#!/bin/sh
# Detekce blesku pobliz zadaneho lokatoru
# ./blesk.sh [locator] [km]
# zavislosti: maiden2lonlat (http://jidanni.org/geo/maidenhead/)
#             zero.png - obrazek s nulovym vyskytem blesku
#########################################
# rozliseni obrazku 2km/px
#
# okraje OK
# 12.09 <---> 18.85E (6.76)
# 51.05N
#   |
# 48.55N (2.5)
# 
# 43 <---> 287px (244) = 0.0277/px
# 151
#  |
# 291px (140) = 0.0178/px
#########################################

locator=$1   # qth locator
km=$2        # polomer sledovane oblasti v km

# prevod lokatoru na souradnice
E=$(echo $locator | ./maiden2lonlat | cut -d " " -f 1)
N=$(echo $locator | ./maiden2lonlat | cut -d " " -f 2)

# prevod souradnic na pixely
qthx=$(echo "($E - 12.09) / 0.0277 + 43" | bc)
qthy=$(echo "(291 - (($N - 48.55) / 0.0178))" | bc)
cutx=$(echo "$qthx - ($km/2)" | bc )
cuty=$(echo "$qthy - ($km/2)" | bc )

# stazeni aktualniho snimku
wget -q -O /tmp/aktual.png http://www.chmi.cz/meteo/rad/blesk/data-png/aktual.png

# existuje soubor (podarilo se ho stahnout?)
if [ -e /tmp/aktual.png ]
then

# vyrez okoli qth
convert /tmp/aktual.png -crop $km\x$km+$cutx+$cuty /tmp/qth.png
convert zero.png -crop $km\x$km+$cutx+$cuty /tmp/qth_zero.png

# podarilo se soubor oriznout?
if [ -e /tmp/qth.png ]
then

# kontrolni soucet vyrezu
sum=$(md5sum /tmp/qth.png | cut -d " " -f1)
sumzero=$(md5sum /tmp/qth_zero.png | cut -d " " -f1)

# porovnani souctu s 'nulovym' kontrolnim souctem
if [ $sum = $sumzero ]
	then
	echo "V okruhu $km km od $locator detekce blesku negativni"
	rm /tmp/qth.png
	rm /tmp/aktual.png
	rm /tmp/qth_zero.png
	exit 0
fi

echo "V okruhu $km km od $locator BLESKY! $(date -u +%F-%H%M)"

# archivace
cp /tmp/aktual.png /tmp/$(date -u +%F-%H%M).png
cp /tmp/qth.png /tmp/$(date -u +%F-%H%M)_qth.png

rm /tmp/qth.png
rm /tmp/aktual.png
rm /tmp/qth_zero.png
exit 0

fi
echo "soubor se nepodarilo oriznout"
exit 0

fi
echo "soubor se nepodarilo stahnout"
exit 0