#!/usr/bin/env python
#-*- coding: utf-8 -*-
"""Simple python library to communicate over USB-TMC protocol with linux's
    usbtmc module.
"""
import time
import sys
import os
import glob
import re

__author__ = "Alexis Jeandet"
__copyright__ = "Copyright 2015, Laboratory of Plasma Physics"
__credits__ = []
__license__ = "GPLv2"
__version__ = "1.0.0"
__maintainer__ = "Alexis Jeandet"
__email__ = "alexis.jeandet@member.fsf.org"
__status__ = "Development"


def find_instrument(ref,serial=""):
    instruments=glob.glob("/dev/usbtmc[0-9]")
    p = re.compile(ref)
    for instrument in instruments:
        dev=UsbTmc(instrument)
        idn=dev.idn().split(",")
        if p.match(idn[1]):
            if serial=="" or serial == idn[2]:
                return instrument
    return ""

class UsbTmc(object):
    def __init__(self,dev):
        self.__PATH__=dev
        self.__FILE__ = os.open(dev, os.O_RDWR)
        if self.__FILE__==-1:
            raise UserWarning("can't open "+dev)
        self.Manufacturer=""
        self.Reference=""
        self.Serial=""
        self.Version=""

    def write(self, command):
        os.write(self.__FILE__, command);

    def read(self, length = 4000):
        return os.read(self.__FILE__, length)

    def idn(self):
        self.write("*IDN?")
        return self.read(100)

    def __str__(self):
        return self.idn() +"\n"+ self.__PATH__