#!/usr/bin/env bash

if [ -z "$1" ] || [ -z "$2" ] || [[ $2 != "encode" && $2 != "decode" ]]
	then echo "launch the script with the desired filename and operation"
	echo "./AmazonPrimeWhatever.sh FILENAME OPERATION(encode or decode)"
	exit
fi




if [ $2 = "encode" ]; then
	imagejpg="random.jpg"
	image="random.DNG"
	#generate random image:
	mx=320;my=256;head -c "$((3*mx*my))" /dev/urandom | convert -depth 8 -size "${mx}x${my}" RGB:- $imagejpg
	mv $imagejpg $image
	imagesize=$(du -b $image | cut -f1)
	origsha=$(sha1sum $1 | cut -d " " -f1)
	destimage="FakeKitten_"$imagesize"_"$1"_"$origsha"_"$image
	mv $image $destimage
	dd if=$1 bs=1M >> "$destimage"
	echo "encode completed in $destimage"
fi

if [ $2 = "decode" ]; then
	imagebs=$(echo $1 | cut -d "_" -f2)
	origname=$(echo $1 | cut -d "_" -f3)
	origsha=$(echo $1 | cut -d "_" -f4)
	origimage=$(echo $1 | cut -d "_" -f5)
	dd if=$1 bs=1M skip=$imagebs iflag=skip_bytes > "$origname"
	echo "decode completed in $origimage, checking file integrity"
	echo $origsha"  "$origname > $origname".sha1"
	shaoutput=$(sha1sum -c $origname".sha1")
	echo $shaoutput
	if [[ $shaoutput != *"OK"* ]]; then
		echo ""
		echo "!!! FAILED SHA VERIFICATION!!! EXITING"
		echo "!!! DELETING ALL CREATED FILES !!!"
		rm $origname
		rm $origname".sha1"
		exit
	fi
	rm $origname".sha1"
fi


echo ""
echo "end of my job"