#!/usr/bin/env python
import shlex
import subprocess

class RFIDReaderWrapper(object):
    """runs rfid reader as a subprocess & parses tag serials
    from its output
    """
    def __init__(self, cmd):
        self._cmd_list = shlex.split(cmd)
        self._subprocess = None
        self._init_subprocess()

    def _init_subprocess(self):
        self._subprocess = subprocess.Popen(self._cmd_list,
            stderr=subprocess.PIPE)

    def read_tag_serial(self):
        """blocks until new tag is read
        returns serial of the tag once the read happens
        """
        if not self._subprocess:
            self._init_subprocess()

        while 1:
            line = self._subprocess.stderr.readline()
            if isinstance(line, bytes):
                # python3 compat
                line = line.decode("utf-8")

            if line == '':
                # EOF
                return None

            if not line.startswith("New tag"):
                continue

            serial = line.split()[-1].split("=", 1)[1]
            return serial

    def get_serialmap(filename):
        """read serial -> name mappings from the given file
        and return them as a dictionary.
        file is assumed to look like:
        [2f75b800]; Peter Pan
        """
        serials = {}
        with open(filename, "r") as fd:
            # lets build serial -> name mapping
            for line in fd.readlines():
                serial, name = line.strip().split(";", 1)
                # XXX: we strip [ ] from the serial
                serials[serial[1:-1]] = name

        return serials



if __name__ == '__main__':
    reader = RFIDReaderWrapper("./rc522_reader -d")
    while 1:
        fobj = open("/root/status.txt","r+")
        serial = reader.read_tag_serial()
        # blink the lights etc.
        print(serial)
        print (get_serialmap(sys.argv[1]))
        fobj.close()