#!/usr/bin/env bash

# compressJPG.sh: compress a JPG with mozjpeg if the savings are worthwhile.
# Author: Gwern Branwen
# Date: 2020-02-07
# When:  Time-stamp: "2026-02-05 22:48:02 gwern"
# License: CC-0

set -e

## Inlining for portability
# shellcheck source=./bash.sh
# . ~/wiki/static/build/bash.sh # for 'get_image_files', 'green', 'red'
red  () { echo -e "\e[41m$@\e[0m"; }
green () { echo -e "\e[32m$@\e[0m"; }
get_image_files () {
    mapfile -t "$1" < <(find . -maxdepth 1 -type f \
                             \( -iname "*.jpg" -o -iname "*.jpeg" \) \
                            | sort --version-sort)
}

args=("$@")
if [ ${#args[@]} -eq 0 ]; then
    get_image_files args
    green "Attempting to use implied arguments: ${args[@]}"
fi

if [ ${#args[@]} -eq 0 ]; then
    red "Error: no arguments available!"; exit 1
else
    command -v jpegtran > /dev/null
    command -v mogrify > /dev/null

    for FILE in "${args[@]}"; do
        JPG_OLD="$(mktemp /tmp/XXXXXX-original.jpg)"
        TMP_NEW="$(mktemp /tmp/XXXXXX-temp.jpg)"
        cp "$FILE" "$JPG_OLD"
        jpegtran -copy none -progressive -optimize -outfile "$TMP_NEW" "$JPG_OLD"
        mogrify -quality 60 "$TMP_NEW"
        ORIGINAL=$(wc -c < "$JPG_OLD") # NOTE: '-c' instead of '--bytes' for portability
        SMALL=$(wc -c < "$TMP_NEW")
        RATIO=$(echo "$ORIGINAL / $SMALL" | bc --mathlib)
        echo "$FILE : from $ORIGINAL to $SMALL ($RATIO)"
        if (( $(echo "$RATIO > 1.2" | bc --mathlib) )); then
            mv "$TMP_NEW" "$FILE"
        else
            green "(Not updating $FILE because savings insufficient.)"
        fi
        rm --force "$JPG_OLD" "$TMP_NEW"
    done
fi