bigcommerce/gruf

# frozen_string_literal: true

# Copyright (c) 2017-present, BigCommerce Pty. Ltd. All rights reserved
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
# documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit
# persons to whom the Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
# Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
module Gruf
  module Controllers
    ##
    # Binds gRPC services to a gruf controller
    #
    class ServiceBinder
      ##
      # Represents a bound RPC descriptor for future-proofing internal helpers
      #
      class BoundDesc < SimpleDelegator; end

      class << self
        ##
        # Bind all methods on the service to the passed controller
        #
        # @param [Class<Gruf::Controllers::Base>] controller
        #
        def bind!(service:, controller:)
          rpc_methods = service.rpc_descs.map { |rd| BoundDesc.new(rd) }
          rpc_methods.each { |name, desc| bind_method(service, controller, name, desc) }
        end

        ##
        # Bind the grpc methods to the service, allowing for server interception and execution control
        #
        # @param [Gruf::Controllers::Base] controller
        # @param [Symbol] method_name
        # @param [BoundDesc] desc
        #
        def bind_method(service_ref, controller, method_name, desc)
          method_key = method_name.to_s.underscore.to_sym
          controller_name = controller.name
          service_ref.class_eval do
            if desc.request_response?
              define_method(method_key) do |message, active_call|
                Gruf::Autoloaders.controllers.with_fresh_controller(controller_name) do |fresh_controller|
                  c = fresh_controller.new(
                    method_key: method_key,
                    service: service_ref,
                    message: message,
                    active_call: active_call,
                    rpc_desc: desc
                  )
                  c.call(method_key)
                end
              end
            elsif desc.client_streamer?
              define_method(method_key) do |active_call|
                Gruf::Autoloaders.controllers.with_fresh_controller(controller_name) do |fresh_controller|
                  c = fresh_controller.new(
                    method_key: method_key,
                    service: service_ref,
                    message: proc { |&block| active_call.each_remote_read(&block) },
                    active_call: active_call,
                    rpc_desc: desc
                  )
                  c.call(method_key)
                end
              end
            elsif desc.server_streamer?
              define_method(method_key) do |message, active_call, &block|
                Gruf::Autoloaders.controllers.with_fresh_controller(controller_name) do |fresh_controller|
                  c = fresh_controller.new(
                    method_key: method_key,
                    service: service_ref,
                    message: message,
                    active_call: active_call,
                    rpc_desc: desc
                  )
                  c.call(method_key, &block)
                end
              end
            else # bidi
              define_method(method_key) do |messages, active_call, &block|
                Gruf::Autoloaders.controllers.with_fresh_controller(controller_name) do |fresh_controller|
                  c = fresh_controller.new(
                    method_key: method_key,
                    service: service_ref,
                    message: messages,
                    active_call: active_call,
                    rpc_desc: desc
                  )
                  c.call(method_key, &block)
                end
              end
            end
          end
        end
      end
    end
  end
end