#!/usr/bin/python3

############################################################################
##
## ir-aprsisd
##
##	This is a KML-feed to APRS-IS forwarding daemon.  It was written
##	for Garmin/DeLorme inReach devices, but might work elsewhere too.
##	It polls a KML feed in which it expects to find a point in rougly
##	the form that the inReach online feeds use, with attendant course
##	and altitude data.  It transfers each new point found there to 
##	APRS-IS.
##
##	K0SIN
##
###########################################################################


import aprslib
import urllib.request
import xml.dom.minidom
import time, calendar, math, re
import platform, sys
import configparser
from optparse import OptionParser


#Name of our configuration file.
cf = "ir-aprsisd.cfg"

#Configuration
conf = configparser.ConfigParser()
#Try /etc, then try the current directory, or just quit.
try:
	conf.read("/etc/" + cf)
	if not conf.has_section('General'):
		conf.read(cf)
	if not conf.has_section('General'):
		sys.exit("Can't read configuration file: " + cf)
except:
	sys.exit("Can't read configuration file: " + cf)


#Command-line options
op = OptionParser()

op.add_option("-s","--ssid",action="store",type="string",dest="ssid",help="APRS SSID")
op.add_option("-p","--pass",action="store",type="int",dest="passwd",help="APRS-IS password")
op.add_option("-P","--port",action="store",type="int",dest="port",help="APRS-IS port")
op.add_option("-u","--user",action="store",type="string",dest="user",help="inReach username")
op.add_option("-U","--url",action="store",type="string",dest="url",help="URL for KML feed")
op.add_option("-c","--comment",action="store",type="string",dest="comment",help="APRS-IS location beacon comment text")
op.add_option("-d","--delay",action="store",type="int",dest="delay",help="Delay between polls of KML feed")
(opts,args) = op.parse_args()

#Allow command-line arguments to override the config file.
if opts.ssid:
	conf['APRS']['SSID'] =		opts.ssid
if opts.passwd:
	conf['APRS']['Password'] =		str(opts.passwd)
if opts.port:
	conf['APRS']['Port'] =		str(opts.port)
if opts.user:
	conf['inReach']['User'] = 	opts.user
if opts.url:
	conf['inReach']['URL'] = 	opts.url
if opts.comment:
	conf['APRS']['Comment'] =	opts.comment
if opts.delay:
	conf['General']['Period'] =	opts.delay

#The beginning of our APRS packets should contain a source, path, 
# q construct, and gateway address.  We'll reuse the same SSID as a gate.
ARPreamble	= ''.join([conf['APRS']['SSID'],'>APRS,','TCPIP*,','qAS,',conf['APRS']['SSID']])

NAME		= "iR-APRSISD"
REV		= "0.1"

#Start with the current time.  We use this to keep track of whether we've
# already sent a position, so if we cut it off when the program starts, we
# won't (re-)send old stale entry from inReach
lastUpdate	= calendar.timegm(time.gmtime())

#Handle connection to APRS-IS
def reconnect():
	global AIS
	while True:
		AIS = aprslib.IS(conf['APRS']['SSID'],passwd=conf['APRS']['Password'],port=conf['APRS']['Port'])
		try:
			AIS.connect()
			break
		except Exception as e:
			print("Trouble connecting to APRS-IS server.")
			print(e)


#APRS-IS Setup
AIS = None
reconnect()


while True:
	try:
		KML = urllib.request.urlopen(conf['inReach']['URL']).read()
	except Exception as e:
		print(''.join(["Error reading URL: ", conf['inReach']['URL']]))
		continue
	try:
		data = xml.dom.minidom.parseString(KML).documentElement
		#The first placemark will have the expanded current location information.
		position = data.getElementsByTagName('Placemark')[0]
		
		#Now process the extended data into something easier to handle.
		extended = {}
		for xd in position.getElementsByTagName('ExtendedData')[0].getElementsByTagName('Data'):
			if not xd.getElementsByTagName('value')[0].firstChild == None:
				extended[xd.getAttribute('name')] = xd.getElementsByTagName('value')[0].firstChild.nodeValue	
	except Exception as e:
		print(''.join(["Could not parse data from URL: ",conf['inReach']['URL']]))
		continue

	try:
		#Here is the position vector
		latitude	= extended['Latitude']
		longitude	= extended['Longitude']
		elevation	= extended['Elevation']
		velocity	= extended['Velocity']
		course		= extended['Course']
		uttime		= extended['Time UTC']
		device		= extended['Device Type']

		#Some time conversions.  First the time struct.
		ts = time.strptime(''.join([uttime," UTC"]),"%m/%d/%Y %I:%M:%S %p %Z")
		#Unix epoch time for local record-keeping.
		etime		= calendar.timegm(ts)
		#MonthDayHoursMinutes_z for APRS-IS packet
		aprstime	= time.strftime("%d%H%Mz",ts)

		#Skip this one if it's old.
		if lastUpdate > etime:
			time.sleep(conf.getfloat('General','Period'))
			continue

		#Append the device type to the comment
		conf['APRS']['Comment'] = ''.join([" ",conf['APRS']['Comment']," : ", NAME," v",REV," : ",platform.system()," on ",platform.machine()," : ",device])

		#Latitude conversion
		#We start with the truncated degrees, filled to two places
		# then add fractional minutes two 2x2 digits.
		latitude	= float(latitude)
		aprslat		= str(abs(math.trunc(latitude))).zfill(2)
		aprslat		+= '{:.02f}'.format(round((abs(latitude)-abs(math.trunc(latitude)))*60,2)).zfill(5)
		if latitude > 0:
			aprslat += "N"
		else:
			aprslat += "S"

		#Longitude next.
		longitude	= float(longitude)
		aprslong	= str(abs(math.trunc(longitude))).zfill(3)
		aprslong	+= '{:.02f}'.format(round((abs(longitude)-abs(math.trunc(longitude)))*60,2)).zfill(5)
		if longitude > 0:
			aprslong += "E"
		else:
			aprslong += "W"

		#Altitude needs to be in feet above sea-level
		# what we get instead is a string with a number of meters
		# at the beginning.
		aprsalt		= re.sub(r'^(\d+\.?\d+)\s*m.*',r'\1',elevation)
		#We need integer feet, six digits
		aprsalt		= str(round(float(aprsalt) * 3.2808399)).zfill(6)
		aprsalt		= "/A=" + aprsalt[0:6]

		#Aprs position
		aprspos		= ''.join([aprslat,conf['APRS']['Separator'],aprslong,conf['APRS']['Symbol']])

		#Course is already in degrees, so we just need to reformat it.
		aprscourse = str(round(float(re.sub(r'(\d+\.?\d+).*',r'\1', course)))).zfill(3)

		#Speed is in km/h.
		aprsspeed = float(re.sub(r'(\d+\.?\d+).*',r'\1',velocity))*0.53995681
		aprsspeed = str(min(round(aprsspeed),999)).zfill(3)

		#Here's the course/speed combination
		aprscs = ''.join([aprscourse,'/',aprsspeed])

	except Exception as e:
		print("Some relevant position vector data is missing or malformatted in this record.")
		print(e)
		#Pass?  Maybe...
		pass
	try:
		#According to spec, one valid format for location beacons is
		# @092345z/4903.50N/07201.75W>088/036
		# with a comment on the end that can include altitude and other
		# information.
		aprsPacket = ''.join([ARPreamble,':@',aprstime,aprspos,aprscs,aprsalt,conf['APRS']['Comment']])
		print(aprsPacket)
		#This will throw an exception if the packet is somehow wrong.
		aprslib.parse(aprsPacket)
		AIS.sendall(aprsPacket)
		lastUpdate = etime
	except Exception as e:
		print("Could not send the update: ")
		if 'aprsPacket' in locals():
			print(aprsPacket)
		print(e)
		print("Attempting reconnection, just in case.")
		reconnect()
		pass
	time.sleep(conf.getfloat('General','Period'))