auto_correct.rb

require "yaml"
require "json"
require "tempfile"

module RuboCopAutoCollrect
  class << self
    def run_all!(targets, *cop_names, commit_log_format:, fixup_commit_log_format:)
      plan(targets, *cop_names).each do |cop_name|
        run!(targets, cop_name, commit_log_format: commit_log_format)
      end
      run!(targets, *cop_names, commit_log_format: fixup_commit_log_format)
    end

    def run!(targets, *cop_names, commit_log_format:)
      cop_list = cop_names.join(",") unless cop_names.empty?
      print "\n*** auto-correct by #{cop_list || 'AllCops'}...\n\n"

      only_cops = cop_list ? ["--only", cop_list] : []
      begin
        rubocop_auto_correct("--format", "autogenconf", *only_cops, *targets)
      rescue
        print "\n** try to detect errors...\n\n"
        rubocop_check(*only_cops, *targets)
        abort
      end
      return unless git_diff?

      git("add", ".")
      git("commit", "-q", "-m", format(commit_log_format, cop_list: cop_list))

      print "\n** commit changes\n\n"
    end

    def plan(targets, *cop_names)
      print "*** calculate auto-correct plan...\n\n"

      only_cops = cop_names.empty? ? [] : ["--only", cop_names.join(",")]
      begin
        output = Tempfile.open("auto_correct_plan") do |tf|
          rubocop_auto_correct(
            *only_cops,
            "--display-cop-names",
            "--format", "fuubar",
            "--format", "json",
            "--out", tf.path,
            *targets,
          )
          tf.read
        end
      rescue
        print "\n** try to detect errors...\n\n"
        rubocop_check(*only_cops, *targets)
        abort
      end

      git("restore", ".")

      categories = cop_names.map {|cop_name| cop_name[%r{\A[^/]*}] }.uniq
      corrected_cops = corrected_cops(JSON.parse(output))
      corrected_cops.keys.sort_by do |cop_name|
        count = corrected_cops[cop_name]
        idx = categories.index {|category| cop_name.start_with?(category) }
        [idx || categories.size, -count]
      end
    end

    private

    def corrected_cops(rubocop_output)
      rubocop_output["files"]
        .map {|f| f["offenses"].select {|o| o["corrected"] } }
        .flatten
        .group_by {|o| o["cop_name"] }
        .transform_values(&:size)
    end

    def rubocop(*args, on_failure: :raise)
      command("rubocop", "--safe", *args)
    rescue => e
      warn "\n#{e}"
      abort if on_failure == :abort
      raise
    end

    def rubocop_auto_correct(*args)
      rubocop(
        "--fail-level", "E",
        "--safe-auto-correct",
        *args,
      )
    end

    def rubocop_check(*args)
      rubocop(
        "--fail-level", "E",
        "--display-only-fail-level-offenses",
        *args,
        on_failure: :abort,
      )
    end

    def git(*args)
      command("git", *args)
    rescue => e
      warn e
      abort
    end

    def git_diff?
      command("git", "diff", "--quiet")
      false
    rescue
      true
    end

    def command(*cmd)
      system(*cmd)
      raise "failed: #{cmd.join(' ')}" unless $?.success?
    end
  end
end

sep_idx = ARGV.index("--") || 0
targets = ARGV[(sep_idx + 1)..-1]
commit_log_prefix, = ARGV[0, sep_idx]
commit_log_format = "#{commit_log_prefix}auto-correct by RuboCop %<cop_list>s"

cop_names = %w(Layout Style)
RuboCopAutoCollrect.run_all!(
  targets, *cop_names,
  commit_log_format: commit_log_format,
  fixup_commit_log_format: "#{commit_log_format} (fix-up)",
)