#!/usr/bin/env python3

from select import poll, POLLPRI, POLLIN, POLLERR
import sys
import os
import threading
import time
import queue
import requests
import configparser
import logging
import paho.mqtt.publish as mqtt

def trans_http():
	global serverconf
	# build together url and headers
	uri = ""
	if serverconf.getboolean("ssl") == True:
		uri = "https://"
	else:
		uri = "http://"
	uri = uri + serverconf["url"] + "/get.php"
	log.info('Remote URI: {}'.format(uri))
	queuelast = time.time()
	while True:
		# get value from queue (blocking)
		queuedata = powerqueue.get()
		powerqueue.task_done()
		queuetime = int(queuedata[0])
		queueval = str(queuedata[1])
		# if more than five seconds passed since last event
		if ((queuetime - queuelast) >= 5):
			# put payload together
			if serverconf.getboolean('timestamp'):
				payload =  {"val": str(queuetime) + ";" + str(queueval)}
			else:
				payload =  {"val": str(queueval)}
			log.debug('request {}:{}{} => {}'.format(mqttconf['host'], mqttconf['port'], mqttconf['topic'], repr(payload)))
			# send to http server
			try:
				if serverconf.getboolean("basicauth") == True:
					r = requests.post(uri, data=payload, verify=False, auth=(serverconf["user"], serverconf["password"]), timeout=10, headers={'connection':'close'})
				else:
					r = requests.post(uri, data=payload, verify=False, timeout=10, headers={'connection':'close'})
			except:
				log.error('server response: {}'.format(str(r.status_code)))
			queuelast = queuetime
		
		else:
			# drop data if less than five seconds passed since last event
			del queuedata
			log.info('dropped queued element')


def trans_mqtt():
	global mqttconf
	queuelast = time.time()
	log.info('sending data via mqtt host: {}, port: {}, topic:{}'.format(mqttconf['host'], mqttconf['port'], mqttconf['topic']))
	while True:
		# get value from queue (blocking)
		queuedata = powerqueue.get()
		powerqueue.task_done()
		queuetime = int(queuedata[0])
		queueval = str(queuedata[1])
		# if more than five seconds passed since last event
		if ((queuetime - queuelast) >= 5):
			# put payload together
			if mqttconf.getboolean('timestamp'):
				payload = str(queuetime) + ";" + str(queueval)
			else:
				payload = str(queueval)
			log.debug('mqtt {} => {}'.format(mqttconf['host'], repr(payload)))
			# send to mqtt broker
			try:
				mqtt.single(mqttconf['topic'], payload=payload, retain=True, hostname=mqttconf['host'], 
					port=mqttconf.getint('port'), client_id=mqttconf['clientid'], transport="tcp")
			except BaseException as e:
				log.error('error while publishing: {}'.format(e))
			queuelast = queuetime
		
		else:
			# drop data if less than five seconds passed since last event
			del queuedata
			log.info('dropped queued element')


def readgpio():
	global gpiopath
	global gpioconf
	global smconf
	# open gpio filehandle
	gpio = open(gpiopath + "value", "r")
	# setup polling
	gpiopoll = poll()
	gpiopoll.register(gpio, POLLERR)
	
	# wait for two interrupts to have a "clean" starting point
	log.info('waiting for 2 interrupts to get a clean start')
	gpioevent = gpiopoll.poll()
	gpio.read()
	gpio.seek(0)
	log.info('waiting for 1 interrupt to get a clean start...')
	gpioevent = gpiopoll.poll()
	last = time.time()
	gpio.read()
	gpio.seek(0)
	
	# start readgpio mainloop
	log.info('start readgpio mainloop')
	while True:
		gpioevent = gpiopoll.poll()
		gpioval = gpio.read(1)
		gpio.seek(0)
		# check if interrupt was a falling edge (yes, really!)
		if gpioval == '0':
			now = time.time()
			# plausibility check
			if ((now-last) >= gpioconf.getfloat("mintime")):
				# calculate current power consumption
				power = round((3600000/smconf.getint("impkwh")) / (now-last),2)
				log.info('Current power consumption: {} Watt'.format(str(power)))
				log.debug('GPIO state: {}'.format(gpioval))
				# put measured value on queue
				powerqueue.put([now, power])
				last = now
		# error if a tty is connected and a raising edge was triggered
		else:
			log.debug('Not a falling edge, ignoring')


if __name__ == "__main__":
	# read config
	dirname, filename = os.path.split(os.path.abspath(__file__))
	conf = configparser.ConfigParser()
	try:
		conf.read(os.path.join(dirname, "powerpi.local.conf"))
	except:
		conf.read(os.path.join(dirname, "powerpi.conf"))
		log.warning('using global config. Use powerpi.local.conf instead')
	conf.sections()
	transconf = conf['transport']
	gpioconf = conf['gpio']
	serverconf = conf['server']
	smconf = conf['smartmeter']
	mqttconf = conf['mqtt']
	# configure logging
	log = logging.getLogger(__name__)
	log.setLevel(logging.DEBUG)
	ch = logging.StreamHandler()
	ch.setLevel(logging.INFO)
	log.info('Running in path {}'.format(dirname))
	if serverconf["url"] == "power.example.com" and mqttconf['host'] == "power.example.com":
		log.critical('Server/Broker -> url still default value')
		exit(1)
	gpiopath = "/sys/class/gpio/gpio" + gpioconf["port"] + "/"
	# initialise gpio interfaces
	try:
		if not os.path.exists(gpiopath):
			# if not already exported, export gpio port
			gpioinit = open("/sys/class/gpio/export", "w") 
			gpioinit.write(gpioconf["port"] + "\n")
			gpioinit.close()
		# set direction of gpio port to "IN"
		gpiopin = open(gpiopath + "direction", "w")
		gpiopin.write("in")
		gpiopin.close()
		# set trigger to falling edge
		gpiotype = open(gpiopath + "edge", "w")
		gpiotype.write("falling")
		gpiotype.close()
	except:
		log.critical('can not initialize gpio interface. aborting.')
		sys.exit(1)
	# defining queue for measured values
	powerqueue = queue.Queue()

	# disable ssl "no verification" warnings
	if serverconf.getboolean("sslself") == True:
		requests.packages.urllib3.disable_warnings()
	
	# initialising and starting threads
	th1 = threading.Thread(target=readgpio)
	if transconf['transport'] == 'mqtt':
		log.info('method of transfer: mqtt')
		th2 = threading.Thread(target=trans_mqtt)
	elif transconf['transport'] == 'http':
		log.info('method of transfer: http')
		th2 = threading.Thread(target=trans_http)
	else:
		log.error('transfer option {} is invalid. Exiting!'.format(transfer['transfer']))
		sys.exit(1)

	th1.setDaemon(True)
	th2.setDaemon(True)
	th1.start()
	th2.start()
	
	#busy loop
	while True:
		time.sleep(1)