.eclipse.xtext.GrammarUtil;
import org.eclipse.xtext.RuleCall;
import org.eclipse.xtext.common.ui.contentassist.TerminalsProposalProvider;
import org.eclipse.xtext.ui.editor.contentassist.ConfigurableCompletionProposal;
import org.eclipse.xtext.ui.editor.contentassist.ContentAssistContext;
import org.eclipse.xtext.ui.editor.contentassist.ICompletionProposalAcceptor;
import org.eclipse.xtext.ui.editor.contentassist.PrefixMatcher;
import org.eclipse.xtext.util.Strings;

/**
 * 
 * @author kraeling
 *
 * A derivation from the standard xtext (non-OSBP) class TerminalsProposalProvider that allows to add a description to dummy variables of 
 * a certain type like TRANSLATABLEID. 
 */

public class TerminalsProposalProviderWithDescription extends TerminalsProposalProvider {

	BasicDSLDocumentationTranslator translator;
	
	public void setDocumentationTranslator(BasicDSLDocumentationTranslator translator)
	{
		this.translator = translator; 
	}
	
	@Override
	public void complete_ID(EObject model, RuleCall ruleCall, final ContentAssistContext context,
			ICompletionProposalAcceptor acceptor) {
		if (doCreateIdProposals()) {
			PrefixMatcher newMatcher = new PrefixMatcher() {
				@Override
				public boolean isCandidateMatchingPrefix(String name, String prefix) {
					String strippedName = name;
					if (name.startsWith("^") && !prefix.startsWith("^")) {
						strippedName = name.substring(1);
					}
					return context.getMatcher().isCandidateMatchingPrefix(strippedName, prefix);
				}
			};
			ContentAssistContext myContext = context.copy().setMatcher(newMatcher).toContext();
			String feature = getAssignedFeature(ruleCall);
			String proposalText = feature != null ? feature : Strings.toFirstUpper(ruleCall.getRule().getName().toLowerCase());
			String displayText = proposalText;
			if (feature != null)
				displayText = proposalText + " - " + ruleCall.getRule().getName();
			// Add a description / translation if one exists.
			displayText = enrichWithDescription(displayText, model, ruleCall.getRule().getName());
			proposalText = getValueConverter().toString(proposalText, ruleCall.getRule().getName());
			ICompletionProposal proposal = createCompletionProposal(proposalText, displayText, null, myContext);
			if (proposal instanceof ConfigurableCompletionProposal) {
				ConfigurableCompletionProposal configurable = (ConfigurableCompletionProposal) proposal;
				configurable.setSelectionStart(configurable.getReplacementOffset());
				configurable.setSelectionLength(proposalText.length());
				configurable.setAutoInsertable(false);
				configurable.setSimpleLinkedMode(myContext.getViewer(), '\t', ' ');
			}
			acceptor.accept(proposal);
		}
	}
	
	private String getAssignedFeature(RuleCall call) {
		Assignment ass = GrammarUtil.containingAssignment(call);
		if (ass != null) {
			String result = ass.getFeature();
			if (result.equals(result.toLowerCase()))
				result = Strings.toFirstUpper(result);
			return result;
		}
		return null;
	}
	
	
	/**
	 * 
	 * @param displayText A string with the name (and type) of a dummy variable for which we want a description.
	 * @param model The model in which the dummy variable is defined.
	 * @param feature The type of the dummy variable.
	 * @return The display text with an additional description from the associated i18n file for the model (if one exists).
	 */
	private String enrichWithDescription(String displayText, EObject model, String feature)
	{
		String result = displayText;
		
		// The translation key needed for the i18n file can be derived from the translation key of the respective model.
		// For example, if the model's translation key is "org.eclipse.osbp.xtext.perspective.Perspective", then 
		// the translation key of the dummy variable of type TRANSLATABLESTRING is "org.eclipse.osbp.xtext.perspective.TRANSLATABLESTRING"
		String modelTranslationKey = BasicDSLDocumentationTranslator.getTranslatorKey(model);
		
		int lastDotIndex = modelTranslationKey.lastIndexOf('.');
		if (lastDotIndex > 0)
		{
			String featureTranslationKey = modelTranslationKey.substring(0, lastDotIndex + 1) + feature; 
		
			// Try to find a translation / documentation for the translation key.
			if (translator != null)
			{
				String translated = translator.getDocumentation(featureTranslationKey, true);
				if (translated == null) {
					translated = "";
				} else {
					// --- if the documentation contains more than one line, use only
					// the first line ---
					translated = " - " + (translated.split("<br>"))[0];
				}
				
				result = result + translated;
			}
		}
		
		return result;
	}
	
	@Override
	public void complete_STRING(EObject model, RuleCall ruleCall, ContentAssistContext context,
			ICompletionProposalAcceptor acceptor) {
		if (doCreateStringProposals()) {
			String feature = getAssignedFeature(ruleCall);
			createStringProposal(context, acceptor, feature, ruleCall);
		}
	}

	private void createStringProposal(ContentAssistContext context, ICompletionProposalAcceptor acceptor,
			String feature, RuleCall ruleCall) {
		String proposalText = feature != null ? feature : Strings.toFirstUpper(ruleCall.getRule().getName().toLowerCase());
		proposalText = getValueConverter().toString(proposalText, ruleCall.getRule().getName());
		String displayText = proposalText;
		if (feature != null)
			displayText = displayText + " - " + ruleCall.getRule().getName();
		ICompletionProposal proposal = createCompletionProposal(proposalText, displayText, null, context);
		if (proposal instanceof ConfigurableCompletionProposal) {
			ConfigurableCompletionProposal configurable = (ConfigurableCompletionProposal) proposal;
			configurable.setSelectionStart(configurable.getReplacementOffset() + 1);
			configurable.setSelectionLength(proposalText.length() - 2);
			configurable.setAutoInsertable(false);
			configurable.setSimpleLinkedMode(context.getViewer(), proposalText.charAt(0), '\t');
			
		}
		acceptor.accept(proposal);
	}
	
	@Override
	public void complete_INT(EObject model, RuleCall ruleCall, ContentAssistContext context,
			ICompletionProposalAcceptor acceptor) {
		String feature = getAssignedFeature(ruleCall);
		if (doCreateIntProposals()) {
			createIntProposal(context, acceptor, ruleCall, feature, 1);
		}
	}

	private void createIntProposal(ContentAssistContext context, ICompletionProposalAcceptor acceptor,
			RuleCall ruleCall, String feature,	int i) {
		String proposalText = getValueConverter().toString(i, ruleCall.getRule().getName());
		String displayText = proposalText + " - " + ruleCall.getRule().getName();
		if (feature != null)
			displayText = proposalText + " - " + feature;
		ICompletionProposal proposal = createCompletionProposal(proposalText, displayText, null, context);
		if (proposal instanceof ConfigurableCompletionProposal) {
			ConfigurableCompletionProposal configurable = (ConfigurableCompletionProposal) proposal;
			configurable.setSelectionStart(configurable.getReplacementOffset());
			configurable.setSelectionLength(proposalText.length());
			configurable.setAutoInsertable(false);
			configurable.setSimpleLinkedMode(context.getViewer(), '\t', ' ');
		}
		acceptor.accept(proposal);
	}
}