#!/usr/bin/python3 -u

 # The -u option above turns off block buffering of python output. This 
 # assures that each error message gets individually printed to the log file.

 #
 # Module: radmonAgent.py
 #

 # Description: This module acts as an agent between the radiation monitoring

 # device and Internet web services.  The agent periodically sends an http

 # request to the radiation monitoring device and processes the response from
 # the device and performs a number of operations:

 #     - conversion of data items

 #     - update a round robin (rrdtool) database with the radiation data
 #     - periodically generate graphic charts for display in html documents

 #     - write the processed radmon data to a JSON file for use by html

 #       documents

 #

 # Copyright 2015 Jeff Owrey

 #    This program is free software: you can redistribute it and/or modify
 #    it under the terms of the GNU General Public License as published by
 #    the Free Software Foundation, either version 3 of the License, or
 #    (at your option) any later version.
 #
 #    This program is distributed in the hope that it will be useful,
 #    but WITHOUT ANY WARRANTY; without even the implied warranty of
 #    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 #    GNU General Public License for more details.
 #
 #    You should have received a copy of the GNU General Public License
 #    along with this program.  If not, see http://www.gnu.org/license.
 #
 # Revision History

 #   * v20 released 15 Sep 2015 by J L Owrey; first release
 #   * v21 released 27 Nov 2017 by J L Owrey; bug fixes; updates

 #   * v22 released 03 Mar 2018 by J L Owrey; improved code readability;
 #         improved radmon device offline status handling

 #   * v23 released 16 Nov 2018 by J L Owrey: improved fault handling
 #         and data conversion

 #   * v24 released 14 Jun 2021 by J L Owrey; minor revisions

 #   * v25 released 9 Jul 2021 by J L Owrey; improved handling of
 #         monitor status function

 #

 #2345678901234567890123456789012345678901234567890123456789012345678901234567890

 
 import os

 import sys
 import signal

 import multiprocessing

 import time
 import calendar

 import json
 from urllib.request import urlopen

 import rrdbase

 
    ### ENVIRONMENT ###

 
 _USER = os.environ['USER']

 _SERVER_MODE = "primary"
 _USE_RADMON_TIMESTAMP = True

    ### DEFAULT RADIATION MONITOR URL ###

 _DEFAULT_RADIATION_MONITOR_URL = \

     "http://192.168.1.24"

     ### FILE AND FOLDER LOCATIONS ###
 

 # folder for containing dynamic data objects

 _DOCROOT_PATH = "/home/%s/public_html/radmon/" % _USER

 # folder for charts and output data file

 _CHARTS_DIRECTORY = _DOCROOT_PATH + "dynamic/"

 # location of data output file

 _OUTPUT_DATA_FILE = _DOCROOT_PATH + "dynamic/radmonData.js"

 # database that stores radmon data

 _RRD_FILE = "/home/%s/database/radmonData.rrd" % _USER

 
     ### GLOBAL CONSTANTS ###

 # maximum number of failed data requests allowed
 _MAX_FAILED_DATA_REQUESTS = 2
 # maximum number of http request retries  allowed
 _MAX_HTTP_RETRIES = 5
 # delay time between http request retries
 _HTTP_RETRY_DELAY = 1.119

 # interval in seconds between data requests

 _DEFAULT_DATA_REQUEST_INTERVAL = 5

 # number seconds to wait for a response to HTTP request
 _HTTP_REQUEST_TIMEOUT = 3

 
 # interval in seconds between database updates
 _DATABASE_UPDATE_INTERVAL = 30
 # interval in seconds between chart updates
 _CHART_UPDATE_INTERVAL = 300

 # standard chart width in pixels

 _CHART_WIDTH = 600

 # standard chart height in pixels

 _CHART_HEIGHT = 150

    ### GLOBAL VARIABLES ###
 

 # turn on or off of verbose debugging information

 verboseMode = False
 debugMode = False

 reportUpdateFails = False

 
 # The following two items are used for detecting system faults
 # and radiation monitor online or offline status.
 # count of failed attempts to get data from radiation monitor

 failedUpdateCount = 0

 httpRetries = 0

 radmonOnline = False

 # status of reset command to radiation monitor
 remoteDeviceReset = False

 # ip address of radiation monitor

 radiationMonitorUrl = _DEFAULT_RADIATION_MONITOR_URL

 # web update frequency
 dataRequestInterval = _DEFAULT_DATA_REQUEST_INTERVAL

 # rrdtool database interface handler
 rrdb = None
 

   ###  PRIVATE METHODS  ###
 
 def getTimeStamp():
     """

     Set the error message time stamp to the local system time.

     Parameters: none

     Returns: string containing the time stamp

     """

     return time.strftime( "%m/%d/%Y %T", time.localtime() )

 ## end def

 def setStatusToOffline():

     """Set the detected status of the radiation monitor to
        "offline" and inform downstream clients by removing input
        and output data files.
        Parameters: none
        Returns: nothing

     """

     global radmonOnline

     # Inform downstream clients by removing output data file.

     if os.path.exists(_OUTPUT_DATA_FILE):
        os.remove(_OUTPUT_DATA_FILE)

     # If the radiation monitor was previously online, then send
     # a message that we are now offline.

     if radmonOnline:
         print('%s radiation monitor offline' % getTimeStamp())
     radmonOnline = False

 ## end def

 def terminateAgentProcess(signal, frame):

     """Send a message to log when the agent process gets killed
        by the operating system.  Inform downstream clients
        by removing input and output data files.
        Parameters:
            signal, frame - dummy parameters

        Returns: nothing
     """

     # Inform downstream clients by removing output data file.
     if os.path.exists(_OUTPUT_DATA_FILE):
        os.remove(_OUTPUT_DATA_FILE)

     print('%s terminating radmon agent process' % \
               (getTimeStamp()))

     sys.exit(0)

 ## end def

   ###  PUBLIC METHODS  ###
 

 def getRadiationData(dData):

     """Send http request to radiation monitoring device.  The
        response from the device contains the radiation data as
        unformatted ascii text.
        Parameters: none 
        Returns: a string containing the radiation data if successful,
                 or None if not successful

     """

     global httpRetries

     sUrl = radiationMonitorUrl

     if remoteDeviceReset:
         sUrl += "/reset" # reboot the radiation monitor

     else:

         sUrl += "/rdata" # request data from the monitor

 
     try:

         currentTime = time.time()
         response = urlopen(sUrl, timeout=_HTTP_REQUEST_TIMEOUT)

         requestTime = time.time() - currentTime

         content = response.read().decode('utf-8')
         content = content.replace('\n', '')
         content = content.replace('\r', '')
         if content == "":
             raise Exception("empty response")

     except Exception as exError:

         # If no response is received from the device, then assume that
         # the device is down or unavailable over the network.  In

         # that case return None to the calling function.

         httpRetries += 1
 
         if reportUpdateFails:
             print("%s " % getTimeStamp(), end='')
         if reportUpdateFails or verboseMode:
             print("http request failed (%d): %s" % \
                 (httpRetries, exError))
 
         if httpRetries > _MAX_HTTP_RETRIES:
             httpRetries = 0
             return False
         else:
             time.sleep(_HTTP_RETRY_DELAY)
             return getRadiationData(dData)
     ## end try

 
     if debugMode:
         print(content)

     if verboseMode:
         print("http request successful: %.4f sec" % requestTime)

     httpRetries = 0

     dData['content'] = content
     return True

 ## end def

 def parseDataString(dData):
     """Parse the data string returned by the radiation monitor
        into its component parts.

        Parameters:

             dData - a dictionary object to contain the parsed data items

        Returns: True if successful, False otherwise

     """

     # Example radiation monitor data string
     # $,UTC=17:09:33 6/22/2021,CPS=0,CPM=26,uSv/hr=0.14,Mode=SLOW,#
     

     try:

         sData = dData.pop('content')
         lData = sData[2:-2].split(',')
     except Exception as exError:
         print("%s parseDataString: %s" % (getTimeStamp(), exError))

         return False
 

     # Verfy the expected number of data items have been received.
     if len(lData) != 5:
         print("%s parse failed: corrupted data string" % getTimeStamp())
         return False;
 

     # Load the parsed data into a dictionary for easy access.

     for item in lData:

         if "=" in item:
             dData[item.split('=')[0]] = item.split('=')[1]

     # Add status to dictionary object

     dData['status'] = 'online'

     dData['serverMode'] = _SERVER_MODE

     return True

 ## end def

 def convertData(dData):

     """Convert individual radiation data items as necessary.
        Parameters:
            dData - a dictionary object containing the radiation data

        Returns: True if successful, False otherwise

     """
     try:

         if _USE_RADMON_TIMESTAMP:
             # Convert the UTC timestamp provided by the radiation monitoring
             # device to epoch local time in seconds.
             ts_utc = time.strptime(dData['UTC'], "%H:%M:%S %m/%d/%Y")
             epoch_local_sec = calendar.timegm(ts_utc)
         else:
             # Use a timestamp generated by the requesting server (this)
             # instead of the timestamp provided by the radiation monitoring
             # device.  Using the server generated timestamp prevents errors
             # that occur when the radiation monitoring device fails to
             # synchronize with a valid NTP time server.

             epoch_local_sec = time.time()

 
         dData['date'] = \

             time.strftime("%m/%d/%Y %T", time.localtime(epoch_local_sec))      

         dData['mode'] = dData.pop('Mode').lower()

         dData['uSvPerHr'] = '%.2f' % float(dData['uSv/hr'])
         # The rrdtool database stores whole units, so convert uSv to Sv.
         dData['SvPerHr'] = float(dData.pop('uSv/hr')) * 1.0E-06

     except Exception as exError:
         print("%s data conversion failed: %s" % (getTimeStamp(), exError))

         return False

     return True

 ## end def

 def writeOutputFile(dData):

     """Write radiation data items to the output data file, formatted as 

        a JSON file.  This file may then be accessed and used by

        by downstream clients, for instance, in HTML documents.

        Parameters:

            dData - a dictionary object containing the data to be written
                    to the output data file
        Returns: True if successful, False otherwise

     """

     # Format the radmon data as string using java script object notation.

     jsData = json.loads("{}")
     try:

         for key in dData:
             jsData.update({key:dData[key]})

         sData = "[%s]" % json.dumps(jsData)
     except Exception as exError:
         print("%s writeOutputFile: %s" % (getTimeStamp(), exError))
         return False

     if debugMode:
         print(sData)

     # Write the string to the output data file for use by html documents.

     try:
         fc = open(_OUTPUT_DATA_FILE, "w")

         fc.write(sData)

         fc.close()

     except Exception as exError:
         print("%s writeOutputFile: %s" % (getTimeStamp(), exError))

         return False

     return True
 ## end def
 

 def setRadmonStatus(updateSuccess):
     """Detect if radiation monitor is offline or not available on
        the network. After a set number of attempts to get data
        from the monitor set a flag that the radmon is offline.
        Parameters:
            updateSuccess - a boolean that is True if data request
                            successful, False otherwise
        Returns: nothing
     """
     global failedUpdateCount, radmonOnline
 
     if updateSuccess:
         failedUpdateCount = 0
         # Set status and send a message to the log if the device
         # previously offline and is now online.
         if not radmonOnline:
             print('%s radiation monitor online' % getTimeStamp())
             radmonOnline = True
         return

     else:
         # The last attempt failed, so update the failed attempts
         # count.
         failedUpdateCount += 1
 
     if failedUpdateCount == _MAX_FAILED_DATA_REQUESTS:

         # Max number of failed data requests, so set
         # device status to offline.
         setStatusToOffline()

 ## end def

     ### GRAPH FUNCTIONS ###

 def generateGraphs():
     """Generate graphs for display in html documents.
        Parameters: none

        Returns: nothing

     """
     autoScale = False
 

     # past 24 hours

     rrdb.createAutoGraph('24hr_cpm', 'CPM', 'counts\ per\ minute', 

                 'CPM\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2, autoScale)

     rrdb.createAutoGraph('24hr_svperhr', 'SvperHr', 'Sv\ per\ hour',

                 'Sv/Hr\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2, autoScale)

     # past 4 weeks

     rrdb.createAutoGraph('4wk_cpm', 'CPM', 'counts\ per\ minute',

                 'CPM\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2, autoScale)

     rrdb.createAutoGraph('4wk_svperhr', 'SvperHr', 'Sv\ per\ hour',

                 'Sv/Hr\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2, autoScale)

     # past year

     rrdb.createAutoGraph('12m_cpm', 'CPM', 'counts\ per\ minute',

                 'CPM\ -\ Past\ Year', 'end-12months', 0, 0, 2, autoScale)

     rrdb.createAutoGraph('12m_svperhr', 'SvperHr', 'Sv\ per\ hour',

                 'Sv/Hr\ -\ Past\ Year', 'end-12months', 0, 0, 2, autoScale)

 ## end def

 def getCLarguments():

     """Get command line arguments.  There are four possible arguments

           -d turns on debug mode

           -v turns on verbose mode

           -t sets the radiation device query interval
           -u sets the url of the radiation monitoring device

        Returns: nothing

     """

     global verboseMode, debugMode, dataRequestInterval, \

            radiationMonitorUrl, reportUpdateFails

 
     index = 1
     while index < len(sys.argv):

         if sys.argv[index] == '-v':
             verboseMode = True
         elif sys.argv[index] == '-d':
             verboseMode = True
             debugMode = True

         elif sys.argv[index] == '-r':
             reportUpdateFails = True
 
         # Update period and url options
         elif sys.argv[index] == '-p':
             try:
                 dataRequestInterval = abs(float(sys.argv[index + 1]))
             except:
                 print("invalid polling period")
                 exit(-1)

             index += 1
         elif sys.argv[index] == '-u':

             radiationMonitorUrl = sys.argv[index + 1]

             if radiationMonitorUrl.find('http://') < 0:
                 radiationMonitorUrl = 'http://' + radiationMonitorUrl

             index += 1
         else:
             cmd_name = sys.argv[0].split('/')

             print("Usage: %s [-d] [-p seconds] [-u url}" % cmd_name[-1])

             exit(-1)
         index += 1

 ## end def

 def setup():

     """Handles timing of events and acts as executive routine managing
        all other functions.

        Parameters: none

        Returns: nothing

     """

     global rrdb

     ## Get command line arguments.
     getCLarguments()
 

     print('====================================================')
     print('%s starting up radmon agent process' % \
                   (getTimeStamp()))
 

     ## Exit with error if rrdtool database does not exist.

     if not os.path.exists(_RRD_FILE):

         print('rrdtool database does not exist\n' \

               'use createRadmonRrd script to ' \

               'create rrdtool database\n')

         exit(1)

 
     signal.signal(signal.SIGTERM, terminateAgentProcess)
     signal.signal(signal.SIGINT, terminateAgentProcess)
 
     # Define object for calling rrdtool database functions.
     rrdb = rrdbase.rrdbase( _RRD_FILE, _CHARTS_DIRECTORY, _CHART_WIDTH, \
                             _CHART_HEIGHT, verboseMode, debugMode )
 ## end def
 
 def loop():
      # last time output JSON file updated
     lastDataRequestTime = -1
     # last time charts generated
     lastChartUpdateTime = - 1
     # last time the rrdtool database updated
     lastDatabaseUpdateTime = -1
 

     while True:
 

         currentTime = time.time() # get current time in seconds

         # Every data update interval request data from the radiation

         # monitor and process the received data.
         if currentTime - lastDataRequestTime > dataRequestInterval:
             lastDataRequestTime = currentTime

             dData = {}

 
             # Get the data string from the device.

             result = getRadiationData(dData)

 
             # If successful parse the data.
             if result:

                 result = parseDataString(dData)

 
             # If parsing successful, convert the data.
             if result:

                 result = convertData(dData)

             # If conversion successful, write data to data files.

             if result:

                 writeOutputFile(dData)

             # At the rrdtool database update interval, update the database.
             if result and (currentTime - lastDatabaseUpdateTime > \
                            _DATABASE_UPDATE_INTERVAL):   
                 lastDatabaseUpdateTime = currentTime
                 ## Update the round robin database with the parsed data.

                 result = rrdb.updateDatabase(dData['date'], \
                              dData['CPM'], dData['SvPerHr'])

             # Set the radmon status to online or offline depending on the

             # success or failure of the above operations.

             setRadmonStatus(result)

 
         # At the chart generation interval, generate charts.
         if currentTime - lastChartUpdateTime > _CHART_UPDATE_INTERVAL:
             lastChartUpdateTime = currentTime
             p = multiprocessing.Process(target=generateGraphs, args=())
             p.start()
 
         # Relinquish processing back to the operating system until
         # the next update interval.
 
         elapsedTime = time.time() - currentTime

         if verboseMode:
             if result:
                 print("update successful: %6f sec\n"
                       % elapsedTime)
             else:
                 print("update failed: %6f sec\n"
                       % elapsedTime)

         remainingTime = dataRequestInterval - elapsedTime
         if remainingTime > 0.0:

             time.sleep(remainingTime)
     ## end while
 ## end def
 
 if __name__ == '__main__':

     setup()
     loop()