#!/bin/bash

# rdf.sh - Set of Bash functions to work with wdef files.
# 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/>.

set -euo pipefail

readonly RDFS_CACHE_DIR=${CACHE_DIR:-"${HOME}/.cache/wdef_tools/rdfs/"}

# Get RDF and return a path to the result into cache dir
# Parameter:
#   $1: Element QID
# Output:
#   Path to the file containing the RDF, in cache dir
function cacheRDF() {
	local -r element_qid="${1}"
	
	local -r rdf_url="https://www.wikidata.org/wiki/Special:EntityData/${element_qid}.rdf"
	local -r rdf_path="${RDFS_CACHE_DIR}${element_qid}.xml"
	
	# Create cache dir
	mkdir -p "${RDFS_CACHE_DIR}"
	
	curl "${rdf_url}" > "${rdf_path}"
	
	echo "${rdf_path}"
}

# Ensure RDF cache is not older than given age
# Parameter:
#   $1: Element QID
#   $2: Max age (in minutes)
# Output:
#   Path to the file containing the RDF, in cache dir
function cacheRDFMaxAge() {
	local -r element_qid="${1}"
	local -r max_age="${2}"

	local -r rdf_path="${RDFS_CACHE_DIR}${element_qid}.xml"
	
	if [ ! -f "${rdf_path}" ]||[[ $(find "${rdf_path}" -mmin "+${max_age}") ]]
	then
		cacheRDF "${element_qid}"
	else
		echo "${rdf_path}"
	fi
}