require 'google/protobuf'
require 'grpc'

# The following definitions for EchoRequest, EchoReply, and EchoServer
# are taken straight from https://github.com/grpc/grpc/tree/master/src/ruby/end2end
Google::Protobuf::DescriptorPool.generated_pool.build do
  add_message "echo.EchoRequest" do
    optional :request, :string, 1
  end
  add_message "echo.EchoReply" do
    optional :response, :string, 1
  end
end

module Echo
  EchoRequest = Google::Protobuf::DescriptorPool.generated_pool.lookup("echo.EchoRequest").msgclass
  EchoReply = Google::Protobuf::DescriptorPool.generated_pool.lookup("echo.EchoReply").msgclass
end

module Echo
  module EchoServer
    class Service

      include GRPC::GenericService

      self.marshal_class_method = :encode
      self.unmarshal_class_method = :decode
      self.service_name = 'echo.EchoServer'

      rpc :Echo, EchoRequest, EchoReply
    end

    Stub = Service.rpc_stub_class
  end
end

class EchoServerImpl < Echo::EchoServer::Service
  # say_hello implements the SayHello rpc method.
  def echo(echo_req, _)
    Echo::EchoReply.new(response: echo_req.request)
  end
end

s = GRPC::RpcServer.new

grpc_host = '0.0.0.0:50051'

begin
  s.add_http2_port(
    grpc_host,
    :this_port_is_insecure
  )
  s.handle(EchoServerImpl)
  s.run_till_terminated
rescue SignalException => e
  puts e.inspect
  s.stop
end