#!/usr/bin/env bash

set -euo pipefail

if [ "$#" -ne 3 ]; then
    echo "Usage: $0 <input image> <border size> <output name>"
    echo "Example: $0 hoodie.png 16 hoodie_border.png"
    exit 1
fi

INPUT="$1"
BORDER_SIZE="$2"
OUTPUT="$3"

EXTENT_SIZE=$((BORDER_SIZE * 2))

magick "$INPUT" \
    -gravity center -background none -extent "%[fx:w+${EXTENT_SIZE}]x%[fx:h+${EXTENT_SIZE}]" \
    \( +clone \
      -channel A -morphology Dilate Disk:${BORDER_SIZE} +channel \
      -fill white -colorize 100 \) \
    +swap \
    -compose Over \
    -composite \
    "$OUTPUT"