doi-repair

#!/bin/sh

# interactively infer DOI and assigns standard PDF metadata fields (Author, Title and Subject) based on it
#	here, Subject contains an ISO 690 reference + DOI as proposed in https://www.crossref.org/blog/metadata-in-pdf-1.-strategies/
# 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/>.


show_hint(){
	printf "Usage: doi-repair [PDF]...\n\nInteractively infer DOI and set corresponding standard PDF metadata (Author, Title and Subject).\nThe \"Subject\" field will contain an ISO 690-style reference with a DOI.\n"
}

prompt(){
	printf "%s (y/n) " "$1"
	old_stty_cfg=$(stty -g)
	stty raw -echo ; answer=$(head -c 1) ; stty "$old_stty_cfg" ; printf "%s\n" "$answer"
	[ ! "$answer" = "${answer#[Yy]}" ]
}

if [ -z "$1" ]; then show_hint && exit ; fi


RED='\033[0;31m'
NC='\033[0m' # No Color

while [ "$#" -ne 0 ]; do
	if [ ! -f "$1" ]; then printf "File %s not found\n" "$1" && shift && continue ; fi

	printf "Processing: ${RED}%s${NC}\n" "$1"

	doi="$(doi-infer "$1")"
	if [ -n "$doi" ]; then
		printf "Detected DOI:\n"
		printf "\t${RED}%s${NC}\n" $doi
	fi

	# without ./ can be considered as a URL
	xdg-open "./$1" > /dev/null 2>&1 &

	skip="0"
	success="0"
	while [ "$success" != "1" ] ; do

		if [ -z "$doi" ]; then
			#if ! prompt ", try to set manually?"; then skip="1" && break ; fi
			printf "Unable to detect DOI, input manually (blank to skip): "
			read -r doi
			doi="$(echo "$doi" | doi-grep)"
			if [ -z "$doi" ]; then echo "Skipped" && skip="1" && break ; fi
		fi

		# doi-infer could output multiple options
		IFS='
		'
		for doi_ in $doi; do
			printf "\nMetadata for ${RED}\"%s\"${NC}:\n" "$doi_"
			printf "%s\n" "$(doi-to-bibtex "$doi_" | bibtex-to-meta | grep "InfoValue:" | sed 's/InfoValue:/\t/g')"
			if prompt "Does it match the document?"; then doi="$doi_" && success="1" && break ; fi
		done

		if [ "$success" != "1" ]; then doi="" ; fi
	done

	# terminate all programs using the PDF in question to close previously started xdg-open
	fuser -s -k -TERM "$1"

	if [ "$skip" = "1" ]; then shift && continue ; fi

	# assign new metadata
	# pdftk can't write in-place
	mv "$1" "$XDG_CACHE_HOME/backup.pdf"
	# dump current metadata
	pdftk "$XDG_CACHE_HOME/backup.pdf" dump_data output "$XDG_CACHE_HOME/pdfmetadata" > /dev/null 2>&1
	# append new entries to metadata file to overwrite existing ones
	doi-to-bibtex "$doi" | bibtex-to-meta >> "$XDG_CACHE_HOME/pdfmetadata"
	# write new metadata
	pdftk "$XDG_CACHE_HOME/backup.pdf" update_info "$XDG_CACHE_HOME/pdfmetadata" output "$1" > /dev/null 2>&1

	# preserve the file modification date
	touch --date="@$(stat -c %Y "$XDG_CACHE_HOME/backup.pdf")" "$1"

	printf "\n"

	shift
done