1 files changed, 138 insertions, 0 deletions
diff --git a/tool/notes-github-pr.rb b/tool/notes-github-pr.rb
new file mode 100644
index 0000000000..d69d479cdf
--- /dev/null
+++ b/tool/notes-github-pr.rb
@@ -0,0 +1,138 @@
+#!/usr/bin/env ruby
+# Add GitHub pull request reference / author info to git notes.
+
+require 'net/http'
+require 'uri'
+require 'tmpdir'
+require 'json'
+require 'yaml'
+
+# Conversion for people whose GitHub account name and SVN_ACCOUNT_NAME are different.
+GITHUB_TO_SVN = {
+  'amatsuda'    => 'a_matsuda',
+  'matzbot'     => 'git',
+  'jeremyevans' => 'jeremy',
+  'znz'         => 'kazu',
+  'k-tsj'       => 'ktsj',
+  'nurse'       => 'naruse',
+  'ioquatix'    => 'samuel',
+  'suketa'      => 'suke',
+  'unak'        => 'usa',
+}
+
+EMAIL_YML_URL = 'https://raw.githubusercontent.com/ruby/git.ruby-lang.org/refs/heads/master/config/email.yml'
+SVN_TO_EMAILS = YAML.safe_load(Net::HTTP.get_response(URI(EMAIL_YML_URL)).tap(&:value).body)
+
+class GitHub
+  ENDPOINT = URI.parse('https://api.github.com')
+
+  def initialize(access_token)
+    @access_token = access_token
+  end
+
+  # https://developer.github.com/changes/2019-04-11-pulls-branches-for-commit/
+  def pulls(owner:, repo:, commit_sha:)
+    resp = get("/repos/#{owner}/#{repo}/commits/#{commit_sha}/pulls", accept: 'application/vnd.github.groot-preview+json')
+    JSON.parse(resp.body)
+  end
+
+  # https://developer.github.com/v3/pulls/#get-a-single-pull-request
+  def pull_request(owner:, repo:, number:)
+    resp = get("/repos/#{owner}/#{repo}/pulls/#{number}")
+    JSON.parse(resp.body)
+  end
+
+  # https://developer.github.com/v3/users/#get-a-single-user
+  def user(username:)
+    resp = get("/users/#{username}")
+    JSON.parse(resp.body)
+  end
+
+  private
+
+  def get(path, accept: 'application/vnd.github.v3+json')
+    Net::HTTP.start(ENDPOINT.host, ENDPOINT.port, use_ssl: ENDPOINT.scheme == 'https') do |http|
+      headers = { 'Accept': accept, 'Authorization': "bearer #{@access_token}" }
+      http.get(path, headers).tap(&:value)
+    end
+  end
+end
+
+module Git
+  class << self
+    def abbrev_ref(refname, repo_path:)
+      git('rev-parse', '--symbolic', '--abbrev-ref', refname, repo_path: repo_path).strip
+    end
+
+    def rev_list(arg, first_parent: false, repo_path: nil)
+      git('rev-list', *[('--first-parent' if first_parent)].compact, arg, repo_path: repo_path).lines.map(&:chomp)
+    end
+
+    def commit_message(sha)
+      git('log', '-1', '--pretty=format:%B', sha)
+    end
+
+    def notes_message(sha)
+      git('log', '-1', '--pretty=format:%N', sha)
+    end
+
+    def committer_name(sha)
+      git('log', '-1', '--pretty=format:%cn', sha)
+    end
+
+    def committer_email(sha)
+      git('log', '-1', '--pretty=format:%cE', sha)
+    end
+
+    private
+
+    def git(*cmd, repo_path: nil)
+      env = {}
+      if repo_path
+        env['GIT_DIR'] = repo_path
+      end
+      out = IO.popen(env, ['git', *cmd], &:read)
+      unless $?.success?
+        abort "Failed to execute: git #{cmd.join(' ')}\n#{out}"
+      end
+      out
+    end
+  end
+end
+
+github = GitHub.new(ENV.fetch('GITHUB_TOKEN'))
+
+repo_path, *rest = ARGV
+rest.each_slice(3).map do |oldrev, newrev, _refname|
+  system('git', 'fetch', 'origin', 'refs/notes/commits:refs/notes/commits', exception: true)
+
+  updated = false
+  Git.rev_list("#{oldrev}..#{newrev}", first_parent: true).each do |sha|
+    github.pulls(owner: 'ruby', repo: 'ruby', commit_sha: sha).each do |pull|
+      number = pull.fetch('number')
+      url = pull.fetch('html_url')
+      next unless url.start_with?('https://github.com/ruby/ruby/pull/')
+
+      # "Merged" notes for "Squash and merge"
+      message = Git.commit_message(sha)
+      notes = Git.notes_message(sha)
+      if !message.include?(url) && !message.match(/[ (]##{number}[) ]/) && !notes.include?(url)
+        system('git', 'notes', 'append', '-m', "Merged: #{url}", sha, exception: true)
+        updated = true
+      end
+
+      # "Merged-By" notes for "Rebase and merge"
+      if Git.committer_name(sha) == 'GitHub' && Git.committer_email(sha) == 'noreply@github.com'
+        username = github.pull_request(owner: 'ruby', repo: 'ruby', number: number).fetch('merged_by').fetch('login')
+        email = github.user(username: username).fetch('email')
+        email ||= SVN_TO_EMAILS[GITHUB_TO_SVN.fetch(username, username)]&.first
+        system('git', 'notes', 'append', '-m', "Merged-By: #{username}#{(" <#{email}>" if email)}", sha, exception: true)
+        updated = true
+      end
+    end
+  end
+
+  if updated
+    system('git', 'push', 'origin', 'refs/notes/commits', exception: true)
+  end
+end