model_helpers.rb

# frozen_string_literal: true

require "rails/generators/active_model"

module Rails
  module Generators
    module ModelHelpers # :nodoc:
      PLURAL_MODEL_NAME_WARN_MESSAGE = "[WARNING] The model name '%s' was recognized as a plural, using the singular '%s' instead. " \
                                       "Override with --force-plural or setup custom inflection rules for this noun before running the generator."
      IRREGULAR_MODEL_NAME_WARN_MESSAGE = <<~WARNING
      [WARNING] Rails cannot recover singular form from its plural form '%s'.
      Please setup custom inflection rules for this noun before running the generator in config/initializers/inflections.rb.
      WARNING
      INFLECTION_IMPOSSIBLE_ERROR_MESSAGE = <<~ERROR
      Rails cannot recover the underscored form from its camelcase form '%s'.
      Please use an underscored name instead, either '%s' or '%s'.
      Or setup custom inflection rules for this noun before running the generator in config/initializers/inflections.rb.
      ERROR
      mattr_accessor :skip_warn

      def self.included(base) # :nodoc:
        base.class_option :force_plural, type: :boolean, default: false,
          desc: "Do not singularize the model name, even if it appears plural"
      end

      def initialize(args, *_options)
        super
        if plural_model_name?(name) && !options[:force_plural]
          singular = name.singularize
          unless ModelHelpers.skip_warn
            say PLURAL_MODEL_NAME_WARN_MESSAGE % [name, singular]
          end
          name.replace singular
          assign_names!(name)
        end
        if inflection_impossible?(name)
          option1 = name.singularize.underscore
          option2 = name.pluralize.underscore.singularize
          raise Error, INFLECTION_IMPOSSIBLE_ERROR_MESSAGE % [name, option1, option2]
        end
        if irregular_model_name?(name) && ! ModelHelpers.skip_warn
          say IRREGULAR_MODEL_NAME_WARN_MESSAGE % [name.pluralize]
        end
        ModelHelpers.skip_warn = true
      end

      private
        def plural_model_name?(name)
          name == name.pluralize && name.singularize != name.pluralize
        end

        def irregular_model_name?(name)
          name.singularize != name.pluralize.singularize
        end

        def inflection_impossible?(name)
          name != name.underscore &&
            name.singularize.underscore != name.pluralize.underscore.singularize
        end
    end
  end
end