#!/bin/bash

covers=("$2"/{.,}{folder,cover}.{jpg,png})
for f in "${covers[@]}"; do
  [ -f "$f" ] && {
    cover=$f
    break
  }
done

if [ -z "$cover" ] || ! convert -thumbnail "$1" "$cover" "$3"; then
  gdbus call --session --dest=org.freedesktop.thumbnails.Cache1 --object-path /org/freedesktop/thumbnails/Cache1 \
             --method org.freedesktop.thumbnails.Cache1.Delete "['$4']" >/dev/null
fi