Pre-commit hook to run Rubocop

Rubocop pre-commit

#!/usr/bin/env ruby

require 'english'
require 'rubocop'
require 'yaml'

ADDED_OR_MODIFIED = /A|AM|^M/.freeze

ignored_files = YAML.load_file('.rubocop.yml')['AllCops']['Exclude'] rescue []

changed_files = `git status --porcelain`.split(/\n/).
    select { |file_name_with_status|
      file_name_with_status =~ ADDED_OR_MODIFIED
    }.
    map { |file_name_with_status|
      file_name_with_status.split(' ')[1]
    }.
    select { |file_name|
      File.extname(file_name) == '.rb'
    }.
    select { |file_name|
      not ignored_files.include? file_name
    }.join(' ')

rubocop_command = "rubocop #{changed_files} -D -R"
unless changed_files.empty?
  puts rubocop_command + "\n"
  system(rubocop_command)
end

exit $CHILD_STATUS.to_s[-1].to_i

curl https://gist.githubusercontent.com/tspacek/ddf8c4d63b110ab3c402/raw/190a207d0327cb0d26aa79e833b8724194877fe0/Rubocop%20pre-commit > .git/hooks/pre-commit && chmod 755 .git/hooks/pre-commit;