#!/bin/sh

if [ $# -ne 2 ]; then
	echo 'usage: tlapse.g1 <number-of-images> <seconds-between-images>'
	exit 0
fi

function tidy_exit ()
{
    sync
    echo 
    np=$(ls -1 tlapse.*.jpg | wc -l)
    pr=$[($a - $st + (($np - 1) / 2)) / ($np - 1)]
    sp=$(du -sc tlapse.*.jpg | grep -e total | tr '\t' ' ' | sed -e 's/ .*$//')
    ps=$[($sp + ($np / 2)) / $np]
    echo $np pictures taken, average $pr seconds apart and $ps Kbytes
    exit 0
}
trap tidy_exit SIGINT
trap tidy_exit SIGHUP

brem=$(grep /proc/acpi/battery/BAT0/state -e remaining | sed -e 's/^.* \([0-9]\+\) .*$/\1/')
cbs=$(gphoto2 --summary 2>&1 | grep -e 'Power status' | sed -e 's/^.*(//' | sed -e 's/)//')
echo $(date), PC Battery = $brem, Camera $cbs

i=1
n=$1
t=$2
b=$(date +%s)
st=0
while [ $i -le $n ]; do
    gphoto2 --capture-preview > /tmp/gphoto.out 2>&1
    if [ $? -ne 0 ]; then
	echo 
	cat /tmp/gphoto.out
	break
    fi
    iz=000000$i
    il=$(expr length $iz)
    iz=$(expr substr $iz $[$il - 5] 6)
    mv canon_preview.jpg tlapse.$iz.jpg
    brem=$(grep /proc/acpi/battery/BAT0/state -e remaining | sed -e 's/^.* \([0-9]\+\) .*$/\1/')
    cbs=$(gphoto2 --summary 2>&1 | grep -e 'Power status' | sed -e 's/^.*(//' | sed -e 's/)//')
    a=$(date +%s)
    if [ $st -eq 0 ]; then
	st=$a
	oldbrem=$brem
	echo -e -n \\r$i - $(date), PC Battery = $brem, Camera $cbs
    else
	brate=$[($oldbrem - $brem) * 60 / ($a - $st)]
	if [ $brate -gt 0 ]; then
	    ml=$[$brem / $brate]
	fi
	echo -e -n \\r$i - $(date), PC Battery = $brem "($brate/minute, $ml minutes left)", Camera $cbs
    fi
    i=$[$i + 1]
    if [ $t -gt $[$a - $b] -a $i -le $n ]; then
	echo powersave > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor 
	sleep $[$t - ($a - $b)]
	echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor 
    fi
    b=$(date +%s)
done
tidy_exit