org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/format/LSPFormatter.java

/*******************************************************************************
 * Copyright (c) 2017 Rogue Wave Software Inc. 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/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *  Michał Niewrzał (Rogue Wave Software Inc.) - initial implementation
 *  Lucas Bullen (Red Hat Inc.) - [Bug 517428] Requests sent before initialization
 *                              - [Bug 528848] Formatting Request should include FormattingOptions
 *******************************************************************************/
package org.eclipse.lsp4e.operations.format;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CompletableFuture;

import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.lsp4e.LSPEclipseUtils;
import org.eclipse.lsp4e.LanguageServerPlugin;
import org.eclipse.lsp4e.LanguageServiceAccessor;
import org.eclipse.lsp4e.LanguageServiceAccessor.LSPDocumentInfo;
import org.eclipse.lsp4j.DocumentFormattingParams;
import org.eclipse.lsp4j.DocumentRangeFormattingParams;
import org.eclipse.lsp4j.FormattingOptions;
import org.eclipse.lsp4j.Position;
import org.eclipse.lsp4j.Range;
import org.eclipse.lsp4j.ServerCapabilities;
import org.eclipse.lsp4j.TextDocumentIdentifier;
import org.eclipse.lsp4j.TextEdit;
import org.eclipse.ui.editors.text.EditorsUI;
import org.eclipse.ui.texteditor.AbstractDecoratedTextEditorPreferenceConstants;

public class LSPFormatter {

	public void applyEdits(IDocument document, List<? extends TextEdit> edits) {
		LSPEclipseUtils.applyEdits(document, edits);
	}

	public CompletableFuture<List<? extends TextEdit>> requestFormatting(@NonNull IDocument document,
			@NonNull ITextSelection textSelection) {
		Collection<@NonNull LSPDocumentInfo> infos = LanguageServiceAccessor.getLSPDocumentInfosFor(document,
				LSPFormatter::supportFormatting);
		if (infos.isEmpty()) {
			return CompletableFuture.completedFuture(Collections.emptyList());
		}
		// TODO consider a better strategy for that, maybe iterate on all LS until one gives a result
		LSPDocumentInfo info = infos.iterator().next();
		try {
			return requestFormatting(info, textSelection);
		} catch (BadLocationException e) {
			LanguageServerPlugin.logError(e);
		}
		return CompletableFuture.completedFuture(Collections.emptyList());
	}

	private CompletableFuture<List<? extends TextEdit>> requestFormatting(LSPDocumentInfo info,
			ITextSelection textSelection) throws BadLocationException {
		TextDocumentIdentifier docId = new TextDocumentIdentifier(info.getFileUri().toString());
		ServerCapabilities capabilities = info.getCapabilites();
		IPreferenceStore store = EditorsUI.getPreferenceStore();
		int tabWidth = store.getInt(AbstractDecoratedTextEditorPreferenceConstants.EDITOR_TAB_WIDTH);
		boolean insertSpaces = store.getBoolean(AbstractDecoratedTextEditorPreferenceConstants.EDITOR_SPACES_FOR_TABS);
		// use range formatting if standard formatting is not supported or text is selected
		if (capabilities != null
				&& isDocumentRangeFormattingSupported(capabilities)
				&& (!isDocumentFormattingSupported(capabilities)
						|| textSelection.getLength() != 0)) {
			DocumentRangeFormattingParams params = new DocumentRangeFormattingParams();
			params.setTextDocument(docId);
			params.setOptions(new FormattingOptions(tabWidth, insertSpaces));
			boolean fullFormat = textSelection.getLength() == 0;
			Position start = LSPEclipseUtils.toPosition(fullFormat ? 0 : textSelection.getOffset(), info.getDocument());
			Position end = LSPEclipseUtils.toPosition(
					fullFormat ? info.getDocument().getLength() : textSelection.getOffset() + textSelection.getLength(),
					info.getDocument());
			params.setRange(new Range(start, end));
			return info.getInitializedLanguageClient()
					.thenComposeAsync(server -> server.getTextDocumentService().rangeFormatting(params));
		}

		DocumentFormattingParams params = new DocumentFormattingParams();
		params.setTextDocument(docId);
		params.setOptions(new FormattingOptions(tabWidth, insertSpaces));
		return info.getInitializedLanguageClient()
				.thenComposeAsync(server -> server.getTextDocumentService().formatting(params));
	}

	private static boolean isDocumentRangeFormattingSupported(ServerCapabilities capabilities) {
		return LSPEclipseUtils.hasCapability(capabilities.getDocumentRangeFormattingProvider());
	}

	private static boolean isDocumentFormattingSupported(ServerCapabilities capabilities) {
		return LSPEclipseUtils.hasCapability(capabilities.getDocumentFormattingProvider());
	}

	public static boolean supportFormatting(ServerCapabilities capabilities) {
		return isDocumentFormattingSupported(capabilities)
				|| isDocumentRangeFormattingSupported(capabilities);
	}

}