# -*- coding: utf-8 -*-
# vim: ts=2 sw=2 et ai
###############################################################################
# Copyright (c) 2012,2021 Andreas Vogel andreas@wellenvogel.net
#
#  Permission is hereby granted, free of charge, to any person obtaining a
#  copy of this software and associated documentation files (the "Software"),
#  to deal in the Software without restriction, including without limitation
#  the rights to use, copy, modify, merge, publish, distribute, sublicense,
#  and/or sell copies of the Software, and to permit persons to whom the
#  Software is furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included
#  in all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
#  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
#  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#  DEALINGS IN THE SOFTWARE.
#
#  parts from this software (AIS decoding) are taken from the gpsd project
#  so refer to this BSD licencse also (see ais.py) or omit ais.py
###############################################################################
'''
Sk notification integration
received                    own
full/delta  source  on      source  on      action
full        own     on      any     on      ---
                            ---     off     enqueue off
                    off     own     on      enqueue on
                            other   on      set off - could race with delta other on
                            ---     off     ---
            other   on      any     on      --- - we have different src - but both show, so leave it
                            ---     off     set on (other) race with own set off
                    off     own     on      enqueue on (let our alarm win) - race with delta other off
                            other   on      set off ##race with delta other on
                            ---     off     ---
            ---     ---     other   on      switch off
                            own     on      enqueue on
                            ---     off     ---
delta       own     on      any     on      ---
                            ---     off     ?enqueue off - leave to full
                    off     own     on      ?enqueue on - leave to full
                            other   on      set off
                            ---     off     ---
            other   on      any     on      ---
                            ---     off     set on (other) ##race with full other off
                    off     own     on      set off ##race with full other off
                            other   on      set off
                            ---     off     ---

races:
full-own-off -> other-on-setOff against delta-other-on->any-off-setOn
full-other-off -> other-on-SetOff against delta-other-on->any-off-setOn

full-other-off -> own-on-enqOn against delta-other-off->any-on-setOff

full-other-on -> own-any-off against our switch off


resolution:
We consider delta's being "better" and full only being for retry/resync handling.
Therefore we keep the delta data for > full query period and always store the newest delta
for each combination of path/source.
We let the delta's do their job immediately. In the full handling we merge the recived full data
with the (still valid) delta items.
If there are different actions for full an delta for a combination we simply do nothing if the value
was coming from a delta.
relevant for:
xxx-other-off->own-on

To solve the race for our alarm deletes potentially not being handled correctly we keep a "lock list" for
them by storing source,timestamp,remoteId for each deleted alarm and only allowing new alarms from Sk if any of the
values has changed.

'''
import base64
import hashlib
import hmac
import json
import os
import re
import sys
import threading
import time
import traceback
import urllib.parse
import urllib.request
import uuid
from functools import reduce

from alarmhandler import AVNAlarmHandler, AlarmConfig
from avnav_nmea import NMEAParser
from avnrouter import AVNRouter, WpData

hasWebsockets=False
try:
  import websocket
  hasWebsockets=True
except:
  pass


from avnav_util import AVNLog, AVNUtil
from avnav_worker import AVNWorker, WorkerParameter, WorkerStatus
from avnuserapps import AVNUserAppHandler
from charthandler import AVNChartHandler
from pluginhandler import AVNPluginHandler
import avnav_handlerList

#from https://stackoverflow.com/questions/68274543/python-manually-create-jwt-token-without-library
def base64url_encode(input: bytes):
  return base64.urlsafe_b64encode(input).decode('utf-8').replace('=','')
def jwt(user,  api_sec):

  segments = []

  header = {"typ": "JWT", "alg": "HS256"}
  payload = {"id": user}

  json_header = json.dumps(header, separators=(",",":")).encode()
  json_payload = json.dumps(payload, separators=(",",":")).encode()

  segments.append(base64url_encode(json_header))
  segments.append(base64url_encode(json_payload))

  signing_input = ".".join(segments).encode()
  key = api_sec.encode()
  signature = hmac.new(key, signing_input, hashlib.sha256).digest()

  segments.append(base64url_encode(signature))

  encoded_string = ".".join(segments)

  return encoded_string


def timeToTs(tm):
  if tm is None:
    return None
  dt=AVNUtil.gt(tm)
  return AVNUtil.datetimeToTsUTC(dt)

class AE(object):
  def __init__(self,path,converter=None):
    self.path=path
    self.converter=converter
  def getValue(self,data):
    value=data
    if type(value) is dict:
      value=value.get('value')
    if value is None:
      return value
    if self.converter is not None:
      return self.converter(value)
    else:
      return value

  def getTimestamp(self,data):
    if not type(data) is dict:
      return None
    ts=data.get('timestamp')
    return timeToTs(ts)

def safeGetItem(data, key):
  if not type(data) is dict:
    return None
  return data.get(key)
def convertAisShipType(value):
  return safeGetItem(value, 'id')
def convertAisClass(value):
  if value == "A":
    return 1
  if value == "B":
    return 18
  return value
def convertAisLon(value):
  return safeGetItem(value, 'longitude')
def convertAisLat(value):
  return safeGetItem(value, 'latitude')

AISPATHMAP={
  'mmsi':AE('mmsi'),
  'shipname':AE('name'),
  'speed':AE('navigation.speedOverGround'),
  'course':AE('navigation.courseOverGroundTrue',converter=AVNUtil.rad2deg),
  'callsign':AE('communication.callsignVhf'),
  'shiptype': AE('design.aisShipType',converter=convertAisShipType),
  'lon': AE('navigation.position',converter=convertAisLon),
  'lat': AE('navigation.position',converter=convertAisLat),
  'destination': AE('navigation.destination'),
  'type': AE('sensors.ais.class',converter=convertAisClass)
}

class Config(object):
  def __init__(self,param):
    self.skHost=AVNSignalKHandler.P_HOST.fromDict(param)
    self.port=AVNSignalKHandler.P_PORT.fromDict(param)
    self.period=AVNSignalKHandler.P_PERIOD.fromDict(param)/1000
    self.chartQueryPeriod=AVNSignalKHandler.P_CHARTPERIOD.fromDict(param) if AVNSignalKHandler.P_CHARTS.fromDict(param) else 0
    self.priority=AVNSignalKHandler.PRIORITY_PARAM_DESCRIPTION.fromDict(param)
    self.proxyMode=AVNSignalKHandler.P_CHARTPROXYMODE.fromDict(param)
    self.decode=AVNSignalKHandler.P_DIRECT.fromDict(param)
    self.aisFetchPeriod=AVNSignalKHandler.P_AISPERIOD.fromDict(param) if AVNSignalKHandler.P_AIS.fromDict(param) else 0
    self.user=AVNSignalKHandler.P_USERNAME.fromDict(param)
    self.password=AVNSignalKHandler.P_PASSWORD.fromDict(param)
    self.write=AVNSignalKHandler.P_WRITE.fromDict(param)
    self.notifyReceive=AVNSignalKHandler.P_WRITE.fromDict(param) and AVNSignalKHandler.P_NOTIFY_RECEIVE.fromDict(param)
    self.notifyWrite=AVNSignalKHandler.P_WRITE.fromDict(param) and AVNSignalKHandler.P_NOTIFY.fromDict(param)
    self.sendWp=AVNSignalKHandler.P_WRITE.fromDict(param) and AVNSignalKHandler.P_SENDWP.fromDict(param)
    self.skSource='avnav-'+AVNSignalKHandler.P_UUID.fromDict(param)
    self.isLocal= (self.skHost == 'localhost' or self.skHost == '127.0.0.1')
    self.ignoreTs=AVNSignalKHandler.P_IGNORE_TS.fromDict(param)
    self.wsRetry=AVNSignalKHandler.P_WEBSOCKETRETRY.fromDict(param)
    self.remoteId=self.skHost+":"+str(self.port)
    self.blackList=set()
    blStr=AVNSignalKHandler.P_NOTIFY_BLACK.fromDict(param)
    for be in blStr.split(','):
      if be is not None and be.strip() != '':
        self.blackList.add(be.strip())
    self.whiteList=set()
    wlStr=AVNSignalKHandler.P_NOTIFY_WHITE.fromDict(param)
    for we in wlStr.split(','):
      if we is not None and we.strip() != '':
        self.whiteList.add(we.strip())


class MappingEntry(object):
  def __init__(self,localPath,converter=None,priority=0):
    self.localPath=localPath
    self.converter=converter
    self.priority=priority

class InfoSetter(object):
  def __init__(self,name,writer):
    self.name=name
    self.writer=writer

  def setInfo(self,info,status):
    self.writer.setInfo(self.name,info,status)
  def deleteInfo(self):
    self.writer.deleteInfo(self.name)

class SKAlarm(object):
  T_RECV=1 #received delta
  T_SEND=2 #message to be send
  def __init__(self,stype,skPath,source,skValue,
               timestamp=None,isOwnSource=False,remoteId=None,
               localTs=None):
    self.stype=stype
    self.skPath=skPath
    self.skValue=skValue
    self.source=source
    self.timestamp=timestamp
    self.isOwnSource=isOwnSource
    self.remoteId=remoteId
    self.shouldSend=False
    self.localTs=localTs if localTs is not None else time.time()
    self.fromDelta=False

  def isSame(self, other : 'SKAlarm'):
    if other is None:
      return False
    if self.skPath != other.skPath:
      return False
    if self.isOwnSource and other.isOwnSource:
      return True
    return self.source == other.source

  def copy(self,**kwargs):
    rt=SKAlarm(self.stype,self.skPath,self.source,self.skValue,
                   timestamp=self.timestamp,
                   isOwnSource=self.isOwnSource,
                   remoteId=self.remoteId,
                   localTs=self.localTs
                   )
    rt.shouldSend=self.shouldSend
    rt.fromDelta=self.fromDelta
    for k in list(rt.__dict__.keys()):
      if k in kwargs:
        setattr(rt,k,kwargs.get(k))
    return rt

  def isNewer(self,other: 'SKAlarm'):
    if other is None:
      return True
    if self.timestamp is None:
      return False
    if other.timestamp is None:
      return True
    return timeToTs(self.timestamp) > timeToTs(other.timestamp)
  def sameState(self,other: 'SKAlarm'):
    if self.skValue is None and other.skValue is None:
      return True
    return self.skValue is not None and other.skValue is not None
  def isInState(self,active):
    if active and self.skValue is not None:
      return True
    if not active and self.skValue is None:
      return True
    return False
  def shouldDo(self):
    return self.shouldSend
  def psKey(self):
    return self.skPath


class SKAlarmList(object):
  def __init__(self,ownSource=None,remoteId=None,currentList=None):
    self.ownSource=ownSource
    self.remoteId=remoteId
    self.skList={} if currentList is None else currentList
  def __checkReady(self):
    if self.ownSource is None:
      raise Exception("alarm list - no ownSource")
    if self.remoteId is None:
      raise Exception("alarm lsit - no remote id")
  def __isOwnSource(self,source):
    self.__checkReady()
    if source is None:
      return False
    return source == self.ownSource or source.endswith('.'+self.ownSource)
  def setParam(self,ownSource,remoteId):
    self.ownSource=ownSource
    self.remoteId=remoteId
    cleanups=[]
    for k,v in self.skList.items():
      if v.remoteId != self.remoteId:
        cleanups.append(k)
    for k in cleanups:
      try:
        del self.skList[k]
      except:
        pass
  def handleNotification(self,path,value,source,timestamp,fromDelta=False):
    skAlarm=SKAlarm(SKAlarm.T_RECV,path,source,value,
                    timestamp=timestamp,
                    remoteId=self.remoteId,
                    isOwnSource=self.__isOwnSource(source))
    skAlarm.fromDelta=fromDelta
    key=skAlarm.psKey()
    existing=self.skList.get(key)
    if not skAlarm.isNewer(existing):
      return None
    self.skList[key]=skAlarm
    return skAlarm
  def add(self,skAlarm:SKAlarm):
    self.__checkReady()
    if skAlarm is None:
      return
    self.skList[skAlarm.psKey()]=skAlarm
  def cleanup(self,oldest):
    self.__checkReady()
    now=time.time()
    cleanupKeys=[]
    for k,v in self.skList.items():
      if v.localTs < oldest or v.localTs > now:
        cleanupKeys.append(k)
    for k in cleanupKeys:
      try:
        del self.skList[k]
      except:
        pass
  def clear(self):
    self.__checkReady()
    self.skList.clear()
  def copy(self):
    return SKAlarmList(self.ownSource,self.remoteId,self.skList.copy())

class LockedSKAlarmList(SKAlarmList):

  def __init__(self, ownSource=None, remoteId=None, currentList=None):
    super().__init__(ownSource, remoteId, currentList)
    self.__lock=threading.Lock()

  def handleNotification(self, path, value, source, timestamp,fromDelta=False):
    with self.__lock:
      return super().handleNotification(path, value, source, timestamp,fromDelta)

  def cleanup(self, oldest):
    with self.__lock:
      super().cleanup(oldest)

  def clear(self):
    with self.__lock:
      super().clear()

  def add(self, skAlarm: SKAlarm):
    with self.__lock:
      super().add(skAlarm)

  def setParam(self, ownSource, remoteId):
    with self.__lock:
      super().setParam(ownSource, remoteId)

  def copy(self):
    with self.__lock:
      return super().copy()


class WebSocketHandler(object):
  def __init__(self,infoSetter:InfoSetter,url:str,messageCallback):
    self.infoSetter=infoSetter
    self.url=url
    self.__messageCallback=messageCallback
    self.__webSocket=None
    self.__firstWebsocketMessage=False
    self.__connected=False
    self.__timeOffset=None
    self.__error=None
    self.__lock=threading.Lock()
  def getUrlForLog(self):
    return re.sub('\\?.*','',self.url)
  def open(self):
    self.infoSetter.setInfo('connecting at %s'%self.getUrlForLog(),WorkerStatus.STARTED)
    with self.__lock:
      if self.__webSocket is not None:
        try:
          self.__webSocket.close()
          self.__webSocket=None
        except:
          pass
      self.__connected=False
      self.__timeOffset=None
      try:
        self.__webSocket=websocket.WebSocketApp(self.url,
                                          on_error=self.__webSocketError,
                                          on_message=self.__webSocketMessage,
                                          on_close=self.__webSocketClose,
                                          on_open=self.__webSocketOpen)
        AVNLog.info("websocket %s created at %s",self.infoSetter.name,self.getUrlForLog())
        webSocketThread=threading.Thread(name="signalk-websocket-%s"%self.infoSetter.name,target=self.__webSocketRun)
        webSocketThread.setDaemon(True)
        webSocketThread.start()
      except Exception as e:
        try:
          self.__webSocket.close()
        except:
          pass
        self.__webSocket=None
        self.infoSetter.setInfo("unable to connect to %s:%s"%(self.getUrlForLog(),str(e)),WorkerStatus.ERROR)
        return False
    return True

  def __webSocketRun(self):
    AVNLog.info("websocket receiver %s started",self.infoSetter.name)
    self.__webSocket.run_forever()
    AVNLog.info("websocket receiver %s finished",self.infoSetter.name)

  def __webSocketOpen(self,*args):
    self.infoSetter.setInfo('connected',WorkerStatus.NMEA)
    self.__firstWebsocketMessage=True
    self.__connected=True

  #there is a change in the websocket client somewhere between
  #0.44 and 0.55 - the newer versions omit the ws parameter
  def getWSParam(self,*args):
    if len(args) > 1:
      return args[1]
    if len(args) > 0:
      return args[0]

  def __webSocketError(self,*args):
    error=self.getWSParam(*args)
    self.__error=error
    AVNLog.error("error on websocket connection %s: %s",self.infoSetter.name, error)
    try:
      self.infoSetter.setInfo("error on websocket connection %s: %s" % (self.getUrlForLog(), error), WorkerStatus.ERROR)
      self.__webSocket.close()
    except:
      pass
    self.__webSocket=None
    self.__connected=False

  def __webSocketClose(self,*args):
    AVNLog.info("websocket connection %s closed",self.infoSetter.name)
    self.__connected=False
    try:
      self.infoSetter.setInfo( "connection closed at %s" % self.getUrlForLog(), WorkerStatus.ERROR)
    except:
      pass
    self.__webSocket=None

  def __webSocketMessage(self,*args):
    message=self.getWSParam(*args)
    AVNLog.debug("received on%s: %s",self.infoSetter.name,message)
    first=False
    try:
      data=json.loads(message)
      if self.__firstWebsocketMessage:
        first=True
        self.__firstWebsocketMessage=False
        timestamp=data.get('timestamp')
        if timestamp is not None:
          skTimeStamp=timeToTs(timestamp)
          localTimeStamp=time.time()
          self.__timeOffset= skTimeStamp - localTimeStamp
        else:
          self.__timeOffset=None
      self.infoSetter.setInfo( "connected at %s, timeOffset=%.0fs" % (self.getUrlForLog(), self.__timeOffset or 0), WorkerStatus.NMEA)
      self.__messageCallback(data,self,first)
    except:
      AVNLog.error("error decoding %s:%s",message,traceback.format_exc())
      try:
        self.__webSocket.close()
      except:
        pass
      self.__webSocket=None
      self.__connected=False

  def close(self):
    with self.__lock:
      if self.__webSocket is None:
        return
      try:
        self.__webSocket.close()
      except:
        pass
      self.__webSocket=None
      self.__connected=False

  def send(self,data):
    sock=None
    with self.__lock:
      if not self.__connected:
        return False
      if self.__webSocket is None:
        return False
      sock=self.__webSocket
    sock.send(data)
    return True

  def isConnected(self):
    return self.__connected
  def getTimeOffset(self):
    return self.__timeOffset
  def getError(self):
    return self.__error

def getItem(item,key):
  if item is None:
    return None
  if key is None:
    return None
  return item.get(key)
def getFromDict(dataDict, keystr):
  mapList=keystr.split(".")
  return reduce(getItem, mapList, dataDict)




class AVNSignalKHandler(AVNWorker):
  P_MIGRATED=WorkerParameter('migrated',type=WorkerParameter.T_BOOLEAN,editable=False,default=False)
  P_PORT= WorkerParameter('port',type=WorkerParameter.T_NUMBER,default=3000,
                          description='set to signalk port')
  P_HOST= WorkerParameter('host',type=WorkerParameter.T_STRING, default='localhost',
                          description="set to signalk host")
  P_PERIOD=WorkerParameter('period',type=WorkerParameter.T_NUMBER,default=1000,
                           description='query time in ms')
  P_CHARTS=WorkerParameter('fetchCharts',type=WorkerParameter.T_BOOLEAN,default=True,
                           description='read charts from signalK')
  P_CHARTPERIOD=WorkerParameter('chartQueryPeriod',type=WorkerParameter.T_NUMBER,default=10,
                                description="query period(s) for SignalK charts",
                                condition={P_CHARTS.name:True})
  P_CHARTPROXYMODE=WorkerParameter('chartProxyMode',type=WorkerParameter.T_SELECT,default='sameHost',
                                   description='proxy tile requests: never,always,sameHost',
                                   rangeOrList=['never','always','sameHost'],
                                   condition={P_CHARTS.name:True})
  P_DIRECT=WorkerParameter('decodeData',type=WorkerParameter.T_BOOLEAN,default=False,
                           description='directly use the signalK data for Navigation')
  P_AIS=WorkerParameter('fetchAis',type=WorkerParameter.T_BOOLEAN,default=False,
                        description='fetch AIS data from signalK')
  P_AISPERIOD=WorkerParameter('aisQueryPeriod',type=WorkerParameter.T_NUMBER,default=10,
                              description="query period for AIS (in s)",
                              condition={P_AIS.name:True})
  P_WRITE=WorkerParameter('sendData',type=WorkerParameter.T_BOOLEAN,default=False,
                          description='send data to signalk. This includes waypoint info and notifications')
  P_USERNAME=WorkerParameter('userName',type=WorkerParameter.T_STRING,default='admin',
                             description='the user name to be used for SignalK. Remark: This user must have write permissions!',
                             condition={P_WRITE.name:True})
  P_PASSWORD=WorkerParameter('password',type=WorkerParameter.T_STRING,default='',
                             description='the password for the SignalK server. You can leave this empty '+
                             'for a local access if signalK is installed in the default location',
                             condition={P_WRITE.name:True})
  P_SENDWP=WorkerParameter('sendWp',type=WorkerParameter.T_BOOLEAN,default=True,
                           description='send current waypoint routing data',
                           condition={P_WRITE.name:True})
  P_NOTIFY=WorkerParameter('sendNotifications',type=WorkerParameter.T_BOOLEAN,default=True,
                           description='send notifications',
                           condition={P_WRITE.name:True})
  P_NOTIFY_RECEIVE=WorkerParameter('receiveNotifications',type=WorkerParameter.T_BOOLEAN,default=False,
                                   description='receive notifications from signalK',
                                   condition={P_WRITE.name:True})
  P_WEBSOCKETRETRY=WorkerParameter('websocketRetry',type=WorkerParameter.T_NUMBER,default=20,
                                   description="retry period (s) for websocket channels to reopen")
  P_UUID=WorkerParameter('uuid',type=WorkerParameter.T_STRING,editable=False,default='avnav')
  P_NOTIFY_WHITE=WorkerParameter('notifyWhiteList','',type=WorkerParameter.T_STRING,
                                 description='a comma separated list of sk notifications that should be received.'+
                                             'e.g. mob,server.newVersion\n'+
                                             'if empty (default) - all notifications',
                                 condition={P_NOTIFY_RECEIVE.name:True}
                                 )
  P_NOTIFY_BLACK=WorkerParameter('notifyBlackList','server.newVersion',type=WorkerParameter.T_STRING,
                                 description='a comma separated list of notifications that should not be received\n'+
                                            'e.g. server.newVersion,navigation.arrivalCircleEntered',
                                 condition={P_NOTIFY_RECEIVE.name:True})
  P_IGNORE_TS=WorkerParameter('ignoreTimestamp',False, type=WorkerParameter.T_BOOLEAN,
                              description='Ignore the timestamp that SignalK sets.\n'+
                              'Normally data being to old will be ignored.\n'+
                              'If you enable this flag, data still will be processed and '+
                              'the expiry is handled locally based on the last received change\n'+
                              'This can be helpful e.g. when using simulated data with timestamps in the past.')


  I_AIS='ais'
  I_CHARTS='charts'
  I_WEBSOCKET="websocket"
  I_MAIN='main'
  I_AUTH='authentication'
  I_WRITE='write'
  I_SOURCE='source'
  I_ALARM='alarms'
  I_TIME='timeoffset'

  ICON="images/signalk.svg"

  @classmethod
  def getConfigParam(cls, child=None):
    rt=[cls.P_DIRECT,cls.P_AIS,cls.PRIORITY_PARAM_DESCRIPTION.copy(default=NMEAParser.DEFAULT_SOURCE_PRIORITY-10),cls.P_PORT,cls.P_HOST,
            cls.P_AISPERIOD,cls.P_PERIOD,cls.P_CHARTS,cls.P_CHARTPERIOD,cls.P_CHARTPROXYMODE, cls.P_MIGRATED,
            cls.P_UUID,cls.P_IGNORE_TS]
    if hasWebsockets:
      rt+=[cls.P_WRITE,cls.P_USERNAME,cls.P_PASSWORD,cls.P_SENDWP,cls.P_NOTIFY,cls.P_NOTIFY_RECEIVE,cls.P_NOTIFY_WHITE,cls.P_NOTIFY_BLACK,cls.P_WEBSOCKETRETRY]
    return rt

  @classmethod
  def canEdit(cls):
    return True

  @classmethod
  def canDisable(cls):
    return True

  @classmethod
  def autoInstantiate(cls):
    return True

  def updateConfig(self, param, child=None):
    rt=super().updateConfig(param, child)
    self.configSequence+=1
    return rt

  USERAPP_NAME="signalk"
  PREFIX='/signalk'
  CHARTPREFIX='charts'


  def stop(self):
    super().stop()
    self.configSequence+=1
  def __init__(self, cfgparam):
    super().__init__(cfgparam)
    self.configSequence=0
    self.sourceName='signalk'
    self.config=None
    self.webSocket=None
    self.writeSocket=None
    self.timeSocket=None
    self.firstWebsocketMessage=False
    self.skCharts=[]
    #compute a time offset from our time to the SK time
    #from the first Websocket message
    self.timeOffset=None
    self.selfMap={}
    self.alarmhandler=None

    self.deleteAndActivateActions=SKAlarmList()
    self.deltas=LockedSKAlarmList()
    self.__alarmCondition=threading.Condition()
    self.ownWpOffSent=False #set if we have sent the own WP off to SK



  def migrateConfig(self):
    pluginName='builtin-signalk'
    pluginHandler=self.findHandlerByName(AVNPluginHandler.getConfigName())
    updates={}
    alreadyMigrated=self.P_MIGRATED.fromDict(self.param)
    if self.P_UUID.fromDict(self.param) == self.P_UUID.default:
      updates[self.P_UUID.name]=str(uuid.uuid4())
    if pluginHandler and not alreadyMigrated:
      updates[self.P_MIGRATED.name]=True
      pluginParam=pluginHandler.param.get(pluginName)
      if pluginParam is not None and type(pluginParam) is list:
        pluginParam=pluginParam[0]
        if type(pluginParam) is dict and not self.P_MIGRATED.fromDict(pluginParam):
          pluginHandler.changeChildConfigDict(pluginName,{self.P_MIGRATED.name:True})
          for p in self.getConfigParam():
            if p.name == self.ENABLE_PARAM_DESCRIPTION.name:
              continue
            if p.name == self.P_MIGRATED.name:
              continue
            ov=pluginParam.get(p.name)
            if ov is not None:
              own=self.param.get(p.name)
              if ov != own:
                updates[p.name]=ov
    for p in self.getConfigParam():
      newParam=updates.get(p.name)
      if newParam is None:
        continue
      try:
        updates[p.name]=p.checkValue(updates[p.name],True)
      except:
        del updates[p.name]
    if len(list(updates.keys())) < 1:
      return
    AVNLog.info("migrating signalk config: %s",",".join(list(map(lambda v: str(v[0])+":"+str(v[1]),updates.items()))))
    super().changeMultiConfig(updates)

  def createMappings(self):
    selfMappings={}
    for k in NMEAParser.GPS_DATA:
      sk=k.signalK
      if sk is not None:
        if type(sk) is not list:
          sk=[sk]
        priority=10
        for skKey in sk:
          priority=priority-1
          if priority< 0:
            priority=0
          selfMappings[skKey]=MappingEntry(k.getKey(),k.signalKConversion,self.config.priority*10+priority)
    self.selfMap=selfMappings

  def closeWebSockets(self):
    for sock in [self.webSocket,self.writeSocket,self.timeSocket]:
      if sock is not None:
        try:
          sock.close()
        except:
          pass
    self.webSocket=None
    self.writeSocket=None
    self.timeSocket=None

  CHARTHANDLER_PREFIX="signalk"
  def run(self):
    self.navdata.registerKey(self.PATH+".*",'signalK',self.sourceName)
    self.migrateConfig()
    self.alarmhandler=self.findHandlerByName(AVNAlarmHandler.getConfigName())
    charthandler = self.findHandlerByName(AVNChartHandler.getConfigName())
    if charthandler is not None:
      charthandler.registerExternalProvider(self.CHARTHANDLER_PREFIX,self.listCharts)
    while not self.shouldStop():
      self.sourceName=self.getParamValue('name') or 'signalk'
      if self.alarmhandler is not None:
        self.alarmhandler.registerHandler(self)
      self._runI()
      self.deleteInfo(self.I_CHARTS)
      self.deleteInfo(self.I_AIS)
      addonhandler=AVNWorker.findHandlerByName(AVNUserAppHandler.getConfigName())
      if self.alarmhandler is not None:
        self.alarmhandler.deregisterHandler(self)
      if addonhandler:
        addonhandler.unregisterAddOn(self.USERAPP_NAME)
      self.closeWebSockets()
    if charthandler is not None:
      charthandler.registerExternalProvider(self.CHARTHANDLER_PREFIX,None)

  def timeChanged(self):
    self.configSequence+=1
    self.wakeUp()

  PATH="gps.signalk"

  def decodeSelf(self,path,value):
    mapping=self.selfMap.get(path)
    if mapping is None:
      return
    if mapping.converter is not None:
      value=mapping.converter(value)
    AVNLog.debug("setting %s:%s from SK %s",mapping.localPath,str(value),path)
    self.navdata.setValue(mapping.localPath,value,source=self.sourceName,priority=mapping.priority)

  def setValue(self,path,value):
    self.navdata.setValue(self.PATH+"."+path,value,source=self.sourceName,priority=self.config.priority*10)
    if self.config.decode:
      if not type(value) is dict:
        self.decodeSelf(path,value)
      else:
        for k,v in value.items():
          self.decodeSelf(path+"."+k,v)

  def fetchAisData(self,baseUrl):
    url=baseUrl+'vessels/'
    response=None
    try:
      response=urllib.request.urlopen(url)
      if response is None:
        self.setInfo(self.I_AIS,'no response from %s'%url,WorkerStatus.ERROR)
        return
      data=json.loads(response.read())
      numTargets=0
      now=AVNUtil.utcnow()
      oldest=now-self.navdata.getAisExpiryPeriod()
      for vessel,values in data.items():
        if vessel.find('mmsi') < 0:
          continue
        mmsi=values.get('mmsi')
        if mmsi is None or mmsi=='':
          continue
        aisdata={'mmsi':mmsi}
        newestTs=None
        for k,e in AISPATHMAP.items():
          av=getFromDict(values,e.path)
          if av is None:
            continue
          ts=e.getTimestamp(av)
          if ts is not None:
            if newestTs is None or ts > newestTs:
              newestTs=ts
          value=e.getValue(av)
          if value is not None:
            aisdata[k]=value
        if newestTs is not None:
          aisdata['timestamp']=newestTs
          if self.timeOffset is not None:
            newestTs-=self.timeOffset
        if newestTs is not None and newestTs < oldest and not self.config.ignoreTs:
          AVNLog.debug("ignore ais mmsi=%s - to old",mmsi)
          continue
        numTargets+=1
        AVNLog.debug("adding ais data for %s",mmsi)
        self.navdata.addAisItem(mmsi,aisdata,self.sourceName,self.config.priority*10,now=newestTs)
      self.setInfo(self.I_AIS,'read %d targets'%numTargets,WorkerStatus.NMEA)
    except Exception as ex:
      self.setInfo(self.I_AIS,'error reading ais data from %s:%s'%(url,str(ex)),WorkerStatus.ERROR)

  def sendAlarms(self):
    '''
    send out notifications towards SK
    a notification will be send if the send flag is set and the sendTs is not set
    retry handling:
    after retry time if:
    ack flag not set and no other alarm of the same path in correct state
    otherwise we will reset the send flag
    ?should we remove in this case?
    @return:
    '''
    sequence=self.configSequence
    errorTS=0
    while(sequence == self.configSequence):
      try:
        if self.config.notifyWrite or self.config.notifyReceive:
          if self.writeSocket is None or not self.writeSocket.isConnected():
            self.setInfo(self.I_ALARM,"write socket not connected",WorkerStatus.ERROR)
            errorTS=0
            with self.__alarmCondition:
              self.__alarmCondition.wait(1)
            continue
          if errorTS < (time.time() - 10):
            self.setInfo(self.I_ALARM,"sender ready",WorkerStatus.NMEA)
          alarms=[]
          cleanups=[]
          now=time.time()
          with self.__alarmCondition:
            for k,alarm in self.deleteAndActivateActions.skList.items():
              if alarm.shouldDo():
                if alarm.isInState(True):
                  if self.config.notifyWrite:
                    alarms.append(alarm)
                  cleanups.append(k)
                else:
                  alarms.append(alarm)
                  alarm.shouldSend=False
            for k in cleanups:
              try:
                del self.deleteAndActivateActions.skList[k]
              except:
                pass
          #outside lock
          for alarm in alarms:
            AVNLog.info("send alarm to SK %s=%s",alarm.skPath,alarm.skValue)
            update=self.buildUpdateRequest({
              alarm.skPath:alarm.skValue
            })
            self.writeSocket.send(json.dumps(update))
      except Exception as e:
        self.setInfo(self.I_ALARM,"error %s"%str(e),WorkerStatus.ERROR)
        errorTS=time.time()
      with self.__alarmCondition:
        self.__alarmCondition.wait(5)



  def _runI(self):
    sequence=self.configSequence
    self.firstResponse=True
    self.config=Config(self.param)
    self.createMappings()
    if self.config.aisFetchPeriod == 0:
      self.setInfo(self.I_AIS,'disabled',WorkerStatus.INACTIVE)

    if self.config.chartQueryPeriod == 0:
      self.setInfo(self.I_CHARTS,'disabled',WorkerStatus.INACTIVE)
    if self.config.write:
      self.setInfo(self.I_SOURCE,self.config.skSource,WorkerStatus.NMEA)
    else:
      self.setInfo(self.I_SOURCE,self.config.skSource,WorkerStatus.INACTIVE)
    with self.__alarmCondition:
      self.deleteAndActivateActions.setParam(self.config.skHost, self.config.remoteId)
    self.deltas.setParam(self.config.skSource,self.config.remoteId)

    """
    the run method
    this will be called after successfully instantiating an instance
    this method will be called in a separate Thread
    The example simply counts the number of NMEA records that are flowing through avnav
    and writes them to the store every 10 records
    @return:
    """
    AVNLog.info("started with host %s port %d, period %d"
                 %(self.config.skHost,self.config.port,self.config.period))
    baseUrl="http://%s:%d/signalk"%(self.config.skHost,self.config.port)

    addonhandler=AVNWorker.findHandlerByName(AVNUserAppHandler.getConfigName())
    if addonhandler:
      if self.config.skHost == "localhost":
        addonhandler.registerAddOn(self.USERAPP_NAME,"http://$HOST:%s"%self.config.port,self.ICON)
      else:
        addonhandler.registerAddOn(self.USERAPP_NAME,"http://%s:%s" %
                                              (self.config.skHost,self.config.port), self.ICON)
    router=None
    if self.config.write:
      router=self.findHandlerByName(AVNRouter.getConfigName())
    errorReported=False
    sendAlarmThread=threading.Thread(target=self.sendAlarms,daemon=True,name="SKSendAlarms")
    sendAlarmThread.start()
    self.setInfo(self.I_MAIN,"connecting at %s" % baseUrl,WorkerStatus.STARTED)
    while sequence == self.configSequence:
      expiryPeriod=self.navdata.getExpiryPeriod()
      apiUrl=None
      websocketUrl=None
      self.closeWebSockets()
      while apiUrl is None :
        if sequence != self.configSequence:
          return
        self.connected=False
        responseData=None
        try:
          response=urllib.request.urlopen(baseUrl)
          if response is None:
            raise Exception("no response on %s"%baseUrl)
          responseData=json.loads(response.read())
          if responseData is None:
            raise Exception("no response on %s"%baseUrl)
          #{"endpoints":{"v1":{"version":"1.20.0","signalk-http":"http://localhost:3000/signalk/v1/api/","signalk-ws":"ws://localhost:3000/signalk/v1/stream","signalk-tcp":"tcp://localhost:8375"}},"server":{"id":"signalk-server-node","version":"1.20.0"}}
          endpoints = responseData.get('endpoints')
          if endpoints is None:
            raise Exception("no endpoints in response to %s"%baseUrl)
          for k in list(endpoints.keys()):
            ep=endpoints[k]
            if apiUrl is None:
              apiUrl=ep.get('signalk-http')
              if apiUrl is not None:
                errorReported=False
            if websocketUrl is None:
              websocketUrl=ep.get("signalk-ws")
        except:
          if not errorReported:
            self.setInfo(self.I_MAIN, "unable to connect at %s" % baseUrl,WorkerStatus.ERROR)
            AVNLog.info("unable to connect at url %s: %s" ,baseUrl, sys.exc_info()[0])
            errorReported=True
          self.wait(1)
          continue
        if apiUrl is None:
          self.wait(1)
        else:
          AVNLog.info("found api url %s",apiUrl)
      selfUrl=apiUrl+"vessels/self"
      self.connected = True
      useWebsockets = hasWebsockets and websocketUrl is not None
      if useWebsockets:
        if self.config.period < expiryPeriod:
          self.config.period=expiryPeriod
        AVNLog.info("using websockets at %s, querying with period %d", websocketUrl,self.config.period)
      else:
        self.setInfo(self.I_WEBSOCKET,'disabled',WorkerStatus.INACTIVE)
        self.setInfo(self.I_TIME,'disabled',WorkerStatus.INACTIVE)
      try:
        lastChartQuery=0
        lastQuery=0
        lastWebsocket=0
        lastWriteSocket=0
        first=True # when we newly connect, just query everything once
        token=None
        errorReported=False
        lastAisFetch=0
        while self.connected and self.configSequence == sequence:
          now = time.time()
          #handle time shift backward
          if lastChartQuery > now:
            lastChartQuery=0
          if lastQuery > now:
            lastQuery=0
          if lastAisFetch > now:
            lastAisFetch=0
          if lastWebsocket > now:
            lastWebsocket=0
          if lastWriteSocket > now:
            lastWriteSocket=0
          if useWebsockets:
            if self.webSocket is None or not self.webSocket.isConnected():
              if (now-lastWebsocket) > self.config.wsRetry:
                if self.webSocket is None:
                  self.webSocket=WebSocketHandler(InfoSetter(self.I_WEBSOCKET,self),
                                                  websocketUrl,self.webSocketMessage)
                self.webSocket.open()
                lastWebsocket=now
          if self.config.write:
            if not useWebsockets:
              self.setInfo(self.I_WRITE,"websockets disabled",WorkerStatus.INACTIVE)
            else:
              if token is None or self.writeSocket is None or not self.webSocket.isConnected():
                if (now - lastWriteSocket) > self.config.wsRetry:
                  lastWriteSocket=now
                  if token is None:
                    token=self.getAuthentication(apiUrl)
                  if token is None:
                    self.setInfo(self.I_WRITE,"unable to get token",WorkerStatus.ERROR)
                  else:
                    url=websocketUrl+"?subscribe=none&token="+urllib.parse.quote(token)
                    if self.writeSocket is not None:
                      self.writeSocket.close()
                    self.writeSocket=WebSocketHandler(InfoSetter(self.I_WRITE,self),url,
                                                      self.writeChannelMessage)
                    self.writeSocket.open()

            if self.config.sendWp and self.writeSocket is not None and self.writeSocket.isConnected():
              self.sendCurrentLeg(router)
          if (now - lastQuery) > self.config.period or first:
            first=False
            lastQuery=now
            if useWebsockets:
              try:
                url=websocketUrl+"?subscribe=none"
                if self.timeSocket is not None:
                  self.timeSocket.close()
                self.timeSocket=WebSocketHandler(InfoSetter(self.I_TIME,self),url,
                                                self.timeChannelMessage)
                self.timeSocket.open()
              except Exception as e:
                self.setInfo(self.I_TIME,"unable to create: %s"%str(e),WorkerStatus.ERROR)
            response=None
            try:
              response=urllib.request.urlopen(selfUrl)
              if response is None:
                self.skCharts = []
                self.setInfo(self.I_CHARTS,"unable to fetch from %s: None"%selfUrl,WorkerStatus.ERROR)
                if not errorReported:
                  AVNLog.error("unable to fetch from %s: None", selfUrl)
                  errorReported=True
            except Exception as e:
              self.skCharts=[]
              self.setInfo(self.I_CHARTS,"unable to fetch from %s: %s"%(selfUrl,str(e)),WorkerStatus.ERROR)
              if not errorReported:
                AVNLog.error("unable to fetch from %s:%s",selfUrl,str(e))
                errorReported=True
            if response is not None:
              errorReported=False
              if not first:
                self.setInfo(self.I_MAIN, "connected at %s" % apiUrl,WorkerStatus.NMEA)
              data=json.loads(response.read())
              AVNLog.debug("read: %s",json.dumps(data))
              oldestDeltas=now - 2 *self.config.period
              self.deltas.cleanup(oldestDeltas)
              self.storeData(data,self.config.priority)
              name=data.get('name')
              if name is not None:
                self.setValue("name",name)
          else:
            pass
          if self.config.chartQueryPeriod > 0 and lastChartQuery < (now - self.config.chartQueryPeriod):
            lastChartQuery=now
            try:
              self.queryCharts(apiUrl,self.config.port)
            except Exception as e:
              self.skCharts=[]
              AVNLog.debug("exception while reading chartlist %s",traceback.format_exc())
          if self.config.aisFetchPeriod > 0 and lastAisFetch < (now - self.config.aisFetchPeriod):
            try:
              self.fetchAisData(apiUrl)
            except Exception as e:
              self.setInfo(self.I_AIS,'error in fetch %s'%str(e),WorkerStatus.ERROR)
            lastAisFetch=now
          sleepTime=1 if self.config.period > 1 else self.config.period
          self.wait(sleepTime)
        self.closeWebSockets()

      except:
        AVNLog.error("error when fetching from signalk %s: %s",apiUrl,traceback.format_exc())
        self.setInfo(self.I_MAIN,"error when fetching from signalk %s"%(apiUrl),WorkerStatus.ERROR)
        self.connected=False
        if sequence != self.configSequence:
          return
        self.wait(5)

  def checkOutdated(self,timestampStr):
    if timestampStr is None:
      return False
    timeStamp=timeToTs(timestampStr)
    expiryPeriod=self.navdata.getExpiryPeriod()
    oldest=time.time()-expiryPeriod
    if self.timeOffset is not None:
      oldest+=self.timeOffset
    if timeStamp < oldest:
      return True
    return False


  def filterNotification(self,skPath):
    if skPath is None:
      return False
    wll=len(self.config.whiteList)
    bll=len(self.config.blackList)
    if bll == 0 and wll == 0:
      return True
    if skPath.startswith(self.NPRFX):
      skPath=skPath[len(self.NPRFX):]
    if wll != 0:
      if not skPath in self.config.whiteList:
        return False
    if bll != 0:
      if skPath in self.config.blackList:
        return False
    return True

  def handleNotifications(self, skAlarms,isFull=False):
    if not self.config.notifyReceive and not self.config.notifyWrite:
      return
    if self.alarmhandler is None:
      return
    handledPathes={}
    with self.__alarmCondition:
      for k,skAlarm  in skAlarms.items():
        if not skAlarm.isOwnSource and not self.config.notifyReceive:
          continue
        if not skAlarm.isOwnSource:
          if not self.filterNotification(skAlarm.skPath):
            AVNLog.debug('filter notification %s:%s due to bl/wl',skAlarm.skPath,skAlarm.skValue)
            continue
        handledPathes[skAlarm.skPath]=skAlarm
        name=self.skAlarmToOur(skAlarm.skPath)
        sendAlarmValue=None
        if not name.startswith('sk:'):
          cfg=self.ALARMS.get(name)
          if cfg is not None:
            sendAlarmValue=cfg.get('value')
        runningAny=self.alarmhandler.isAlarmActive(name)
        runningOwn=self.alarmhandler.isAlarmActive(name,True)
        runningOther=False if runningOwn else runningAny
        category=None
        if type(skAlarm.skValue) is dict:
          state=skAlarm.skValue.get('state')
          if state == 'emergency':
            category=AlarmConfig.C_CRITICAL
          if state == 'normal':
            category=AlarmConfig.C_INFO
        if skAlarm.isOwnSource:
          if skAlarm.isInState(True):
            #SK own on
            if not runningAny:
              AVNLog.info("prepare alarm %s off to SK (sk: ownOn)",skAlarm.skPath)
              cp=skAlarm.copy(stype=SKAlarm.T_SEND,shouldSend=True,skValue=None)
              self.deleteAndActivateActions.add(cp)
          else:
            #SK: own off
            if runningOwn:
              if sendAlarmValue:
                AVNLog.info("prepare alarm %s on to SK (sk: own off, local: own on)",skAlarm.skPath)
                cp=skAlarm.copy(stype=SKAlarm.T_SEND,shouldSend=True,skValue=sendAlarmValue)
                self.deleteAndActivateActions.add(cp)
              else:
                AVNLog.debug("own alarm from sk without mapping %s",skAlarm.skPath)
            elif runningOther:
              AVNLog.info("own alarm off %s (sk:own off, local: other on")
              self.alarmhandler.stopAlarm(name,caller=self)
        else:
          if skAlarm.isInState(True):
            #check if we switched this off
            existing=self.deleteAndActivateActions.skList.get(skAlarm.psKey())
            if existing:
              #when we delete an SK alarm (not our own) we copy the original
              #timestamp to the deleteAndActivateActions
              #we cannot safely use isNewer here as the SK time could have changed
              #but if the timestamp at least changed the SK server must have been writing the value again
              #and it should be ok to consider this as a new alarm now
              if existing.isInState(False) and existing.timestamp == skAlarm.timestamp:
                AVNLog.info("ignore SK alarm on %s, having switch off")
                continue
            #SK other on
            if not runningAny:
              AVNLog.info("own alarm on %s (sk: other on, local: nothing on)",skAlarm.skPath)
              self.alarmhandler.startAlarm(name,defaultCategory=category,caller=self,info=skAlarm.copy())
          else:
            #SK other off
            if runningOwn:
              if skAlarm.fromDelta:
                AVNLog.info("own alarm off %s (sk: other off, local: own on, isDelta)",skAlarm.skPath)
                self.alarmhandler.stopAlarm(name,caller=self)
              else:
                AVNLog.info("prepare alarm %s on on SK (sk: other off, local: own on, noDelta",skAlarm.skPath)
                self.deleteAndActivateActions.add(skAlarm.copy(stype=SKAlarm.T_SEND,shouldSend=True,skValue=sendAlarmValue))
            elif runningOther:
              AVNLog.info("own alarm off %s (sk: other off, local: other on")
              self.alarmhandler.stopAlarm(name,caller=self)
      if isFull:
        #now handle alarms not found at all
        ownAlarmNames=self.alarmhandler.getRunningAlarmNames()
        for name in ownAlarmNames:
          skAlarm=self.getSkAlarmFromOwn(name,False)
          if skAlarm is None:
            continue
          if handledPathes.get(skAlarm.skPath):
            continue
          runningOwn=self.alarmhandler.isAlarmActive(name,True)
          if not runningOwn:
            AVNLog.info("switch off local alarm %s (sk: none, local: other on",name)
            self.alarmhandler.stopAlarm(name,caller=self)
          else:
            skAlarm.shouldSend=True
            AVNLog.info("prepare alarm %s on SK on (sk: none, local: own on)",skAlarm.skPath)
            self.deleteAndActivateActions.add(skAlarm)
      self.__alarmCondition.notifyAll()

  def webSocketMessage(self,data,socket,first):
    if first:
      to=socket.getTimeOffset()
      if to is not None:
        self.timeOffset=to
    try:
      updates=data.get('updates')
      if updates is None:
        return
      for update in updates:
        values=update.get('values')
        timestamp=update.get('timestamp')
        source=update.get('$source')
        if values is None:
          continue
        if not self.config.ignoreTs and self.checkOutdated(timestamp):
          AVNLog.debug("ignore outdated delta, ts=%s",timestamp)
          continue
        for item in values:
          value=item.get('value')
          path=item.get('path')
          if  path is not None:
            if path.startswith("notifications"):
              skAlarm=self.deltas.handleNotification(path, value,source,update.get('timestamp'),True)
              if skAlarm is not None:
                self.handleNotifications({skAlarm.psKey():skAlarm},False)
            else:
              if value is not None:
                self.setValue(path,value)
    except:
      AVNLog.error("error decoding %s:%s",str(data),traceback.format_exc())
      try:
        self.webSocket.close()
      except:
        pass
      self.webSocket=None
      self.connected=False
  def timeChannelMessage(self,data,socket,first):
    if not first:
      return
    to=socket.getTimeOffset()
    if to is not None:
      self.timeOffset=to

  def writeChannelMessage(self,data,socket,first):
    pass
  def buildUpdateRequest(self,values):
    uvalues=[]
    for k,v in values.items():
      uvalues.append({
        'path':k,
        'value':v
      })
    update={
      '$source':self.config.skSource,
      'values':uvalues
    }
    rt={
      'context':'vessels.self',
      'updates':[update]
    }
    return rt

  def getLegData(self,wpData: WpData):
    PRFX='navigation.courseGreatCircle'
    rt={
      PRFX+'.nextPoint.position':{
        'latitude':wpData.lat,
        'longitude':wpData.lon,
      } if wpData.validData else None,
      PRFX+'.previousPoint.position':{
        'latitude':wpData.fromLat,
        'longitude':wpData.fromLon,
      } if (wpData.fromLat is not None and wpData.fromLon is not None) else None,
      PRFX+'.nextPoint.distance':wpData.distance,
      PRFX+'.nextPoint.bearingTrue':AVNUtil.deg2rad(wpData.dstBearing),
      PRFX+'.crossTrackError':wpData.xte,
      PRFX+'.nextPoint.arrivalCircle':wpData.approachDistance,
      PRFX+'.bearingTrackTrue':AVNUtil.deg2rad(wpData.bearing)
    }
    return rt
  def sendCurrentLeg(self,router : AVNRouter):
    try:
      if router is None:
        return
      wpData=router.getWpData()
      if wpData is None:
        return
      if not wpData.validData and self.ownWpOffSent:
        return
      self.ownWpOffSent=False
      update=self.buildUpdateRequest(self.getLegData(wpData))
      self.writeSocket.send(json.dumps(update))
      #hopefully we will have an error if we are unable to send our WP off
      if not wpData.validData:
        self.ownWpOffSent=True

    except Exception as e:
      AVNLog.debug("error sending current leg %",str(e))

  def isOwnSource(self,src):
    if src is None:
      return False
    return src == self.config.skSource or src.endswith('.'+self.config.skSource)

  ALARMS={
    'mob': {
      'path':'mob',
      'value':{
        'state':'emergency',
        'method':['visual','sound'],
        'message':'man overboard'
      }
    },
    'waypoint':{
      'path': 'arrivalCircleEntered',
      'value':{
        'state': 'normal',
        'method': ['visual','sound'],
        'message': 'arrival circle entered'
      }
    },
    'anchor':{
      'path':'navigation.anchor',
      'value': {
        'state':'emergency',
        'method': ['visual','sound'],
        'message': 'anchor drags'
      }
    }
  }
  NPRFX='notifications.'
  def skAlarmToOur(self, skpath, generic=True):
    for k,v in self.ALARMS.items():
      if (self.NPRFX+v['path']) == skpath:
        return k
    if not skpath.startswith(self.NPRFX):
      return None
    if not generic:
      return None
    return "sk:"+skpath[len(self.NPRFX):]

  def getSkAlarmFromOwn(self,name,on) -> SKAlarm:
    rt=self.ALARMS.get(name)
    if rt is not None:
      return SKAlarm(SKAlarm.T_SEND,self.NPRFX+rt['path'],'local.'+self.config.skSource,
                     rt['value'] if on else None,isOwnSource=True,remoteId=self.config.remoteId)
    else:
      if on:
        return None
      if not name.startswith('sk:'):
        return None
      return SKAlarm(SKAlarm.T_SEND,self.NPRFX+name[3:],'local.'+self.config.skSource,
                     None,isOwnSource=True,remoteId=self.config.remoteId)

  def handleAlarm(self,name,on,info):
    if not self.ENABLE_PARAM_DESCRIPTION.fromDict(self.param) or not self.config.notifyWrite:
      return
    skAlarm=self.getSkAlarmFromOwn(name,on)
    if skAlarm is None:
      return
    skAlarm.shouldSend=True
    if not on and isinstance(info,SKAlarm):
      #ensure to keep the source and timestamp of the alarm that we delete
      #in the action list to prevent a re-enabling e.g. with the next full update
      #see handleNotifications SK other on
      skAlarm.timestamp=info.timestamp
      skAlarm.source=info.source
    with self.__alarmCondition:
      self.deleteAndActivateActions.add(skAlarm)
      self.__alarmCondition.notifyAll()





  def queryCharts(self,apiUrl,port):
    charturl = apiUrl + "resources/charts"
    try:
      chartlistResponse = urllib.request.urlopen(charturl)
    except Exception as e:
      self.setInfo(self.I_CHARTS,'unable to read charts: %s'%str(e),WorkerStatus.ERROR)
      self.skCharts=[]
      raise
    if chartlistResponse is None:
      self.setInfo(self.I_CHARTS,'no charts',WorkerStatus.STARTED)
      self.skCharts = []
      return
    chartlist = json.loads(chartlistResponse.read())
    newList = []
    baseUrl = self.PREFIX+"/"+self.CHARTPREFIX+"/"
    for chart in list(chartlist.values()):
      name = chart.get('identifier')
      if name is None:
        continue
      url = baseUrl + urllib.parse.quote(name)
      bounds=chart.get('bounds')
      #bounds is upperLeftLon,upperLeftLat,lowerRightLon,lowerRightLat
      #          minlon,      maxlat,      maxlon,       minlat
      if bounds is None:
        bounds=[-180,85,180,-85]
      if bounds[1] < bounds[3]:
        #it seems that the plugin does not really provide the BB correctly...
        tmp=bounds[3]
        bounds[3]=bounds[1]
        bounds[1]=tmp
      chartInfo = {
        'name': name,
        'url': url,
        'charturl': url,
        'sequence': self.configSequence,
        'canDelete': False,
        'icon': "images/signalk.svg",
        'upzoom': True,
        'internal': {
          'url': "http://%s:%d" % (self.config.skHost, port) + chart.get('tilemapUrl'),
          'minlon': bounds[0],
          'maxlat': bounds[1],
          'maxlon': bounds[2],
          'minlat': bounds[3],
          'format': chart.get('format') or 'png',
          'bounds': chart.get('bounds'),
          'minzoom': chart.get('minzoom'),
          'maxzoom': chart.get('maxzoom')
        }
      }
      newList.append(chartInfo)
    self.skCharts = newList
    self.setInfo(self.I_CHARTS,'read %d charts'%len(newList),WorkerStatus.NMEA)

  def iterateToValue(self,node,prefix,callback):
    if not type(node) is dict:
      return
    if 'value' in node:
      callback(prefix,node.get('value'),node.get('$source'),node.get('timestamp'))
      return
    for k,v in node.items():
      if type(v) is dict:
        path=k if prefix is None else prefix+"."+k
        self.iterateToValue(v,path,callback)


  def storeData(self,node,priority):
    if 'notifications' in node:
      alarmList=self.deltas.copy()
      item = node.get('notifications')
      if item is not None:
        for k,v in item.items():
          self.iterateToValue(v,'notifications.'+k,alarmList.handleNotification)
      self.handleNotifications(alarmList.skList,True)
    def store(path,value,source,timestamp):
      if self.checkOutdated(timestamp):
        AVNLog.debug('ignore outdated value %s',path)
        return
      self.setValue(path, value)
    self.iterateToValue(node,None,store)

  def getLocalToken(self,user):
    allowedTypes=['readwrite','admin']
    cfgPath=os.path.join(os.path.expanduser('~'),'.signalk','security.json')
    AVNLog.debug("trying to get token for %s in %s",user,cfgPath)
    if not os.path.exists(cfgPath):
      raise Exception("signalK security config %s not found"%cfgPath)
    with open(cfgPath,'r') as ch:
       secData=json.load(ch)
       if not 'secretKey' in secData:
         raise Exception("secretKey not found in %s"%cfgPath)
       secretKey=secData.get('secretKey')
       users=secData.get('users')
       if users is None:
         raise Exception("no users list found in %s"%cfgPath)
       if type(users) is not list:
         raise Exception("invalid type of users list in %s"%cfgPath)
       found=False
       for us in users:
         if us.get('username') == user:
           found = True
           if us.get('type') not in allowedTypes:
             raise Exception("user %s has no write permissions"%user)
           break
       if not found:
         raise Exception("user %s not found in %s"%(user,cfgPath))
       token=jwt(user,secretKey)
       AVNLog.debug("created token %s for user %s",token,user)
       return token

  def getAuthentication(self,baseUrl):
    isLocal= self.config.isLocal
    lString='locally' if isLocal else 'on host %s'%self.config.skHost
    user=self.config.user
    if self.config.password == '' and not isLocal:
      self.setInfo(self.I_AUTH,"must provide a password for non local auth",WorkerStatus.ERROR)
      return
    if self.config.password == '':
      #trying local
      try:
        token=self.getLocalToken(user)
        if token is not None:
          self.setInfo(self.I_AUTH,"successfully authenticated locally %s"%user,WorkerStatus.NMEA)
          return token
        self.setInfo(self.I_AUTH,"unable to get local token for %s"%user,WorkerStatus.ERROR)
        return
      except Exception as ex:
        self.setInfo(self.I_AUTH,"error when trying to get local auth for %s:%s"%(user,str(ex)),WorkerStatus.ERROR)
        return
    self.setInfo(self.I_AUTH,"trying to authenticate %s %s"%(user,lString),WorkerStatus.STARTED)
    if baseUrl.endswith('/'):
      baseUrl=baseUrl[0:-1]
    if baseUrl.endswith('/api'):
      baseUrl=baseUrl[0:-4]
    url=baseUrl+'/auth/login'
    try:
      req = urllib.request.Request(url,method='POST')
      req.add_header('Content-Type', 'application/json')
      body={'username':user,'password':self.config.password}
      jsondata = json.dumps(body)
      jsondataasbytes = jsondata.encode('utf-8')   # needs to be bytes
      req.add_header('Content-Length', str(len(jsondataasbytes)))
      response = urllib.request.urlopen(req, jsondataasbytes)
      data=response.read()
      decoded=json.loads(data)
      token=decoded.get('token')
      if token is not None:
        self.setInfo(self.I_AUTH,"successfully retrieved token for %s"%user,WorkerStatus.NMEA)
        return token
      raise Exception(decoded.get('message') or 'unknown result')
    except Exception as e:
      self.setInfo(self.I_AUTH,"unable to login %s : %s"%(user,str(e)),WorkerStatus.ERROR)


  def listCharts(self,hostip):
    AVNLog.debug("listCharts %s"%hostip)
    if not self.connected:
      AVNLog.debug("not yet connected")
      return []
    try:
      rt=[]
      items=self.skCharts+[]
      for item in items:
        cp=item.copy()
        del cp['internal']
        rt.append(cp)
      return rt
    except:
      AVNLog.debug("unable to list charts: %s"%traceback.format_exc())
      return []

  def getHandledCommands(self):
    return {'path': self.PREFIX+"/"+self.CHARTPREFIX}

  def handleApiRequest(self, type, command, requestparam, **kwargs):
    handler = kwargs.get('handler')
    if type == 'path':
      prefix=self.PREFIX+"/"+self.CHARTPREFIX
      if not command.startswith(prefix+"/"):
        raise Exception("unknown path %s"%command)
      path=command[len(prefix)+1:]
      return self.handleChartRequest(path,handler)
    raise Exception("unable to handle user request %s"%(type))

  AVNAV_XML="""<?xml version="1.0" encoding="UTF-8" ?>
  <TileMapService version="1.0.0" >
   <Title>%(title)s</Title>
   <TileMaps>
     <TileMap 
       title="%(title)s" 
       href="%(url)s"
       minzoom="%(minzoom)s"
       maxzoom="%(maxzoom)s"
       projection="EPSG:4326">
             <BoundingBox minlon="%(minlon)f" minlat="%(minlat)f" maxlon="%(maxlon)f" maxlat="%(maxlat)f" title="layer"/>
       <TileFormat width="256" height="256" mime-type="x-%(format)s" extension="%(format)s" />
    </TileMap>       
   </TileMaps>
 </TileMapService>

  """
  def handleChartRequest(self,url,handler):
    '''
    handle api requests
    @param url:
    @param handler:
    @return:
    '''

    parr=url.split("/")
    if len(parr) < 2:
      raise Exception("invalid chart url %s"%url)
    chartName = parr[0]
    chart=None
    for chartinfo in self.skCharts:
      if chartinfo.get('name')==chartName:
        chart=chartinfo
        break
    if chart is None:
      raise Exception("chart %s not found"%chartName)
    if parr[1] == "sequence":
      sData={'status':'OK','sequence':self.configSequence}
      handler.sendNavResponse(json.dumps(sData))
      return
    if parr[1] == "avnav.xml":
      requestHost = handler.headers.get('host')
      requestHostAddr = requestHost.split(':')[0]
      url='tiles'
      doProxy=False
      if self.config.proxyMode=='always' or ( self.config.proxyMode=='sameHost' and not self.config.isLocal):
        doProxy=True
      if not doProxy:
        #no proxying, direct access to sk for charts
        url=chart['internal']['url'].replace('localhost',requestHostAddr)
      param=chart['internal'].copy()
      param.update({
        'title':chart['name'],
        'url':url,
      })
      data=self.AVNAV_XML%param
      handler.send_response(200)
      handler.send_header("Content-type", "text/xml")
      handler.send_header("Content-Length", len(data))
      handler.send_header("Last-Modified", handler.date_time_string())
      handler.end_headers()
      handler.wfile.write(data.encode('utf-8'))
      return True
    if parr[1] == "sequence":
      return {'status':'OK','sequence':0}
    if len(parr) < 5:
      raise Exception("invalid request to chart %s: %s" % (chartName, url))
    replaceV={'z':parr[2],
              'x':parr[3],
              'y':re.sub("\..*","",parr[4])}
    skurl=chart['internal']['url']
    for k in list(replaceV.keys()):
      skurl=skurl.replace("{"+k+"}",replaceV[k])
    try:
      tile = urllib.request.urlopen(skurl)
      if tile is None:
        return None
      tileData = tile.read()
    except:
      AVNLog.debug("unable to read tile from sk %s:%s"%(url,traceback.format_exc()))
      return
    handler.send_response(200)
    handler.send_header("Content-type", "image/%s"%chart['internal']['format'])
    handler.send_header("Content-Length", len(tileData))
    handler.send_header("Last-Modified", handler.date_time_string())
    handler.end_headers()
    handler.wfile.write(tileData)
    return True

avnav_handlerList.registerHandler(AVNSignalKHandler)






