#!/bin/bash

# get_equivalent.sh - Search equivalent element on Wikidata.
# Copyright (C) 2022  Pierre Choffet
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of version 3 of the GNU General Public License as
# published by the Free Software Foundation.
#
# 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/>.

source "$(dirname "$0")/query.sh"

set -euo pipefail

function buildQuery() {
	local -r pid="${1}"
	shift
	local -r values=( "${@}" )

	echo 'SELECT DISTINCT ?element WHERE {'
	
	for index in ${!values[@]}
	do
		if [ "${index}" -ne 0 ]
		then
			echo 'UNION'
		fi
		echo "{ ?element p:${pid} ?id${index}. ?id${index} (ps:${pid}) ${values[$index]@Q}. }"
	done

	echo '} LIMIT 2'
}

function usage() {
	cat << EOF
USAGE: get_qid_from_property.sh <wdef_path> <element_id> <element_pid>

This script will get Wikidata's equivalent element to an entry in a wdef. If
uniqueness can be ensured from a literal value (typically an external identifier),
it's an easy way to merge your wdef with Wikidata.
EOF
}

if [ "$#" -ne 3 ]
then
	usage >&2
	exit 1
fi

readonly WDEF_PATH="${1}"
readonly ELEMENT_ID="${2}"
readonly ELEMENT_PID="${3}"

# Get wdef
readarray -t VALUES<<<$(xmlstarlet sel -t -m "/wdef:knowledge/wdef:element[@wdef:id = \"${ELEMENT_ID}\"]/wdef:property[@wdef:pid = \"${ELEMENT_PID}\"]/wdef:value/wdef:literal" -v '.' -n "${WDEF_PATH}")

# Build query
readonly QUERY_PATH=$(mktemp)
buildQuery "${ELEMENT_PID}" ${VALUES[@]} > "${QUERY_PATH}"
readonly RESULT_PATH=$(query "${QUERY_PATH}")

# Cleanup
rm "${QUERY_PATH}"

# Print potential result in stdout, cleanup, exit
readonly QID=$(xmlstarlet sel -t -m '/_:sparql/_:results[count(_:result) = 1]' -v '_:result/_:binding[@name = "element"]/_:uri' "${RESULT_PATH}")

if [ "${QID}" != '' ]
then
	echo "${QID##*/}"
else
	exit 1
fi