#!/bin/sh
set -e # exit on failure
IFS=$(printf '\n\t') # smarter ifs

error() {
    echo "$@" >&2
    exit 1
}

help() {
    echo "Usage: wallmanip [options...]"
    echo '*defaults*: -a PAD -p CENTER -r 16:9'
    echo "  -a, --action            One of {blurpad, crop, pad, reflect}"
    echo "  -f, --filename          Specify file. Switch can be omitted."
    echo "  -p, --position          One of {top, bottom, left, right}"
    echo "  -r, --ratio             Specify aspect ratio, as W:H (e.g. 16:9)"
    echo "  -s, --scale             Specify output resolution, as WxH (e.g. 1920x1080)"

    echo "  -h, --help              Print this help text"
    echo "  -v, --version           Print the wallmanip version"
    exit
}

{ # block to initially set config vars
    ACTION=PAD
    FILE=''
    POS=CENTER

    RATIOW=16
    RATIOH=9

    RESIZE=0
    SCALEW=1920
    SCALEH=1080
}

# handle symlink names
case "$(basename "$0")" in
    blurborder ) 
        ACTION=BLURPAD
        ;;
    croptop )
        ACTION=CROP
        POS=TOP
        ;;
    padjpeg ) ;;
esac

while [ $# -gt 0 ]; do
    case "$1" in
        -a | --action )
            ACTION=$(echo "$2" | tr "[:lower:]" "[:upper:]")
            shift 2 ;;
        -p | --position )
            POS=$(echo "$2" | tr "[:lower:]" "[:upper:]")
            shift 2 ;;
        -r | --ratio )
            RATIOW=$(echo "$2" | cut -d: -f1)
            RATIOH=$(echo "$2" | cut -d: -f2)
            shift 2 ;;
        -s | --scale )
            RESIZE=1
            SCALEW=$(echo "$2" | cut -dx -f1)
            SCALEH=$(echo "$2" | cut -dx -f2)
            shift 2 ;;
        --resize )
            RESIZE=1
            shift ;;
        --version | -v )
            printf '\e[32m'
            echo 'wallmanip 2024.05.11'
            printf '\e[36m'
            echo Built by July 🏳️‍🌈
            printf '\e[0m'
            exit ;;
        -h | --help)
            help ;;
        -f | --filename)
            shift;;
        *)
            [ "$FILE" != '' ] && help # give helptext if already set
            FILE=$1
            shift 1 ;;
    esac
done

{ # initial error/sanity checking blocking
    test -f "$FILE" || error Invalid/missing filename
    identify -format '' "$FILE" || error File is not an image

    case "$ACTION" in
        BLURPAD | CROP | SCALE | PAD | REFLECT) ;;
        *) error Invalid action ;;
    esac

    case "$POS" in
        BOTTOM | CENTER | LEFT | RIGHT | TOP ) ;;
        *) error Invalid position ;;
    esac

    for i in "$RATIOW" "$RATIOH" "$SCALEW" "$SCALEH"; do
        if [ -n "$i" ] && [ "$i" -eq "$i" ]; then
            continue
        fi
        error Invalid numerical argument
    done
}

divide() { # helper for precise division
    printf '3k %s %s /p' "$1" "$2" | dc
}
truncate() { # specify truncation of floats where desired
    cut -d. -f1
}

{ # build image information
    img_height=$(identify -format %h "$FILE")
    img_width=$(identify -format %w "$FILE")

    des_ratio=$(divide "$RATIOW" "$RATIOH")
    img_ratio=$(divide "$img_width" "$img_height")
    wide="$(echo "$img_ratio > $des_ratio" | bc )"

    jpg="$(file -bi "$FILE" | grep -q '^image/jpeg' && echo 1 || echo 0)"
    jxl="$(file -bi "$FILE" | grep -q '^image/jxl'  && echo 1 || echo 0)"

    out="$(dirname "$FILE")/tran_$(basename "$FILE")"
    work=$(mktemp)
}

{ # build working jpeg file, for as needed
    if [ "$jxl" -eq 1 ]; then 
        djxl "$FILE" "$work" --output_format jpg
    elif [ "$jpg" -eq 1 ]; then
        cp "$FILE" "$work"
    else
        cjpegli "$FILE" "$work"
    fi

    if [ "$wide" -eq 1 ] && [ "$ACTION" != CROP ]; then
        jpegtran -rotate 90 -outfile "$work" "$work"
        img_height=$(identify -format %h "$work")
        img_width=$(identify -format %w "$work")
        des_ratio=$(divide 1 "$des_ratio")
    fi
}

border() {
    border=$(mktemp)
    backdrop=$(mktemp)
    des_width=$(echo "$des_ratio * $img_height" | bc | truncate)
    gravity=center
    convert "$work" -bordercolor black -border 10x0 PPM:"$border"
    convert "$work" -blur 0x7 -resize "$des_width"x PPM:"$backdrop"
    composite -gravity $gravity "$border" "$backdrop" PPM:"$backdrop"
    convert -gravity center -crop "x$img_height+0" "$backdrop" JPEG:"$work"
    rm -f "$border" "$backdrop"
}

crop() {
    des_height=$(divide "$img_width" "$des_ratio" | truncate) 
    offset=$(echo "$img_height - $des_height" | bc)
    case $POS in
        LEFT | TOP ) offset=0 ;;
        CENTER ) offset=$(echo "$offset / 2" | bc) ;;
        RIGHT | BOTTOM ) ;;
    esac
    jpegtran -crop "$img_width"x"$des_height"+0+"$offset" -outfile "$work" "$work"
}

pad() {
    des_width=$(echo "$des_ratio * $img_height" | bc | truncate)
    offset=$(echo "$des_width - $img_width" | bc)
    case $POS in
        LEFT | BOTTOM ) offset=0 ;;
        CENTER ) offset=$(echo "$offset / 2" | bc) ;;
        RIGHT | TOP ) ;;
    esac
    jpegtran -crop "$des_width$1+$offset" -outfile "$work" "$work"
}

case "$ACTION" in
    BLURPAD )
        border ;;
    CROP )
        crop ;;
    REFLECT )
        pad r;;
    PAD )
        pad f;;
esac

{ # transfer back to output file
    if [ "$wide" -eq 1 ] && [ "$ACTION" != CROP ]; then
        jpegtran -rotate 270 -outfile "$work" "$work"
    fi
    if [ "$RESIZE" -eq 1 ]; then
        ffmpeg -i "$work" -vf zscale="$SCALEW":"$SCALEH":filter=spline36 -vcodec ppm -f image2pipe - | convert - JPEG:"$work"
    fi

    if [ "$jxl" -eq 1 ]; then 
        cjxl "$work" "$out"
    elif [ "$jpg" -eq 1 ]; then
        cp "$work" "$out"
    else
        djpegli "$work" "$out"
    fi
}

rm "$work" -f