#!/bin/bash

# compressJPG2.sh: compress a JPG with mozjpeg if the savings are worthwhile.
# Author: Gwern Branwen
# Date: 2020-02-07
# When:  Time-stamp: "2023-02-13 17:55:22 gwern"
# License: CC-0

set -e

if [ $# -eq 0 ]; then
    exit 0;
else
    JPG="$(mktemp /tmp/XXXXXX-original.jpg)";
    TMP="$(mktemp /tmp/XXXXXX-temp.jpg)"
    cp "$1" "$JPG"
    jpegtran -copy none -progressive -optimize -outfile "$TMP" "$JPG"
    mogrify -quality 60 "$TMP"

    ORIGINAL=$(wc -c < "$JPG")
    SMALL=$(wc -c < "$TMP")
    RATIO=$(echo "$ORIGINAL / $SMALL" | bc -l)
    echo "$1 : from $ORIGINAL to $SMALL ($RATIO)"

    if (( $(echo "$RATIO > 1.2" | bc -l) ));
    then
        mv "$TMP" "$1"
    fi
    rm "$JPG" "$TMP" &> /dev/null || true

    shift;
    compressJPG2 "$@";
fi