thumbnailer

#!/bin/bash

die() { echo "$@"; exit 1; }

min() { [ "$1" -lt "$2" ] && echo "$1" || echo "$2"; }

extension() { basename "$1" | sed -e 's/^.*\.\([^\.]*\)$/\L\1/'; }
cache_path() { echo "${CACHE}$(realpath "$1")" | sed 's/\(.png\)\?$/.png/'; }

match_vid_ext() { extension "$1" | grep -qxE "avi|mp4|wmv|dat|3gp|ogv|mkv|mpg|mpeg|vob|fl[icv]|m2v|mov|webm|ts|mts|m4v|r[am]|qt|divx"; }
make_vid_cache() {
  cached="$(cache_path "$1")"
  [ -f "$cached" ] && return
  mkdir -p "$(dirname "$cached")"
  ffmpegthumbnailer -i "$1" -o "$cached"
}

match_img_ext() { extension "$1" | grep -qxE "bmp|jpg|jpeg|png|xpm|webp|gif"; }
make_img_cache() {
  cached="$(cache_path "$1")"
  [ -f "$cached" ] && return
  mkdir -p "$(dirname "$cached")"
  convert "$1[0]" -resize "${MAX_W}x${MAX_H}>" "$cached"
}

gen_thumb() {
  if match_vid_ext "$1"; then
    make_vid_cache "$1"
  elif match_img_ext "$1"; then
    make_img_cache "$1"
  fi
}

for binary in ffmpegthumbnailer convert; do
  which "$binary" &>/dev/null || die "Required '$binary' is not available."
done

CACHE="$HOME/.cache/thumbs"
MAX_W=400
MAX_H=400

if ! ( match_vid_ext "$1" || match_img_ext "$1" ); then
  die "Extension not supported"
fi

while [ "${1:0:1}" = "-" ]; do
  case "${1:1}" in
    path) cache_path "$2"; exit 0 ;;
    *) die "Option not supported" ;;
  esac
  shift
done

while [ -n "$1" ]; do
  gen_thumb "$1" && cache_path "$1"
  shift
done