Add package:trebuchet to repo.

README.md

@@ -14,6 +14,7 @@ This repository is home to general Dart Ecosystem tools and packages.
 | [firehose](pkgs/firehose/) | A tool to automate publishing of Pub packages from GitHub actions. | [![pub package](https://img.shields.io/pub/v/firehose.svg)](https://pub.dev/packages/firehose) |
 | [repo_manage](pkgs/repo_manage/) | Miscellaneous issue, repo, and PR query tools. |  |
 | [sdk_triage_bot](pkgs/sdk_triage_bot/) | A triage automation tool for dart-lang/sdk issues. |  |
+| [trebuchet](pkgs/trebuchet/) | A tool for hurling packages into monorepos. |  |
 
 ## Publishing automation
 

pkgs/trebuchet/README.md

@@ -0,0 +1,7 @@
+Run
+
+```bash
+dart run bin/trebuchet.dart --input-name coverage --branch-name master --input-path ~/projects/coverage/ --target-path ~/projects/tools/ --git-filter-repo ~/tools/git-filter-repo 
+```
+
+This basically executes the instructions at https://github.com/dart-lang/ecosystem/wiki/Merging-existing-repos-into-a-monorepo

pkgs/trebuchet/analysis_options.yaml

@@ -0,0 +1,5 @@
+include: package:dart_flutter_team_lints/analysis_options.yaml
+
+linter:
+  rules:
+    - prefer_final_locals

pkgs/trebuchet/bin/trebuchet.dart

@@ -0,0 +1,212 @@
+// Copyright (c) 2024, 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:io';
+
+import 'package:args/args.dart';
+import 'package:path/path.dart' as p;
+
+Future<void> main(List<String> arguments) async {
+  final argParser = ArgParser()
+    ..addOption(
+      'input-name',
+      help: 'Name of the package which should be transferred to a mono-repo',
+    )
+    ..addOption(
+      'input-path',
+      help: 'Path to the package which should be transferred to a mono-repo',
+    )
+    ..addOption(
+      'target-path',
+      help: 'Path to the mono-repo',
+    )
+    ..addOption(
+      'branch-name',
+      help: 'The name of the main branch on the input repo',
+      defaultsTo: 'main',
+    )
+    ..addOption(
+      'git-filter-repo',
+      help: 'Path to the git-filter-repo tool',
+    )
+    ..addFlag(
+      'push',
+      help: 'Whether to push the branch to remote',
+      defaultsTo: true,
+    )
+    ..addFlag(
+      'help',
+      abbr: 'h',
+      help: 'Prints usage info',
+      negatable: false,
+    )
+    ..addFlag(
+      'dry-run',
+      help: 'Do not actually execute any of the steps',
+      defaultsTo: false,
+    );
+
+  String input;
+  String inputPath;
+  String targetPath;
+  String branchName;
+  String gitFilterRepo;
+  bool push;
+  bool dryRun;
+  try {
+    final parsed = argParser.parse(arguments);
+    if (parsed.flag('help')) {
+      print(argParser.usage);
+      exit(0);
+    }
+
+    input = parsed['input-name'] as String;
+    inputPath = parsed['input-path'] as String;
+    targetPath = parsed['target-path'] as String;
+    branchName = parsed['branch-name'] as String;
+    gitFilterRepo = parsed['git-filter-repo'] as String;
+    push = parsed.flag('push');
+    dryRun = parsed.flag('dry-run');
+  } catch (e) {
+    print(e);
+    print('');
+    print(argParser.usage);
+    exit(1);
+  }
+
+  final trebuchet = Trebuchet(
+    input: input,
+    inputPath: inputPath,
+    targetPath: targetPath,
+    branchName: branchName,
+    gitFilterRepo: gitFilterRepo,
+    push: push,
+    dryRun: dryRun,
+  );
+
+  await trebuchet.hurl();
+}
+
+class Trebuchet {
+  final String input;
+  final String inputPath;
+  final String targetPath;
+  final String branchName;
+  final String gitFilterRepo;
+  final bool push;
+  final bool dryRun;
+
+  Trebuchet({
+    required this.input,
+    required this.inputPath,
+    required this.targetPath,
+    required this.branchName,
+    required this.gitFilterRepo,
+    required this.push,
+    required this.dryRun,
+  });
+
+  Future<void> hurl() async {
+    print('Rename to `pkgs/`');
+    await filterRepo(['--path-rename', ':pkgs/$input/']);
+
+    print('Prefix tags');
+    await filterRepo(['--tag-rename', ':$input-']);
+
+    print('Replace issue references in commit messages');
+    await inTempDir((tempDirectory) async {
+      final regexFile = File(p.join(tempDirectory.path, 'expressions.txt'));
+      await regexFile.create();
+      await regexFile.writeAsString('regex:#(\\d)==>dart-lang/$input#\\1');
+      await filterRepo(['--replace-message', regexFile.path]);
+    });
+
+    print('Create branch at target');
+    await runProcess('git', ['checkout', '-b', 'merge-$input-package']);
+
+    print('Add a remote for the local clone of the moving package');
+    await runProcess(
+      'git',
+      ['remote', 'add', '${input}_package', inputPath],
+    );
+    await runProcess('git', ['fetch', '${input}_package']);
+
+    print('Merge branch into monorepo');
+    await runProcess(
+      'git',
+      [
+        'merge',
+        '--allow-unrelated-histories',
+        '${input}_package/$branchName',
+        '-m',
+        'Merge package:$input into shared tool repository'
+      ],
+    );
+
+    if (push) {
+      print('Push to remote');
+      await runProcess(
+        'git',
+        ['push', '--set-upstream', 'origin', 'merge-$input-package'],
+      );
+    }
+
+    print('DONE!');
+    print('''
+Steps left to do:
+
+- Move and fix workflow files
+${push ? '' : '- Run `git push --set-upstream origin merge-$input-package` in the monorepo directory'}
+- Disable squash-only in GitHub settings, and merge with a fast forward merge to the main branch, enable squash-only in GitHub settings.
+- Push tags to github using `git tag --list '$input*' | xargs git push origin`
+- Follow up with a PR adding links to the top-level readme table.
+- Add a commit to https://github.com/dart-lang/$input/ with it's readme pointing to the monorepo.
+- Update the auto-publishing settings on pub.dev/packages/$input.
+- Archive https://github.com/dart-lang/$input/.
+''');
+  }
+
+  Future<void> runProcess(
+    String executable,
+    List<String> arguments, {
+    bool inTarget = true,
+  }) async {
+    final workingDirectory = inTarget ? targetPath : inputPath;
+    print('----------');
+    print('Running `$executable $arguments` in $workingDirectory');
+    if (!dryRun) {
+      final processResult = await Process.run(
+        executable,
+        arguments,
+        workingDirectory: workingDirectory,
+      );
+      print('stdout:');
+      print(processResult.stdout);
+      if ((processResult.stderr as String).isNotEmpty) {
+        print('stderr:');
+        print(processResult.stderr);
+      }
+      if (processResult.exitCode != 0) {
+        throw ProcessException(executable, arguments);
+      }
+    } else {
+      print('Not running, as --dry-run is set.');
+    }
+    print('==========');
+  }
+
+  Future<void> filterRepo(List<String> args) async {
+    await runProcess(
+      'python3',
+      [p.relative(gitFilterRepo, from: inputPath), ...args],
+      inTarget: false,
+    );
+  }
+}
+
+Future<void> inTempDir(Future<void> Function(Directory temp) f) async {
+  final tempDirectory = await Directory.systemTemp.createTemp();
+  await f(tempDirectory);
+  await tempDirectory.delete(recursive: true);
+}

pkgs/trebuchet/pubspec.yaml

@@ -0,0 +1,16 @@
+name: trebuchet
+description: A tool for hurling packages into monorepos.
+
+publish_to: none
+
+environment:
+  sdk: ^3.3.0
+
+dependencies:
+  args: ^2.5.0
+  path: ^1.9.0
+
+dev_dependencies:
+  dart_flutter_team_lints: ^3.2.0
+  lints: ^4.0.0
+  test: ^1.24.0