ltk/org.eclipse.statet.ltk.ui/src/org/eclipse/statet/ltk/ui/sourceediting/assist/LinkedNamesAssistProposal.java

/*=============================================================================#
 # Copyright (c) 2008, 2021 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ltk.ui.sourceediting.assist;

import static org.eclipse.statet.ltk.ui.LtkUI.BUNDLE_ID;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.link.LinkedModeModel;
import org.eclipse.jface.text.link.LinkedModeUI;
import org.eclipse.jface.text.link.LinkedModeUI.ExitFlags;
import org.eclipse.jface.text.link.LinkedModeUI.IExitPolicy;
import org.eclipse.jface.text.link.LinkedPosition;
import org.eclipse.jface.text.link.LinkedPositionGroup;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.VerifyEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.ui.statushandlers.StatusManager;
import org.eclipse.ui.texteditor.link.EditorLinkedModeUI;

import org.eclipse.statet.jcommons.lang.NonNullByDefault;
import org.eclipse.statet.jcommons.lang.Nullable;
import org.eclipse.statet.jcommons.text.core.TextRegion;

import org.eclipse.statet.ltk.ui.LtkUI;
import org.eclipse.statet.ltk.ui.sourceediting.SourceEditor;
import org.eclipse.statet.ltk.ui.sourceediting.TextEditToolSynchronizer;


@NonNullByDefault
public abstract class LinkedNamesAssistProposal<TContext extends AssistInvocationContext>
		extends CommandAssistProposal<TContext> {
	
	
	/**
	 * An exit policy that skips Backspace and Delete at the beginning and at the end
	 * of a linked position, respectively.
	 */
	public static class DeleteBlockingExitPolicy implements IExitPolicy {
		
		private final IDocument document;
		
		public DeleteBlockingExitPolicy(final IDocument document) {
			this.document= document;
		}
		
		@Override
		public @Nullable ExitFlags doExit(final LinkedModeModel model, final VerifyEvent event,
				final int offset, final int length) {
			switch (event.character) {
			case SWT.BS:
				{	//skip backspace at beginning of linked position
					final LinkedPosition position= model.findPosition(new LinkedPosition(
							this.document, offset, 0, LinkedPositionGroup.NO_STOP));
					if (position != null && offset <= position.getOffset() && length == 0) {
						event.doit= false;
					}
					return null;
				}
			case SWT.DEL:
				{	//skip delete at end of linked position
					final LinkedPosition position= model.findPosition(new LinkedPosition(
							this.document, offset, 0, LinkedPositionGroup.NO_STOP));
					if (position != null && offset >= position.getOffset() + position.getLength() && length == 0) {
						event.doit= false;
					}
					return null;
				}
			}
			return null;
		}
	}
	
	
	private @Nullable String valueSuggestion;
	
	
	public LinkedNamesAssistProposal(final ProposalParameters<TContext> parameters) {
		super(parameters);
	}
	
	
	@Override
	public Image getImage() {
		return LtkUI.getUIResources().getImage(LtkUI.OBJ_TEXT_LINKEDRENAME_IMAGE_ID);
	}
	
	
	@Override
	public boolean validate(final IDocument document, final int offset,
			final @Nullable DocumentEvent event) {
		return false;
	}
	
	
	@Override
	public void apply(final ITextViewer viewer, final char trigger, final int stateMask,
			final int offset) {
		try {
			// by default full word is selected by linked model ui
			// instead we want to keep the original selection by default
			int selectionStartOffset;
			int selectionEndOffset;
			{	final Point selection= viewer.getSelectedRange();
				selectionStartOffset= selection.x;
				selectionEndOffset= selection.x + selection.y;
			}
			final IDocument document= viewer.getDocument();
			if (document == null) {
				return;
			}
			
			final LinkedModeModel model= new LinkedModeModel();
			
			final LinkedPositionGroup group= new LinkedPositionGroup();
			collectPositions(document, group);
			if (group.isEmpty()) {
				return;
			}
			model.addGroup(group);
			
			model.forceInstall();
			{	final SourceEditor editor= getInvocationContext().getEditor();
				final TextEditToolSynchronizer synchronizer;
				if (editor != null && (synchronizer= editor.getTextEditToolSynchronizer()) != null) {
					synchronizer.install(model);
				}
			}
			
			final LinkedModeUI ui= new EditorLinkedModeUI(model, viewer);
			ui.setExitPolicy(new DeleteBlockingExitPolicy(document));
			ui.setExitPosition(viewer, offset, 0, LinkedPositionGroup.NO_STOP);
			ui.enter();
			
			final String valueSuggestion= this.valueSuggestion;
			final Position position0= group.getPositions()[0];
			if (valueSuggestion != null) {
				document.replace(position0.getOffset(), position0.getLength(), valueSuggestion);
				selectionStartOffset= position0.getOffset();
				selectionEndOffset= selectionStartOffset + valueSuggestion.length();
			}
			else {
				// correct selection if larger/outside of the initial position
				final int positionEndOffset= position0.getOffset() + position0.getLength();
				if (selectionStartOffset < position0.getOffset()) {
					selectionStartOffset= position0.getOffset();
				}
				else if (selectionStartOffset > positionEndOffset) {
					selectionStartOffset= positionEndOffset;
				}
				if (selectionEndOffset < selectionStartOffset) {
					selectionEndOffset= selectionStartOffset;
				}
				else if (selectionEndOffset > positionEndOffset) {
					selectionEndOffset= positionEndOffset;
				}
			}
			
			viewer.setSelectedRange(selectionStartOffset, selectionEndOffset - selectionStartOffset);
		}
		catch (final BadLocationException e) {
			StatusManager.getManager().handle(new Status(IStatus.ERROR, BUNDLE_ID, -1,
					"Error initializing linked rename.", e )); //$NON-NLS-1$
		}
	}
	
	protected abstract void collectPositions(final IDocument document, final LinkedPositionGroup group)
			throws BadLocationException;
	
	protected int addPosition(final LinkedPositionGroup group, final IDocument document,
			final @Nullable Position position, final int idx) throws BadLocationException {
		if (position != null) {
			group.addPosition(new LinkedPosition(document, position.getOffset(), position.getLength(), idx));
			return idx + 1;
		}
		return idx;
	}
	
	protected int addPosition(final LinkedPositionGroup group, final IDocument document,
			final @Nullable TextRegion position, final int idx) throws BadLocationException {
		if (position != null) {
			group.addPosition(new LinkedPosition(document, position.getStartOffset(), position.getLength(), idx));
			return idx + 1;
		}
		return idx;
	}
	
	
}