def split(string, limit = nil)
  string.split(/\s+/, limit)
end

def report_error(client, whole_command, error)
  $stderr.puts "=== ERROR WHILE PROCESSING THE COMMAND \"#{whole_command}\" ===\n"\
    "#{error.class.name}: #{error.message}\n#{error.backtrace.join("\n")}"
  client.puts "sorry"
end

def dev_log(*a)
  $stdout.puts(*a) if Rails.env.development?
end

def log(*a)
  $stdout.puts(*a) unless Rails.env.test?
end

# ==== Send Format: =======
# One line strings: "#{command} #{arg1} #{arg2} #{etc}"
# The last argument, depending on the command, may contain spaces (but usually does not need to)
# =========================
# === Receive Format: =====
# Usually one string, like "yes", or "no".
# Returns "denied"  if an unauthorized command was attempted.
# Returns "invalid" if an invalid command was attempted.
# Returns "sorry"   if an error was raised while processing the command.
# Can be a json argument, often following "yes ".
# =========================
def address_of(socket)
  _family, port, name, host = socket.addr
  if host == name
    "#{host}:#{port}"
  else
    "#{name}(#{host}):#{port}"
  end
end

def start_server!(*args)
  log "Connecting...!"
  
  if args.size > 1
    port = args.first
  else
    port = ENV['port'] || ENV['PORT'] || 2900
  end

  server = TCPServer.new port
  log "Ready! Using \"#{ActiveRecord::Base.connection.current_database}\" database"

  client_count = 0
  commands = args.last

  loop do
    Thread.start(server.accept) do |client|
      begin
        client.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
      rescue Exception => e
        puts "Couldn't set TCP_NODELAY"
      end

      client_count += 1
      dev_log "New client! ##{client_count} #{address_of client}"

      if Rails.env.development?
        response_logger = Module.new do
          def puts(s)
            $stdout.puts "==> #{s}"
            super
          end
        end
        client.singleton_class.send :include, response_logger
      end

      while line_in = client.gets.chomp
        log "Processing \"#{line_in}\"" if Rails.env.test?

        command, rest_of_command = split(line_in, 2)

        before = Time.now
        begin
          command = commands[command.downcase.to_sym]

          if command.nil?
            log "SOMEONE attempted invalid command: \"#{line_in}\""
          else
            dev_log "<== #{line_in}"
            ActiveRecord::Base.connection_pool.with_connection do
              command.call(client, rest_of_command)
              client.flush
            end
          end

        rescue StandardError => e
          report_error(client, line_in, e)
        rescue Exception => e
          report_error(client, line_in, e)
          break
        end
        after = Time.now

        ms = (after - before) * 1000
        dev_log %((#{'%.2f' % ms}ms) from #{address_of(client)})
        dev_log ""
      end

      client_count -= 1
      client.close rescue nil
      dev_log "Client disconnected. #{address_of client}"
    end
  end
end