feat: Support syntax coloration for code block in LSP hover

Fixes #297

Signed-off-by: azerr <azerr@redhat.com>

Author: angelozerr

docs/LSPSupport.md

@@ -192,13 +192,64 @@ Here is an example with the [Qute language server](https://github.com/redhat-dev
 
 #### Hover
 
-[textDocument/hover](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_hover) is implemented with `platform.backend.documentation.targetProvider` 
-extension point to support any language and `textDocument/hover` works out-of-the-box.
+[textDocument/hover](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_hover) is implemented with the `platform.backend.documentation.targetProvider` 
+extension point, to support any language, making `textDocument/hover` work out-of-the-box for all languages.
 
 Here is an example with the [Qute language server](https://github.com/redhat-developer/quarkus-ls/tree/master/qute.ls) showing documentation while hovering over an `include` section:
 
 ![textDocument/hover](./images/lsp-support/textDocument_hover.png)
 
+##### Syntax Coloration
+
+LSP4IJ supports `Syntax Coloration` on hover and completion documentation. Here is an example with [Rust Analyzer](https://rust-analyzer.github.io/): 
+
+![textDocument/hover Syntax Coloration](./images/lsp-support/textDocument_hover_syntax_coloration.png)
+
+`Syntax Coloration` is supported in:
+
+ * MarkDown [Fenced Code Block](https://www.markdownguide.org/extended-syntax/#fenced-code-blocks).
+
+  ~~~
+     ```ts
+     const s = "";
+     const c = s.charAt(0);
+     ```
+  ~~~
+   
+ It will apply the `TypeScript TextMate` highlighting, inferred from the `ts` file extension, and will be rendered like:
+
+![textDocument/hover Syntax Coloration Code Block](./images/lsp-support/textDocument_hover_syntax_coloration_codeBlock.png)
+
+ * MarkDown [Indented Blockquote](https://www.markdownguide.org/basic-syntax/#blockquotes-1) (`>` following with `5 spaces`).
+
+  ```
+  >     const s = '';
+  >     const c = s.charAt(0);
+  ```
+
+will use the Syntax coloration which triggers the hover / completion.
+
+![textDocument/hover Syntax Coloration Blockquote](./images/lsp-support/textDocument_hover_syntax_coloration_codeBlock.png)
+
+###### Syntax coloration discovery
+
+The rules to retrieve the proper syntax coloration are:
+
+ * if the code block defines the file extension, LSP4IJ tries to apply a matching TextMate grammar or custom syntax coloration by filename, mimetype.
+ * if the code block defines a language Id (e.g. `typescript`) and the syntax coloration must be retrieved from TextMate, it will use the 
+[fileNamePatterns extension point](./DeveloperGuide.md#file-name-pattern-mapping) or [./UserDefinedLanguageServer.md#mappings-tab](fileNamePattern of User defined language server)
+to find the file extension (e.g. `ts`) associated with the languageId (e.g. `typescript`) 
+  ~~~
+     ```typescript
+     const s = "";
+     const c = s.charAt(0);
+     ```
+  ~~~
+ * if the code block doesn't define the language, or indented blockquotes are used, it will fall back to the syntax coloration from the file in which the hover / completion documentation request was triggered.
+
+If those strategies are insufficient for your needs, please [create an issue](https://github.com/redhat-developer/lsp4ij/issues) to request an extension point 
+for mapping the language and the file extension.
+
 #### CodeLens
 
 [textDocument/codeLens](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_codeLens) is implemented with the `codeInsight.codeVisionProvider` extension point.

docs/images/lsp-support/textDocument_hover_syntax_coloration.png

@@ -13,7 +13,7 @@ platformType=IC
 platformVersion=2023.2
 # Plugin Dependencies -> https://plugins.jetbrains.com/docs/intellij/plugin-dependencies.html
 # Example: platformPlugins = com.intellij.java, com.jetbrains.php:203.4449.22
-platformPlugins=com.redhat.devtools.intellij.telemetry:1.1.0.52
+platformPlugins=com.redhat.devtools.intellij.telemetry:1.1.0.52, textmate
 # Gradle Releases -> https://github.com/gradle/gradle/releases
 gradleVersion=8.5
 channel=nightly

docs/images/lsp-support/textDocument_hover_syntax_coloration_codeBlock.png

@@ -58,6 +58,9 @@ public static LanguageServersRegistry getInstance() {
 
     private final List<LanguageServerFileAssociation> fileAssociations = new ArrayList<>();
 
+    private final Map<String /* languageId (ex : typescript) */,
+            List<String> /* file extensions (ex : ts) */> languageIdFileExtensionsCache = new HashMap<>();
+
     private final Collection<LanguageServerDefinitionListener> listeners = new CopyOnWriteArrayList<>();
 
     private final List<ProviderInfo<? extends Object>> inlayHintsProviders = new ArrayList<>();
@@ -71,7 +74,6 @@ private void initialize() {
         loadServersAndMappingsFromExtensionPoint();
         // Load language servers / mappings from user settings
         loadServersAndMappingFromSettings();
-
         updateLanguages();
     }
 
@@ -192,7 +194,7 @@ private void updateFindUsagesProvider(Set<Language> distinctLanguages) {
         LSPFindUsagesProvider provider = new LSPFindUsagesProvider();
         for (Language language : distinctLanguages) {
             var existingProviders = LanguageFindUsages.INSTANCE.allForLanguage(language);
-            if (existingProviders.isEmpty() ||  (existingProviders.size() == 1 && existingProviders.get(0) instanceof EmptyFindUsagesProvider)) {
+            if (existingProviders.isEmpty() || (existingProviders.size() == 1 && existingProviders.get(0) instanceof EmptyFindUsagesProvider)) {
                 LanguageFindUsages.INSTANCE.addExplicitExtension(language, provider);
             }
         }
@@ -258,6 +260,21 @@ public void registerAssociation(@NotNull LanguageServerDefinition serverDefiniti
             @Nullable String languageId = mapping.getLanguageId();
             if (!StringUtils.isEmpty(languageId)) {
                 serverDefinition.registerAssociation(matchers, languageId);
+                // Update the mapping languageId -> file extensions
+                var fileExtensions = languageIdFileExtensionsCache.get(languageId);
+                if (fileExtensions == null) {
+                    fileExtensions = new ArrayList<>();
+                    languageIdFileExtensionsCache.put(languageId, fileExtensions);
+                }
+                fileExtensions.addAll(fileNamePatternMapping
+                        .getFileNamePatterns()
+                        .stream()
+                        .map(fileExtension -> {
+                            int index = fileExtension.indexOf('.');
+                            return index != -1 ? fileExtension.substring(index + 1, fileExtension.length()) : fileExtension;
+                        })
+                        .toList());
+
             }
             fileAssociations.add(new LanguageServerFileAssociation(matchers, serverDefinition, mapping.getDocumentMatcher(), languageId));
         }
@@ -521,12 +538,24 @@ public List<ProviderInfo<? extends Object>> getInlayHintProviderInfos() {
         return inlayHintsProviders;
     }
 
-    public record UpdateServerDefinitionRequest(@NotNull Project project, @NotNull UserDefinedLanguageServerDefinition serverDefinition,
+    public record UpdateServerDefinitionRequest(@NotNull Project project,
+                                                @NotNull UserDefinedLanguageServerDefinition serverDefinition,
                                                 @Nullable String name, @Nullable String commandLine,
                                                 @Nullable Map<String, String> userEnvironmentVariables,
                                                 boolean includeSystemEnvironmentVariables,
                                                 @NotNull List<ServerMappingSettings> mappings,
                                                 @Nullable String configurationContent,
                                                 @Nullable String initializationOptionsContent) {
     }
+
+    /**
+     * Returns the list of supported file extensions (ex: ts) for the given language Id (ex : typescript) and null otherwise.
+     *
+     * @param languageId the language Id (ex : typescript).
+     * @return the list of supported file extensions (ex: ts) for the given language Id (ex : typescript) and null otherwise.
+     */
+    @Nullable
+    public List<String> getFileExtensions(String languageId) {
+        return languageIdFileExtensionsCache.get(languageId);
+    }
 }

gradle.properties

@@ -27,15 +27,14 @@
 import com.intellij.openapi.ui.popup.JBPopupListener;
 import com.intellij.openapi.ui.popup.LightweightWindowEvent;
 import com.redhat.devtools.lsp4ij.console.LSPConsoleToolWindowPanel;
+import com.redhat.devtools.lsp4ij.features.documentation.MarkdownConverter;
 import com.redhat.devtools.lsp4ij.internal.StringUtils;
 import org.eclipse.lsp4j.*;
 import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
 import java.util.concurrent.CompletableFuture;
 
-import static com.redhat.devtools.lsp4ij.features.documentation.MarkdownConverter.toHTML;
-
 public class ServerMessageHandler {
 
     public static final String LSP_WINDOW_SHOW_MESSAGE_GROUP_ID = "LSP/window/showMessage";
@@ -87,7 +86,7 @@ public static void showMessage(@NotNull String title,
                                    @NotNull Project project) {
         Notification notification = new Notification(LSP_WINDOW_SHOW_MESSAGE_GROUP_ID,
                 title,
-                toHTML(params.getMessage()),
+                MarkdownConverter.getInstance(project).toHtml(params.getMessage()),
                 messageTypeToNotificationType(params.getType()));
         notification.setListener(NotificationListener.URL_OPENING_LISTENER);
         notification.setIcon(messageTypeToIcon(params.getType()));
@@ -101,13 +100,14 @@ public static void showMessage(@NotNull String title,
      * @param params  the message request parameters
      */
     public static CompletableFuture<MessageActionItem> showMessageRequest(@NotNull LanguageServerWrapper serverWrapper,
-                                                                          @NotNull ShowMessageRequestParams params) {
+                                                                          @NotNull ShowMessageRequestParams params,
+                                                                          @NotNull Project project) {
         CompletableFuture<MessageActionItem> future = new CompletableFuture<>();
         ApplicationManager.getApplication()
                 .invokeLater(() -> {
                     String languageServerName = serverWrapper.getServerDefinition().getDisplayName();
                     String title = params.getMessage();
-                    String content = toHTML(params.getMessage());
+                    String content = MarkdownConverter.getInstance(project).toHtml(params.getMessage());
                     final Notification notification = new Notification(
                             LSP_WINDOW_SHOW_MESSAGE_REQUEST_GROUP_ID,
                             languageServerName,

src/main/java/com/redhat/devtools/lsp4ij/LanguageServersRegistry.java

@@ -79,7 +79,7 @@ public void telemetryEvent(Object object) {
 
     @Override
     public final CompletableFuture<MessageActionItem> showMessageRequest(ShowMessageRequestParams requestParams) {
-        return ServerMessageHandler.showMessageRequest(wrapper, requestParams);
+        return ServerMessageHandler.showMessageRequest(wrapper, requestParams, getProject());
     }
 
     @Override

src/main/java/com/redhat/devtools/lsp4ij/ServerMessageHandler.java

@@ -32,6 +32,7 @@
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.PsiFile;
 import com.redhat.devtools.lsp4ij.*;
+import com.redhat.devtools.lsp4ij.features.documentation.MarkdownConverter;
 import org.eclipse.lsp4j.*;
 import org.eclipse.lsp4j.services.LanguageServer;
 import org.jetbrains.annotations.NotNull;
@@ -47,8 +48,6 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.stream.Stream;
 
-import static com.redhat.devtools.lsp4ij.features.documentation.MarkdownConverter.toHTML;
-
 /**
  * This class provides methods to execute LSP {@link Command} instances.
  */
@@ -105,11 +104,12 @@ public static boolean executeCommand(LSPCommandContext context) {
             }
         }
         if (context.isShowNotificationError()) {
+            Project project = context.getProject();
             String commandId = context.getCommand().getCommand();
             var preferredLanguageServer = context.getPreferredLanguageServer();
             String content = preferredLanguageServer != null ?
-                    toHTML(LanguageServerBundle.message("lsp.command.error.with.ls.content", commandId, preferredLanguageServer.getServerWrapper().getServerDefinition().getDisplayName())):
-                    toHTML(LanguageServerBundle.message("lsp.command.error.without.ls.content", commandId));
+                    MarkdownConverter.getInstance(project).toHtml(LanguageServerBundle.message("lsp.command.error.with.ls.content", commandId, preferredLanguageServer.getServerWrapper().getServerDefinition().getDisplayName())):
+                    MarkdownConverter.getInstance(project).toHtml(LanguageServerBundle.message("lsp.command.error.without.ls.content", commandId));
 
             Notification notification = new Notification(LSPNotificationConstants.LSP4IJ_GENERAL_NOTIFICATIONS_ID,
                     LanguageServerBundle.message("lsp.command.error.title", commandId),

src/main/java/com/redhat/devtools/lsp4ij/client/LanguageClientImpl.java

@@ -49,7 +49,8 @@
 import java.util.concurrent.ExecutionException;
 
 import static com.redhat.devtools.lsp4ij.features.completion.snippet.LspSnippetVariableConstants.*;
-import static com.redhat.devtools.lsp4ij.features.documentation.LSPDocumentationHelper.convertToHTML;
+import static com.redhat.devtools.lsp4ij.features.documentation.LSPDocumentationHelper.convertToHtml;
+import static com.redhat.devtools.lsp4ij.features.documentation.LSPDocumentationHelper.getValidMarkupContents;
 import static com.redhat.devtools.lsp4ij.internal.CompletableFutures.isDoneNormally;
 import static com.redhat.devtools.lsp4ij.internal.CompletableFutures.waitUntilDone;
 import static com.redhat.devtools.lsp4ij.ui.IconMapper.getIcon;
@@ -584,16 +585,22 @@ private static Integer getPrefixStartOffsetWhichMatchesLeftContent(@NotNull Docu
     public DocumentationResult computeDocumentation() {
         var documentation = item.getDocumentation();
         if (documentation != null) {
-            MarkupContent content = getDocumentation(documentation);
-            return DocumentationResult.documentation(convertToHTML(content, editor));
+            var contents = getValidMarkupContents(item);
+            if (contents.isEmpty()) {
+                return null;
+            }
+            return DocumentationResult.documentation(convertToHtml(contents, file));
         } else if (supportResolveCompletion) {
             if (resolvedCompletionItemFuture != null && resolvedCompletionItemFuture.isDone()) {
                 CompletionItem resolved = getResolvedCompletionItem();
                 if (resolved != null) {
                     item.setDocumentation(resolved.getDocumentation());
                 }
-                MarkupContent content = getDocumentation(documentation);
-                return DocumentationResult.documentation(convertToHTML(content, editor));
+                var contents = getValidMarkupContents(item);
+                if (contents.isEmpty()) {
+                    return null;
+                }
+                return DocumentationResult.documentation(convertToHtml(contents, file));
             } else {
                 DocumentationResult.asyncDocumentation(() -> {
                     // The LSP completion item 'documentation' is not filled, try to resolve it
@@ -602,26 +609,17 @@ public DocumentationResult computeDocumentation() {
                     if (resolved != null) {
                         item.setDocumentation(resolved.getDocumentation());
                     }
-                    MarkupContent content = getDocumentation(documentation);
-                    return DocumentationResult.documentation(convertToHTML(content, editor));
+                    var contents = getValidMarkupContents(item);
+                    if (contents.isEmpty()) {
+                        return null;
+                    }
+                    return DocumentationResult.documentation(convertToHtml(contents, file));
                 });
             }
         }
         return null;
     }
 
-    private static MarkupContent getDocumentation(Either<String, MarkupContent> documentation) {
-        if (documentation == null) {
-            return null;
-        }
-        if (documentation.isLeft()) {
-            String content = documentation.getLeft();
-            return new MarkupContent(MarkupKind.PLAINTEXT, content);
-        }
-        return documentation.getRight();
-    }
-
-
     @NotNull
     @Override
     public TargetPresentation computePresentation() {