# Module to find all current VISA-compatible devices and VISA-USB devices.

try:
    import visa as v
except :
    print '\nWarning: PyVisa is not available.'
    try:
        import visa_fake as v
        print '\nA pseudo PyVisa, visa_fake, was imported.'
    except:
        print '\nWarning: Fake PyVisa is not available.'
        exit(0)
import string as s

## Use PyVisa to find all visa-compatible devices on usb, com, lpt, gpib connections
def FindVisaDevices(print_messages=False, write_log=False) :
    logfile = "log_visa.txt"
    # a is list of strings, one per instrument.  Each string contains the connection, vendor id, model number and serial number.
    a = v.get_instruments_list()
    # Print the list of instruments to the terminal.
    if print_messages :
        print('\nVISA devices found:')
        print(a)
        #print('\t' + '\n\t'.join(a))
    # Writing result of actions to a log file can be useful for trouble-shooting.
    if write_log :
        f = open(logfile, "w")   #Open a text file to record the output. The 'w' means "write".
        f.write('Result of search for VISA devices:')
        f.write('\n\t' + '\n\t'.join(a))      # '\t' is a tab and '\n' is a new line or linefeed (lf).
        f.close()       # Always close whatever you have opened.
        print('\n' + logfile + ' written.')
    return a

## Find just the USB-connected devices
def FindUSBDevices(print_messages=False, write_log=False) :
    logfile = "log_visa_usb.txt"
    visa_devs = FindVisaDevices(write_log)   # Use FindVisaDevices function defined in find_visa_devices.py
    usb_devs = {}           # Create an empty dictionary
    for dev in visa_devs :
        if dev.find('USB') > -1 :
            protocol, vid, pid, sn  = s.split(dev, '::')
            usb_devs[dev] = {'protocol' : protocol, 'pid' : pid, 'sn' : sn,'vid' : vid} # Each device is specified by visa identifier string dev.
    if print_messages :
        print('\nVISA USB devices found ( {visa id string : {protocol, product id, serial number, vendor id}):')
        for thing in usb_devs :
            print('\t"' + thing + '" : {' + ', '.join(['"%s" : %s' % (key, value) for (key, value) in sorted(usb_devs[thing].items())]) + '}')
    if write_log :
        f = open(logfile, 'w')
        f.write('\nVISA USB devices found ( {visa id string : {protocol, product id, serial number, vendor id}):')
        for thing in usb_devs :
            f.write('\n\t{"' + thing + '" : {' + ', '.join(['"%s" : %s' % (key, value) for (key, value) in sorted(usb_devs[thing].items())]) + '}}')
        f.close()
        print('\n' + logfile + ' written.')
    return usb_devs     # Return a dictionary of visa-usb devices

#-------------------------------------------------------------------------------

if __name__ == '__main__' :
    #FindVisaDevices(print_messages=True, write_log=True)
    usb = FindUSBDevices(print_messages=True, write_log=True)