Add a generate script to generate the googleapis libraries.

lib/googleapis_generator.dart

Index: lib/googleapis_generator.dart
diff --git a/lib/googleapis_generator.dart b/lib/googleapis_generator.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5f738edf4a372454ae54a6c578c822106547b140
--- /dev/null
+++ b/lib/googleapis_generator.dart
@@ -0,0 +1,78 @@
+// Copyright (c) 2015, 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.
+
+library googleapis_generator;
+
+import "dart:io";
+import "dart:async";
+import "dart:convert";
+
+import 'package:discoveryapis_generator/discoveryapis_generator.dart';
+import 'package:http/http.dart' as http;
+
+import 'src/package_configuration.dart';
+
+Future<List<DirectoryListItems>> _listAllApis() {
+  var client = new http.Client();
+  return _discoveryClient(client).apis.list().then((DirectoryList list) {
+    return list.items;
+  }).whenComplete(() => client.close());
+}
+
+Future<List<GenerateResult>> downloadDiscoveryDocuments(
+    String outputDir, {List<String> ids}) {
+  var apiDescriptions = <RestDescription>[];
+
+  var client = new http.Client();
+  var discovery = _discoveryClient(client);
+  return discovery.apis.list().then((DirectoryList list) {
+    var futures = <Future>[];
+    for (var item in list.items) {
+      if (ids == null || ids.contains(item.id)) {
+        futures.add(discovery.apis.getRest(item.name, item.version).then((doc) {
+          apiDescriptions.add(doc);
+        }));
+      }
+    }
+    return Future.wait(futures).whenComplete(() => client.close());
+  }).then((_) {
+    var directory = new Directory(outputDir);
+    if (directory.existsSync()) {
+      print('Deleting directory $outputDir.');
+      directory.deleteSync(recursive: true);
+    }
+    directory.createSync(recursive: true);
+
+    for (var description in apiDescriptions) {
+      var name = '$outputDir/${description.name}__${description.version}.json';
+      var file = new File(name);
+      var encoder = new JsonEncoder.withIndent('    ');
+      file.writeAsStringSync(encoder.convert(description.toJson()));
+      print('Written: $name');
+    }
+  });
+}
+
+Future generateFromConfiguration(String configFile) {
+  return _listAllApis().then((List<DirectoryListItems> items) {
+    var configuration = new DiscoveryPackagesConfiguration(configFile, items);
+
+    // Print warnings for APIs not mentioned.
+    if (configuration.missingApis.isNotEmpty) {
+      print('WARNING: No configuration for the following APIs:');
+      configuration.missingApis.forEach((id) => print('- $id'));
+    }
+    if (configuration.excessApis.isNotEmpty) {
+      print('WARNING: The following APIs do not exist:');
+      configuration.excessApis.forEach((id) => print('- $id'));
+    }
+
+    // Generate the packages.
+    var configFileUri = new Uri.file(configFile);
+    return configuration.generate(configFileUri.resolve('discovery').path,
+                                  configFileUri.resolve('generated').path);
+  });
+}
+
+DiscoveryApi _discoveryClient(http.Client client) => new DiscoveryApi(client);