#debug
#set -x

#Which battery should be tested. Usualy it's BAT0, but hey, not in my computer...
battery="BAT1"

#Where should the log be created?
logfile=~/battery_log-`date '+%Y.%m.%d-%R'`

#how long should the logging endure?
logging_time_in_minutes=30

#how many seconds should lay between two measurements?
logging_interval_in_seconds=5 

#####################################

file=$logfile.txt
picture=$logfile.png

times_to_log=$(($logging_time_in_minutes * 60 / $logging_interval_in_seconds ))

#max and min power (for the gnuplot range)
maxpower="0"
minpower="10000000"

#starting the logfile. Let there ligh... a date/time combination
echo `date` >> $file

#with an sleep onb 5 seconds, a count to 360 is exactly half an hour
while [[ $count -lt $times_to_log ]]; do

#ampere is the value of electric charge. measured in milliampere
ampere=`grep rate /proc/acpi/battery/$battery/state | cut -f14 -d" "`

#voltage is the vlaue of the current. measured in millivolt
voltage=`grep voltage /proc/acpi/battery/$battery/state | cut -f11 -d" "`

#power is the multiplication of ampere and voltage, measured in microwatt
power=$(( $ampere * $voltage))
#set maxpower
if [[ $power -gt $maxpower ]]; then
  maxpower=$power
fi

#set minpower
if [[ $power -lt $minpower ]]; then
  minpower=$power
fi

#echo $ampere \* $voltage = $power
echo $power >> $file
(( count += 1 ))

sleep 5
done
#again a date
echo `date` >> $file


echo minpower ist $minpower
echo maxpower ist $maxpower

##################
#gnuplot
gnuplot <<EOF 
row=0
set yrange[$minpower/1000:$maxpower/1000]
set xrange[0:$count]
set term png size 800,600
set output "$picture"
set grid
plot "$file" using (row,row=row+1):(\$1/1000) title 'Milliwatt' with lines
EOF