require 'active_support/concern'

module Grape
  module DSL
    module Configuration
      extend ActiveSupport::Concern

      module ClassMethods
        attr_writer :logger

        include Grape::DSL::Settings

        # Set or retrive the configured logger. If none was configured, this
        # method will create a new one, logging to stdout.
        # @param logger [Object] the new logger to use
        def logger(logger = nil)
          if logger
            global_setting(:logger, logger)
          else
            global_setting(:logger) || global_setting(:logger, Logger.new($stdout))
          end
        end

        # Add a description to the next namespace or function.
        # @param description [String] descriptive string for this endpoint
        #   or namespace
        # @param options [Hash] other properties you can set to describe the
        #   endpoint or namespace. Optional.
        # @option options :detail [String] additional detail about this endpoint
        # @option options :params [Hash] param types and info. normally, you set
        #   these via the `params` dsl method.
        # @option options :entity [Grape::Entity] the entity returned upon a
        #   successful call to this action
        # @option options :http_codes [Array[Array]] possible HTTP codes this
        #   endpoint may return, with their meanings, in a 2d array
        # @option options :named [String] a specific name to help find this route
        # @option options :headers [Hash] HTTP headers this method can accept
        # @yield a block yielding an instance context with methods mapping to
        #   each of the above, except that :entity is also aliased as #success
        #   and :http_codes is aliased as #failure.
        #
        # @example
        #
        #     desc 'create a user'
        #     post '/users' do
        #       # ...
        #     end
        #
        #     desc 'find a user' do
        #       detail 'locates the user from the given user ID'
        #       failure [ [404, 'Couldn\'t find the given user' ] ]
        #       success User::Entity
        #     end
        #     get '/user/:id' do
        #       # ...
        #     end
        #
        def desc(description, options = {}, &config_block)
          if block_given?
            config_class = Grape::DSL::Configuration.desc_container

            config_class.configure do
              description description
            end

            config_class.configure(&config_block)
            options = config_class.settings
          else
            options = options.merge(description: description)
          end

          namespace_setting :description, options
          route_setting :description, options
        end

        def description_field(field, value = nil)
          if value
            description = route_setting(:description)
            description ||= route_setting(:description, {})
            description[field] = value
          else
            description = route_setting(:description)
            description[field] if description
          end
        end

        def unset_description_field(field)
          description = route_setting(:description)
          description.delete(field) if description
        end
      end

      module_function

      # Merge multiple layers of settings into one hash.
      def stacked_hash_to_hash(settings)
        return nil if settings.nil? || settings.blank?
        settings.each_with_object(ActiveSupport::OrderedHash.new) { |value, result| result.deep_merge!(value) }
      end

      # Returns an object which configures itself via an instance-context DSL.
      def desc_container
        Module.new do
          include Grape::Util::StrictHashConfiguration.module(
            :description,
            :detail,
            :params,
            :entity,
            :http_codes,
            :named,
            :headers
          )

          def config_context.success(*args)
            entity(*args)
          end

          def config_context.failure(*args)
            http_codes(*args)
          end
        end
      end
    end
  end
end