#!/usr/bin/python

#
# Talk to a GwInstek GPD-4303s benchtop power supply
#

import time
import serial
import getopt
import sys
import subprocess
import re
import curses

def findDevice():
	p = subprocess.Popen("dmesg", stdout = subprocess.PIPE, stderr = subprocess.PIPE)
	pout, perr = p.communicate()
	device = None
	for line in pout.split("\n"):
		if 'FTDI USB Serial Device converter now attached' in line:
			device = '/dev/' + line.split()[-1]
	return device

def parseArgs(cfg):
	try:
		opts, args = getopt.getopt(sys.argv[1:], "hD:v", ["help", "device=", "port1=", "port2=", "port3=", "port4="])
	except getopt.GetoptError, err:
		print str(err)
		print usage()
		sys.exit(2)

	device = None
	for o, a in opts:
		if o in ("-h", "--help"):
			print usage()
			sys.exit(0)
		elif o in ("-D", "--device"):
			device = a
		elif o in ("--port1", "--port2", "--port3", "--port4"):
			port = int(o[6:])
			cfg['port'][port]['name'] = a
		else:
			assert False, "unhandled option"

	if device == None:
		device = findDevice()
	if device == None:
		print "Could not find serial device. Try -D argument"
		sys.exit(2)

	return device

def numQuery(ser, string):
	ser.write(string + "\n")
	l = ser.readline()
	# return only the number
	return float(re.compile('[^\\d\\.]').sub('', l))

def getCurrent(ser, port):
	return numQuery(ser, "IOUT" + str(port) + "?")

def getVoltage(ser, port):
	return numQuery(ser, "VOUT" + str(port) + "?")

def setup(ser, port, voltage):
	ser.write("VSET" + str(port) + ":" + str(voltage) + "\n")

def enableOutput(ser):
	ser.write("OUT1\n")

def getavg(samples, now, seconds):
	r = [w for (t, w) in samples if t + seconds >= now]
	return (seconds, sum(r), len(r))

def getPort(cfg, ser, port):
	voltage = cfg['port'][port]['voltage']
	samples = cfg['port'][port]['samples']
	history = cfg['history']
	try:
		current = getCurrent(ser, port)
		watts = voltage * current
		now = time.time()
		samples.append((now, watts))
		samples = [(t, w) for (t, w) in samples if t + max(history) >= now]
		timeaverages = [(0, watts, 1)] + [getavg(samples, now, s) for s in history]
		cfg['port'][port]['samples'] = samples
		return ', '.join(["%ds: %1.4fW (%d)" % (s, w / l, l) for (s, w, l) in timeaverages])
	except:
		return ''


def runLoop(cfg, ser, stdscr):
	for port in cfg['ports']:
		cfg['port'][port]['samples'] = []
	running = True
	while running:
		stdscr.addstr(0, 0, cfg['id'] + ' (press \'q\' to quit)')
		for port in cfg['ports']:
			portname = cfg['port'][port]['name']
			s = getPort(cfg, ser, port)
			stdscr.addstr(port, 0, portname + ": " + s)
		c = stdscr.getch()
		if c in [27, ord('q')]:
			running = False
		stdscr.refresh()

def initCurses():
	stdscr = curses.initscr()
	curses.noecho()
	curses.cbreak()
	curses.noqiflush()
	stdscr.nodelay(True)
	return stdscr

def exitCurses():
	curses.endwin()

def run(cfg, ser):
	stdscr = initCurses()
	for port in cfg['ports']:
		setup(ser, port, cfg['port'][port]['voltage'])
	enableOutput(ser)
	runLoop(cfg, ser, stdscr)
	exitCurses()

def runSerial(cfg, device):
	ser = serial.Serial(
			port = device,
			baudrate = 9600,
			parity = serial.PARITY_NONE,
			stopbits = serial.STOPBITS_ONE,
			bytesize = serial.EIGHTBITS,
			timeout = 2)
	ser.open()
	if ser.isOpen():
		ser.write("*IDN?\n")
		id = ser.readline()
		if "GW INSTEK" in id:
			print "Connected to: " + id,
			cfg['id'] = id.strip()
			run(cfg, ser)
		else:
			print "Power supply not found on " + device
	ser.close()

if __name__ == '__main__':
	cfg = {}
	cfg['port'] = {}
	cfg['ports'] = [1, 2]
	cfg['history'] = [1, 10, 60]	#seconds
	for port in cfg['ports']:
		cfg['port'][port] = {}
		cfg['port'][port]['voltage'] = 5.000
		cfg['port'][port]['name'] = 'port' + str(port)
	device = parseArgs(cfg)
	runSerial(cfg, device)