#!/usr/bin/env bash

# A simple script that losslessly optimizes image files given to it.
#
# Examples:
#   imgoptim image.jpg image.png image.gif
#   imgoptim directory_of_images/
#   imgoptim directory_of_images/*.png
#
# Requires:
#   PNGs: optipng, pngquant (lossy)
#   JPGs: jpegtran, jpegoptim (lossy)
#   GIFs: gifsicle

set -e

LOSSY=

usage() {
    cat <<EOL
Usage: ${0##*/} [-lh] IMAGE [IMAGE2 [IMAGE3 [...]]]

    -l    enable lossy compression
    -h    this help
EOL
}

while getopts hl opt; do
    case $opt in
        h) usage; exit;;
        l) LOSSY=1;;
        :) >&2 echo "$OPTARG requires an argument"; usage; exit 1;;
        *) >&2 echo "Not a valid arg: $opt"; usage; exit 1;;
    esac
done
shift $((OPTIND-1))

_filesize() {
    case $OSTYPE in
        darwin*) stat -c%s "$1" ;;
        *) stat --printf="%s" "$1" ;;
    esac
}

for file in $@; do
    if [[ -d $file ]]; then
        imgoptim $file/*
    elif [[ -f $file ]]; then
        pre_size=$(_filesize "$file")
        case ${file##*.} in
            png)
                [[ $LOSSY ]] && pngquant $file
                optipng -nc -nb -o7 $file
                ;;
            gif)
                gifsicle --batch --optimize=3 "$file"
                ;;
            jpg|jpeg)
                [[ $LOSSY ]] && jpegoptim --max=90 "$file"
                jpegtran -copy none -optimize -progressive -outfile "$file" "$file"
                ;;
            *)  printf "Unrecognized file '$file': ignored"
                ;;
        esac
        post_size=$(_filesize "$file")
        perc=$(echo "((${pre_size} - ${post_size}) / ${pre_size}) * 100" | bc -l)
        printf "* %s: %d => %d (%.2f%% reduction)\n" "$file" "${pre_size}" "${post_size}" "$perc"
    fi
done