Very early UI on top of rake-version gem

release.rake

desc "Bump the version, update the changelog, create a new tag"
task :release, [:semver, :debug] do |task, args|
  @debug       = false
  @semver_type = nil
  @old_version = nil
  @new_version = nil
  @commit_log  = nil
  @today       = Date.today.strftime('%Y-%m-%d')

  @debug = true unless args[:debug].nil?

  if args[:semver].nil?
    puts "No semver type given {major,minor,patch}. Exiting."
    puts args.to_hash.inspect if @debug
    exit 1
  else
    @semver_type = args[:semver]
    puts "Creating new #{@semver_type} release." if @debug
  end

  #############################################################################
  # Get current version.
  @old_version = `cat VERSION`
  puts "Previous version #{@old_version}" if @debug

  #############################################################################
  # Bump the version.
  print "New version "
  Rake::Task["version:bump:#{@semver_type}"].invoke
  @new_version = `cat VERSION`

  #############################################################################
  # List commits since last version.
  @commit_log = `git log --pretty=format:'%h %s (%aN)' #{@old_version}..HEAD`.split "\n"
  if @debug
    puts "New changes:"
    puts @commit_log.map { |c| "  #{c}" }
  end

  #############################################################################
  # Add the changelog entries.
  additions = "\n## %s (%s)\n\n" % [@new_version, @today]
  additions << @commit_log.map { |c| "  * #{c}\n" }.reduce(:+)
  existing = IO.read 'CHANGELOG.md'
  IO.write 'CHANGELOG.md', additions + existing
  puts `cat CHANGELOG.md` if @debug

  #############################################################################
  # Create a new commit with the version and changelog.
  `git add VERSION CHANGELOG.md`
  `git commit -m "Release version #{@new_version}"`
  puts `git show` if @debug

  #############################################################################
  # Create a new tag for the version.
  `git tag #{@new_version} HEAD`
  if @debug
    print "Created new release tag: "
    puts `git tag --list -n1 --contains HEAD`
  end

end