import math
import datetime
import time

class Sun:

    def getSunriseTime( self, coords ):
        return self.calcSunTime( coords, True )

    def getSunsetTime( self, coords ):
        return self.calcSunTime( coords, False )

    def getCurrentUTC( self ):
        now = datetime.datetime.now()
        return [ now.day, now.month, now.year ]

    def calcSunTime( self, coords, isRiseTime, zenith = 90.8 ):

        # isRiseTime == False, returns sunsetTime

        day, month, year = self.getCurrentUTC()

        longitude = coords['longitude']
        latitude = coords['latitude']

        TO_RAD = math.pi/180

        #1. first calculate the day of the year
        N1 = math.floor(275 * month / 9)
        N2 = math.floor((month + 9) / 12)
        N3 = (1 + math.floor((year - 4 * math.floor(year / 4) + 2) / 3))
        N = N1 - (N2 * N3) + day - 30

        #2. convert the longitude to hour value and calculate an approximate time
        lngHour = longitude / 15

        if isRiseTime:
            t = N + ((6 - lngHour) / 24)
        else: #sunset
            t = N + ((18 - lngHour) / 24)

        #3. calculate the Sun's mean anomaly
        M = (0.9856 * t) - 3.289

        #4. calculate the Sun's true longitude
        L = M + (1.916 * math.sin(TO_RAD*M)) + (0.020 * math.sin(TO_RAD * 2 * M)) + 282.634
        L = self.forceRange( L, 360 ) #NOTE: L adjusted into the range [0,360)

        #5a. calculate the Sun's right ascension

        RA = (1/TO_RAD) * math.atan(0.91764 * math.tan(TO_RAD*L))
        RA = self.forceRange( RA, 360 ) #NOTE: RA adjusted into the range [0,360)

        #5b. right ascension value needs to be in the same quadrant as L
        Lquadrant  = (math.floor( L/90)) * 90
        RAquadrant = (math.floor(RA/90)) * 90
        RA = RA + (Lquadrant - RAquadrant)

        #5c. right ascension value needs to be converted into hours
        RA = RA / 15

        #6. calculate the Sun's declination
        sinDec = 0.39782 * math.sin(TO_RAD*L)
        cosDec = math.cos(math.asin(sinDec))

        #7a. calculate the Sun's local hour angle
        cosH = (math.cos(TO_RAD*zenith) - (sinDec * math.sin(TO_RAD*latitude))) / (cosDec * math.cos(TO_RAD*latitude))

        if cosH > 1:
            return {'status': False, 'msg': 'the sun never rises on this location (on the specified date)'}

        if cosH < -1:
            return {'status': False, 'msg': 'the sun never sets on this location (on the specified date)'}

        #7b. finish calculating H and convert into hours

        if isRiseTime:
            H = 360 - (1/TO_RAD) * math.acos(cosH)
        else: #setting
            H = (1/TO_RAD) * math.acos(cosH)

        H = H / 15

        #8. calculate local mean time of rising/setting
        T = H + RA - (0.06571 * t) - 6.622

        #9. adjust back to UTC
        UT = T - lngHour
        UT = self.forceRange( UT, 24) # UTC time in decimal format (e.g. 23.23)

        #10. Return
        hr = self.forceRange(int(UT), 24)
        min = round((UT - int(UT))*60,0)

        def convert_unix_time(datetime_obj):
            return int(time.mktime(datetime_obj.timetuple()))

        unixtime = convert_unix_time(datetime.datetime(int(year), int(month), int(day), int(hr), int(min), int(0)))

        return {
            'status': True,
            'decimal': UT,
            'hr': hr,
            'min': min,
            'unixtime': unixtime
        }

    def forceRange( self, v, max ):
        # force v to be >= 0 and < max
        if v < 0:
            return v + max
        elif v >= max:
            return v - max

        return v

--- timelit.sh.orig	2020-09-17 22:45:55.414873702 +0000
+++ timelit.sh	2020-09-17 22:45:37.886601266 +0000
@@ -1,11 +1,19 @@
 #!/bin/bash

+cd "$(dirname "$0")"
+
 # if the Kindle is not being used as clock, then just quit
 test -f /mnt/us/timelit/clockisticking || exit

+# my latitude and longitude
+lat=35.8034315
+lng=139.4275599
+offset=+9
+dark_mode='Auto'

 # find the current minute of the day
-MinuteOTheDay="$(env TZ=CEST date -R +"%H%M")";
+#MinuteOTheDay="$(env TZ=CEST date -R +"%H%M")";
+MinuteOTheDay="$(env TZ=GMT-9 date -R +"%H%M")";

 # check if there is at least one image for this minute
 lines="$(find /mnt/us/timelit/images/quote_$MinuteOTheDay* 2>/dev/null | wc -l)"
@@ -16,9 +24,40 @@
 	echo $lines' files found for '$MinuteOTheDay
 fi

+exec_dark_mode() {
+    t_sunrise=$(python -c "from Sun import Sun; coords = {'longitude' : $lng, 'latitude' : $lat }; sun = Sun(); print sun.getSunriseTime( coords )['unixtime']")
+    t_sunset=$(python -c "from Sun import Sun; coords = {'longitude' : $lng, 'latitude' : $lat }; sun = Sun(); print sun.getSunsetTime( coords )['unixtime']")
+    t_now=$(date '+%s')
+
+    [ "$t_sunrise" -gt "$t_sunset" ] && t_sunrise=$(( $t_sunrise - 86400 ))
+
+    t_sunrise=$(( ($t_sunrise + $offset * 3600) % 86400 ))
+    t_sunset=$(( ($t_sunset + $offset * 3600) % 86400 ))
+    t_now=$(( ($t_now + $offset * 3600) % 86400 ))
+
+    if [ "$t_now" -lt "$t_sunrise" ] || [ "$t_now" -gt "$t_sunset" ]; then
+        mode='dark_mode/'
+    else
+        mode=''
+    fi
+}
+
+case "$dark_mode" in
+    "Auto")
+        exec_dark_mode
+        ;;
+    "True")
+        mode='dark_mode/'
+        ;;
+    *)
+        mode=''
+        ;;
+esac
+

 # randomly pick a png file for that minute (since we have multiple for some minutes)
-ThisMinuteImage=$( find /mnt/us/timelit/images/quote_$MinuteOTheDay* 2>/dev/null | python -c "import sys; import random; print(''.join(random.sample(sys.stdin.readlines(), int(sys.argv[1]))).rstrip())" 1)
+#ThisMinuteImage=$( find /mnt/us/timelit/images/quote_$MinuteOTheDay* 2>/dev/null | python -c "import sys; import random; print(''.join(random.sample(sys.stdin.readlines(), int(sys.argv[1]))).rstrip())" 1)
+ThisMinuteImage=$( find /mnt/us/timelit/images/${mode}quote_$MinuteOTheDay* 2>/dev/null | python -c "import sys; import random; print ''.join(random.sample(sys.stdin.readlines(), int(sys.argv[1]))).rstrip()" 1)

 echo $ThisMinuteImage > /mnt/us/timelit/clockisticking

mkdir /mnt/us/timelit/images/dark_mode
cd /mnt/us/timelit/images/dark_mode

#!/bin/sh

ls ../*.png |while read f; do
    echo -n "- converting ${f#../}:"
    convert -size 600x800 -background white -depth 8 -negate "$f" "${f#../}"
    pngcrush -s -c 0 -ow "${f#../}"
    echo " result $?"
done