src/derails/action_dispatch/routing/mapper.rb
# frozen_string_literal: true

# :markup: markdown

require "active_support/core_ext/hash/slice"
require "active_support/core_ext/enumerable"
require "active_support/core_ext/array/extract_options"
require "active_support/core_ext/regexp"
require "action_dispatch/routing/redirection"
require "action_dispatch/routing/endpoint"

module ActionDispatch
  module Routing
    class Mapper
      class BacktraceCleaner < ActiveSupport::BacktraceCleaner # :nodoc:
        def initialize
          super
          remove_silencers!
          add_core_silencer
          add_stdlib_silencer
        end
      end

      URL_OPTIONS = [:protocol, :subdomain, :domain, :host, :port]

      cattr_accessor :route_source_locations, instance_accessor: false, default: false
      cattr_accessor :backtrace_cleaner, instance_accessor: false, default: BacktraceCleaner.new

      class Constraints < Routing::Endpoint # :nodoc:
        attr_reader :app, :constraints

        SERVE = ->(app, req) { app.serve req }
        CALL  = ->(app, req) { app.call req.env }

        def initialize(app, constraints, strategy)
          # Unwrap Constraints objects. I don't actually think it's possible to pass a
          # Constraints object to this constructor, but there were multiple places that
          # kept testing children of this object. I **think** they were just being
          # defensive, but I have no idea.
          if app.is_a?(self.class)
            constraints += app.constraints
            app = app.app
          end

          @strategy = strategy

          @app, @constraints, = app, constraints
        end

        def dispatcher?; @strategy == SERVE; end

        def matches?(req)
          @constraints.all? do |constraint|
            (constraint.respond_to?(:matches?) && constraint.matches?(req)) ||
              (constraint.respond_to?(:call) && constraint.call(*constraint_args(constraint, req)))
          end
        end

        def serve(req)
          return [ 404, { Constants::X_CASCADE => "pass" }, [] ] unless matches?(req)

          @strategy.call @app, req
        end

        private
          def constraint_args(constraint, request)
            arity = if constraint.respond_to?(:arity)
              constraint.arity
            else
              constraint.method(:call).arity
            end

            if arity < 1
              []
            elsif arity == 1
              [request]
            else
              [request.path_parameters, request]
            end
          end
      end

      class Mapping # :nodoc:
        ANCHOR_CHARACTERS_REGEX = %r{\A(\\A|\^)|(\\Z|\\z|\$)\Z}
        OPTIONAL_FORMAT_REGEX = %r{(?:\(\.:format\)+|\.:format|/)\Z}

        attr_reader :path, :requirements, :defaults, :to, :default_controller,
                    :default_action, :required_defaults, :ast, :scope_options

        def self.build(scope, set, ast, controller, default_action, to, via, formatted, options_constraints, anchor, internal, options)
          scope_params = {
            blocks: scope[:blocks] || [],
            constraints: scope[:constraints] || {},
            defaults: (scope[:defaults] || {}).dup,
            module: scope[:module],
            options: scope[:options] || {}
          }

          new set: set, ast: ast, controller: controller, default_action: default_action,
              to: to, formatted: formatted, via: via, options_constraints: options_constraints,
              anchor: anchor, scope_params: scope_params, internal: internal, options: scope_params[:options].merge(options)
        end

        def self.check_via(via)
          if via.empty?
            msg = "You should not use the `match` method in your router without specifying an HTTP method.\n" \
              "If you want to expose your action to both GET and POST, add `via: [:get, :post]` option.\n" \
              "If you want to expose your action to GET, use `get` in the router:\n" \
              "  Instead of: match \"controller#action\"\n" \
              "  Do: get \"controller#action\""
            raise ArgumentError, msg
          end
          via
        end

        def self.normalize_path(path, format)
          path = Mapper.normalize_path(path)

          if format == true
            "#{path}.:format"
          elsif optional_format?(path, format)
            "#{path}(.:format)"
          else
            path
          end
        end

        def self.optional_format?(path, format)
          format != false && !path.match?(OPTIONAL_FORMAT_REGEX)
        end

        def initialize(set:, ast:, controller:, default_action:, to:, formatted:, via:, options_constraints:, anchor:, scope_params:, internal:, options:)
          @defaults           = scope_params[:defaults]
          @set                = set
          @to                 = intern(to)
          @default_controller = intern(controller)
          @default_action     = intern(default_action)
          @anchor             = anchor
          @via                = via
          @internal           = internal
          @scope_options      = scope_params[:options]
          ast                 = Journey::Ast.new(ast, formatted)

          options = ast.wildcard_options.merge!(options)

          options = normalize_options!(options, ast.path_params, scope_params[:module])

          split_options = constraints(options, ast.path_params)

          constraints = scope_params[:constraints].merge Hash[split_options[:constraints] || []]

          if options_constraints.is_a?(Hash)
            @defaults = Hash[options_constraints.find_all { |key, default|
              URL_OPTIONS.include?(key) && (String === default || Integer === default)
            }].merge @defaults
            @blocks = scope_params[:blocks]
            constraints.merge! options_constraints
          else
            @blocks = blocks(options_constraints)
          end

          requirements, conditions = split_constraints ast.path_params, constraints
          verify_regexp_requirements requirements, ast.wildcard_options

          formats = normalize_format(formatted)

          @requirements = formats[:requirements].merge Hash[requirements]
          @conditions = Hash[conditions]
          @defaults = formats[:defaults].merge(@defaults).merge(normalize_defaults(options))

          if ast.path_params.include?(:action) && !@requirements.key?(:action)
            @defaults[:action] ||= "index"
          end

          @required_defaults = (split_options[:required_defaults] || []).map(&:first)

          ast.requirements = @requirements
          @path = Journey::Path::Pattern.new(ast, @requirements, JOINED_SEPARATORS, @anchor)
        end

        JOINED_SEPARATORS = SEPARATORS.join # :nodoc:

        def make_route(name, precedence)
          Journey::Route.new(name: name, app: application, path: path, constraints: conditions,
                             required_defaults: required_defaults, defaults: defaults,
                             via: @via, precedence: precedence,
                             scope_options: scope_options, internal: @internal, source_location: route_source_location)
        end

        def application
          app(@blocks)
        end

        def conditions
          build_conditions @conditions, @set.request_class
        end

        def build_conditions(current_conditions, request_class)
          conditions = current_conditions.dup

          conditions.keep_if do |k, _|
            request_class.public_method_defined?(k)
          end
        end
        private :build_conditions

        private
          def intern(object)
            object.is_a?(String) ? -object : object
          end

          def normalize_options!(options, path_params, modyoule)
            if path_params.include?(:controller)
              raise ArgumentError, ":controller segment is not allowed within a namespace block" if modyoule

              # Add a default constraint for :controller path segments that matches namespaced
              # controllers with default routes like :controller/:action/:id(.:format), e.g:
              # GET /admin/products/show/1
              # # > { controller: 'admin/products', action: 'show', id: '1' }
              options[:controller] ||= /.+?/
            end

            if to.respond_to?(:action) || to.respond_to?(:call)
              options
            else
              if to.nil?
                controller = default_controller
                action = default_action
              elsif to.is_a?(String)
                if to.include?("#")
                  to_endpoint = to.split("#").map!(&:-@)
                  controller  = to_endpoint[0]
                  action      = to_endpoint[1]
                else
                  controller = default_controller
                  action = to
                end
              else
                raise ArgumentError, ":to must respond to `action` or `call`, or it must be a String that includes '#', or the controller should be implicit"
              end

              controller = add_controller_module(controller, modyoule)

              options.merge! check_controller_and_action(path_params, controller, action)
            end
          end

          def split_constraints(path_params, constraints)
            constraints.partition do |key, requirement|
              path_params.include?(key) || key == :controller
            end
          end

          def normalize_format(formatted)
            case formatted
            when true
              { requirements: { format: /.+/ },
                defaults:     {} }
            when Regexp
              { requirements: { format: formatted },
                defaults:     { format: nil } }
            when String
              { requirements: { format: Regexp.compile(formatted) },
                defaults:     { format: formatted } }
            else
              { requirements: {}, defaults: {} }
            end
          end

          def verify_regexp_requirements(requirements, wildcard_options)
            requirements.each do |requirement, regex|
              next unless regex.is_a? Regexp

              if ANCHOR_CHARACTERS_REGEX.match?(regex.source)
                raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
              end

              if regex.multiline?
                next if wildcard_options.key?(requirement)

                raise ArgumentError, "Regexp multiline option is not allowed in routing requirements: #{regex.inspect}"
              end
            end
          end

          def normalize_defaults(options)
            Hash[options.reject { |_, default| Regexp === default }]
          end

          def app(blocks)
            if to.respond_to?(:action)
              Routing::RouteSet::StaticDispatcher.new to
            elsif to.respond_to?(:call)
              Constraints.new(to, blocks, Constraints::CALL)
            elsif blocks.any?
              Constraints.new(dispatcher(defaults.key?(:controller)), blocks, Constraints::SERVE)
            else
              dispatcher(defaults.key?(:controller))
            end
          end

          def check_controller_and_action(path_params, controller, action)
            hash = check_part(:controller, controller, path_params, {}) do |part|
              translate_controller(part) {
                message = +"'#{part}' is not a supported controller name. This can lead to potential routing problems."
                message << " See https://guides.rubyonrails.org/routing.html#specifying-a-controller-to-use"

                raise ArgumentError, message
              }
            end

            check_part(:action, action, path_params, hash) { |part|
              part.is_a?(Regexp) ? part : part.to_s
            }
          end

          def check_part(name, part, path_params, hash)
            if part
              hash[name] = yield(part)
            else
              unless path_params.include?(name)
                message = "Missing :#{name} key on routes definition, please check your routes."
                raise ArgumentError, message
              end
            end
            hash
          end

          def add_controller_module(controller, modyoule)
            if modyoule && !controller.is_a?(Regexp)
              if controller&.start_with?("/")
                -controller[1..-1]
              else
                -[modyoule, controller].compact.join("/")
              end
            else
              controller
            end
          end

          def translate_controller(controller)
            return controller if Regexp === controller
            return controller.to_s if /\A[a-z_0-9][a-z_0-9\/]*\z/.match?(controller)

            yield
          end

          def blocks(callable_constraint)
            unless callable_constraint.respond_to?(:call) || callable_constraint.respond_to?(:matches?)
              raise ArgumentError, "Invalid constraint: #{callable_constraint.inspect} must respond to :call or :matches?"
            end
            [callable_constraint]
          end

          def constraints(options, path_params)
            options.group_by do |key, option|
              if Regexp === option
                :constraints
              else
                if path_params.include?(key)
                  :path_params
                else
                  :required_defaults
                end
              end
            end
          end

          def dispatcher(raise_on_name_error)
            Routing::RouteSet::Dispatcher.new raise_on_name_error
          end

          def route_source_location
            if Mapper.route_source_locations
              action_dispatch_dir = File.expand_path("..", __dir__)
              Thread.each_caller_location do |location|
                next if location.path.start_with?(action_dispatch_dir)

                cleaned_path = Mapper.backtrace_cleaner.clean_frame(location.path)
                next if cleaned_path.nil?

                return "#{cleaned_path}:#{location.lineno}"
              end
              nil
            end
          end
      end

      # Invokes Journey::Router::Utils.normalize_path, then ensures that /(:locale)
      # becomes (/:locale). Except for root cases, where the former is the correct
      # one.
      def self.normalize_path(path)
        path = Journey::Router::Utils.normalize_path(path)

        # the path for a root URL at this point can be something like
        # "/(/:locale)(/:platform)/(:browser)", and we would want
        # "/(:locale)(/:platform)(/:browser)" reverse "/(", "/((" etc to "(/", "((/" etc
        path.gsub!(%r{/(\(+)/?}, '\1/')
        # if a path is all optional segments, change the leading "(/" back to "/(" so it
        # evaluates to "/" when interpreted with no options. Unless, however, at least
        # one secondary segment consists of a static part, ex.
        # "(/:locale)(/pages/:page)"
        path.sub!(%r{^(\(+)/}, '/\1') if %r{^(\(+[^)]+\))(\(+/:[^)]+\))*$}.match?(path)
        path
      end

      def self.normalize_name(name)
        normalize_path(name)[1..-1].tr("/", "_")
      end

      module Base
        # Matches a URL pattern to one or more routes.
        #
        # You should not use the `match` method in your router without specifying an
        # HTTP method.
        #
        # If you want to expose your action to both GET and POST, use:
        #
        #     # sets :controller, :action, and :id in params
        #     match ':controller/:action/:id', via: [:get, :post]
        #
        # Note that `:controller`, `:action`, and `:id` are interpreted as URL query
        # parameters and thus available through `params` in an action.
        #
        # If you want to expose your action to GET, use `get` in the router:
        #
        # Instead of:
        #
        #     match ":controller/:action/:id"
        #
        # Do:
        #
        #     get ":controller/:action/:id"
        #
        # Two of these symbols are special, `:controller` maps to the controller and
        # `:action` to the controller's action. A pattern can also map wildcard segments
        # (globs) to params:
        #
        #     get 'songs/*category/:title', to: 'songs#show'
        #
        #     # 'songs/rock/classic/stairway-to-heaven' sets
        #     #  params[:category] = 'rock/classic'
        #     #  params[:title] = 'stairway-to-heaven'
        #
        # To match a wildcard parameter, it must have a name assigned to it. Without a
        # variable name to attach the glob parameter to, the route can't be parsed.
        #
        # When a pattern points to an internal route, the route's `:action` and
        # `:controller` should be set in options or hash shorthand. Examples:
        #
        #     match 'photos/:id', to: 'photos#show', via: :get
        #     match 'photos/:id', controller: 'photos', action: 'show', via: :get
        #
        # A pattern can also point to a `Rack` endpoint i.e. anything that responds to
        # `call`:
        #
        #     match 'photos/:id', to: -> (hash) { [200, {}, ["Coming soon"]] }, via: :get
        #     match 'photos/:id', to: PhotoRackApp, via: :get
        #     # Yes, controller actions are just rack endpoints
        #     match 'photos/:id', to: PhotosController.action(:show), via: :get
        #
        # Because requesting various HTTP verbs with a single action has security
        # implications, you must either specify the actions in the via options or use
        # one of the [HttpHelpers](rdoc-ref:HttpHelpers) instead `match`
        #
        # ### Options
        #
        # Any options not seen here are passed on as params with the URL.
        #
        # :controller
        # :   The route's controller.
        #
        # :action
        # :   The route's action.
        #
        # :param
        # :   Overrides the default resource identifier `:id` (name of the dynamic
        #     segment used to generate the routes). You can access that segment from
        #     your controller using `params[<:param>]`. In your router:
        #
        #         resources :users, param: :name
        #
        #     The `users` resource here will have the following routes generated for it:
        #
        #         GET       /users(.:format)
        #         POST      /users(.:format)
        #         GET       /users/new(.:format)
        #         GET       /users/:name/edit(.:format)
        #         GET       /users/:name(.:format)
        #         PATCH/PUT /users/:name(.:format)
        #         DELETE    /users/:name(.:format)
        #
        #     You can override `ActiveRecord::Base#to_param` of a related model to
        #     construct a URL:
        #
        #         class User < ActiveRecord::Base
        #           def to_param
        #             name
        #           end
        #         end
        #
        #         user = User.find_by(name: 'Phusion')
        #         user_path(user)  # => "/users/Phusion"
        #
        # :path
        # :   The path prefix for the routes.
        #
        # :module
        # :   The namespace for :controller.
        #
        #         match 'path', to: 'c#a', module: 'sekret', controller: 'posts', via: :get
        #         # => Sekret::PostsController
        #
        #     See `Scoping#namespace` for its scope equivalent.
        #
        # :as
        # :   The name used to generate routing helpers.
        #
        # :via
        # :   Allowed HTTP verb(s) for route.
        #
        #         match 'path', to: 'c#a', via: :get
        #         match 'path', to: 'c#a', via: [:get, :post]
        #         match 'path', to: 'c#a', via: :all
        #
        # :to
        # :   Points to a `Rack` endpoint. Can be an object that responds to `call` or a
        #     string representing a controller's action.
        #
        #         match 'path', to: 'controller#action', via: :get
        #         match 'path', to: -> (env) { [200, {}, ["Success!"]] }, via: :get
        #         match 'path', to: RackApp, via: :get
        #
        # :on
        # :   Shorthand for wrapping routes in a specific RESTful context. Valid values
        #     are `:member`, `:collection`, and `:new`. Only use within `resource(s)`
        #     block. For example:
        #
        #         resource :bar do
        #           match 'foo', to: 'c#a', on: :member, via: [:get, :post]
        #         end
        #
        #     Is equivalent to:
        #
        #         resource :bar do
        #           member do
        #             match 'foo', to: 'c#a', via: [:get, :post]
        #           end
        #         end
        #
        # :constraints
        # :   Constrains parameters with a hash of regular expressions or an object that
        #     responds to `matches?`. In addition, constraints other than path can also
        #     be specified with any object that responds to `===` (e.g. String, Array,
        #     Range, etc.).
        #
        #         match 'path/:id', constraints: { id: /[A-Z]\d{5}/ }, via: :get
        #
        #         match 'json_only', constraints: { format: 'json' }, via: :get
        #
        #         class PermitList
        #           def matches?(request) request.remote_ip == '1.2.3.4' end
        #         end
        #         match 'path', to: 'c#a', constraints: PermitList.new, via: :get
        #
        #     See `Scoping#constraints` for more examples with its scope equivalent.
        #
        # :defaults
        # :   Sets defaults for parameters
        #
        #         # Sets params[:format] to 'jpg' by default
        #         match 'path', to: 'c#a', defaults: { format: 'jpg' }, via: :get
        #
        #     See `Scoping#defaults` for its scope equivalent.
        #
        # :anchor
        # :   Boolean to anchor a `match` pattern. Default is true. When set to false,
        #     the pattern matches any request prefixed with the given path.
        #
        #         # Matches any request starting with 'path'
        #         match 'path', to: 'c#a', anchor: false, via: :get
        #
        # :format
        # :   Allows you to specify the default value for optional `format` segment or
        #     disable it by supplying `false`.
        #
        def match(path, options = nil)
        end

        # Mount a Rack-based application to be used within the application.
        #
        #     mount SomeRackApp, at: "some_route"
        #
        # For options, see `match`, as `mount` uses it internally.
        #
        # All mounted applications come with routing helpers to access them. These are
        # named after the class specified, so for the above example the helper is either
        # `some_rack_app_path` or `some_rack_app_url`. To customize this helper's name,
        # use the `:as` option:
        #
        #     mount(SomeRackApp, at: "some_route", as: "exciting")
        #
        # This will generate the `exciting_path` and `exciting_url` helpers which can be
        # used to navigate to this mounted app.
        def mount(app = nil, deprecated_options = nil, as: DEFAULT, via: nil, at: nil, defaults: nil, constraints: nil, anchor: false, format: false, path: nil, internal: nil, **mapping, &block)
          if deprecated_options.is_a?(Hash)
            as = assign_deprecated_option(deprecated_options, :as, :mount) if deprecated_options.key?(:as)
            via ||= assign_deprecated_option(deprecated_options, :via, :mount)
            at ||= assign_deprecated_option(deprecated_options, :at, :mount)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :mount)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :mount)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :mount) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :mount) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :mount)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :mount)
            assign_deprecated_options(deprecated_options, mapping, :mount)
          end

          path_or_action = at

          if app.nil?
            hash_app, hash_path = mapping.find { |key, _| key.respond_to?(:call) }
            mapping.delete(hash_app) if hash_app

            app ||= hash_app
            path_or_action ||= hash_path
          end

          raise ArgumentError, "A rack application must be specified" unless app.respond_to?(:call)
          raise ArgumentError, <<~MSG unless path_or_action
            Must be called with mount point

              mount SomeRackApp, at: "some_route"
              or
              mount(SomeRackApp => "some_route")
          MSG

          rails_app = rails_app? app
          as = app_name(app, rails_app) if as == DEFAULT

          target_as = name_for_action(as, path_or_action)
          via ||= :all

          match(path_or_action, to: app, as:, via:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, &block)

          define_generate_prefix(app, target_as) if rails_app
          self
        end

        def default_url_options=(options)
          @set.default_url_options = options
        end
        alias_method :default_url_options, :default_url_options=

        def with_default_scope(scope, &block)
          scope(**scope) do
            instance_exec(&block)
          end
        end

        # Query if the following named route was already defined.
        def has_named_route?(name)
          @set.named_routes.key?(name)
        end

        private
          def assign_deprecated_option(deprecated_options, key, method_name)
            if (deprecated_value = deprecated_options.delete(key))
              ActionDispatch.deprecator.warn(<<~MSG.squish)
                #{method_name} received a hash argument #{key}. Please use a keyword instead. Support to hash argument will be removed in Rails 8.2.
              MSG
              deprecated_value
            end
          end

          def assign_deprecated_options(deprecated_options, options, method_name)
            deprecated_options.each do |key, value|
              ActionDispatch.deprecator.warn(<<~MSG.squish)
                #{method_name} received a hash argument #{key}. Please use a keyword instead. Support to hash argument will be removed in Rails 8.2.
              MSG
              options[key] = value
            end
          end

          def rails_app?(app)
            app.is_a?(Class) && app < Rails::Railtie
          end

          def app_name(app, rails_app)
            if rails_app
              app.railtie_name
            elsif app.is_a?(Class)
              class_name = app.name
              ActiveSupport::Inflector.underscore(class_name).tr("/", "_")
            end
          end

          def define_generate_prefix(app, name)
            _route = @set.named_routes.get name
            _routes = @set
            _url_helpers = @set.url_helpers

            script_namer = ->(options) do
              prefix_options = options.slice(*_route.segment_keys)
              prefix_options[:script_name] = "" if options[:original_script_name]

              if options[:_recall]
                prefix_options.reverse_merge!(options[:_recall].slice(*_route.segment_keys))
              end

              # We must actually delete prefix segment keys to avoid passing them to next
              # url_for.
              _route.segment_keys.each { |k| options.delete(k) }
              _url_helpers.public_send("#{name}_path", prefix_options)
            end

            app.routes.define_mounted_helper(name, script_namer)

            app.routes.extend Module.new {
              def optimize_routes_generation?; false; end

              define_method :find_script_name do |options|
                if options.key?(:script_name) && options[:script_name].present?
                  super(options)
                else
                  script_namer.call(options)
                end
              end
            }
          end
      end

      module HttpHelpers
        # Define a route that only recognizes HTTP GET. For supported arguments, see
        # [match](rdoc-ref:Base#match)
        #
        #     get 'bacon', to: 'food#bacon'
        def get(*path_or_actions, as: DEFAULT, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: nil, format: nil, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :get) if deprecated_options.key?(:as)
            to ||= assign_deprecated_option(deprecated_options, :to, :get)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :get)
            action ||= assign_deprecated_option(deprecated_options, :action, :get)
            on ||= assign_deprecated_option(deprecated_options, :on, :get)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :get)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :get)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :get) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :get) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :get)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :get)
            assign_deprecated_options(deprecated_options, mapping, :get)
          end

          match(*path_or_actions, as:, to:, controller:, action:, on:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, via: :get, &block)
          self
        end

        # Define a route that only recognizes HTTP POST. For supported arguments, see
        # [match](rdoc-ref:Base#match)
        #
        #     post 'bacon', to: 'food#bacon'
        def post(*path_or_actions, as: DEFAULT, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: nil, format: nil, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :post) if deprecated_options.key?(:as)
            to ||= assign_deprecated_option(deprecated_options, :to, :post)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :post)
            action ||= assign_deprecated_option(deprecated_options, :action, :post)
            on ||= assign_deprecated_option(deprecated_options, :on, :post)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :post)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :post)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :post) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :post) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :post)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :post)
            assign_deprecated_options(deprecated_options, mapping, :post)
          end

          match(*path_or_actions, as:, to:, controller:, action:, on:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, via: :post, &block)
          self
        end

        # Define a route that only recognizes HTTP PATCH. For supported arguments, see
        # [match](rdoc-ref:Base#match)
        #
        #     patch 'bacon', to: 'food#bacon'
        def patch(*path_or_actions, as: DEFAULT, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: nil, format: nil, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :patch) if deprecated_options.key?(:as)
            to ||= assign_deprecated_option(deprecated_options, :to, :patch)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :patch)
            action ||= assign_deprecated_option(deprecated_options, :action, :patch)
            on ||= assign_deprecated_option(deprecated_options, :on, :patch)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :patch)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :patch)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :patch) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :patch) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :patch)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :patch)
            assign_deprecated_options(deprecated_options, mapping, :patch)
          end

          match(*path_or_actions, as:, to:, controller:, action:, on:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, via: :patch, &block)
          self
        end

        # Define a route that only recognizes HTTP PUT. For supported arguments, see
        # [match](rdoc-ref:Base#match)
        #
        #     put 'bacon', to: 'food#bacon'
        def put(*path_or_actions, as: DEFAULT, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: nil, format: nil, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :put) if deprecated_options.key?(:as)
            to ||= assign_deprecated_option(deprecated_options, :to, :put)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :put)
            action ||= assign_deprecated_option(deprecated_options, :action, :put)
            on ||= assign_deprecated_option(deprecated_options, :on, :put)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :put)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :put)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :put) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :put) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :put)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :put)
            assign_deprecated_options(deprecated_options, mapping, :put)
          end

          match(*path_or_actions, as:, to:, controller:, action:, on:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, via: :put, &block)
          self
        end

        # Define a route that only recognizes HTTP DELETE. For supported arguments, see
        # [match](rdoc-ref:Base#match)
        #
        #     delete 'broccoli', to: 'food#broccoli'
        def delete(*path_or_actions, as: DEFAULT, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: nil, format: nil, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :delete) if deprecated_options.key?(:as)
            to ||= assign_deprecated_option(deprecated_options, :to, :delete)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :delete)
            action ||= assign_deprecated_option(deprecated_options, :action, :delete)
            on ||= assign_deprecated_option(deprecated_options, :on, :delete)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :delete)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :delete)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :delete) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :delete) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :delete)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :delete)
            assign_deprecated_options(deprecated_options, mapping, :delete)
          end

          match(*path_or_actions, as:, to:, controller:, action:, on:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, via: :delete, &block)
          self
        end

        # Define a route that only recognizes HTTP OPTIONS. For supported arguments, see
        # [match](rdoc-ref:Base#match)
        #
        #     options 'carrots', to: 'food#carrots'
        def options(*path_or_actions, as: DEFAULT, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: false, format: false, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :options) if deprecated_options.key?(:as)
            to ||= assign_deprecated_option(deprecated_options, :to, :options)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :options)
            action ||= assign_deprecated_option(deprecated_options, :action, :options)
            on ||= assign_deprecated_option(deprecated_options, :on, :options)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :options)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :options)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :options) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :options) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :options)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :options)
            assign_deprecated_options(deprecated_options, mapping, :options)
          end

          match(*path_or_actions, as:, to:, controller:, action:, on:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, via: :options, &block)
          self
        end

        # Define a route that recognizes HTTP CONNECT (and GET) requests. More
        # specifically this recognizes HTTP/1 protocol upgrade requests and HTTP/2
        # CONNECT requests with the protocol pseudo header. For supported arguments,
        # see [match](rdoc-ref:Base#match)
        #
        #     connect 'live', to: 'live#index'
        def connect(*path_or_actions, as: DEFAULT, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: false, format: false, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :connect) if deprecated_options.key?(:as)
            to ||= assign_deprecated_option(deprecated_options, :to, :connect)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :connect)
            action ||= assign_deprecated_option(deprecated_options, :action, :connect)
            on ||= assign_deprecated_option(deprecated_options, :on, :connect)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :connect)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :connect)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :connect) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :connect) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :connect)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :connect)
            assign_deprecated_options(deprecated_options, mapping, :connect)
          end

          match(*path_or_actions, as:, to:, controller:, action:, on:, defaults:, constraints:, anchor:, format:, path:, internal:, **mapping, via: [:get, :connect], &block)
          self
        end
      end

      # You may wish to organize groups of controllers under a namespace. Most
      # commonly, you might group a number of administrative controllers under an
      # `admin` namespace. You would place these controllers under the
      # `app/controllers/admin` directory, and you can group them together in your
      # router:
      #
      #     namespace "admin" do
      #       resources :posts, :comments
      #     end
      #
      # This will create a number of routes for each of the posts and comments
      # controller. For `Admin::PostsController`, Rails will create:
      #
      #     GET       /admin/posts
      #     GET       /admin/posts/new
      #     POST      /admin/posts
      #     GET       /admin/posts/1
      #     GET       /admin/posts/1/edit
      #     PATCH/PUT /admin/posts/1
      #     DELETE    /admin/posts/1
      #
      # If you want to route /posts (without the prefix /admin) to
      # `Admin::PostsController`, you could use
      #
      #     scope module: "admin" do
      #       resources :posts
      #     end
      #
      # or, for a single case
      #
      #     resources :posts, module: "admin"
      #
      # If you want to route /admin/posts to `PostsController` (without the `Admin::`
      # module prefix), you could use
      #
      #     scope "/admin" do
      #       resources :posts
      #     end
      #
      # or, for a single case
      #
      #     resources :posts, path: "/admin/posts"
      #
      # In each of these cases, the named routes remain the same as if you did not use
      # scope. In the last case, the following paths map to `PostsController`:
      #
      #     GET       /admin/posts
      #     GET       /admin/posts/new
      #     POST      /admin/posts
      #     GET       /admin/posts/1
      #     GET       /admin/posts/1/edit
      #     PATCH/PUT /admin/posts/1
      #     DELETE    /admin/posts/1
      module Scoping
        # Scopes a set of routes to the given default options.
        #
        # Take the following route definition as an example:
        #
        #     scope path: ":account_id", as: "account" do
        #       resources :projects
        #     end
        #
        # This generates helpers such as `account_projects_path`, just like `resources`
        # does. The difference here being that the routes generated are like
        # /:account_id/projects, rather than /accounts/:account_id/projects.
        #
        # ### Options
        #
        # Takes same options as `Base#match` and `Resources#resources`.
        #
        #     # route /posts (without the prefix /admin) to Admin::PostsController
        #     scope module: "admin" do
        #       resources :posts
        #     end
        #
        #     # prefix the posts resource's requests with '/admin'
        #     scope path: "/admin" do
        #       resources :posts
        #     end
        #
        #     # prefix the routing helper name: sekret_posts_path instead of posts_path
        #     scope as: "sekret" do
        #       resources :posts
        #     end
        def scope(*args, only: nil, except: nil, **options)
          if args.grep(Hash).any? && (deprecated_options = args.extract_options!)
            only ||= assign_deprecated_option(deprecated_options, :only, :scope)
            only ||= assign_deprecated_option(deprecated_options, :except, :scope)
            assign_deprecated_options(deprecated_options, options, :scope)
          end

          scope = {}

          options[:path] = args.flatten.join("/") if args.any?
          options[:constraints] ||= {}

          unless nested_scope?
            options[:shallow_path] ||= options[:path] if options.key?(:path)
            options[:shallow_prefix] ||= options[:as] if options.key?(:as)
          end

          if options[:constraints].is_a?(Hash)
            defaults = options[:constraints].select do |k, v|
              URL_OPTIONS.include?(k) && (v.is_a?(String) || v.is_a?(Integer))
            end

            options[:defaults] = defaults.merge(options[:defaults] || {})
          else
            block, options[:constraints] = options[:constraints], {}
          end

          if only || except
            scope[:action_options] = { only:, except: }
          end

          if options.key? :anchor
            raise ArgumentError, "anchor is ignored unless passed to `match`"
          end

          @scope.options.each do |option|
            if option == :blocks
              value = block
            elsif option == :options
              value = options
            else
              value = options.delete(option) { POISON }
            end

            unless POISON == value
              scope[option] = send("merge_#{option}_scope", @scope[option], value)
            end
          end

          @scope = @scope.new scope
          yield
          self
        ensure
          @scope = @scope.parent
        end

        POISON = Object.new # :nodoc:

        # Scopes routes to a specific controller
        #
        #     controller "food" do
        #       match "bacon", action: :bacon, via: :get
        #     end
        def controller(controller)
          @scope = @scope.new(controller: controller)
          yield
        ensure
          @scope = @scope.parent
        end

        # Scopes routes to a specific namespace. For example:
        #
        #     namespace :admin do
        #       resources :posts
        #     end
        #
        # This generates the following routes:
        #
        #         admin_posts GET       /admin/posts(.:format)          admin/posts#index
        #         admin_posts POST      /admin/posts(.:format)          admin/posts#create
        #      new_admin_post GET       /admin/posts/new(.:format)      admin/posts#new
        #     edit_admin_post GET       /admin/posts/:id/edit(.:format) admin/posts#edit
        #          admin_post GET       /admin/posts/:id(.:format)      admin/posts#show
        #          admin_post PATCH/PUT /admin/posts/:id(.:format)      admin/posts#update
        #          admin_post DELETE    /admin/posts/:id(.:format)      admin/posts#destroy
        #
        # ### Options
        #
        # The `:path`, `:as`, `:module`, `:shallow_path`, and `:shallow_prefix` options
        # all default to the name of the namespace.
        #
        # For options, see `Base#match`. For `:shallow_path` option, see
        # `Resources#resources`.
        #
        #     # accessible through /sekret/posts rather than /admin/posts
        #     namespace :admin, path: "sekret" do
        #       resources :posts
        #     end
        #
        #     # maps to Sekret::PostsController rather than Admin::PostsController
        #     namespace :admin, module: "sekret" do
        #       resources :posts
        #     end
        #
        #     # generates sekret_posts_path rather than admin_posts_path
        #     namespace :admin, as: "sekret" do
        #       resources :posts
        #     end
        def namespace(name, deprecated_options = nil, as: DEFAULT, path: DEFAULT, shallow_path: DEFAULT, shallow_prefix: DEFAULT, **options, &block)
          if deprecated_options.is_a?(Hash)
            as = assign_deprecated_option(deprecated_options, :as, :namespace) if deprecated_options.key?(:as)
            path ||= assign_deprecated_option(deprecated_options, :path, :namespace)  if deprecated_options.key?(:path)
            shallow_path ||= assign_deprecated_option(deprecated_options, :shallow_path, :namespace) if deprecated_options.key?(:shallow_path)
            shallow_prefix ||= assign_deprecated_option(deprecated_options, :shallow_prefix, :namespace)  if deprecated_options.key?(:shallow_prefix)
            assign_deprecated_options(deprecated_options, options, :namespace)
          end

          name = name.to_s
          options[:module] ||= name
          as = name if as == DEFAULT
          path = name if path == DEFAULT
          shallow_path = path if shallow_path == DEFAULT
          shallow_prefix = as if shallow_prefix == DEFAULT

          path_scope(path) do
            scope(**options, as:, shallow_path:, shallow_prefix:, &block)
          end
        end

        # ### Parameter Restriction
        # Allows you to constrain the nested routes based on a set of rules. For
        # instance, in order to change the routes to allow for a dot character in the
        # `id` parameter:
        #
        #     constraints(id: /\d+\.\d+/) do
        #       resources :posts
        #     end
        #
        # Now routes such as `/posts/1` will no longer be valid, but `/posts/1.1` will
        # be. The `id` parameter must match the constraint passed in for this example.
        #
        # You may use this to also restrict other parameters:
        #
        #     resources :posts do
        #       constraints(post_id: /\d+\.\d+/) do
        #         resources :comments
        #       end
        #     end
        #
        # ### Restricting based on IP
        #
        # Routes can also be constrained to an IP or a certain range of IP addresses:
        #
        #     constraints(ip: /192\.168\.\d+\.\d+/) do
        #       resources :posts
        #     end
        #
        # Any user connecting from the 192.168.* range will be able to see this
        # resource, where as any user connecting outside of this range will be told
        # there is no such route.
        #
        # ### Dynamic request matching
        #
        # Requests to routes can be constrained based on specific criteria:
        #
        #     constraints(-> (req) { /iPhone/.match?(req.env["HTTP_USER_AGENT"]) }) do
        #       resources :iphones
        #     end
        #
        # You are able to move this logic out into a class if it is too complex for
        # routes. This class must have a `matches?` method defined on it which either
        # returns `true` if the user should be given access to that route, or `false` if
        # the user should not.
        #
        #     class Iphone
        #       def self.matches?(request)
        #         /iPhone/.match?(request.env["HTTP_USER_AGENT"])
        #       end
        #     end
        #
        # An expected place for this code would be `lib/constraints`.
        #
        # This class is then used like this:
        #
        #     constraints(Iphone) do
        #       resources :iphones
        #     end
        def constraints(constraints = {}, &block)
          scope(constraints: constraints, &block)
        end

        # Allows you to set default parameters for a route, such as this:
        #
        #     defaults id: 'home' do
        #       match 'scoped_pages/(:id)', to: 'pages#show'
        #     end
        #
        # Using this, the `:id` parameter here will default to 'home'.
        def defaults(defaults = {})
          @scope = @scope.new(defaults: merge_defaults_scope(@scope[:defaults], defaults))
          yield
        ensure
          @scope = @scope.parent
        end

        private
          def merge_path_scope(parent, child)
            Mapper.normalize_path("#{parent}/#{child}")
          end

          def merge_shallow_path_scope(parent, child)
            Mapper.normalize_path("#{parent}/#{child}")
          end

          def merge_as_scope(parent, child)
            parent ? "#{parent}_#{child}" : child
          end

          def merge_shallow_prefix_scope(parent, child)
            parent ? "#{parent}_#{child}" : child
          end

          def merge_module_scope(parent, child)
            parent ? "#{parent}/#{child}" : child
          end

          def merge_controller_scope(parent, child)
            child
          end

          def merge_action_scope(parent, child)
            child
          end

          def merge_via_scope(parent, child)
            child
          end

          def merge_format_scope(parent, child)
            child
          end

          def merge_path_names_scope(parent, child)
            merge_options_scope(parent, child)
          end

          def merge_constraints_scope(parent, child)
            merge_options_scope(parent, child)
          end

          def merge_defaults_scope(parent, child)
            merge_options_scope(parent, child)
          end

          def merge_blocks_scope(parent, child)
            merged = parent ? parent.dup : []
            merged << child if child
            merged
          end

          def merge_options_scope(parent, child)
            (parent || {}).merge(child)
          end

          def merge_shallow_scope(parent, child)
            child ? true : false
          end

          def merge_to_scope(parent, child)
            child
          end
      end

      # Resource routing allows you to quickly declare all of the common routes for a
      # given resourceful controller. Instead of declaring separate routes for your
      # `index`, `show`, `new`, `edit`, `create`, `update`, and `destroy` actions, a
      # resourceful route declares them in a single line of code:
      #
      #     resources :photos
      #
      # Sometimes, you have a resource that clients always look up without referencing
      # an ID. A common example, /profile always shows the profile of the currently
      # logged in user. In this case, you can use a singular resource to map /profile
      # (rather than /profile/:id) to the show action.
      #
      #     resource :profile
      #
      # It's common to have resources that are logically children of other resources:
      #
      #     resources :magazines do
      #       resources :ads
      #     end
      #
      # You may wish to organize groups of controllers under a namespace. Most
      # commonly, you might group a number of administrative controllers under an
      # `admin` namespace. You would place these controllers under the
      # `app/controllers/admin` directory, and you can group them together in your
      # router:
      #
      #     namespace "admin" do
      #       resources :posts, :comments
      #     end
      #
      # By default the `:id` parameter doesn't accept dots. If you need to use dots as
      # part of the `:id` parameter add a constraint which overrides this restriction,
      # e.g:
      #
      #     resources :articles, id: /[^\/]+/
      #
      # This allows any character other than a slash as part of your `:id`.
      module Resources
        # CANONICAL_ACTIONS holds all actions that does not need a prefix or a path
        # appended since they fit properly in their scope level.
        VALID_ON_OPTIONS  = [:new, :collection, :member]
        RESOURCE_OPTIONS  = [:as, :controller, :path, :only, :except, :param, :concerns]
        CANONICAL_ACTIONS = %w(index create new show update destroy)

        class Resource # :nodoc:
          class << self
            def default_actions(api_only)
              if api_only
                [:index, :create, :show, :update, :destroy]
              else
                [:index, :create, :new, :show, :update, :destroy, :edit]
              end
            end
          end

          attr_reader :controller, :path, :param

          def initialize(entities, api_only, shallow, only: nil, except: nil, **options)
            if options[:param].to_s.include?(":")
              raise ArgumentError, ":param option can't contain colons"
            end

            valid_actions = self.class.default_actions(false) # ignore api_only for this validation
            if (invalid_actions = invalid_only_except_options(valid_actions, only:, except:).presence)
              error_prefix = "Route `resource#{"s" unless singleton?} :#{entities}`"
              raise ArgumentError, "#{error_prefix} - :only and :except must include only #{valid_actions}, but also included #{invalid_actions}"
            end

            @name       = entities.to_s
            @path       = (options[:path] || @name).to_s
            @controller = (options[:controller] || @name).to_s
            @as         = options[:as]
            @param      = (options[:param] || :id).to_sym
            @options    = options
            @shallow    = shallow
            @api_only   = api_only
            @only       = only
            @except     = except
          end

          def default_actions
            self.class.default_actions(@api_only)
          end

          def actions
            if @except
              available_actions - Array(@except).map(&:to_sym)
            else
              available_actions
            end
          end

          def available_actions
            if @only
              Array(@only).map(&:to_sym)
            else
              default_actions
            end
          end

          def name
            @as || @name
          end

          def plural
            @plural ||= name.to_s
          end

          def singular
            @singular ||= name.to_s.singularize
          end

          alias :member_name :singular

          # Checks for uncountable plurals, and appends "_index" if the plural and
          # singular form are the same.
          def collection_name
            singular == plural ? "#{plural}_index" : plural
          end

          def resource_scope
            controller
          end

          alias :collection_scope :path

          def member_scope
            "#{path}/:#{param}"
          end

          alias :shallow_scope :member_scope

          def new_scope(new_path)
            "#{path}/#{new_path}"
          end

          def nested_param
            :"#{singular}_#{param}"
          end

          def nested_scope
            "#{path}/:#{nested_param}"
          end

          def shallow?
            @shallow
          end

          def singleton?; false; end

          private
            def invalid_only_except_options(valid_actions, only:, except:)
              [only, except].flatten.compact.uniq.map(&:to_sym) - valid_actions
            end
        end

        class SingletonResource < Resource # :nodoc:
          class << self
            def default_actions(api_only)
              if api_only
                [:show, :create, :update, :destroy]
              else
                [:show, :create, :update, :destroy, :new, :edit]
              end
            end
          end

          def initialize(entities, api_only, shallow, **options)
            super
            @as         = nil
            @controller = (options[:controller] || plural).to_s
            @as         = options[:as]
          end

          def default_actions
            self.class.default_actions(@api_only)
          end

          def plural
            @plural ||= name.to_s.pluralize
          end

          def singular
            @singular ||= name.to_s
          end

          alias :member_name :singular
          alias :collection_name :singular

          alias :member_scope :path
          alias :nested_scope :path

          def singleton?; true; end
        end

        def resources_path_names(options)
          @scope[:path_names].merge!(options)
        end

        # Sometimes, you have a resource that clients always look up without referencing
        # an ID. A common example, /profile always shows the profile of the currently
        # logged in user. In this case, you can use a singular resource to map /profile
        # (rather than /profile/:id) to the show action:
        #
        #     resource :profile
        #
        # This creates six different routes in your application, all mapping to the
        # `Profiles` controller (note that the controller is named after the plural):
        #
        #     GET       /profile/new
        #     GET       /profile
        #     GET       /profile/edit
        #     PATCH/PUT /profile
        #     DELETE    /profile
        #     POST      /profile
        #
        # If you want instances of a model to work with this resource via record
        # identification (e.g. in `form_with` or `redirect_to`), you will need to call
        # [resolve](rdoc-ref:CustomUrls#resolve):
        #
        #     resource :profile
        #     resolve('Profile') { [:profile] }
        #
        #     # Enables this to work with singular routes:
        #     form_with(model: @profile) {}
        #
        # ### Options
        # Takes same options as [resources](rdoc-ref:#resources)
        def resource(*resources, concerns: nil, **options, &block)
          if resources.grep(Hash).any? && (deprecated_options = resources.extract_options!)
            concerns = assign_deprecated_option(deprecated_options, :concerns, :resource) if deprecated_options.key?(:concerns)
            assign_deprecated_options(deprecated_options, options, :resource)
          end

          if apply_common_behavior_for(:resource, resources, concerns:, **options, &block)
            return self
          end

          with_scope_level(:resource) do
            options = apply_action_options :resource, options
            resource_scope(SingletonResource.new(resources.pop, api_only?, @scope[:shallow], **options)) do
              yield if block_given?

              concerns(*concerns) if concerns

              new do
                get :new
              end if parent_resource.actions.include?(:new)

              set_member_mappings_for_resource

              collection do
                post :create
              end if parent_resource.actions.include?(:create)
            end
          end

          self
        end

        # In Rails, a resourceful route provides a mapping between HTTP verbs and URLs
        # and controller actions. By convention, each action also maps to particular
        # CRUD operations in a database. A single entry in the routing file, such as
        #
        #     resources :photos
        #
        # creates seven different routes in your application, all mapping to the
        # `Photos` controller:
        #
        #     GET       /photos
        #     GET       /photos/new
        #     POST      /photos
        #     GET       /photos/:id
        #     GET       /photos/:id/edit
        #     PATCH/PUT /photos/:id
        #     DELETE    /photos/:id
        #
        # Resources can also be nested infinitely by using this block syntax:
        #
        #     resources :photos do
        #       resources :comments
        #     end
        #
        # This generates the following comments routes:
        #
        #     GET       /photos/:photo_id/comments
        #     GET       /photos/:photo_id/comments/new
        #     POST      /photos/:photo_id/comments
        #     GET       /photos/:photo_id/comments/:id
        #     GET       /photos/:photo_id/comments/:id/edit
        #     PATCH/PUT /photos/:photo_id/comments/:id
        #     DELETE    /photos/:photo_id/comments/:id
        #
        # ### Options
        # Takes same options as [match](rdoc-ref:Base#match) as well as:
        #
        # :path_names
        # :   Allows you to change the segment component of the `edit` and `new`
        #     actions. Actions not specified are not changed.
        #
        #         resources :posts, path_names: { new: "brand_new" }
        #
        #     The above example will now change /posts/new to /posts/brand_new.
        #
        # :path
        # :   Allows you to change the path prefix for the resource.
        #
        #         resources :posts, path: 'postings'
        #
        #     The resource and all segments will now route to /postings instead of
        #     /posts.
        #
        # :only
        # :   Only generate routes for the given actions.
        #
        #         resources :cows, only: :show
        #         resources :cows, only: [:show, :index]
        #
        # :except
        # :   Generate all routes except for the given actions.
        #
        #         resources :cows, except: :show
        #         resources :cows, except: [:show, :index]
        #
        # :shallow
        # :   Generates shallow routes for nested resource(s). When placed on a parent
        #     resource, generates shallow routes for all nested resources.
        #
        #         resources :posts, shallow: true do
        #           resources :comments
        #         end
        #
        #     Is the same as:
        #
        #         resources :posts do
        #           resources :comments, except: [:show, :edit, :update, :destroy]
        #         end
        #         resources :comments, only: [:show, :edit, :update, :destroy]
        #
        #     This allows URLs for resources that otherwise would be deeply nested such
        #     as a comment on a blog post like `/posts/a-long-permalink/comments/1234`
        #     to be shortened to just `/comments/1234`.
        #
        #     Set `shallow: false` on a child resource to ignore a parent's shallow
        #     parameter.
        #
        # :shallow_path
        # :   Prefixes nested shallow routes with the specified path.
        #
        #         scope shallow_path: "sekret" do
        #           resources :posts do
        #             resources :comments, shallow: true
        #           end
        #         end
        #
        #     The `comments` resource here will have the following routes generated for
        #     it:
        #
        #         post_comments    GET       /posts/:post_id/comments(.:format)
        #         post_comments    POST      /posts/:post_id/comments(.:format)
        #         new_post_comment GET       /posts/:post_id/comments/new(.:format)
        #         edit_comment     GET       /sekret/comments/:id/edit(.:format)
        #         comment          GET       /sekret/comments/:id(.:format)
        #         comment          PATCH/PUT /sekret/comments/:id(.:format)
        #         comment          DELETE    /sekret/comments/:id(.:format)
        #
        # :shallow_prefix
        # :   Prefixes nested shallow route names with specified prefix.
        #
        #         scope shallow_prefix: "sekret" do
        #           resources :posts do
        #             resources :comments, shallow: true
        #           end
        #         end
        #
        #     The `comments` resource here will have the following routes generated for
        #     it:
        #
        #         post_comments           GET       /posts/:post_id/comments(.:format)
        #         post_comments           POST      /posts/:post_id/comments(.:format)
        #         new_post_comment        GET       /posts/:post_id/comments/new(.:format)
        #         edit_sekret_comment     GET       /comments/:id/edit(.:format)
        #         sekret_comment          GET       /comments/:id(.:format)
        #         sekret_comment          PATCH/PUT /comments/:id(.:format)
        #         sekret_comment          DELETE    /comments/:id(.:format)
        #
        # :format
        # :   Allows you to specify the default value for optional `format` segment or
        #     disable it by supplying `false`.
        #
        # :param
        # :   Allows you to override the default param name of `:id` in the URL.
        #
        #
        # ### Examples
        #
        #     # routes call Admin::PostsController
        #     resources :posts, module: "admin"
        #
        #     # resource actions are at /admin/posts.
        #     resources :posts, path: "admin/posts"
        def resources(*resources, concerns: nil, **options, &block)
          if resources.grep(Hash).any? && (deprecated_options = resources.extract_options!)
            concerns = assign_deprecated_option(deprecated_options, :concerns, :resources) if deprecated_options.key?(:concerns)
            assign_deprecated_options(deprecated_options, options, :resources)
          end

          if apply_common_behavior_for(:resources, resources, concerns:, **options, &block)
            return self
          end

          with_scope_level(:resources) do
            options = apply_action_options :resources, options
            resource_scope(Resource.new(resources.pop, api_only?, @scope[:shallow], **options)) do
              yield if block_given?

              concerns(*concerns) if concerns

              collection do
                get  :index if parent_resource.actions.include?(:index)
                post :create if parent_resource.actions.include?(:create)
              end

              new do
                get :new
              end if parent_resource.actions.include?(:new)

              set_member_mappings_for_resource
            end
          end

          self
        end

        # To add a route to the collection:
        #
        #     resources :photos do
        #       collection do
        #         get 'search'
        #       end
        #     end
        #
        # This will enable Rails to recognize paths such as `/photos/search` with GET,
        # and route to the search action of `PhotosController`. It will also create the
        # `search_photos_url` and `search_photos_path` route helpers.
        def collection(&block)
          unless resource_scope?
            raise ArgumentError, "can't use collection outside resource(s) scope"
          end

          with_scope_level(:collection) do
            path_scope(parent_resource.collection_scope, &block)
          end
        end

        # To add a member route, add a member block into the resource block:
        #
        #     resources :photos do
        #       member do
        #         get 'preview'
        #       end
        #     end
        #
        # This will recognize `/photos/1/preview` with GET, and route to the preview
        # action of `PhotosController`. It will also create the `preview_photo_url` and
        # `preview_photo_path` helpers.
        def member(&block)
          unless resource_scope?
            raise ArgumentError, "can't use member outside resource(s) scope"
          end

          with_scope_level(:member) do
            if shallow?
              shallow_scope {
                path_scope(parent_resource.member_scope, &block)
              }
            else
              path_scope(parent_resource.member_scope, &block)
            end
          end
        end

        def new(&block)
          unless resource_scope?
            raise ArgumentError, "can't use new outside resource(s) scope"
          end

          with_scope_level(:new) do
            path_scope(parent_resource.new_scope(action_path(:new)), &block)
          end
        end

        def nested(&block)
          unless resource_scope?
            raise ArgumentError, "can't use nested outside resource(s) scope"
          end

          with_scope_level(:nested) do
            if shallow? && shallow_nesting_depth >= 1
              shallow_scope do
                path_scope(parent_resource.nested_scope) do
                  scope(**nested_options, &block)
                end
              end
            else
              path_scope(parent_resource.nested_scope) do
                scope(**nested_options, &block)
              end
            end
          end
        end

        # See ActionDispatch::Routing::Mapper::Scoping#namespace.
        def namespace(name, deprecated_options = nil, as: DEFAULT, path: DEFAULT, shallow_path: DEFAULT, shallow_prefix: DEFAULT, **options, &block)
          if resource_scope?
            nested { super }
          else
            super
          end
        end

        def shallow
          @scope = @scope.new(shallow: true)
          yield
        ensure
          @scope = @scope.parent
        end

        def shallow?
          !parent_resource.singleton? && @scope[:shallow]
        end

        # Loads another routes file with the given `name` located inside the
        # `config/routes` directory. In that file, you can use the normal routing DSL,
        # but *do not* surround it with a `Rails.application.routes.draw` block.
        #
        #     # config/routes.rb
        #     Rails.application.routes.draw do
        #       draw :admin                 # Loads `config/routes/admin.rb`
        #       draw "third_party/some_gem" # Loads `config/routes/third_party/some_gem.rb`
        #     end
        #
        #     # config/routes/admin.rb
        #     namespace :admin do
        #       resources :accounts
        #     end
        #
        #     # config/routes/third_party/some_gem.rb
        #     mount SomeGem::Engine, at: "/some_gem"
        #
        # **CAUTION:** Use this feature with care. Having multiple routes files can
        # negatively impact discoverability and readability. For most applications —
        # even those with a few hundred routes — it's easier for developers to have a
        # single routes file.
        def draw(name)
          path = @draw_paths.find do |_path|
            File.exist? "#{_path}/#{name}.rb"
          end

          unless path
            msg  = "Your router tried to #draw the external file #{name}.rb,\n" \
                   "but the file was not found in:\n\n"
            msg += @draw_paths.map { |_path| " * #{_path}" }.join("\n")
            raise ArgumentError, msg
          end

          route_path = "#{path}/#{name}.rb"
          instance_eval(File.read(route_path), route_path.to_s)
        end

        # Matches a URL pattern to one or more routes. For more information, see
        # [match](rdoc-ref:Base#match).
        #
        #     match 'path', to: 'controller#action', via: :post
        #     match 'otherpath', on: :member, via: :get
        def match(*path_or_actions, as: DEFAULT, via: nil, to: nil, controller: nil, action: nil, on: nil, defaults: nil, constraints: nil, anchor: nil, format: nil, path: nil, internal: nil, **mapping, &block)
          if path_or_actions.grep(Hash).any? && (deprecated_options = path_or_actions.extract_options!)
            as = assign_deprecated_option(deprecated_options, :as, :match) if deprecated_options.key?(:as)
            via ||= assign_deprecated_option(deprecated_options, :via, :match)
            to ||= assign_deprecated_option(deprecated_options, :to, :match)
            controller ||= assign_deprecated_option(deprecated_options, :controller, :match)
            action ||= assign_deprecated_option(deprecated_options, :action, :match)
            on ||= assign_deprecated_option(deprecated_options, :on, :match)
            defaults ||= assign_deprecated_option(deprecated_options, :defaults, :match)
            constraints ||= assign_deprecated_option(deprecated_options, :constraints, :match)
            anchor = assign_deprecated_option(deprecated_options, :anchor, :match) if deprecated_options.key?(:anchor)
            format = assign_deprecated_option(deprecated_options, :format, :match) if deprecated_options.key?(:format)
            path ||= assign_deprecated_option(deprecated_options, :path, :match)
            internal ||= assign_deprecated_option(deprecated_options, :internal, :match)
            assign_deprecated_options(deprecated_options, mapping, :match)
          end

          raise ArgumentError, "Wrong number of arguments (expect 1, got #{path_or_actions.count})" if path_or_actions.count > 1

          if path_or_actions.none? && mapping.any?
            hash_path, hash_to = mapping.find { |key, _| key.is_a?(String) }
            if hash_path.nil?
              raise ArgumentError, "Route path not specified"
            else
              mapping.delete(hash_path)
            end

            if hash_path
              path_or_actions.push hash_path
              case hash_to
              when Symbol
                action ||= hash_to
              when String
                if hash_to.include?("#")
                  to ||= hash_to
                else
                  controller ||= hash_to
                end
              else
                to ||= hash_to
              end
            end
          end

          path_or_actions.each do |path_or_action|
            if defaults
              defaults(defaults) { map_match(path_or_action, as:, via:, to:, controller:, action:, on:, constraints:, anchor:, format:, path:, internal:, mapping:, &block) }
            else
              map_match(path_or_action, as:, via:, to:, controller:, action:, on:, constraints:, anchor:, format:, path:, internal:, mapping:, &block)
            end
          end
        end

        # You can specify what Rails should route "/" to with the root method:
        #
        #     root to: 'pages#main'
        #
        # For options, see `match`, as `root` uses it internally.
        #
        # You can also pass a string which will expand
        #
        #     root 'pages#main'
        #
        # You should put the root route at the top of `config/routes.rb`, because this
        # means it will be matched first. As this is the most popular route of most
        # Rails applications, this is beneficial.
        def root(path, options = {})
          if path.is_a?(String)
            options[:to] = path
          elsif path.is_a?(Hash) && options.empty?
            options = path
          else
            raise ArgumentError, "must be called with a path and/or options"
          end

          if @scope.resources?
            with_scope_level(:root) do
              path_scope(parent_resource.path) do
                match_root_route(options)
              end
            end
          else
            match_root_route(options)
          end
        end

        private
          def parent_resource
            @scope[:scope_level_resource]
          end

          def apply_common_behavior_for(method, resources, shallow: nil, **options, &block)
            if resources.length > 1
              resources.each { |r| public_send(method, r, shallow:, **options, &block) }
              return true
            end

            if shallow
              self.shallow do
                public_send(method, resources.pop, **options, &block)
              end
              return true
            end

            if resource_scope?
              nested { public_send(method, resources.pop, shallow:, **options, &block) }
              return true
            end

            options.keys.each do |k|
              (options[:constraints] ||= {})[k] = options.delete(k) if options[k].is_a?(Regexp)
            end

            scope_options = options.slice!(*RESOURCE_OPTIONS)
            if !scope_options.empty? || !shallow.nil?
              scope(**scope_options, shallow:) do
                public_send(method, resources.pop, **options, &block)
              end
              return true
            end

            false
          end

          def apply_action_options(method, options)
            return options if action_options? options
            options.merge scope_action_options(method)
          end

          def action_options?(options)
            options[:only] || options[:except]
          end

          def scope_action_options(method)
            return {} unless @scope[:action_options]

            actions = applicable_actions_for(method)
            @scope[:action_options].dup.tap do |options|
              (options[:only] = Array(options[:only]) & actions) if options[:only]
              (options[:except] = Array(options[:except]) & actions) if options[:except]
            end
          end

          def applicable_actions_for(method)
            case method
            when :resource
              SingletonResource.default_actions(api_only?)
            when :resources
              Resource.default_actions(api_only?)
            end
          end

          def resource_scope?
            @scope.resource_scope?
          end

          def resource_method_scope?
            @scope.resource_method_scope?
          end

          def nested_scope?
            @scope.nested?
          end

          def with_scope_level(kind) # :doc:
            @scope = @scope.new_level(kind)
            yield
          ensure
            @scope = @scope.parent
          end

          def resource_scope(resource, &block)
            @scope = @scope.new(scope_level_resource: resource)

            controller(resource.resource_scope, &block)
          ensure
            @scope = @scope.parent
          end

          def nested_options
            options = { as: parent_resource.member_name }
            options[:constraints] = {
              parent_resource.nested_param => param_constraint
            } if param_constraint?

            options
          end

          def shallow_nesting_depth
            @scope.find_all { |node|
              node.frame[:scope_level_resource]
            }.count { |node| node.frame[:scope_level_resource].shallow? }
          end

          def param_constraint?
            @scope[:constraints] && @scope[:constraints][parent_resource.param].is_a?(Regexp)
          end

          def param_constraint
            @scope[:constraints][parent_resource.param]
          end

          def canonical_action?(action)
            resource_method_scope? && CANONICAL_ACTIONS.include?(action.to_s)
          end

          def shallow_scope
            @scope = @scope.new(
              as: @scope[:shallow_prefix],
              path: @scope[:shallow_path],
            )

            yield
          ensure
            @scope = @scope.parent
          end

          def path_for_action(action, path)
            return "#{@scope[:path]}/#{path}" if path

            if canonical_action?(action)
              @scope[:path].to_s
            else
              "#{@scope[:path]}/#{action_path(action)}"
            end
          end

          def action_path(name)
            @scope[:path_names][name.to_sym] || name
          end

          def prefix_name_for_action(as, action)
            if as && as != DEFAULT
              prefix = as
            elsif !canonical_action?(action)
              prefix = action
            end

            if prefix && prefix != "/" && !prefix.empty?
              Mapper.normalize_name prefix.to_s.tr("-", "_")
            end
          end

          def name_for_action(as, action)
            prefix = prefix_name_for_action(as, action)
            name_prefix = @scope[:as]

            if parent_resource
              return nil unless as != DEFAULT || action

              collection_name = parent_resource.collection_name
              member_name = parent_resource.member_name
            end

            action_name = @scope.action_name(name_prefix, prefix, collection_name, member_name)
            candidate = action_name.select(&:present?).join("_")

            unless candidate.empty?
              # If a name was not explicitly given, we check if it is valid and return nil in
              # case it isn't. Otherwise, we pass the invalid name forward so the underlying
              # router engine treats it and raises an exception.
              if as == DEFAULT
                candidate unless !candidate.match?(/\A[_a-z]/i) || has_named_route?(candidate)
              else
                candidate
              end
            end
          end

          def set_member_mappings_for_resource # :doc:
            member do
              get :edit if parent_resource.actions.include?(:edit)
              get :show if parent_resource.actions.include?(:show)
              if parent_resource.actions.include?(:update)
                patch :update
                put   :update
              end
              delete :destroy if parent_resource.actions.include?(:destroy)
            end
          end

          def api_only? # :doc:
            @set.api_only?
          end

          def path_scope(path)
            @scope = @scope.new(path: merge_path_scope(@scope[:path], path))
            yield
          ensure
            @scope = @scope.parent
          end

          def map_match(path_or_action, constraints: nil, anchor: nil, format: nil, path: nil, as: DEFAULT, via: nil, to: nil, controller: nil, action: nil, on: nil, internal: nil, mapping: nil)
            if on && !VALID_ON_OPTIONS.include?(on)
              raise ArgumentError, "Unknown scope #{on.inspect} given to :on"
            end

            if @scope[:to]
              to ||= @scope[:to]
            end

            if @scope[:controller] && @scope[:action]
              to ||= "#{@scope[:controller]}##{@scope[:action]}"
            end

            controller ||= @scope[:controller]
            via = Mapping.check_via Array(via || @scope[:via])
            format ||= @scope[:format] if format.nil?
            anchor ||= true if anchor.nil?
            constraints ||= {}

            case path_or_action
            when String
              if path_or_action && path
                raise ArgumentError, "Ambiguous route definition. Both :path and the route path were specified as strings."
              end
              path = path_or_action
              to = get_to_from_path(path_or_action, to, action)
              decomposed_match(path, controller, as, action, path, to, via, format, anchor, constraints, internal, mapping, on)
            when Symbol
              decomposed_match(path_or_action, controller, as, action, path, to, via, format, anchor, constraints, internal, mapping, on)
            end

            self
          end

          def get_to_from_path(path, to, action)
            return to if to || action

            path_without_format = path.sub(/\(\.:format\)$/, "")
            if using_match_shorthand?(path_without_format)
              path_without_format.delete_prefix("/").sub(%r{/([^/]*)$}, '#\1').tr("-", "_")
            else
              nil
            end
          end

          def using_match_shorthand?(path)
            %r{^/?[-\w]+/[-\w/]+$}.match?(path)
          end

          def decomposed_match(path, controller, as, action, _path, to, via, formatted, anchor, options_constraints, internal, options_mapping, on = nil)
            if on
              send(on) { decomposed_match(path, controller, as, action, _path, to, via, formatted, anchor, options_constraints, internal, options_mapping) }
            else
              case @scope.scope_level
              when :resources
                nested { decomposed_match(path, controller, as, action, _path, to, via, formatted, anchor, options_constraints, internal, options_mapping) }
              when :resource
                member { decomposed_match(path, controller, as, action, _path, to, via, formatted, anchor, options_constraints, internal, options_mapping) }
              else
                add_route(path, controller, as, action, _path, to, via, formatted, anchor, options_constraints, internal, options_mapping)
              end
            end
          end

          def add_route(action, controller, as, options_action, _path, to, via, formatted, anchor, options_constraints, internal, options_mapping)
            path = path_for_action(action, _path)
            raise ArgumentError, "path is required" if path.blank?

            action = action.to_s

            default_action = options_action || @scope[:action]

            if /^[\w\-\/]+$/.match?(action)
              default_action ||= action.tr("-", "_") unless action.include?("/")
            else
              action = nil
            end

            as   = name_for_action(as, action) if as
            path = Mapping.normalize_path URI::RFC2396_PARSER.escape(path), formatted
            ast  = Journey::Parser.parse path

            mapping = Mapping.build(@scope, @set, ast, controller, default_action, to, via, formatted, options_constraints, anchor, internal, options_mapping)
            @set.add_route(mapping, as)
          end

          def match_root_route(options)
            match("/", as: :root, via: :get, **options)
          end
      end

      # Routing Concerns allow you to declare common routes that can be reused inside
      # others resources and routes.
      #
      #     concern :commentable do
      #       resources :comments
      #     end
      #
      #     concern :image_attachable do
      #       resources :images, only: :index
      #     end
      #
      # These concerns are used in Resources routing:
      #
      #     resources :messages, concerns: [:commentable, :image_attachable]
      #
      # or in a scope or namespace:
      #
      #     namespace :posts do
      #       concerns :commentable
      #     end
      module Concerns
        # Define a routing concern using a name.
        #
        # Concerns may be defined inline, using a block, or handled by another object,
        # by passing that object as the second parameter.
        #
        # The concern object, if supplied, should respond to `call`, which will receive
        # two parameters:
        #
        #     * The current mapper
        #     * A hash of options which the concern object may use
        #
        # Options may also be used by concerns defined in a block by accepting a block
        # parameter. So, using a block, you might do something as simple as limit the
        # actions available on certain resources, passing standard resource options
        # through the concern:
        #
        #     concern :commentable do |options|
        #       resources :comments, options
        #     end
        #
        #     resources :posts, concerns: :commentable
        #     resources :archived_posts do
        #       # Don't allow comments on archived posts
        #       concerns :commentable, only: [:index, :show]
        #     end
        #
        # Or, using a callable object, you might implement something more specific to
        # your application, which would be out of place in your routes file.
        #
        #     # purchasable.rb
        #     class Purchasable
        #       def initialize(defaults = {})
        #         @defaults = defaults
        #       end
        #
        #       def call(mapper, options = {})
        #         options = @defaults.merge(options)
        #         mapper.resources :purchases
        #         mapper.resources :receipts
        #         mapper.resources :returns if options[:returnable]
        #       end
        #     end
        #
        #     # routes.rb
        #     concern :purchasable, Purchasable.new(returnable: true)
        #
        #     resources :toys, concerns: :purchasable
        #     resources :electronics, concerns: :purchasable
        #     resources :pets do
        #       concerns :purchasable, returnable: false
        #     end
        #
        # Any routing helpers can be used inside a concern. If using a callable, they're
        # accessible from the Mapper that's passed to `call`.
        def concern(name, callable = nil, &block)
          callable ||= lambda { |mapper, options| mapper.instance_exec(options, &block) }
          @concerns[name] = callable
        end

        # Use the named concerns
        #
        #     resources :posts do
        #       concerns :commentable
        #     end
        #
        # Concerns also work in any routes helper that you want to use:
        #
        #     namespace :posts do
        #       concerns :commentable
        #     end
        def concerns(*args, **options)
          args.flatten.each do |name|
            if concern = @concerns[name]
              concern.call(self, options)
            else
              raise ArgumentError, "No concern named #{name} was found!"
            end
          end
        end
      end

      module CustomUrls
        # Define custom URL helpers that will be added to the application's routes. This
        # allows you to override and/or replace the default behavior of routing helpers,
        # e.g:
        #
        #     direct :homepage do
        #       "https://rubyonrails.org"
        #     end
        #
        #     direct :commentable do |model|
        #       [ model, anchor: model.dom_id ]
        #     end
        #
        #     direct :main do
        #       { controller: "pages", action: "index", subdomain: "www" }
        #     end
        #
        # The return value from the block passed to `direct` must be a valid set of
        # arguments for `url_for` which will actually build the URL string. This can be
        # one of the following:
        #
        # *   A string, which is treated as a generated URL
        # *   A hash, e.g. `{ controller: "pages", action: "index" }`
        # *   An array, which is passed to `polymorphic_url`
        # *   An Active Model instance
        # *   An Active Model class
        #
        #
        # NOTE: Other URL helpers can be called in the block but be careful not to
        # invoke your custom URL helper again otherwise it will result in a stack
        # overflow error.
        #
        # You can also specify default options that will be passed through to your URL
        # helper definition, e.g:
        #
        #     direct :browse, page: 1, size: 10 do |options|
        #       [ :products, options.merge(params.permit(:page, :size).to_h.symbolize_keys) ]
        #     end
        #
        # In this instance the `params` object comes from the context in which the block
        # is executed, e.g. generating a URL inside a controller action or a view. If
        # the block is executed where there isn't a `params` object such as this:
        #
        #     Rails.application.routes.url_helpers.browse_path
        #
        # then it will raise a `NameError`. Because of this you need to be aware of the
        # context in which you will use your custom URL helper when defining it.
        #
        # NOTE: The `direct` method can't be used inside of a scope block such as
        # `namespace` or `scope` and will raise an error if it detects that it is.
        def direct(name, options = {}, &block)
          unless @scope.root?
            raise RuntimeError, "The direct method can't be used inside a routes scope block"
          end

          @set.add_url_helper(name, options, &block)
        end

        # Define custom polymorphic mappings of models to URLs. This alters the behavior
        # of `polymorphic_url` and consequently the behavior of `link_to`, `form_with`
        # and `form_for` when passed a model instance, e.g:
        #
        #     resource :basket
        #
        #     resolve "Basket" do
        #       [:basket]
        #     end
        #
        # This will now generate "/basket" when a `Basket` instance is passed to
        # `link_to`, `form_with` or `form_for` instead of the standard "/baskets/:id".
        #
        # NOTE: This custom behavior only applies to simple polymorphic URLs where a
        # single model instance is passed and not more complicated forms, e.g:
        #
        #     # config/routes.rb
        #     resource :profile
        #     namespace :admin do
        #       resources :users
        #     end
        #
        #     resolve("User") { [:profile] }
        #
        #     # app/views/application/_menu.html.erb
        #     link_to "Profile", @current_user
        #     link_to "Profile", [:admin, @current_user]
        #
        # The first `link_to` will generate "/profile" but the second will generate the
        # standard polymorphic URL of "/admin/users/1".
        #
        # You can pass options to a polymorphic mapping - the arity for the block needs
        # to be two as the instance is passed as the first argument, e.g:
        #
        #     resolve "Basket", anchor: "items" do |basket, options|
        #       [:basket, options]
        #     end
        #
        # This generates the URL "/basket#items" because when the last item in an array
        # passed to `polymorphic_url` is a hash then it's treated as options to the URL
        # helper that gets called.
        #
        # NOTE: The `resolve` method can't be used inside of a scope block such as
        # `namespace` or `scope` and will raise an error if it detects that it is.
        def resolve(*args, &block)
          unless @scope.root?
            raise RuntimeError, "The resolve method can't be used inside a routes scope block"
          end

          options = args.extract_options!
          args = args.flatten(1)

          args.each do |klass|
            @set.add_polymorphic_mapping(klass, options, &block)
          end
        end
      end

      class Scope # :nodoc:
        OPTIONS = [:path, :shallow_path, :as, :shallow_prefix, :module,
                   :controller, :action, :path_names, :constraints,
                   :shallow, :blocks, :defaults, :via, :format, :options, :to]

        RESOURCE_SCOPES = [:resource, :resources]
        RESOURCE_METHOD_SCOPES = [:collection, :member, :new]

        attr_reader :parent, :scope_level

        def initialize(hash, parent = ROOT, scope_level = nil)
          @parent = parent
          @hash = parent ? parent.frame.merge(hash) : hash
          @scope_level = scope_level
        end

        def nested?
          scope_level == :nested
        end

        def null?
          @hash.nil? && @parent.nil?
        end

        def root?
          @parent == ROOT
        end

        def resources?
          scope_level == :resources
        end

        def resource_method_scope?
          RESOURCE_METHOD_SCOPES.include? scope_level
        end

        def action_name(name_prefix, prefix, collection_name, member_name)
          case scope_level
          when :nested
            [name_prefix, prefix]
          when :collection
            [prefix, name_prefix, collection_name]
          when :new
            [prefix, :new, name_prefix, member_name]
          when :member
            [prefix, name_prefix, member_name]
          when :root
            [name_prefix, collection_name, prefix]
          else
            [name_prefix, member_name, prefix]
          end
        end

        def resource_scope?
          RESOURCE_SCOPES.include? scope_level
        end

        def options
          OPTIONS
        end

        def new(hash)
          self.class.new hash, self, scope_level
        end

        def new_level(level)
          self.class.new(frame, self, level)
        end

        def [](key)
          frame[key]
        end

        def frame; @hash; end

        include Enumerable

        def each
          node = self
          until node.equal? ROOT
            yield node
            node = node.parent
          end
        end

        ROOT = Scope.new({}, nil)
      end

      DEFAULT = Object.new # :nodoc:

      def initialize(set) # :nodoc:
        @set = set
        @draw_paths = set.draw_paths
        @scope = Scope.new(path_names: @set.resources_path_names)
        @concerns = {}
      end

      include Base
      include HttpHelpers
      include Redirection
      include Scoping
      include Concerns
      include Resources
      include CustomUrls
    end
  end
end
