#!/bin/bash

usage="\
Usage: $0 [-p PREFIX] [-s SUFFIX] [-e EXTENSION] [-g \"GEOMETRY\"] [-q QUALITY] [-v] image1 image2 image3 ...\n
Use ImageMagick's convert tool to reduce the size of a selection of image files.\n
\n
  Options:\n
  -p PREFIX\tAdd a prefix to output file name. Can be used to provide a \n
\t\tdifferent output folder.\n
  -s SUFFIX\tAppend a suffix to the file name, before the extension.\n
  -t\t\tReplace the filename with creation time from exif\n
  -g \"GEOMETRY\"\tSpecify a desired geometry. Default : \"1920x1080>\" \n
\t\t(see https://www.imagemagick.org/Magick++/Geometry.html\n
\t\tfor detailled doc)\n
  -e EXTENSION\tSpecify a file extension (recognized by Magick).\n
\t\tIf not specified, reuse orinal file's extension. \n
  -q QUALITY\tSet the jpeg compression rate in %. Default : 85\n
  -x\t\tStrip exif metadata. Default off\n
  -t\t\tUse exif creation time instead of original filename when renaming.\n
\t\tCan be used with -p and -s\n
  -S\t\tDeactivate JPEG sampling factor. First level of compression, very little \n
\t\tloss in quality. Default on (4:2:0)\n
  -m\t\tDeactivate median blurring of the image. This filter can smooth some of\n
\t\tthe noise with minimal loss in details. \n
\t\tBetter compression, with some loss of quality. Default on.\n
  -M SIZE\tSpecify the size of the median blurr (useful for fine-tuning text scans).\n
 \t\tDefault: 2\n
  -G\t\tApply gaussian blurr to the image. Smooths noise in background or low-light\n
\t\timages, but creates a loss of detail. \n
\t\tBest compression, most loss of quality. Default off\n
  -v\t\tMake verbose\n
  -P\t\tPrint progress (for use with zenity --progress)\n
  -h\t\tPrint this help and exit.\n"

if [[ $# == 0 ]] ; then echo -e $usage ; exit 0 ; fi

#Preset defaults
nopt=1
geom="1920x1080>"
qual="85"
ext="jpg"
verbose=false
sampling="-sampling-factor 4:2:0"
median="2x2-1-1"

while getopts p:s:g:q:M:e:xGmhSvPt option ; do
	case "${option}"
		in
		p) ((nopt+=2)) ; 
			prefix=${OPTARG}
			;;
		s) ((nopt+=2)) ; 
			suffix=${OPTARG}
			;;
		g) ((nopt+=2)) ; 
			geom=${OPTARG}
			;;
		q) ((nopt+=2)) ; 
			qual=${OPTARG}
			;;
		t) ((nopt+=1)) ; 
			time=true;
			;;
		e) ((nopt+=2)) ; 
			EXT=${OPTARG}
			;;
		v) ((nopt+=1)) ; 
			verbose=true;
			;;
		P) ((nopt+=1)) ; 
			progress=0;
			;;
		x) ((nopt+=1)) ; 
			exif=true;
			;;
		S) ((nopt+=1)) ; 
			unset sampling;
			;;
		G) ((nopt+=1)) ; 
			gaussian=true;
			;;
		m) ((nopt+=1)) ; 
			unset median
			;;
		M) ((nopt+=2)) ; 
			a=${OPTARG}
			b=$((a/2))
			median=$a\x$a-$b-$b
			echo $median
			unset a
			unset b
			;;
		h | -help) 
			echo -e $usage ; 
			exit 0
			;;
		*) 
			echo -e $usage ; 
			echo "Unreconized option: ${option} ${OPTARG}"
			exit 0
			;;
	esac
done

test $verbose == true && echo -e "Old file \t Old size \t Old res \t New res \t New size \t New file \t Compression"

for f in "${@:$nopt}" ; do
	
	test "$verbose" == true && status="$f \t $(ls -lh $f | cut -d " " -f 5) \t $(identify $f | rev | cut -d " " -f 7 | rev) \t " ; size=$(ls -l "$f" | cut -d " " -f 5)
	
	name="$(echo $f | rev | cut -d '.' -f 2- | rev)"
	ext="${EXT:-$(echo $f | rev | cut -d '.' -f 1 | rev)}"
	
	test "$time" && exif -m -t "DateTime" "$f" > /dev/null && name="$(exif -m -t "DateTime" $f | tr ": " ".-")" || echo "$f : no DateTime found in exif data. Using filename instead."

	nf="$prefix""$name""$suffix"."$ext"

	while test -e $nf ; do nf="$prefix""$name""$suffix"_$(((++i)))."$ext" ; done
	unset i
	
	((insize+=$(ls -l "$f" | cut -d " " -f 5)))
	
	convert \
		-auto-orient \
		-define jpeg:dct-method=float \
		$sampling \
		${median:+\-median $median} \
		-interlace Plane \
		${gaussian:+-gaussian-blur 0.1} \
		-colorspace RGB \
		-resize "$geom" \
		-quality "$qual" "$f" "$nf"; 

	test "$exif" = true && exif --remove --no-fixup -o $nf $nf > /dev/null 

	((outsize+=$(ls -l "$nf" | cut -d " " -f 5)))
	
	test $verbose == true && echo -e $status"$(identify "$nf" | rev | cut -d " " -f 7 | rev) \t $(ls -lh "$nf" | cut -d " " -f 5) \t "$nf" \t $((100*$(ls -l "$nf" | cut -d " " -f 5)/$size))% "
	
	test $progress && echo $(((++progress * 100 / $#)))
done

test $verbose == true && echo -e "Average compression : $((100*outsize/insize))%"