#!/usr/bin/env bash
# ---------------------------------------------------
# Thumbnailer for LibreOffice & OpenOffice documents
#
# Procedure :
#   http://bernaerts.dyndns.org/linux/76-gnome/285-gnome-shell-generate-libreoffice-thumbnail-nautilus
# Depends on :
#   * libreoffice or soffice
#   * mimetype
#   * unzip
#   * pbmmake, pngtopnm, pnmtopng, pnmscalefixed and pnmcomp (netpbm package)
# Parameters :
#   $1 - path of office file
#   $2 - path of generated thumbnail
#   $3 - height of thumbnail in pixels
# Revision history :
# 04/08/2013, V1.0 - Creation by N. Bernaerts
# 15/11/2014, V2.0 - Use URI to handle network shares
# 07/10/2017, V2.1 - Speedup with netpbm tools
# 09/03/2018, V3.0 - Add flat XML files support
# 12/03/2018, V3.1 - Handle libreoffice and soffice binaries
# 08/11/2018, V3.2 - Handle gio and gvfs-copy tools
# 11/12/2018, V3.3 - Rework for bubblewrap compatibility (thanks to Li Chong)
# 22/08/2012, V3.4 - Fix libreoffice content size to 256x256
# ---------------------------------------------------

# check libreoffice availability
CMD_OFFICE="libreoffice"
command -v "${CMD_OFFICE}" >/dev/null 2>&1 || CMD_OFFICE="soffice"
command -v "${CMD_OFFICE}" >/dev/null 2>&1 || { echo "[error] libreoffice missing"; exit 1; }

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

# system ressources
PATH_SYSTEM="/usr/local/sbin/lo-thumbnailer.res"
[ ! -d "${PATH_SYSTEM}" ] && { echo "[error] directory ${PATH_SYSTEM} missing"; exit 1; }

# generate temporary files and directory
TMP_DIR=$(mktemp -t -d "thumb-lo-XXXXXXXX")
TMP_PNM="${TMP_DIR}/original.pnm"
TMP_THUMB="${TMP_DIR}/thumbnail.pnm"

# get document type (text, spreadsheet, graphics or presentation)
DOC_TYPE=$(mimetype -b "${FILE_LOCAL}" | sed 's/.*: //' | sed 's/^.*opendocument.\([^-]*\).*/\1/' | cut -d'-' -f1)

# get document tag and mask
DOC_TAG="${PATH_SYSTEM}/lo-${DOC_TYPE}.pnm"
DOC_ALPHA="${PATH_SYSTEM}/lo-${DOC_TYPE}-alpha.pnm"

# if file is zipped, extract thumbnail
IS_ZIPPED=$(file -ib "${FILE_LOCAL}" | cut -d';' -f2 | grep "binary")
if [ "${IS_ZIPPED}" != "" ]
then
	# extract thumbnail from zipped document
	unzip -p "${FILE_LOCAL}" "Thumbnails/thumbnail.png" | pngtopnm | pnmscalefixed -xysize 256 256 - > "${TMP_PNM}"

# else, file is a flat one, generate thumbnail
else
	# convert first page to PNG
	${CMD_OFFICE} "-env:UserInstallation=file://${TMP_DIR}" --headless --convert-to png --outdir "${TMP_DIR}" "${FILE_LOCAL}"

	# convert PNG to PNM
	FILE_NAME=$(basename "${FILE_LOCAL}")
	FILE_NAME="${FILE_NAME%.*}"
	pngtopnm "${TMP_DIR}/${FILE_NAME}.png" | pnmscalefixed -xysize 256 256 - > "${TMP_PNM}"
fi

# generate 256x256 thumbnail with masks
pbmmake -white 208 256 | pnmcomp -align center -valign middle "${TMP_PNM}" - | pnmcomp -align center -valign middle -alpha "${DOC_ALPHA}" "${DOC_TAG}" - > "${TMP_THUMB}"

# downscale to final size and convert to png
pnmscalefixed -xysize ${SIZE} ${SIZE} "${TMP_THUMB}" | pnmtopng -downscale - > "${FILE_THUMB}"

# remove temporary directory
rm -r "${TMP_DIR}"