#!/bin/bash

function recomp {
    ofn="$1"
    if [ -f "$ofn" ] ; then
        nfn="${ofn/.jpg/.$$.jpg}"
        if [ -f "$nfn" ] ; then
           rm "$nfn"
        fi

        convert -verbose -quality 93 "$ofn" "$nfn"

        if [ -f "$nfn" ] ; then
            osize=$(wc -c "$ofn" | cut -f1 -d' ')
            nsize=$(wc -c "$nfn" | cut -f1 -d' ')
            let ratio="($nsize * 100) / $osize"

            echo "Recompress of $ofn:" >> /dev/stderr
            if [ $ratio -lt 33 ] ; then
                echo "Dubious result: $osize -> $nsize = $ratio%), check $nfn." >> /dev/stderr
            elif [ $ratio -lt 66 ] ; then
                echo "Recompress usefull ($osize -> $nsize = $ratio%)" >> /dev/stderr
                rm "$ofn"
                mv "$nfn" "$ofn"
            else
                echo "Recompress useless ($osize -> $nsize = $ratio%)" >> /dev/stderr
                rm "$nfn"
            fi
        else
            echo "Could not convert $ofn in $nfn."
        fi
    else
        echo "Original $ofn not found."
    fi
}

if [ "$1" = "-" -o -z "$1" ] ; then
    while true ; do
	read f
	if [ -z "$f" ] ; then 
            break
        fi
	recomp "$f"
    done
else
    while [ "$1" ] ; do
	recomp "$1"
	shift
    done
fi