MotionEyeOS Day and Night Python script

See also:

• Calculation of sunrise and sunset

Source:

• https://blog.ligos.net/2016-04-18/Day-Night-Cycle-For-MotionEye.html

Setup crontab to execute the script (here every 10 minutes)

crontab -e

  02,12,22,32,42,52 * * * * /usr/bin/python /data/etc/daynight/daynight.py >> /data/log/daynight.log

Setup logrotate to limit the size of the logfile.

Script

nano /data/etc/daynight/daynight.py

from math import cos,sin,acos,asin,tan
from math import degrees as deg, radians as rad
from datetime import date,datetime,time
from pytz import timezone
import os
import os.path
import shutil
import time as time2

# Variant of time zone available on MotionEyeOS
localTimezone = timezone('Europe/Amsterdam')

# Location of here in lat / long
localLat = 51.49
localLong = 5.48

# Sunrise and sunset delay (in minutes)
# + is later, - is earlier.
sunriseDelayMins = -10
sunsetDelayMins = +10

# Current state of day / night is stored in this file.
dayNightStateFile = '/data/etc/daynight/daynight.dat'

# sun module
class sun:
 """ 
 Calculate sunrise and sunset based on equations from NOAA
 http://www.srrb.noaa.gov/highlights/sunrise/calcdetails.html
 """
 def __init__(self,lat=52.37,long=4.90,when=None):
  """
  default Amsterdam + local time zone
  (including daylight saving if present)
  """
  self.lat=lat
  self.long=long
  if when is None : when = datetime.now(tz=localTimezone)
  self.__preptime(when)
  self.__calc()
   
 """
 The two fudge factors are in minutes. Negative is earlier. 
 """
 def dayornight(self,now=None,sunriseFudge=0,sunsetFudge=0):
  if now is None : now = datetime.now(tz=localTimezone)
  self.__preptime(when=now)
  self.__calc()
  sunriseFudge = sunriseFudge/60.0/24.0
  sunsetFudge = sunsetFudge/60.0/24.0
  if (self.time >= (self.sunrise_t + sunriseFudge) and self.time <= (self.sunset_t + sunsetFudge)):
   return 'day'
  else:
   return 'night'
  
 @staticmethod
 def timefromdecimalday(day):
  """
  returns a datetime.time object.
  day is a decimal day between 0.0 and 1.0, e.g. noon = 0.5
  """
  hours  = 24.0*day
  h      = int(hours)
  minutes= (hours-h)*60
  m      = int(minutes)
  seconds= (minutes-m)*60
  s      = int(seconds)
  return time(hour=h,minute=m,second=s)

 def __preptime(self,when):
  """
  Extract information in a suitable format from when, 
  a datetime.datetime object.
  """
  self.day = when.toordinal()-(734124-40529)
  t=when.time()
  self.time= (t.hour + t.minute/60.0 + t.second/3600.0)/24.0
  
  self.timezone=0
  offset=when.utcoffset()
  if not offset is None:
   self.timezone=offset.seconds/3600.0
  
 def __calc(self):
  """
  Perform the actual calculations for sunrise, sunset and
  a number of related quantities.   
  The results are stored in the instance variables
  sunrise_t, sunset_t and solarnoon_t
  """
  timezone = self.timezone # in hours, east is positive
  longitude= self.long     # in decimal degrees, east is positive
  latitude = self.lat      # in decimal degrees, north is positive

  time     = self.time    # percentage past midnight, i.e. noon  is 0.5
  day      = self.day     # daynumber 1=1/1/1900
 
  Jday     = day+2415018.5+time-timezone/24 # Julian day
  Jcent    = (Jday-2451545)/36525           # Julian century

  Manom    = 357.52911+Jcent*(35999.05029-0.0001537*Jcent)
  Mlong    = 280.46646+Jcent*(36000.76983+Jcent*0.0003032)%360
  Eccent   = 0.016708634-Jcent*(0.000042037+0.0001537*Jcent)
  Mobliq   = 23+(26+((21.448-Jcent*(46.815+Jcent*(0.00059-Jcent*0.001813))))/60)/60
  obliq    = Mobliq+0.00256*cos(rad(125.04-1934.136*Jcent))
  vary     = tan(rad(obliq/2))*tan(rad(obliq/2))
  Seqcent  = sin(rad(Manom))*(1.914602-Jcent*(0.004817+0.000014*Jcent))+sin(rad(2*Manom))*(0.019993-0.000101*Jcent)+sin(rad(3*Manom))*0.000289
  Struelong= Mlong+Seqcent
  Sapplong = Struelong-0.00569-0.00478*sin(rad(125.04-1934.136*Jcent))
  declination = deg(asin(sin(rad(obliq))*sin(rad(Sapplong))))
  
  eqtime   = 4*deg(vary*sin(2*rad(Mlong))-2*Eccent*sin(rad(Manom))+4*Eccent*vary*sin(rad(Manom))*cos(2*rad(Mlong))-0.5*vary*vary*sin(4*rad(Mlong))-1.25*Eccent*Eccent*sin(2*rad(Manom)))

  hourangle= deg(acos(cos(rad(90.833))/(cos(rad(latitude))*cos(rad(declination)))-tan(rad(latitude))*tan(rad(declination))))

  self.solarnoon_t=(720-4*longitude-eqtime+timezone*60)/1440
  self.sunrise_t  =self.solarnoon_t-hourangle*4/1440
  self.sunset_t   =self.solarnoon_t+hourangle*4/1440

def readLineOfFile(path):
 if not os.path.isfile(path): return ""
 f = open(path, "r")
 result = f.readline()
 f.close()
 return result.rstrip()
 
def updateContentsOfFile(path, data):
 f = open(path, "w")
 f.write(data)
 f.close()

# The main program
if __name__ == "__main__":
 
 # Calculate
 s=sun(lat=localLat,long=localLong)
 
 # Previous day/night -state from file.
 fileDayOrNight = readLineOfFile(dayNightStateFile)
 
 # Log
 print(datetime.now().strftime('%Y-%m-%d_%H.%M.%S ') 
  + 'Day from ' + sun.timefromdecimalday(s.sunrise_t).strftime('%H.%M') + ['(', '(+'][sunriseDelayMins > 0] + str(sunriseDelayMins)+')'
  + ' to ' + sun.timefromdecimalday(s.sunset_t).strftime('%H.%M') + ['(', '(+'][sunsetDelayMins > 0] + str(sunsetDelayMins)+')'
  + ', current state: ' + fileDayOrNight
  )
 
 # Current day/night -state based on time-of-day.
 currentDayOrNight = s.dayornight(sunriseFudge=sunriseDelayMins,sunsetFudge=sunsetDelayMins)

 # New day/night -state?
 if fileDayOrNight != currentDayOrNight:
  print(datetime.now().strftime('%Y-%m-%d_%H:%M:%S ') + 'Changing state to: ' + currentDayOrNight)
  
  # Backup the old settings if the selected config is newer  
  if os.stat("/data/etc/thread-1.conf").st_mtime > os.stat("/data/etc/thread-1.conf." + fileDayOrNight).st_mtime:
    # Backup old day/night settings file
    shutil.copy2("/data/etc/thread-1.conf." + fileDayOrNight
      , "/data/etc/thread-1.conf." + fileDayOrNight + "." + datetime.now().strftime('%Y-%m-%d_%H.%M'))
    # Store new day/night settings file
    shutil.copy2("/data/etc/thread-1.conf", "/data/etc/thread-1.conf." + fileDayOrNight)

  # Select the other day/night settings file
  shutil.copy2("/data/etc/thread-1.conf." + currentDayOrNight, "/data/etc/thread-1.conf")

  # Restart MotionEye
  print(datetime.now().strftime('%Y-%m-%d_%H:%M:%S ') + 'Stop MotionEye...')
  os.system("/etc/init.d/S85motioneye stop")
  time2.sleep(10)
  print(datetime.now().strftime('%Y-%m-%d_%H:%M:%S ') + 'Start MotionEye...')
  os.system("/etc/init.d/S85motioneye start")  
  print(datetime.now().strftime('%Y-%m-%d_%H:%M:%S ') + 'MotionEye Started.')
  
  # Update day/night -state file
  updateContentsOfFile(dayNightStateFile, currentDayOrNight)