Quick and Dirty Authority to Pundit Conversion Script

authority_to_pundit.rake

task authority_to_pundit: :environment do
  # please note, this script was hastily created and does not convert everything but makes a good start to save some time
  
  # get list of models first because eager loading will crash later after the script modifies code
  Rails.application.eager_load!
  policies = ApplicationRecord.subclasses.map { |item| { class_name: item.name, policy_name: item.name.underscore } }

  # move authorizers to policies
  if File.exist?(Rails.root.join('app', 'authorizers'))
    FileUtils.mv Rails.root.join('app', 'authorizers'), Rails.root.join('app', 'policies')
  end

  # search and replace known patterns
  search_and_replace 'include Authority::Abilities', ''
  search_and_replace 'include Authority::UserAbilities', ''
  search_and_replace 'authorize_action_for', 'authorize'
  search_and_replace 'Authorizer < ApplicationAuthorizer', 'Policy < ApplicationPolicy'
  search_and_replace '# class rules', ''

  search_and_replace 'def self.creatable_by?(_user)', 'def create?'
  search_and_replace 'def self.creatable_by?(user)', 'def create?'

  search_and_replace 'def self.readable_by?(_user)', 'def show?'
  search_and_replace 'def self.readable_by?(user)', 'def show?'

  search_and_replace 'def self.updatable_by?(_user)', 'def update?'
  search_and_replace 'def self.updatable_by?(user)', 'def update?'

  search_and_replace 'def self.deletable_by?(_user)', 'def destroy?'
  search_and_replace 'def self.deletable_by?(user)', 'def destroy?'

  search_and_replace 'Authorizer, type: :authorizer do', 'Policy, type: :policy do'
  system "find . -type f -name \"*authorizer.rb\" -print0 | xargs -0 sed -i '' -e 's/resource/record/g'"

  # add missing policies
  policies.each do |policy|
    path = Rails.root.join('app', 'policies', "#{policy[:policy_name]}_policy.rb")
    legacy_path = Rails.root.join('app', 'policies', "#{policy[:policy_name]}_authorizer.rb")
    next if File.exist?(path) || File.exist?(legacy_path)

    open(path, 'w') do |file|
      file << "class #{policy[:class_name]}Policy < ApplicationPolicy \n"
      file << "end\n"
    end
  end

  # rename authorizers to policies
  files_to_rename = Dir.glob(Rails.root.join('app', 'policies', '*_authorizer.rb'))
  files_to_rename.each do |file_to_rename|
    next if file_to_rename.include?('application_authorizer.rb')

    FileUtils.mv file_to_rename, file_to_rename.gsub('_authorizer.rb', '_policy.rb')
  end

  # remove old config
  config_file = Rails.root.join('config', 'initializers', 'authority.rb')
  File.delete config_file if File.exist?(config_file)
end

def search_and_replace(search_string, replace_string)
  system "find . -type f -name \"*.rb\" -print0 | xargs -0 sed -i '' -e 's/#{search_string}/#{replace_string}/g'"
end