Provide documentation on hover, in .kafka files

Fixes jlandersen#149

Signed-off-by: azerr <[email protected]>

src/kafka-file/kafkaFileClient.ts

@@ -61,6 +61,12 @@ export function startLanguageClient(
     const diagnostics = new KafkaFileDiagnostics(kafkaFileDocuments, languageService);
     context.subscriptions.push(diagnostics);
 
+    // Hover
+    const hover = new KafkaFileHoverProvider(kafkaFileDocuments, languageService);
+    context.subscriptions.push(
+        vscode.languages.registerHoverProvider(documentSelector, hover)
+    );
+
     // Open / Close document
     context.subscriptions.push(vscode.workspace.onDidOpenTextDocument(e => {
         if (e.languageId === 'kafka') {
@@ -181,7 +187,7 @@ class KafkaFileCompletionItemProvider extends AbstractKafkaFileFeature implement
         return runSafeAsync(async () => {
             const kafkaFileDocument = this.getKafkaFileDocument(document);
             return this.languageService.doComplete(document, kafkaFileDocument, position);
-        }, new vscode.CompletionList(), `Error while computing code lenses for ${document.uri}`, token);
+        }, new vscode.CompletionList(), `Error while computing completion for ${document.uri}`, token);
     }
 
 }
@@ -230,3 +236,13 @@ class KafkaFileDiagnostics extends AbstractKafkaFileFeature implements vscode.Di
         this.diagnosticCollection.dispose();
     }
 }
+
+class KafkaFileHoverProvider extends AbstractKafkaFileFeature implements vscode.HoverProvider {
+    provideHover(document: vscode.TextDocument, position: vscode.Position, token: vscode.CancellationToken): vscode.ProviderResult<vscode.Hover> {
+        return runSafeAsync(async () => {
+            const kafkaFileDocument = this.getKafkaFileDocument(document);
+            return this.languageService.doHover(document, kafkaFileDocument, position);
+        }, null, `Error while computing hover for ${document.uri}`, token);       
+    }
+
+}

src/kafka-file/languageservice/kafkaFileLanguageService.ts

@@ -1,10 +1,11 @@
-import { CodeLens, CompletionList, Diagnostic, Position, TextDocument, Uri } from "vscode";
+import { CodeLens, CompletionList, Diagnostic, Hover, Position, TextDocument, Uri } from "vscode";
 import { ConsumerLaunchState } from "../../client";
 import { ProducerLaunchState } from "../../client/producer";
 import { KafkaFileDocument, parseKafkaFile } from "./parser/kafkaFileParser";
 import { KafkaFileCodeLenses } from "./services/codeLensProvider";
 import { KafkaFileCompletion } from "./services/completion";
 import { KafkaFileDiagnostics } from "./services/diagnostics";
+import { KafkaFileHover } from "./services/hover";
 
 /**
  * Provider API which gets the state for a given producer.
@@ -45,6 +46,7 @@ export interface TopicProvider {
  *
  */
 export interface LanguageService {
+
     /**
      * Parse the given text document and returns an AST.
      *
@@ -80,6 +82,15 @@ export interface LanguageService {
      * @param kafkaFileDocument the parsed AST.
      */
     doDiagnostics(document: TextDocument, kafkaFileDocument: KafkaFileDocument): Diagnostic[];
+
+    /**
+     * Returns the hover result for the given text document and parsed AST at given position.
+     *
+     * @param document the text document.
+     * @param kafkaFileDocument the parsed AST.
+     * @param position the position where the hover was triggered.
+     */
+    doHover(document: TextDocument, kafkaFileDocument: KafkaFileDocument, position: Position): Promise<Hover | undefined>;
 }
 
 /**
@@ -95,10 +106,12 @@ export function getLanguageService(producerLaunchStateProvider: ProducerLaunchSt
     const codeLenses = new KafkaFileCodeLenses(producerLaunchStateProvider, consumerLaunchStateProvider, selectedClusterProvider);
     const completion = new KafkaFileCompletion(selectedClusterProvider, topicProvider);
     const diagnostics = new KafkaFileDiagnostics();
+    const hover = new KafkaFileHover(selectedClusterProvider, topicProvider);
     return {
         parseKafkaFileDocument: (document: TextDocument) => parseKafkaFile(document),
         getCodeLenses: codeLenses.getCodeLenses.bind(codeLenses),
         doComplete: completion.doComplete.bind(completion),
-        doDiagnostics: diagnostics.doDiagnostics.bind(diagnostics)
+        doDiagnostics: diagnostics.doDiagnostics.bind(diagnostics),
+        doHover: hover.doHover.bind(hover)
     };
 }

src/kafka-file/languageservice/parser/kafkaFileParser.ts

@@ -18,6 +18,7 @@ export interface Node {
     start: Position;
     end: Position;
     findNodeBefore(offset: Position): Node;
+    findNodeAt(offset: Position): Node;
     lastChild: Node | undefined;
     parent: Node | undefined;
     kind: NodeKind;
@@ -36,6 +37,10 @@ class BaseNode implements Node {
         return this;
     }
 
+    public findNodeAt(offset: Position): Node {
+        return this;
+    }
+
     public get lastChild(): Node | undefined { return undefined; }
 }
 
@@ -65,6 +70,17 @@ class ChildrenNode<T extends Node> extends BaseNode {
         return this;
     }
 
+    public findNodeAt(offset: Position): Node {
+        const idx = findFirst(this.children, c => offset.isBeforeOrEqual(c.start)) - 1;
+        if (idx >= 0) {
+            const child = this.children[idx];
+            if (offset.isAfter(child.start) && offset.isBeforeOrEqual(child.end)) {
+                return child.findNodeAt(offset);
+            }
+        }
+        return this;
+    }
+
     public get lastChild(): Node | undefined { return this.children.length ? this.children[this.children.length - 1] : void 0; };
 }
 

src/kafka-file/languageservice/services/hover.ts

@@ -0,0 +1,20 @@
+import { Hover, Position, TextDocument } from "vscode";
+import { SelectedClusterProvider, TopicProvider } from "../kafkaFileLanguageService";
+import { KafkaFileDocument } from "../parser/kafkaFileParser";
+
+export class KafkaFileHover {
+
+    constructor(selectedClusterProvider: SelectedClusterProvider, topicProvider: TopicProvider) {
+
+    }
+
+    async doHover(document: TextDocument, kafkaFileDocument: KafkaFileDocument, position: Position): Promise<Hover | undefined> {
+         // Get the AST node before the position where complation was triggered
+         const node = kafkaFileDocument.findNodeAt(position);
+         if (!node) {
+             return;
+         }
+
+         return new Hover('TODO ' + node.kind);
+    }
+}