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

/*=============================================================================#
 # Copyright (c) 2011, 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.jcommons.lang.ObjectUtils.nonNullAssert;

import static org.eclipse.statet.ecommons.ui.actions.UIActions.NO_COMMAND_ID;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.jface.bindings.keys.KeySequence;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.contentassist.ICompletionProposalExtension5;
import org.eclipse.jface.text.contentassist.ICompletionProposalExtension6;
import org.eclipse.jface.text.contentassist.IContextInformation;
import org.eclipse.jface.viewers.StyledString;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;

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

import org.eclipse.statet.ecommons.text.ui.DefaultBrowserInformationInput;
import org.eclipse.statet.ecommons.ui.workbench.WorkbenchUIUtils;

import org.eclipse.statet.ltk.ui.sourceediting.CommandAccess;


@NonNullByDefault
public abstract class CommandAssistProposal<TContext extends AssistInvocationContext>
		implements AssistProposal, CommandAccess, ICompletionProposalExtension5, ICompletionProposalExtension6 {
	
	
	public static class ProposalParameters<TContext extends AssistInvocationContext> {
		
		
		public final TContext context;
		
		public final String commandId;
		
		public final String label;
		public final @Nullable String description;
		
		public int relevance;
		
		
		public ProposalParameters(final TContext context, final String commandId,
				final String label, final @Nullable String description,
				final int relevance) {
			this.context= nonNullAssert(context);
			this.commandId= nonNullAssert(commandId);
			this.label= nonNullAssert(label);
			this.description= description;
			this.relevance= relevance;
		}
		
		
	}
	
	
	protected static class ApplyData {
		
		
		private @Nullable TextRegion selectionToSet;
		
		private @Nullable IContextInformation contextInformation;
		
		
		public ApplyData() {
		}
		
		
		public void setSelection(final TextRegion region) {
			this.selectionToSet= region;
		}
		
		public void setSelection(final int offset) {
			this.selectionToSet= new BasicTextRegion(offset, offset);
		}
		
		public void setSelection(final int offset, final int length) {
			assert (length >= 0);
			this.selectionToSet= new BasicTextRegion(offset, offset + length);
		}
		
		public void clearSelection() {
			this.selectionToSet= null;
		}
		
		public @Nullable TextRegion getSelection() {
			return this.selectionToSet;
		}
		
		public void setContextInformation(final IContextInformation info) {
			this.contextInformation= info;
		}
		
		public @Nullable IContextInformation getContextInformation() {
			return this.contextInformation;
		}
		
	}
	
	
	protected static StyledString addAcceleratorStyled(final String message,
			final @Nullable KeySequence binding) {
		final StyledString styledString= new StyledString(message);
		if (binding != null) {
			styledString.append(" (", StyledString.QUALIFIER_STYLER); //$NON-NLS-1$
			styledString.append(binding.format(), StyledString.QUALIFIER_STYLER);
			styledString.append(')', StyledString.QUALIFIER_STYLER);
		}
		return styledString;
	}
	
	
	private final TContext context;
	
	private final String commandId;
	
	private final String label;
	private final @Nullable String description;
	
	private final int relevance;
	
	private @Nullable ApplyData applyData;
	
	
	public CommandAssistProposal(final ProposalParameters<TContext> parameters) {
		this.context= parameters.context;
		this.commandId= parameters.commandId;
		this.label= parameters.label;
		this.description= parameters.description;
		this.relevance= parameters.relevance;
	}
	
	@SuppressWarnings("null")
	protected CommandAssistProposal(final TContext invocationContext, final String commandId,
			final String label, final @Nullable String description) {
		this.context= nonNullAssert(invocationContext);
		this.commandId= nonNullAssert(commandId);
		
		this.label= label;
		this.description= description;
		this.relevance= 0;
	}
	
	
	@Override
	public final String getCommandId() {
		return this.commandId;
	}
	
	protected final TContext getInvocationContext() {
		return this.context;
	}
	
	protected final ApplyData getApplyData() {
		ApplyData applyData= this.applyData;
		if (applyData == null) {
			applyData= createApplyData();
			this.applyData= applyData;
		}
		return applyData;
	}
	
	protected ApplyData createApplyData() {
		return new ApplyData();
	}
	
	
	@Override
	public int getRelevance() {
		return this.relevance;
	}
	
	@Override
	public String getSortingString() {
		return this.label;
	}
	
	
	@Override
	public @Nullable Image getImage() {
		return null;
	}
	
	@Override
	public String getDisplayString() {
		return this.label;
	}
	
	@Override
	public StyledString getStyledDisplayString() {
		return addAcceleratorStyled(getDisplayString(), (this.commandId != NO_COMMAND_ID) ?
				WorkbenchUIUtils.getBestKeyBinding(this.commandId) :
				null );
	}
	
	
	@Override
	public boolean validate(final IDocument document, final int offset,
			final @Nullable DocumentEvent event) {
		return false;
	}
	
	@Override
	public @Nullable String getAdditionalProposalInfo() {
		return this.description;
	}
	
	@Override
	public @Nullable Object getAdditionalProposalInfo(final IProgressMonitor monitor) {
		final var description= this.description;
		if (description == null) {
			return null;
		}
		return new DefaultBrowserInformationInput(getDisplayString(),
				description, DefaultBrowserInformationInput.FORMAT_TEXT_INPUT );
	}
	
	
	@Override
	public void apply(final IDocument document) {
		throw new UnsupportedOperationException();
	}
	
	@Override
	public @Nullable Point getSelection(final IDocument document) {
		final var applyData= this.applyData;
		if (applyData != null) {
			final TextRegion selection= applyData.getSelection();
			if (selection != null) {
				return new Point(selection.getStartOffset(), selection.getLength());
			}
		}
		return null;
	}
	
	@Override
	public @Nullable IContextInformation getContextInformation() {
		return null;
	}
	
}