pkg/docgen: support dartdoc-viewer with the viewer app at the root of the repo

pkg/docgen/lib/docgen.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// **docgen** is a tool for creating machine readable representations of Dart
 /// code metadata, including: classes, members, comments and annotations.
 ///
 /// docgen is run on a `.dart` file or a directory containing `.dart` files.
 ///
 ///      $ dart docgen.dart [OPTIONS] [FILE/DIR]
@@ skipping 646 matching lines @@
 /// Convenience methods wrapped up in a class to pull down the docgen viewer for
 /// a viewable website, and start up a server for viewing.
 class _Viewer {
   static String _dartdocViewerString = path.join(Directory.current.path,
       'dartdoc-viewer');
   static Directory _dartdocViewerDir = new Directory(_dartdocViewerString);
   static Directory _topLevelTempDir;
   static Directory _webDocsDir;
   static bool movedViewerCode = false;
 
+  static String _viewerCodePath;
+
+  /*
+   * dartdoc-viewer currently has the web app code under a 'client' directory
+   *
+   * This is confusing for folks that want to clone and modify the code.
+   * It also includes a number of python files and other content related to
+   * app engine hosting that are not needed.
+   *
+   * This logic exists to support the current model and a (future) updated
+   * dartdoc-viewer repo where the 'client' content exists at the root of the
+   * project and the other content is removed.
+   */
+  static String get viewerCodePath {
+    if(_viewerCodePath == null) {
+      var pubspecFileName = 'pubspec.yaml';
+
+      var thePath = _dartdocViewerDir.path;
+
+      if(!FileSystemEntity.isFileSync(path.join(thePath, pubspecFileName))) {
+        thePath = path.join(thePath, 'client');
+        print('trying the fallback: $thePath');
+        if (!FileSystemEntity.isFileSync(path.join(thePath, pubspecFileName))) {
+          throw new StateError('Could not find a pubspec file');
+        }
+      }
+
+      _viewerCodePath = thePath;
+    }
+    return _viewerCodePath;
+  }
+
   /// If our dartdoc-viewer code is already checked out, move it to a temporary
   /// directory outside of the package directory, so we don't try to process it
   /// for documentation.
   static void ensureMovedViewerCode() {
     // TODO(efortuna): This will need to be modified to run on anyone's package
     // outside of the checkout!
     if (_dartdocViewerDir.existsSync()) {
       _topLevelTempDir = new Directory(
           _Generator._rootDirectory).createTempSync();
       _dartdocViewerDir.renameSync(_topLevelTempDir.path);
@@ skipping 14 matching lines @@
     else {
       var processResult = Process.runSync('git', ['clone', '-b', 'master',
           'git://github.com/dart-lang/dartdoc-viewer.git'],
           runInShell: true);
 
       if (processResult.exitCode == 0) {
         /// Move the generated json/yaml docs directory to the dartdoc-viewer
         /// directory, to run as a webpage.
         var processResult = Process.runSync(_Generator._pubScript,
             ['upgrade'], runInShell: true,
-            workingDirectory: path.join(_dartdocViewerDir.path, 'client'));
+            workingDirectory: path.join(viewerCodePath, 'client'));
         print('process output: ${processResult.stdout}');
         print('process stderr: ${processResult.stderr}');
 
         var dir = new Directory(_Generator._outputDirectory == null? 'docs' :
             _Generator._outputDirectory);
-        _webDocsDir = new Directory(path.join(_dartdocViewerDir.path, 'client',
+        _webDocsDir = new Directory(path.join(viewerCodePath, 'client',
             'web', 'docs'));
         if (dir.existsSync()) {
           // Move the docs folder to dartdoc-viewer/client/web/docs
           dir.renameSync(_webDocsDir.path);
         }
       } else {
         print('Error cloning git repository:');
         print('process output: ${processResult.stdout}');
         print('process stderr: ${processResult.stderr}');
       }
     }
   }
 
   static void _compile() {
     if (_webDocsDir.existsSync()) {
       // Compile the code to JavaScript so we can run on any browser.
       print('Compile app to JavaScript for viewing.');
       var processResult = Process.runSync(_Generator._dartBinary,
-          ['deploy.dart'], workingDirectory : path.join(_dartdocViewerDir.path,
+          ['deploy.dart'], workingDirectory : path.join(viewerCodePath,
           'client'), runInShell: true);
       print('process output: ${processResult.stdout}');
       print('process stderr: ${processResult.stderr}');
-      var outputDir = path.join(_dartdocViewerDir.path, 'client', 'out', 'web');
+      var outputDir = path.join(viewerCodePath, 'client', 'out', 'web');
       print('Docs are available at $outputDir');
     }
   }
 
   /// A simple HTTP server. Implemented here because this is part of the SDK,
   /// so it shouldn't have any external dependencies.
   static void _runServer() {
     // Launch a server to serve out of the directory dartdoc-viewer/client/web.
     HttpServer.bind('localhost', 8080).then((HttpServer httpServer) {
       print('Server launched. Navigate your browser to: '
           'http://localhost:${httpServer.port}');
       httpServer.listen((HttpRequest request) {
         var response = request.response;
-        var basePath = path.join(_dartdocViewerDir.path, 'client', 'out',
+        var basePath = path.join(viewerCodePath, 'client', 'out',
             'web');
         var requestPath = path.join(basePath, request.uri.path.substring(1));
         bool found = true;
         var file = new File(requestPath);
         if (file.existsSync()) {
           // Set the correct header type.
           if (requestPath.endsWith('.html')) {
             response.headers.set('Content-Type', 'text/html');
           } else if (requestPath.endsWith('.js')) {
             response.headers.set('Content-Type', 'application/javascript');
@@ skipping 1446 matching lines @@
         .map((e) => originalMirror.getField(e.simpleName).reflectee)
         .where((e) => e != null)
         .toList();
   }
 
   Map toMap() => {
     'name': Indexable.getDocgenObject(mirror, owningLibrary).docName,
     'parameters': parameters
   };
 }