require 'celluloid/io'

require 'listen/tcp/message'

module Listen
  module Adapter
    # Adapter to receive file system modifications over TCP
    class TCP < Base
      OS_REGEXP = // # match any

      include Celluloid::IO
      finalizer :finalize

      DEFAULTS = {
        host: 'localhost',
        port: '4000'
      }

      attr_reader :buffer, :socket

      # Initializes and starts a Celluloid::IO-powered TCP-recipient
      def start
        attempts ||= 3
        _log :info, "TCP: opening socket #{options.host}:#{options.port}"
        @socket = TCPSocket.new(options.host, options.port)
        @buffer = ''
        async.run
      rescue Celluloid::Task::TerminatedError
        _log :debug, "TCP adapter was terminated: #{$ERROR_INFO.inspect}"
      rescue Errno::ECONNREFUSED
        sleep 1
        attempts -= 1
        _log :warn, "TCP.start: #{$ERROR_INFO.inspect}"
        retry if attempts > 0
        _log :error, format('TCP.start: %s:%s', $ERROR_INFO.inspect,
                            $ERROR_POSITION * "\n")
        raise
      rescue
        _log :error, format('TCP.start: %s:%s', $ERROR_INFO.inspect,
                            $ERROR_POSITION * "\n")
        raise
      end

      # Cleans up buffer and socket
      def finalize
        @buffer = nil
        return unless @socket

        @socket.close
        @socket = nil
      end

      # Number of bytes to receive at a time
      RECEIVE_WINDOW = 1024

      # Continuously receive and asynchronously handle data
      def run
        while (data = @socket.recv(RECEIVE_WINDOW))
          async.handle_data(data)
        end
      end

      # Buffers incoming data and handles messages accordingly
      def handle_data(data)
        @buffer << data
        while (message = Listen::TCP::Message.from_buffer(@buffer))
          handle_message(message)
        end
      rescue
        _log :error, format('TCP.handle_data crashed: %s:%s', $ERROR_INFO,
                            $ERROR_POSITION * "\n")
        raise
      end

      # Handles incoming message by notifying of path changes
      def handle_message(message)
        type, change, dir, path, _ = message.object
        _log :debug, "TCP message: #{[type, change, dir, path].inspect}"
        _queue_change(type.to_sym, Pathname(dir), path, change: change.to_sym)
      end

      def self.local_fs?
        false
      end
    end
  end
end