Add summary command to bot.

tools/gardening/lib/src/bot.dart

Index: tools/gardening/lib/src/bot.dart
diff --git a/tools/gardening/lib/src/bot.dart b/tools/gardening/lib/src/bot.dart
new file mode 100644
index 0000000000000000000000000000000000000000..c0cce3cd24d71509dbbc6cb0b0cc1656c26f82c9
--- /dev/null
+++ b/tools/gardening/lib/src/bot.dart
@@ -0,0 +1,67 @@
+// Copyright (c) 2017, 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.
+
+import 'dart:async';
+
+import 'buildbot_data.dart';
+import 'buildbot_structures.dart';
+import 'client.dart';
+import 'util.dart';
+
+class Bot {
+  final bool usesLogdog;
+  final BuildbotClient _client;
+
+  /// Instantiates a Bot.
+  ///
+  /// Bots must be [close]d when they aren't needed anymore.
+  Bot({bool logdog = false})
+      : usesLogdog = logdog,
+        _client =
+            logdog ? new LogdogBuildbotClient() : new HttpBuildbotClient();
+
+  /// Reads the build result of [buildUri] and the [previousCount] earlier
+  /// builds.
+  Future<List<BuildResult>> readHistoricResults(BuildUri buildUri,
+      {int previousCount = 0}) {
+    log("Fetching $buildUri and $previousCount previous builds in parallel");
+    var uris = [buildUri];
+    for (int i = 0; i < previousCount; i++) {
+      buildUri = buildUri.prev();
+      uris.add(buildUri);
+    }
+    return readResults(uris);
+  }
+
+  Future<BuildResult> readResult(BuildUri buildUri) {
+    return _client.readResult(buildUri);
+  }
+
+  Future<List<BuildResult>> readResults(List<BuildUri> buildUris) async {
+    var result = <BuildResult>[];
+    int i = 0;
+    const maxParallel = 20;
+    while (i < buildUris.length) {
+      var end = i + maxParallel;
+      if (end > buildUris.length) end = buildUris.length;
+      var parallelChunk = buildUris.sublist(i, end);
+      log("Fetching ${end - i} uris in parallel");
+      result.addAll(await Future.wait(parallelChunk.map(_client.readResult)));
+      i = end + 1;
+    }
+    return result;
+  }
+
+  /// Returns uris for the most recent build of all build groups.
+  List<BuildUri> get mostRecentUris {
+    List<BuildUri> result = [];
+    for (BuildGroup group in buildGroups) {
+      result.addAll(group.createUris(_client.mostRecentBuildNumber));
+    }
+    return result;
+  }
+
+  /// Closes the bot.
+  void close() => _client.close();
+}