#!/usr/bin/env python
import constants
import readdata
import sys
import json
import traceback
import subprocess
from devicer import simple_devicer
# import requests # As this takes SEVEN SECONDS, it's delayed until needed
from sys import stdout, stderr
from datetime import timedelta, datetime
from time import sleep
from itertools import islice, takewhile
from database_records import GenericTimestampedRecord, EGVRecord, EventRecord
# from pytz import UTC # Since the dependency is external, don't import unless needed

from optparse import OptionParser

G5_IS_DEFAULT = True

def get_dracos_host():
	res = subprocess.check_output([
		'sh',
		'-c',
		'dracos_host=localhost:8001; [ -e /etc/dracos.conf ] && . /etc/dracos.conf; printf "%s" "$dracos_host" || true'])
	return res.decode('utf-8')

parser = OptionParser()
parser.add_option("--g4", action="store_false", dest="g5", default=G5_IS_DEFAULT, help="use Dexcom G4 instead of Dexcom G5")
parser.add_option("--g5", action="store_true",  dest="g5", default=G5_IS_DEFAULT, help="use Dexcom G5 instead of Dexcom G4")

parser.add_option("-a", "--all",  action="store_const", dest="command", const="dump_everything", help="dump all available records")
parser.add_option("-p", "--poll", action="store_const", dest="command", const="poll",            help="poll for latest CGM record")
parser.add_option("--test",       action="store_const", dest="command", const="test",            help="test")

parser.add_option("--hours", type="int", dest="hours", default=None, help="display N most recent hours of CGM records")
parser.add_option("-n", type="int", dest="num_records", default=None, help="number of CGM records to display")
parser.add_option("-v", "--verbose", action="store_true", dest="verbose", help="verbosity (currently for debugging)")
parser.add_option("-H", "--human", action="store_true", dest="human", help="print human-readable times")
parser.add_option("-j", "--json", action="store_true", dest="json", help="print JSON output")
parser.add_option("--http", type="string", dest="host", help="submit via HTTP")
parser.add_option("--client", action="store_true", dest="client", help="act as client to dracos")

(options, args) = parser.parse_args()

command = options.command or "dump_cgm"
VERBOSE = options.verbose
HUMAN = options.human
JSON = options.json
HOST = options.host

if options.client and not HOST:
	dracos_host = get_dracos_host()
	if dracos_host:
		HOST = "http://" + dracos_host
	else:
		raise ValueError("Option '--client' specified but 'dracos_host' not specified in '/etc/dracos.conf'")


if command is 'dump_cgm' and options.num_records is None and not options.hours:
        options.hours = 2
if options.num_records <= 0:
        options.num_records = None

def get_dexcom_reader():
        if options.g5:
                dd = readdata.DexcomG5.FindDevice()
                return readdata.DexcomG5(dd)
        else:
                dd = readdata.Dexcom.FindDevice()
                return readdata.Dexcom(dd)

dr = None

if command is not 'poll':
        dr = get_dexcom_reader()

def parseable_record_types():
        unparseable = ['FIRMWARE_PARAMETER_DATA', 'RECEIVER_LOG_DATA', 'USER_SETTING_DATA', 'MAX_VALUE', 'RECEIVER_ERROR_DATA']
        parsed_to_xml = ['MANUFACTURING_DATA', 'PC_SOFTWARE_PARAMETER']
        skip = unparseable + parsed_to_xml
        return filter(lambda v: not v in skip, constants.RECORD_TYPES)

def choose_range(rs):
        if options.hours:
                now = dr.ReadSystemTime()
                when = now - timedelta(hours=options.hours)
                return takewhile(lambda r: r.system_time > when, rs)
        else:
                return islice(rs, options.num_records)

def dump_everything():
        for t in parseable_record_types():
                print t + ":"
                for r in choose_range(dr.iter_records(t)):
                        print toJSON(r) if JSON else r

def dump_cgm():
        for cr in reversed(list(choose_range(dr.iter_records('EGV_DATA')))):
                if not cr.display_only:
                        print toJSON(cr) if JSON else cr

def recent(t):
        now = dr.ReadSystemTime()
        return t.system_time > now - timedelta(minutes=5)

def print_verbose(s, newline=True):
        global VERBOSE
        if VERBOSE:
                stderr.write('%s%s' % (str(s), '\n' if newline else ''))

def read_recent_egv_data():
        now = dr.ReadSystemTime()
        r = dr.ReadRecords('EGV_DATA', 1)[-1]
        if recent(r) and not r.is_special and not r.display_only:
                return (r, now)
        else:
                return (None, now)

def time_fmt(t):
        global HUMAN
        return t.strftime('%c' if HUMAN else '%s')

def format_times(now, stamp):
        diff = (stamp - now).total_seconds()
        operand = '-' if diff < 0 else '+' # should always be -
        return '%s %s %d' % (time_fmt(now), operand, abs(diff))

CONNECTED = None
def connected(state):
        global CONNECTED
        if (state == CONNECTED):
                return
        else:
                CONNECTED = state
                print_verbose('Dexcom receiver %s connected.' % ('is' if state else 'is not'))

VERBOSITY_INSANE = False
def sleep_verbose(n):
        if VERBOSITY_INSANE:
                print_verbose('sleep(%d)' % n)
        sleep(n)

imported_requests = None
def import_requests():
        global imported_requests
        if not imported_requests:
                print_verbose("Loading 'requests' HTTP client library... ", newline=False)
                import requests
                print_verbose("done.")
                imported_requests = requests
        return imported_requests

def POST(path, json_str):
        msg = None
        try:
                requests = import_requests()
                resp = requests.post(HOST + path, data=json_str,
                                     headers={'Content-type': 'application/json'})
                msg = resp.text
                resp.raise_for_status()
                return True
        except requests.exceptions.HTTPError as e:
                print_verbose(e)
                if msg:
                        print_verbose(msg)
                return False

def send_ping(now):
        if HOST:
                POST('/ping', toJSON(now))

def print_cgm_bg(now, r):
        if JSON:
                print toJSON(r)
        else:
                print '%s: %s %s' % (format_times(now, r.system_time), r.glucose, r.trend_arrow)
        stdout.flush()

MAX_POLL_WAIT_SECONDS = 5
MIN_POLL_WAIT_SECONDS = 1

def poll_remote():
        (n, r) = remote_update('EGV_DATA')
        if n is None:
                return MAX_POLL_WAIT_SECONDS
        else:
                now = dr.ReadSystemTime()
                if n == 0:
                        send_ping(now)
                if r:
                        for t in ['METER_DATA', 'INSERTION_TIME', 'USER_EVENT_DATA']:
                        # TODO: track how long this takes & adjust sleep accordingly
                                try:
                                        remote_update(t)
                                except:
                                        traceback.print_exc()
                        next_reading = (r.system_time - now + timedelta(minutes=5, seconds=2)).total_seconds()
                        return max(MIN_POLL_WAIT_SECONDS, min(MAX_POLL_WAIT_SECONDS, next_reading))
                else:
                        return MAX_POLL_WAIT_SECONDS

def poll():
        print_verbose('Started dexcom_dumper.')
	if HOST:
		print_verbose("Acting as client to dracos server at " + HOST)
        poll_once = poll_remote if HOST else poll_stdout

        dexcom_g5_product = '22a3/47/100'

        def is_dexcom_g5(dev):
                try: return dev.parent.get('PRODUCT') == dexcom_g5_product
                except: return False

        devicer = simple_devicer('tty', is_dexcom_g5)

        while True:
            try:
                print_verbose("Waiting for device.")
                if not devicer.wait_add(600):
                        # This does not really need to time out, but if there
                        # is no timeout, then keyboard interrupt does not work.
                        # Might as well use the opportunity to print more
                        # garbage into the log, though.
                        continue
                print_verbose("Device found.")

                global dr
                if dr:
                        dr.Disconnect()
                dr = readdata.DexcomG5(devicer.device.device_node)

                print("Device opened.")
                while devicer.have():
                        print_verbose("Polling device.")
                        try:
                                sleeptime = poll_once()
                        except:
				traceback.print_exc(0)
                                sleeptime = 10

                        if devicer.wait_remove(sleeptime):
                                print_verbose("Device unplugged.")
                                dr.Disconnect()
                                dr = None
            except KeyboardInterrupt:
                break

def poll_stdout():
        (r, now) = read_recent_egv_data()
        if r is None:
                return 10
        else:
                print_cgm_bg(now, r)
                next_reading = (r.system_time - now + timedelta(minutes=5, seconds=2)).total_seconds()
                return next_reading if (next_reading > 0) else 10


def since(when, rectype):
        filt = lambda r: (r.system_time > when) if when else True
        return list(reversed(list(takewhile(filt, dr.iter_records(rectype)))))

def since_and_first(when, rectype):
        class closure:
                fst = None
        def filt(r):
                closure.fst = closure.fst or r
                return (r.system_time > when) if when else True
        return (list(reversed(list(takewhile(filt, dr.iter_records(rectype))))), closure.fst)

def parsetime(s):
        return datetime.strptime(s, "%Y-%m-%dT%H:%M:%SZ")

# Update the remote site with any records of 'rectype' that are missing.
# The server is queried to determine its last update.
#
# Returns (a,b) where:
#
# a = the number of records sent to the server (possibly zero), or None for a server error
#
# b = the latest record available on the Dexcom
#
# TODO: This has a race condition if you imagine multiple clients,
# server restarts, etc.; it should send back the value it got in the
# query to the server, so that the server can verify that the updates
# are consecutive.
REMOTE_HAS = {}
def check_remote_has(rectype):
        global REMOTE_HAS

        if REMOTE_HAS.get(rectype, None) is not None:
                return REMOTE_HAS[rectype]

        requests = import_requests()

        resp = requests.get(HOST + '/' + rectype + '/1')
        resp.raise_for_status()

        when = None
        if len(resp.json()):
                when = parsetime(resp.json()[0]['system_time'])
                print_verbose("Latest %s record on server: %s" % (rectype, when.isoformat()))

        REMOTE_HAS[rectype] = when
        return when

def remote_update(rectype):
        global REMOTE_HAS
        when = check_remote_has(rectype)

        (rs, r) = since_and_first(when, rectype)

        connected(True)
        if len(rs):
                REMOTE_HAS[rectype] = None
                print_verbose("Sending %d %s record%s... " % (len(rs), rectype, '' if len(rs) == 1 else 's'), newline=False)
                result = POST('/' + rectype, toJSON(rs))
                print_verbose("done.  (Result: %s.)" % 'success' if result else 'failure')
                return (len(rs) if result else None, r)
        else:
                return (0, r)

def test():
        remote_update('USER_EVENT_DATA')

def test0():
        for t in parseable_record_types():
                remote_update(t)

from datetime import tzinfo, timedelta, datetime

ZERO = timedelta(0)

class UTCtzinfo(tzinfo):
    def utcoffset(self, dt):
        return ZERO

    def tzname(self, dt):
        return "UTC"

    def dst(self, dt):
        return ZERO

UTC = UTCtzinfo()

class JSON_Time(json.JSONEncoder):
        def default(self, o):
                if isinstance(o, datetime):
                        if o.tzinfo is None:

                                return o.replace(tzinfo=UTC).isoformat()
                        else:
                                return o.isoformat()

                return json.JSONEncoder.default(self, o)

class JSON_CGM(JSON_Time):
        def default(self, o):

                if isinstance(o, EGVRecord) and o.is_special:
                        op={}
                        record={}
                        for k in o.BASE_FIELDS:
                                op[k] = getattr(o, k)
                        op['record'] = [getattr(o, 'glucose_special_meaning'), []]
                        return op

                elif isinstance(o, EventRecord):
                        op={}
                        for k in o.BASE_FIELDS:
                                op[k] = getattr(o, k)
                        if o.event_sub_type:
                                op['record'] = [o.event_type + '_' + str(o.event_sub_type), []]
                        else:
                                op['record'] = [o.event_type, o.event_value]
                        return op

                elif isinstance(o, GenericTimestampedRecord):
                        op={}
                        record={}
                        for k in o.BASE_FIELDS:
                                op[k] = getattr(o, k)
                        for k in o.FIELDS:
                                record[k] = getattr(o, k)

                        if isinstance(o, EGVRecord):
                                record = ['EGVRecord', record]

                        op['record'] = record
                        return op

                else:
                        return JSON_Time.default(self, o)

def toJSON(o):
        return json.dumps(o, cls=JSON_CGM)

{"dump_everything": dump_everything,
 "dump_cgm":        dump_cgm,
 "poll":            poll,
 "test":            poll,
}[command]()