bibtex-to-meta

#!/bin/sh

# Generate metadata for pdftk based on DOI
# The GPLv3 License (GPLv3)
#
# Copyright (c) 2024 Ivan Boikov
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


if [ -t 0 ] && [ -z "$1" ]; then
	echo "Usage: bibtex-to-meta [STRING]\n\nGenerate pdftk metadata file based on a Bibtex entry.\nWith no STRING, read from standard input."
	exit
fi

parse_bibtex(){
	echo "$1" | grep -Po "$2={.+?}" | awk -F '[{}]' '{print $2}'
}

add_pdf_meta(){
	# the format used by pdftk
	printf "InfoBegin\nInfoKey: %s\nInfoValue: %s\n" "$1" "$2"
}

flip_name_surname(){
	name="$(echo "$1" | cut -d, -f2 | xargs)"
	# -s to handle cases w/o ',' like the last author of 10.1109/jqe.1983.1071749
	surname="$(echo "$1" | cut -s -d, -f1 | xargs)"
	echo "$name $surname"
}

process_bibtex(){
	author="$(parse_bibtex "$1" "author")"
	# convert Bibtex-style author list to natural style
	author="$(echo "$author" | sed 's/ and /\n/g' | while read -r line ; do
		flip_name_surname "$line"
	done)"
	author="$(echo "$author" | paste -sd "," - | sed 's/,/, /g')"
	title="$(parse_bibtex "$1" "title")"
	journal="$(parse_bibtex "$1" "journal")"
	# maybe more fallbacks?
	if [ -z "$journal" ]; then journal="$(parse_bibtex "$1" "booktitle")" ; fi

	year="$(parse_bibtex "$1" "year")"
	volume="$(parse_bibtex "$1" "volume")"
	number="$(parse_bibtex "$1" "number")"
	pages="$(parse_bibtex "$1" "pages")"
	doi="$(parse_bibtex "$1" "DOI" | tr '[:lower:]' '[:upper:]')"

	subject=""
	# ISO 690 (kind of, no guarantees)
	[ -n "$journal" ] && subject="$subject, $journal"
	[ -n "$year" ]    && subject="$subject, $year"
	[ -n "$volume" ]  && subject="$subject, vol. $volume"
	[ -n "$number" ]  && subject="$subject, no. $number"
	[ -n "$pages" ]   && subject="$subject, p. $pages"
	[ -n "$doi" ]     && subject="$subject, doi:$doi"

	add_pdf_meta "Title"   "$title"
	add_pdf_meta "Author"  "$author"
	add_pdf_meta "Subject" "${subject#??}" # cut off ", " in the beginning
}

[ ! -t 0 ] && process_bibtex "$(cat)"
[ -n "$1" ] && process_bibtex "$1"