Fix deprecated ActiveModel::Dirty methods for Active Record 5.1

fix_callbacks.rb

class After < Struct.new(:text)
  def call
    text.gsub(Model::FIXES[0], 'saved_change_to_\1?')
        .gsub(Model::FIXES[1], '\1_before_last_save')
  end
end

class Before < Struct.new(:text)
  def call
    text.gsub(Model::FIXES[0], 'will_save_change_to_\1?')
        .gsub(Model::FIXES[1]) { raise "Failed to convert: #{line}" }
  end
end

class Model
  attr_reader :file

  FIXES = [
    /(\w+)_changed\?/,
    /(\w+)_was/
  ]

  def initialize(file)
    @file = file
  end

  def solve
    fixed_lines = File.readlines(file).reduce([]) do |acc, line|
      fixed = fix(line, acc) if needs_fix?(line)

      if fixed && commit?(line, fixed)
        acc + [fixed.call]
      else
        acc + [line]
      end
    end

    File.open(file, 'w') { |f| f.write(fixed_lines.join) }
  end

  def needs_fix?(line)
    FIXES.any? { |re| line.match? re }
  end

  def commit?(line, fixed)
    puts "FILE:     #{file}"
    puts "CALLBACK: #{fixed.class.to_s.downcase}_*"
    puts "CHANGE:   #{line}"
    puts "TO:       #{fixed.call}"

    loop do
      print 'Replace? (y/n): '
      answer = $stdin.gets.chomp
      next unless answer.match?(/[yn]/i)
      puts "\n"
      break answer.match?(/y/i)
    end
  end

  def fix(text, previous_lines)
    find_solution(text, previous_lines)
  end

  def find_solution(text, previous_lines)
    (previous_lines + [text]).reverse.each do |line|
      case line
      when /after_(create|update|save|destroy)/
        return After.new(text)
      when /before_(create|update|save|destroy)/
        return Before.new(text)
      when /def ([\w?]+)/
        return find_def_solution(Regexp.last_match[1], text, previous_lines)
      end
    end

    nil
  end

  def find_def_solution(meth, text, previous_lines)
    previous_lines.each do |line|
      case line
      when /after_(create|update|save|destroy)\s*:#{meth}/
        return After.new(text)
      when /before_(create|update|save|destroy)\s*:#{meth}/
        return Before.new(text)
      end
    end

    nil
  end
end

Dir.glob(ARGV.first || 'app/models/**/*.rb').each do |f|
  Model.new(f).solve
end