ldraw-wrapper

#!/bin/bash

# Run LDraw application after checking/creating of $LDRAWHOME directory

# This is a wrapper for all the programs that are part of the
# linux-ldraw project.  The system LDraw library is installed in
# /usr/share/ldraw To allow users to have their own unofficial
# parts, a custom ldconfig.ldr or other custom files, all the
# programs are configured to use ~/.ldraw as the LDraw library
# path by setting the LDRAWDIR environment variable.
#
# If this directory does not exist, it is created and the
# contents of the system-wide ldraw library is symlinked there.
#
# All the linux-ldraw packages are supposed to suffix their
# binary name with .bin and create a symlink named with the
# original binary name pointing to this script


function die() {
	ERROR="ERROR: $1"
	if [ -t 0 ] ; then
		echo "$ERROR" >&2
	else
		xmessage "$ERROR"
	fi
	exit 1
}


APPLICATION="$(which -- "${0##*/}.bin")" || die "unknown application"
LDRAWHOME="${HOME}/.ldraw"
LDRAWSYS="/usr/share/ldraw"

function create_ldraw_dir() {
	local LDRAWHOME="$1"
	echo "Creating LDraw directory $LDRAWHOME ."
	mkdir "$LDRAWHOME" || die "Cannot create ${LDRAWHOME}. You may want to set the LDRAWDIR environment variable to point to a copy of the LDraw library."
}

function fill_ldraw_dir() {
	local LDRAWHOME="$1"
	for d_full in "${LDRAWSYS}"/*; do
		d="${d_full##*/}"
		if [[ ! -e "${LDRAWHOME}/${d}" ]]; then
			echo "Creating symlink ${LDRAWHOME}/${d} -> ${LDRAWSYS}/${d}:"
			ln -s "${LDRAWSYS}/${d}" "${LDRAWHOME}/${d}" || die "Cannot create symlink ${LDRAWHOME}/${d} ."
		elif  [[ ! -L "${LDRAWHOME}/${d}" ]] || [[ $(readlink "${LDRAWHOME}/${d}") != "${LDRAWSYS}/${d}" ]]; then
			echo "Warning: $LDRAWHOME/$d is not a symlink to the system LDraw library."
		fi
	done
	mkdir -p "${LDRAWHOME}/unofficial/{p,parts}"
}


# main()

if [ -z "${LDRAWDIR}" ] ; then
	if [ ! -d "$LDRAWHOME" ] ; then
		if [ -e "$LDRAWHOME" ] ; then
			die "Cannot create $LDRAWHOME directory."
		else
			create_ldraw_dir "$LDRAWHOME"
		fi
	fi
	fill_ldraw_dir "$LDRAWHOME"
	export LDRAWDIR="${LDRAWHOME}"
fi

exec $APPLICATION "$@"