Attempt to autodetect language using "resolve queries"

Author: shati-patel

extensions/ql-vscode/package.json

@@ -245,6 +245,10 @@
         "command": "codeQL.runQuery",
         "title": "CodeQL: Run Query"
       },
+      {
+        "command": "codeQL.findLanguage",
+        "title": "CodeQL: Find Language"
+      },
       {
         "command": "codeQL.runQueryOnMultipleDatabases",
         "title": "CodeQL: Run Query on Multiple Databases"
@@ -684,6 +688,10 @@
           "command": "codeQL.runQuery",
           "when": "resourceLangId == ql && resourceExtname == .ql"
         },
+        {
+          "command": "codeQL.findLanguage",
+          "when": "resourceLangId == ql && resourceExtname == .ql"
+        },
         {
           "command": "codeQL.runQueryOnMultipleDatabases",
           "when": "resourceLangId == ql && resourceExtname == .ql"

extensions/ql-vscode/src/cli.ts

@@ -8,7 +8,7 @@ import { Readable } from 'stream';
 import { StringDecoder } from 'string_decoder';
 import * as tk from 'tree-kill';
 import { promisify } from 'util';
-import { CancellationToken, Disposable } from 'vscode';
+import { CancellationToken, Disposable, Uri, window } from 'vscode';
 
 import { BQRSInfo, DecodedBqrsChunk } from './pure/bqrs-cli-types';
 import { CliConfig } from './config';
@@ -482,6 +482,36 @@ export class CodeQLCliServer implements Disposable {
     return await this.runJsonCodeQlCliCommand<QuerySetup>(['resolve', 'library-path'], subcommandArgs, 'Resolving library paths');
   }
 
+  /**
+   * Finds the language that a query is analyzing.
+   * @param queryUri The URI of the query
+   */
+  async findLanguage(workspaces: string[], queryUri?: Uri): Promise<string> {
+    let language = '';
+    if (queryUri) {
+      const subcommandArgs = [
+        '--format', 'bylanguage',
+        queryUri.fsPath,
+        '--additional-packs',
+        workspaces.join(path.delimiter)
+      ];
+      try {
+        const JSONResults = await this.runCodeQlCliCommand(['resolve', 'queries'], subcommandArgs, 'Finding query language');
+
+        // This corresponds to `codeql resolve queries <query> --format bylanguage | jq -r '.byLanguage | keys[]'`
+        language = Object.keys(JSON.parse(JSONResults).byLanguage)[0];
+      }
+      catch (e) {
+        // Add an option to manually specify the language, in case automatic language detection fails.
+        void this.logger.log('Failed to detect language. Using manual prompt instead.');
+        language = await window.showQuickPick(
+          ['cpp', 'csharp', 'go', 'java', 'javascript', 'python'], { placeHolder: 'Select language' }
+        ) || '';
+      }
+    }
+    return language;
+  }
+
   /**
    * Finds all available QL tests in a given directory.
    * @param testPath Root of directory tree to search for tests.

extensions/ql-vscode/src/extension.ts

@@ -559,6 +559,17 @@ async function activateWithInstalledDistribution(
       }
     )
   );
+  // TODO: Remove this and the package.json changes
+  // (Temporary new command to test `cliServer.findLanguage`)
+  ctx.subscriptions.push(
+    commandRunner('codeQL.findLanguage', async (
+      uri: Uri | undefined
+    ) => {
+      const diskWorkspaceFolders = helpers.getOnDiskWorkspaceFolders();
+      const language = await cliServer.findLanguage(diskWorkspaceFolders, uri || window.activeTextEditor?.document.uri);
+      void helpers.showAndLogInformationMessage(language);
+    })
+  );
   interface DatabaseQuickPickItem extends QuickPickItem {
     databaseItem: DatabaseItem;
   }