# frozen_string_literal: true

require 'grpc_kit'

require 'griffin/engine'
require 'griffin/server_config_builder'
require 'griffin/thread_pool'

module Griffin
  class Server
    DEFAULT_WORKER_SIZE = 10
    DEFAULT_BACKLOG_SIZE = 1024

    GRACEFUL_SHUTDOWN = '0'
    FORCIBLE_SHUTDOWN = '1'

    class << self
      def run
        c = config_builder.build
        Griffin::Engine.start(c, cluster: Integer(c[:workers]) > 1)
      end

      def configure
        yield(config_builder)
      end

      def config_builder
        @config_builder ||= Griffin::ServerConfigBuilder.new
      end
    end

    def initialize(worker_size: DEFAULT_WORKER_SIZE, **opts)
      @worker_size = worker_size
      @server = GrpcKit::Server.new
      @opts = opts
      @status = :run
      @worker_id = 0
    end

    def handle(handler)
      @server.handle(handler)
      handler.class.rpc_descs.each do |path, _|
        Griffin.logger.debug("Handle #{path}")
      end
    end

    def before_run(worker_id = 0)
      @worker_id = worker_id

      # To separete fd with other forked process
      @socks = []
      @command, @signal = IO.pipe
      @socks << @command
    end

    def run(sock, blocking: true)
      @socks << sock

      @thread_pool = Griffin::ThreadPool.new(@worker_size) do |conn|
        @server.run(conn)
      end

      if blocking
        handle_server
      else
        Thread.new { handle_server }
      end
    end

    def shutdown(reason = GRACEFUL_SHUTDOWN)
      @signal.write(reason)
    end

    private

    def handle_server
      while @status == :run
        io = IO.select(@socks, [], [])

        io[0].each do |sock|
          if sock == @command
            break if handle_command
          end

          begin
            conn = sock.accept_nonblock
            @thread_pool.schedule(conn[0])
          rescue IO::WaitReadable, Errno::EINTR => e
            Griffin.logger.debug("Error raised #{e}")
            # nothing
          end
        end
      end

      @thread_pool.shutdown
      # unless @sever.session_count == 0
      # end

      @command.close
      @signal.close
    end

    def handle_command
      case @command.read(1)
      when FORCIBLE_SHUTDOWN
        Griffin.logger.info("Shutting down sever(id=#{@worker_id}) forcibly...")

        @status = :halt
        @server.graceful_shutdown
        true
      when GRACEFUL_SHUTDOWN
        Griffin.logger.info("Shutting down sever(id=#{@worker_id}) gracefully...")
        @status = :stop
        true
      end
    end
  end
end