Bug 558664 - Cquery integration should be extracted from LSP Core

Part 2:
Introduce SupportedLanguageServers interface and remove knowledge about
specific language server from CPPStreamConnectionProvider. Replace
ICPPLanguageServer with LanguageServerConfiguration.
Move Clangd and Cquery server configurations to its packages.

Change-Id: I825c39bc6f8004616e639fda28660d3c98d08057
Signed-off-by: Alexander Fedorov <alexander.fedorov@arsysop.ru>

lsp/org.eclipse.cdt.lsp.core/META-INF/MANIFEST.MF

@@ -23,8 +23,8 @@ Require-Bundle: com.google.gson;bundle-version="2.8.2",
 Import-Package: org.eclipse.ui.editors.text,
  org.eclipse.ui.texteditor
 Export-Package: org.eclipse.cdt.cquery;x-friends:="org.eclipse.cdt.lsp.ui",
- org.eclipse.cdt.internal.cquery;x-internal:=true,
- org.eclipse.cdt.internal.cquery.core;x-internal:=true,
+ org.eclipse.cdt.internal.clangd;x-friends:="org.eclipse.cdt.lsp.ui",
+ org.eclipse.cdt.internal.cquery;x-friends:="org.eclipse.cdt.lsp.ui",
  org.eclipse.cdt.internal.cquery.ui;x-internal:=true,
  org.eclipse.cdt.lsp.core;x-friends:="org.eclipse.cdt.lsp.ui",
  org.eclipse.cdt.lsp.internal.core;x-internal:=true,

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/internal/clangd/ClangdLanguageServer.java

@@ -9,15 +9,29 @@
  * SPDX-License-Identifier: EPL-2.0
  *******************************************************************************/
 
-package org.eclipse.cdt.lsp.core;
+package org.eclipse.cdt.internal.clangd;
 
 import java.net.URI;
 
-public class ClangdLanguageServer implements ICPPLanguageServer {
+import org.eclipse.cdt.lsp.LanguageServerConfiguration;
+
+public class ClangdLanguageServer implements LanguageServerConfiguration {
+
+	public static final String CLANGD_ID = "clangd"; //$NON-NLS-1$
 
 	@Override
-	public Object getLSSpecificInitializationOptions(Object defaultInitOptions, URI rootPath) {
-		return defaultInitOptions;
+	public String identifier() {
+		return ClangdLanguageServer.CLANGD_ID;
+	}
+
+	@Override
+	public String label() {
+		return "ClangD";
+	}
+
+	@Override
+	public Object options(Object defaults, URI uri) {
+		return defaults;
 	}
 
 }

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/internal/cquery/CqueryLanguageServer.java

@@ -9,28 +9,37 @@
  * SPDX-License-Identifier: EPL-2.0
  *******************************************************************************/
 
-package org.eclipse.cdt.internal.cquery.core;
+package org.eclipse.cdt.internal.cquery;
 
 import java.net.URI;
 
 import org.eclipse.cdt.internal.ui.editor.CEditor;
-import org.eclipse.cdt.lsp.core.ICPPLanguageServer;
+import org.eclipse.cdt.lsp.LanguageServerConfiguration;
 import org.eclipse.cdt.ui.CUIPlugin;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.Path;
 
 import com.google.gson.JsonObject;
 
-public class CqueryLanguageServer implements ICPPLanguageServer {
+public class CqueryLanguageServer implements LanguageServerConfiguration {
+
+	public static final String CQUERY_ID = "cquery"; //$NON-NLS-1$
 
 	@Override
-	public Object getLSSpecificInitializationOptions(Object defaultInitOptions, URI rootPath) {
+	public String identifier() {
+		return CqueryLanguageServer.CQUERY_ID;
+	}
 
+	@Override
+	public String label() {
+		return "CQuery";
+	}
+
+	@Override
+	public Object options(Object defaults, URI uri) {
 		// TODO: Allow user to specify cache directory path
-
-		IPath cacheDirectory = Path.fromOSString(rootPath.getPath()).append(".cdt-lsp/cquery_index"); //$NON-NLS-1$
-		JsonObject result = (defaultInitOptions instanceof JsonObject) ? (JsonObject) defaultInitOptions
-				: new JsonObject();
+		IPath cacheDirectory = Path.fromOSString(uri.getPath()).append(".cdt-lsp/cquery_index"); //$NON-NLS-1$
+		JsonObject result = (defaults instanceof JsonObject) ? (JsonObject) defaults : new JsonObject();
 		result.addProperty("cacheDirectory", cacheDirectory.toString()); //$NON-NLS-1$
 		result.addProperty("emitInactiveRegions", //$NON-NLS-1$
 				CUIPlugin.getDefault().getPreferenceStore().getBoolean(CEditor.INACTIVE_CODE_ENABLE));

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/LanguageServerConfiguration.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2018 Manish Khurana , Nathan Ridge and others.
+ * Copyright (c) 2020 ArSysOp and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -7,17 +7,25 @@
  * https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
  *******************************************************************************/
-
-package org.eclipse.cdt.lsp.core;
+package org.eclipse.cdt.lsp;
 
 import java.net.URI;
 
-/*
- * Encapsulates functionality specific to a particular C++ language server (e.g., CQuery)
+/**
+ *
+ * Holds the configuration for a contributed language server.
+ *
  */
-public interface ICPPLanguageServer {
+public interface LanguageServerConfiguration {
 
-	public Object getLSSpecificInitializationOptions(Object defaultInitOptions, URI rootPath);
+	String identifier();
+
+	String label();
+
+	Object options(Object defaults, URI uri);
 
 }

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/SupportedLanguageServers.java

@@ -0,0 +1,29 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp;
+
+import java.util.Collection;
+
+/**
+ *
+ * Provides access to configurations of supported language servers.
+ *
+ */
+public interface SupportedLanguageServers {
+
+	Collection<LanguageServerConfiguration> all();
+
+	LanguageServerConfiguration preferred() throws IllegalStateException;
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/core/CPPStreamConnectionProvider.java

@@ -24,8 +24,8 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.eclipse.cdt.internal.cquery.core.CqueryLanguageServer;
-import org.eclipse.cdt.lsp.internal.core.LspCoreMessages;
+import org.eclipse.cdt.lsp.LanguageServerConfiguration;
+import org.eclipse.cdt.lsp.internal.core.ContributedLanguageServers;
 import org.eclipse.cdt.utils.CommandLineUtil;
 import org.eclipse.core.resources.IContainer;
 import org.eclipse.core.resources.IProject;
@@ -43,29 +43,19 @@ public class CPPStreamConnectionProvider extends ProcessStreamConnectionProvider
 
 	private static final IPreferenceStore store = Activator.getDefault().getPreferenceStore();
 
-	private ICPPLanguageServer languageServer;
+	private final LanguageServerConfiguration configuration;
 
-	public static final String CLANGD_ID = "clangd"; //$NON-NLS-1$
-
-	public static final String CQUERY_ID = "cquery"; //$NON-NLS-1$
-
-	//FIXME: AF: the list of available servers should be extracted from some service
 	public CPPStreamConnectionProvider() throws UnsupportedOperationException {
-		List<String> commands = new ArrayList<>();
-		if (store.getString(PreferenceConstants.P_SERVER_CHOICE).equals(CQUERY_ID)) {
-			languageServer = new CqueryLanguageServer();
-		} else if (store.getString(PreferenceConstants.P_SERVER_CHOICE).equals(CLANGD_ID)) {
-			languageServer = new ClangdLanguageServer();
-		} else {
-			throw new UnsupportedOperationException(LspCoreMessages.CPPStreamConnectionProvider_e_unsupported);
-		}
-		File defaultLSLocation = getDefaultLSLocation(store.getString(PreferenceConstants.P_SERVER_CHOICE));
+		//FIXME: should obtain an instance of interface
+		configuration = new ContributedLanguageServers().preferred();
+		File defaultLSLocation = getDefaultLSLocation(configuration.identifier());
 		if (defaultLSLocation != null) {
 			store.setDefault(PreferenceConstants.P_SERVER_PATH, defaultLSLocation.getAbsolutePath());
 		}
 		File languageServerLocation = getLanguageServerLocation();
 		String parent = ""; //$NON-NLS-1$
 		String flags = store.getString(PreferenceConstants.P_SERVER_OPTIONS);
+		List<String> commands = new ArrayList<>();
 		if (languageServerLocation != null) {
 			commands.add(languageServerLocation.getAbsolutePath());
 			if (!flags.isEmpty()) {
@@ -89,8 +79,7 @@ public class CPPStreamConnectionProvider extends ProcessStreamConnectionProvider
 	@Override
 	public Object getInitializationOptions(URI rootPath) {
 		installResourceChangeListener(rootPath);
-		Object defaultInitOptions = super.getInitializationOptions(rootPath);
-		return languageServer.getLSSpecificInitializationOptions(defaultInitOptions, rootPath);
+		return configuration.options(super.getInitializationOptions(rootPath), rootPath);
 	}
 
 	private void installResourceChangeListener(URI rootPath) {

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/ContributedLanguageServers.java

@@ -0,0 +1,73 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.core;
+
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Optional;
+
+import org.eclipse.cdt.internal.clangd.ClangdLanguageServer;
+import org.eclipse.cdt.internal.cquery.CqueryLanguageServer;
+import org.eclipse.cdt.lsp.LanguageServerConfiguration;
+import org.eclipse.cdt.lsp.SupportedLanguageServers;
+import org.eclipse.cdt.lsp.core.PreferenceConstants;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.InstanceScope;
+import org.osgi.framework.FrameworkUtil;
+
+//FIXME ok, not really contributed at the moment, but will be
+public final class ContributedLanguageServers implements SupportedLanguageServers {
+
+	private final Map<String, LanguageServerConfiguration> configs;
+
+	public ContributedLanguageServers() {
+		configs = new LinkedHashMap<>();
+		register(new ClangdLanguageServer());
+		register(new CqueryLanguageServer());
+	}
+
+	@Override
+	public Collection<LanguageServerConfiguration> all() {
+		return configs.values();
+	}
+
+	public void register(LanguageServerConfiguration configuration) {
+		configs.put(configuration.identifier(), configuration);
+	}
+
+	public void unregister(LanguageServerConfiguration configuration) {
+		configs.remove(configuration.identifier());
+	}
+
+	@Override
+	public LanguageServerConfiguration preferred() throws IllegalStateException {
+		return Optional.ofNullable(InstanceScope.INSTANCE.getNode(nodeQualifier()))//
+				.filter(IEclipsePreferences.class::isInstance)//
+				.map(IEclipsePreferences.class::cast)//
+				.flatMap(x -> Optional.ofNullable(x.get(nodePath(), null)))//
+				.map(configs::get)//
+				.orElseThrow(() -> new IllegalStateException("No preferred server was found"));
+	}
+
+	private String nodeQualifier() {
+		return FrameworkUtil.getBundle(getClass()).getSymbolicName();
+	}
+
+	private String nodePath() {
+		//FIXME: rework
+		return PreferenceConstants.P_SERVER_CHOICE;
+	}
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/LspCoreMessages.java

@@ -23,7 +23,6 @@ public class LspCoreMessages extends NLS {
 		NLS.initializeMessages(BUNDLE_NAME, LspCoreMessages.class);
 	}
 
-	public static String CPPStreamConnectionProvider_e_unsupported;
 	public static String ShowStatus_busy;
 	public static String ShowStatus_idle;
 

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/LspCoreMessages.properties

@@ -12,6 +12,5 @@
 #     Alexander Fedorov <alexander.fedorov@arsysop.ru> - Bug 558484
 ###############################################################################
 
-CPPStreamConnectionProvider_e_unsupported=Unsupported Language Server
 ShowStatus_busy={0} : Busy | {1} Jobs
 ShowStatus_idle={0} : Idle

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/preferences/CPPLanguageServerPreferencePage.java

@@ -18,6 +18,8 @@ package org.eclipse.cdt.lsp.internal.ui.preferences;
 
 import java.io.File;
 
+import org.eclipse.cdt.internal.clangd.ClangdLanguageServer;
+import org.eclipse.cdt.internal.cquery.CqueryLanguageServer;
 import org.eclipse.cdt.lsp.core.CPPStreamConnectionProvider;
 import org.eclipse.cdt.lsp.core.PreferenceConstants;
 import org.eclipse.cdt.lsp.internal.ui.LspUiActivator;
@@ -52,9 +54,8 @@ public class CPPLanguageServerPreferencePage extends FieldEditorPreferencePage i
 		serverChoice = new RadioGroupFieldEditor(PreferenceConstants.P_SERVER_CHOICE,
 				LspUiMessages.CPPLanguageServerPreferencePage_server_selector, 1,
 				new String[][] {
-						{ LspUiMessages.CPPLanguageServerPreferencePage_clangd, CPPStreamConnectionProvider.CLANGD_ID },
-						{ LspUiMessages.CPPLanguageServerPreferencePage_cquery,
-								CPPStreamConnectionProvider.CQUERY_ID } },
+						{ LspUiMessages.CPPLanguageServerPreferencePage_clangd, ClangdLanguageServer.CLANGD_ID },
+						{ LspUiMessages.CPPLanguageServerPreferencePage_cquery, CqueryLanguageServer.CQUERY_ID } },
 				getFieldEditorParent());
 		addField(serverChoice);