#!/usr/bin/env bash
# --------------------------------------------
# Thumbnailer for Graphviz .DOT files
#
# Procedure :
#   http://bernaerts.dyndns.org/linux/76-gnome/333-gnome-shell-graphviz-viewer-thumbnailer
# Depends on :
#   * dot (graphviz package)
#   * pngtopnm, pnmtopng and pnmscalefixed (netpbm package)
# Parameters :
#   $1 - path of graphviz file
#   $2 - path of generated thumbnail
#   $3 - height of thumbnail in pixels
# Revision history :
#   04/08/2013, V1.0 - Creation by N. Bernaerts
#   25/04/2015, V1.1 - Convert to bash
#   07/10/2017, V1.2 - Conversion to URI and speedup with netpbm
#   15/12/2018, V1.3 - Rework for bubblewrap compatibility
# -------------------------------------------

# check tools availability
command -v dot >/dev/null 2>&1 || { echo "[error] dot missing"; exit 1; }
command -v pngtopnm >/dev/null 2>&1 || { echo "[error] pngtopnm missing"; exit 1; }
command -v pnmtopng >/dev/null 2>&1 || { echo "[error] pnmtopng missing"; exit 1; }
command -v pnmscalefixed >/dev/null 2>&1 || { echo "[error] pnmscalefixed missing"; exit 1; }

# check params
[ "$3" = "" ] && { echo "[error] 3 params are needed : file file-thumb thumb-size"; exit 1; }

# get parameters
FILE_LOCAL="$1"
FILE_THUMB="$2"
SIZE="$3"

# generation
dot -Tpng "${FILE_LOCAL}" | pngtopnm - | pnmscalefixed -xysize ${SIZE} ${SIZE} - | pnmtopng -downscale -compression 0 - > "${FILE_THUMB}"