#!/bin/bash

# valore alto significa sensibilita' alta
LIMITE=22
# qualita' jpeg
JPEG_Q="60%"
# messaggio vocale di uscita prematura
MSG_USCITA="stop"
# messaggio vocale di allarme
MSG_ALLARME="allarrme"

# nome foto significativa precedente
fname_0=""
# nome foto appena scattata
fname_1=""

echo Partenza tra 30 secondi...
sleep 30

while true; do

	fname_1="webcam_$(date +%Y%m%d-%H%M%S).png"
	echo "foto $fname_1"
	fswebcam -q -r 640x480 -D 1 --no-banner --png 9 $fname_1
	if [ -n "$fname_0" ]; then
		DIFFERENZA=$(compare -metric PSNR $fname_0 $fname_1 null: 2>&1 | cut -d "." -f 1)
		echo "    diff=$DIFFERENZA"
		if [ $LIMITE -gt $DIFFERENZA ]; then
			echo "    DIFFERENZA tra $fname_0 e $fname_1"
			#espeak -v it+f5 "$MSG_ALLARME" &
			convert -quality $JPEG_Q $fname_0 $fname_0.jpg
			rm $fname_0
			fname_0=$fname_1
		else
			rm $fname_1
			echo "    no diff"
		fi
	else
		fname_0=$fname_1
	fi
	if [ -f "stop" ]; then
		echo "uscita forzata"
		rm stop
		sleep 1;
		espeak "$MSG_USCITA"
		break
	fi

done

# converte l'ultima immagine
if [ -f "$fname_1" ]; then
	convert -quality $JPEG_Q $fname_1 $fname_1.jpg
	rm $fname_1
fi
if [ -f "$fname_0" ]; then
	convert -quality $JPEG_Q $fname_0 $fname_0.jpg
	rm $fname_0
fi