start_rubocop.rb

# frozen_string_literal: true

require 'yaml'
require 'json'
require 'tempfile'

if ARGV.include?('-h') || ARGV.include?('--help')
  <<~HELP.display
    Usage: #{$0} [-r extension ...] [-- targets...]

    Command line example:

      #{$0} -r rubocop-rails -r rubocop-performance -- app lib Gemfile
  HELP
  exit
end

sep_idx = ARGV.index('--')
if sep_idx
  options = ARGV[0, sep_idx]
  targets = ARGV[(sep_idx + 1)..-1]
else
  options = ARGV
  targets = []
end

run_rubocop = ->(*opts, &b) { IO.popen(['rubocop', *options, *opts], &b) }
run_rubocop_with_targets = ->(*opts, &b) { run_rubocop[*opts, *targets, &b] }

all_cops = run_rubocop['--force-default-config', '--show-cops'] {|io| YAML.load(io) }
configs = []
default_styles = Hash.new {|h, k| h[k] = {} }
summary = Hash.new {|h, k| h[k] = Hash.new {|hh, kk| hh[kk] = {} } }
all_cops.each do |cop_name, spec|
  items = {}
  spec.each_key do |item_name|
    m = /\AEnforcedStyle(.*)\z/.match(item_name)
    next unless m

    styles = spec["SupportedStyles#{m[1]}"]
    next unless styles

    items[m[0]] = styles
    default_styles[cop_name][item_name] = spec[m[0]]
  end

  items.each do |item_name, styles|
    styles.each_with_index do |style, idx|
      configs[idx] ||= Hash.new {|h, k| h[k] = Hash.new {|hh, kk| hh[kk] = {} } }
      configs[idx][cop_name][item_name] = style
      summary[cop_name][item_name][style] = 0
    end
  end
end

configs.each_with_index do |config, idx|
  warn "#{idx + 1} / #{configs.size} ..."

  Tempfile.open('start_rubocop') do |tf|
    YAML.dump(config, tf)
    tf.close

    cops = config.keys
    result = run_rubocop_with_targets[
      '--config', tf.path,
      '--only', cops.join(','),
      '--format', 'json',
    ] {|io| JSON.parse(io.read) }

    result['files'].each do |file_result|
      file_result['offenses'].each do |offense|
        cop_name = offense['cop_name']
        item_name, style = config[cop_name].first
        next unless item_name && style

        summary[cop_name][item_name][style] += 1
      end
    end
  end
end

summary.each do |cop_name, s|
  s.each do |item_name, styles|
    offense_counts = styles.values
    next if offense_counts.all?(&:zero?)

    min_offense_count = offense_counts.min
    default_style = default_styles[cop_name][item_name]
    next if styles[default_style] == min_offense_count

    puts "#{cop_name}:"
    w = styles.each_key.map(&:length).max
    styles.sort_by {|_, offense_count| offense_count }.each do |style, offense_count|
      printf "  %s: %-#{w}s # %d offenses%s\n",
             item_name, style, offense_count,
             style == default_style ? ' (default)' : ''
    end
  end
end