#!/usr/bin/python2 -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: nodepowerAgent.py
 #
 # Description: This module acts as an agent between the mesh network and
 # node power and enviromental sensors.  The agent periodically polls the
 # sensors and processes the data returned from the sensors, including
 #     - conversion of data items
 #     - update a round robin (rrdtool) database with the sensor data
 #     - periodically generate graphic charts for display in html documents
 #     - write the processed node status to a JSON file for use by html
 #       documents
 #
 # Copyright 2021 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
 #   * v10 released 01 June 2021 by J L Owrey; first release
 #
 #2345678901234567890123456789012345678901234567890123456789012345678901234567890
 
 # Import required python libraries.
 import os
 import sys
 import signal
 import subprocess
 import multiprocessing
 import time
 
 # Import sensor libraries.
 import ina260 # power sensor
 import tmp102 # temperature sensor
 
     ### SENSOR BUS ADDRESSES ###
 
 # Set bus addresses of sensors
 _PWR_SENSOR_ADDR = 0X40
 _BAT_TMP_SENSOR_ADDR = 0x48
 _AMB_TMP_SENSOR_ADDR = 0x4B
 # Set bus selector
 _BUS_SEL = 1
 
     ### FILE AND FOLDER LOCATIONS ###
 
 _USER = os.environ['USER']
 # folder for containing dynamic data objects
 _DOCROOT_PATH = "/home/%s/public_html/power/" % _USER
 # folder for charts and output data file
 _CHARTS_DIRECTORY = _DOCROOT_PATH + "dynamic/"
 # location of data output file
 _OUTPUT_DATA_FILE = _DOCROOT_PATH + "dynamic/powerData.js"
 # database that stores node data
 _RRD_FILE = "/home/%s/database/powerData.rrd" % _USER
 
     ### GLOBAL CONSTANTS ###
 
 # rrdtool database update interval in seconds
 _DATABASE_UPDATE_INTERVAL = 30
 # sensor data request interval in seconds
 _DEFAULT_DATA_REQUEST_INTERVAL = 2
 # chart update interval in seconds
 _CHART_UPDATE_INTERVAL = 600
 # standard chart width in pixels
 _CHART_WIDTH = 600
 # standard chart height in pixels
 _CHART_HEIGHT = 150

 # chart average line color
 _AVERAGE_LINE_COLOR = '#006600'

 
    ### GLOBAL VARIABLES ###
 
 # turn on or off of verbose debugging information
 debugOption = False
 verboseDebug = False
 
 # frequency of data requests to sensors
 dataRequestInterval = _DEFAULT_DATA_REQUEST_INTERVAL
 # chart update interval
 chartUpdateInterval = _CHART_UPDATE_INTERVAL
 # last node request time
 lastDataPointTime = -1
 
 # Define each sensor.  This also initialzes each sensor.
 pwr = ina260.ina260(_PWR_SENSOR_ADDR, _BUS_SEL)
 btmp = tmp102.tmp102(_BAT_TMP_SENSOR_ADDR, _BUS_SEL)
 atmp = tmp102.tmp102(_AMB_TMP_SENSOR_ADDR, _BUS_SEL)
 
   ###  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 getEpochSeconds(sTime):
     """Convert the time stamp supplied in the weather data string
        to seconds since 1/1/1970 00:00:00.
        Parameters: 
            sTime - the time stamp to be converted must be formatted
                    as %m/%d/%Y %H:%M:%S
        Returns: epoch seconds
     """
     try:
         t_sTime = time.strptime(sTime, '%m/%d/%Y %H:%M:%S')
     except Exception, exError:
         print '%s getEpochSeconds: %s' % (getTimeStamp(), exError)
         return None
     tSeconds = int(time.mktime(t_sTime))
     return tSeconds

 ## 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 npw agent process' % \
               (getTimeStamp())
     sys.exit(0)

 ## end def

 
   ###  PUBLIC METHODS  ###
 
 def getSensorData(dData):
     """Poll sensors for data.
        Parameters: none
        Returns: a string containing the node signal data if successful,
                 or None if not successful
     """
     try:
         dData["time"] = getTimeStamp()
         dData["current"] = pwr.getCurrent()
         dData["voltage"] = pwr.getVoltage()
         dData["power"] = pwr.getPower()

         dData["battemp"] = btmp.getTempF()
         dData["ambtemp"] = atmp.getTempF()

      
     except Exception, exError:
         print "%s sensor error: %s" % (getTimeStamp(), exError)
         return False
 
     return True

 ## end def

 
 def updateDatabase(dData):
     """
     Update the rrdtool database by executing an rrdtool system command.
     Format the command using the data extracted from the sensors.
     Parameters: dData - dictionary object containing data items to be
                         written to the rr database file
     Returns: True if successful, False otherwise
     """
  
     epochTime = getEpochSeconds(dData['time'])
 
     # Format the rrdtool update command.
     strFmt = "rrdtool update %s %s:%s:%s:%s:%s:%s"
     strCmd = strFmt % (_RRD_FILE, epochTime, dData['current'], \
              dData['voltage'], dData['power'], dData['battemp'], \
              dData['ambtemp'])
 
     if debugOption:
         print "%s" % strCmd # DEBUG
 
     # Run the command as a subprocess.
     try:
         subprocess.check_output(strCmd, shell=True,  \
                              stderr=subprocess.STDOUT)
     except subprocess.CalledProcessError, exError:
         print "%s: rrdtool update failed: %s" % \
                     (getTimeStamp(), exError.output)
         return False
 
     return True

 ## end def

 
 def writeOutputDataFile(dData):
     """Write node data items to the output data file, formatted as 
        a Javascript file.  This file may then be accessed and used by
        by downstream clients, for instance, in HTML documents.
        Parameters:
            sData - a string object containing the data to be written
                    to the output data file
        Returns: True if successful, False otherwise
     """
     # Write a JSON formatted file for use by html clients.  The following
     # data items are sent to the client file.
     #    * The last database update date and time
     #    * The data request interval
     #    * The sensor values
 
     # Create a JSON formatted string from the sensor data.
     sData = "[{\"period\":\"%s\", " % \
            (chartUpdateInterval)
     for key in dData:
         sData += '\"%s\":\"%s\", ' % (key, dData[key])
     sData = sData[:-2] + '}]\n'
 
     # Write the JSON formatted data to the output data file.
     try:
         fc = open(_OUTPUT_DATA_FILE, "w")
         fc.write(sData)
         fc.close()
     except Exception, exError:
         print "%s write output file failed: %s" % \
               (getTimeStamp(), exError)
         return False
 
     if verboseDebug:
         print sData[:-1]
     if debugOption:
         print "writing output data file: %d bytes" % len(sData)
 
     return True
 ## end def
 
 def createGraph(fileName, dataItem, gLabel, gTitle, gStart,

                 lower, upper, trendLine, scaleFactor=1, autoScale=True, 
                 alertLine=""):

     """Uses rrdtool to create a graph of specified node data item.
        Parameters:
            fileName - name of file containing the graph
            dataItem - data item to be graphed
            gLabel - string containing a graph label for the data item
            gTitle - string containing a title for the graph
            gStart - beginning time of the graphed data
            lower - lower bound for graph ordinate #NOT USED
            upper - upper bound for graph ordinate #NOT USED

            trendLine 
                 0, show only graph data
                 1, show only a trend line
                 2, show a trend line and the graph data
            scaleFactor - amount to pre-scale the data before charting
                 the data [default=1]

            autoScale - if True, then use vertical axis auto scaling

                 (lower and upper parameters must be zero)
            alertLine - value for which to print a critical
                 low voltage alert line on the chart. If not provided
                 alert line will not be printed.

        Returns: True if successful, False otherwise
     """
     gPath = _CHARTS_DIRECTORY + fileName + ".png"
     trendWindow = { 'end-1day': 7200,
                     'end-4weeks': 172800,
                     'end-12months': 604800 }
  
     # Format the rrdtool graph command.
 
     # Set chart start time, height, and width.
     strCmd = "rrdtool graph %s -a PNG -s %s -e now -w %s -h %s " \
              % (gPath, gStart, _CHART_WIDTH, _CHART_HEIGHT)
    
     # Set the range and scaling of the chart y-axis.
     if lower < upper:
         strCmd  +=  "-l %s -u %s -r " % (lower, upper)
     elif autoScale:
         strCmd += "-A "
     strCmd += "-Y "
 
     # Set the chart ordinate label and chart title. 
     strCmd += "-v %s -t %s " % (gLabel, gTitle)
  
     # Show the data, or a moving average trend line over
     # the data, or both.

     strCmd += "DEF:rSeries=%s:%s:LAST " % (_RRD_FILE, dataItem)
     strCmd += "CDEF:dSeries=rSeries,%s,/ " % (scaleFactor)
 
     if trendLine == 0:

         strCmd += "LINE1:dSeries#0400ff "

     elif trendLine == 1:
         strCmd += "CDEF:smoothed=dSeries,%s,TREND LINE2:smoothed%s " \
                   % (trendWindow[gStart], _AVERAGE_LINE_COLOR)
     elif trendLine == 2:

         strCmd += "LINE1:dSeries#0400ff "

         strCmd += "CDEF:smoothed=dSeries,%s,TREND LINE2:smoothed%s " \
                   % (trendWindow[gStart], _AVERAGE_LINE_COLOR)
 
     if alertLine != "":
         strCmd += "HRULE:%s#FF0000:Critical\ Low\ Voltage " % (alertLine)

      
     if verboseDebug:
         print "%s" % strCmd # DEBUG
     
     # Run the formatted rrdtool command as a subprocess.
     try:
         result = subprocess.check_output(strCmd, \
                      stderr=subprocess.STDOUT,   \
                      shell=True)
     except subprocess.CalledProcessError, exError:
         print "rrdtool graph failed: %s" % (exError.output)
         return False
 
     if debugOption:
         print "rrdtool graph: %s\n" % result,
     return True
 

 ## end def

 
 def generateGraphs():
     """Generate graphs for display in html documents.
        Parameters: none
        Returns: nothing
     """
 
     # 24 hour stock charts
 

     createGraph('24hr_current', 'CUR', 'Amps',
                 'Current\ -\ Last\ 24\ Hours', 'end-1day', \
                 0, 0, 2, 1000)
     createGraph('24hr_voltage', 'VOLT', 'Volts',
                 'Voltage\ -\ Last\ 24\ Hours', 'end-1day', \
                 9, 15, 0, 1, True, 11)
     createGraph('24hr_power', 'PWR', 'Watts', 
                 'Power\ -\ Last\ 24\ Hours', 'end-1day', \
                 0, 0, 2, 1000)

     createGraph('24hr_battemp', 'BTMP', 'deg\ F', 

                 'Battery\ Temperature\ -\ Last\ 24\ Hours', 'end-1day', \

                 0, 0, 0)

     createGraph('24hr_ambtemp', 'ATMP', 'deg\ F', 

                 'Ambient\ Temperature\ -\ Last\ 24\ Hours', 'end-1day', \

                 0, 0, 0)

 
     # 4 week stock charts
 

     createGraph('4wk_current', 'CUR', 'Amps',
                 'Current\ -\ Last\ 4\ Weeks', 'end-4weeks', \
                 0, 0, 2, 1000)
     createGraph('4wk_voltage', 'VOLT', 'Volts',
                 'Voltage\ -\ Last\ 4\ Weeks', 'end-4weeks', \
                 9, 15, 0, 1, True, 11)
     createGraph('4wk_power', 'PWR', 'Watts', 
                 'Power\ -\ Last\ 4\ Weeks', 'end-4weeks', \
                 0, 0, 2, 1000)

     createGraph('4wk_battemp', 'BTMP', 'deg\ F', 

                 'Battery\ Temperature\ -\ Last\ 4\ Weeks', 'end-4weeks', \

                 0, 0, 2)

     createGraph('4wk_ambtemp', 'ATMP', 'deg\ F', 

                 'Ambient\ Temperature\ -\ Last\ 4\ Weeks', 'end-4weeks', \

                 0, 0, 2)

 
     # 12 month stock charts
 

     createGraph('12m_current', 'CUR', 'Amps',
                 'Current\ -\ Past\ Year', 'end-12months', \
                 0, 0, 2, 1000)
     createGraph('12m_voltage', 'VOLT', 'Volts',
                 'Voltage\ -\ Past\ Year', 'end-12months', \
                 9, 15, 0, 1, True, 11)
     createGraph('12m_power', 'PWR', 'Watts', 
                 'Power\ -\ Past\ Year', 'end-12months', \
                 0, 0, 2, 1000)

     createGraph('12m_battemp', 'BTMP', 'deg\ F', 

                 'Battery\ Temperature\ -\ Past\ Year', 'end-12months', \

                 0, 0, 2)

     createGraph('12m_ambtemp', 'ATMP', 'deg\ F', 

                 'Ambient\ Temperature\ -\ Past\ Year', 'end-12months', \

                 0, 0, 2)
 ## end def

 
 def getCLarguments():
     """Get command line arguments.  There are three possible arguments
           -d turns on debug mode
           -v turns on verbose debug mode
           -t sets the sensor query interval
        Returns: nothing
     """
     global debugOption, verboseDebug, dataRequestInterval
 
     index = 1
     while index < len(sys.argv):
         if sys.argv[index] == '-d':
             debugOption = True
         elif sys.argv[index] == '-v':
             debugOption = True
             verboseDebug = True
         elif sys.argv[index] == '-p':
             try:
                 dataRequestInterval = abs(int(sys.argv[index + 1]))
             except:
                 print "invalid polling period"
                 exit(-1)
             index += 1
         else:
             cmd_name = sys.argv[0].split('/')
             print "Usage: %s [-d] [-v] [-p seconds]" % cmd_name[-1]
             exit(-1)
         index += 1
 ##end def
 
 def main():
     """Handles timing of events and acts as executive routine managing
        all other functions.
        Parameters: none
        Returns: nothing
     """
     global dataRequestInterval
 
     signal.signal(signal.SIGTERM, terminateAgentProcess)
 
     print '%s starting up node power agent process' % \
                   (getTimeStamp())
 
     # last time output JSON file updated
     lastDataRequestTime = -1
     # last time charts generated
     lastChartUpdateTime = - 1
     # last time the rrdtool database updated
     lastDatabaseUpdateTime = -1
 
     ## Get command line arguments.
     getCLarguments()
 
     ## Exit with error if rrdtool database does not exist.
     if not os.path.exists(_RRD_FILE):
         print 'rrdtool database does not exist\n' \
               'use createArednsigRrd script to ' \
               'create rrdtool database\n'
         exit(1)
  
     ## main loop
     while True:
 
         currentTime = time.time() # get current time in seconds
 
         # Every web update interval request data from the aredn
         # node and process the received data.
         if currentTime - lastDataRequestTime > dataRequestInterval:
             lastDataRequestTime = currentTime
             dData = {}
             result = True
 
             # Get the data from the sensors.
             result =getSensorData(dData)
  
             # If get data successful, write data to data files.
             if result:
                 result = writeOutputDataFile(dData)

                 pass

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

                     pass

 
         # At the chart generation interval, generate charts.
         if currentTime - lastChartUpdateTime > chartUpdateInterval:
             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 debugOption:
             if result:
                 print "%s update successful:" % getTimeStamp(),
             else:
                 print "%s update failed:" % getTimeStamp(),
             print "%6f seconds processing time\n" % elapsedTime 
         remainingTime = dataRequestInterval - elapsedTime
         if remainingTime > 0.0:
             time.sleep(remainingTime)
     ## end while
     return
 ## end def
 
 if __name__ == '__main__':
     try:
         main()
     except KeyboardInterrupt:
         print '\n',
         terminateAgentProcess('KeyboardInterrupt','Module')