thumbnail_creator.sh

#!/bin/dash

[ -z "$1" ] || [ ! -f "$1" ] && exit 1

XDG_CACHE_HOME="${XDG_CACHE_HOME:-$HOME/.cache}"
cache="$XDG_CACHE_HOME/vidthumb"
index="$cache/index.json"
movie="$(realpath "$1")"

mkdir -p "$cache"

[ -f "$index" ] && thumbnail=$(jq -r ". \"$movie\"" <"$index") && [ "$thumbnail" != "null" ] && [ -f "$cache/$thumbnail" ] && echo "$cache/$thumbnail" && exit 0

thumbnail=$(uuidgen).jpg

ffmpegthumbnailer -i "$movie" -o "$cache/$thumbnail" -s 0 2>/dev/null || exit 1

[ ! -f "$index" ] && echo "{\"$movie\": \"$thumbnail\"}" >"$index" || {
    json=$(jq -r --arg movie "$movie" --arg thumbnail "$thumbnail" '. + {($movie): $thumbnail}' <"$index")
    echo "$json" >"$index"
}

echo "$cache/$thumbnail"