begin
  Kernel::require 'serialport'
rescue Exception
  require 'serialport'
end

module RfidUsbGomSensor
  class Node < Gom::Remote::Entry

    Defaults = {
      :device => "/dev/ttyUSB0", 
      :baudrate => 9600,
    }

    include OAttr
    oattr :device, :baudrate

    def initialize path, options = {}
      @path = path
      @options = Defaults.merge(gnode @path).merge(options)
      puts "options: #{@options.inspect}"

      @ip = connection.callback_server.host
      @sp = SerialPort.new device, baudrate
    end

    # reader commands
    STX = 0x02
    ETX = 0x03
    GetInfo =      [STX, 0x01, 0x47, 0x46, ETX].pack "c*"
    GoContinuous = [STX, 0x01, 0x43, 0x04, 0x46, ETX].pack "c*"

    def preroll
      #info = [0x02, 0x01, 0x47, 0x46, 0x03]
      #info.each {|c| @sp.putc c.to_i}
      @sp.puts GetInfo
      2.times {@sp.getc}
      print "Detected reader: "
      37.times {putc(@sp.getc)}
      print "\n"
      6.times {@sp.getc}

      #continuous = [0x02, 0x01, 0x43, 0x04, 0x46, 0x03]
      #continuous.each {|c| @sp.putc c.to_i}
      @sp.puts GoContinuous
      6.times {@sp.getc}
    end

    class << self 
      def checksum buf, expected
        cc = (buf.unpack "C*").inject(0) { |cc, c| cc ^ c }
        (cc != expected) and raise "checksum missmatch: #{cc} != #{expected}"
        cc
      end

      def decode blk
        #validate 
        rec = (blk.unpack 'c2Qc*')
        checksum blk[1..10], rec[4]
        puts "-#{rec.inspect}-"
        rec
      end
    end

    def detect
      buf = ""
      loop do
        buf << (blk = @sp.read(13))
        stx, adx, uid, err, bcc, etx = (Node.decode buf)
        buf = ""
      end
    rescue SignalException => e
      :stop # if (e.signm == "INT")
    end

    def _detect
=begin
Format:
 0 STX  0x02
 1 ADR  0x01
 2 UID7 0xE0
 3 UID6  
 4 UID5  
 5 UID4  
 6 UID3  
 7 UID2  
 8 UID1  
 9 UID0  
10 ERR  0x00
11 BCC  XOR[1..10]
12 ETX  0x03
=end
      while @sp.getc!=0x02 do end # STX
      while @sp.getc!=0x01 do end # ADR
      v = 0
      0.upto(7) do |i|
        v += @sp.getc*2**((7-i)*8) # UID
      end
      while @sp.getc!=0x00 do end # ERR
      puts "Detected tag: #{v}"
      connection.write "#{@path}/tags/#{v}:sensor_ip", @ip
      puts "-#{@sp.getc}-" # BCC
      while @sp.getc!=0x03 do end # ETX
    rescue SignalException => e
      :stop # if (e.signm == "INT")
    end
  end
end