#!/usr/bin/env bash
set -euo pipefail

PICS="$HOME/Pictures"
AVATAR="$PICS/avatar.png"
BCKP="$PICS/.bckp"

NO_BCKP=0
DEL_SRC=0

while getopts ":nr" opt; do
    case "$opt" in
        n) NO_BCKP=1 ;;
        r) DEL_SRC=1 ;;
        *) echo "Usage: $0 [-n] [-r] <file.png>" >&2; exit 2 ;;
    esac
done
shift $((OPTIND-1))

src=${1:-}
if [ -z "$src" ]; then
    echo "Usage: $0 [-n] [-r] <file.png>" >&2
    exit 2
fi
if [ ! -f "$src" ]; then
    echo "Error: '$src' not found" >&2
    exit 3
fi

orig_src="$src"

if command -v magick >/dev/null 2>&1; then
    IM_CMD="magick"
else
    echo "Error: ImageMagick 'convert' not found" >&2
    exit 5
fi

tmp=$(mktemp --suffix=.png) || { echo "Error: mktemp failed" >&2; exit 6; }

if ! $IM_CMD -- "$src" "$tmp" >/dev/null 2>&1; then
    echo "Error: ImageMagick conversion failed" >&2
    rm -f -- "$tmp"
    exit 7
fi

src="$tmp"
case "${src,,}" in
    *.png) ;;
    *) echo "Error: only .png files are accepted" >&2; exit 4 ;;
esac

if [ "$NO_BCKP" -eq 0 ] && [ -f "$AVATAR" ]; then
    mkdir -p "$BCKP"
    ts=$(date +%Y%m%d_%H%M%S)
    mv -f -- "$AVATAR" "$BCKP/avatar${ts}.png"
fi

cp -f -- "$src" "$AVATAR"

if [ "$DEL_SRC" -eq 1 ]; then
    rm -f -- "$orig_src"
fi