#!/bin/bash
set -e

# check dependencies
count=0
for dependency in hxnormalize hxselect grep sed sort tail; do
	if [ ! -x "$(command -v $dependency)" ]; then
		echo "$dependency missing"
		count=$((count+1))
	fi
done

# exit script if any dependencies missing
if [ $count -ne 0 ]; then
	exit 1
fi

# upstream URL
UPSTREAM_URL="https://www.w3.org/Tools/HTML-XML-utils/"

# options to pass to cURL, including custom user agent
USER_AGENT="hxu-version-checker/1.0 george@rawlinson.net.nz"
CURL_OPTS=(--silent --user-agent "$USER_AGENT")

curl "${CURL_OPTS[@]}" "$UPSTREAM_URL" | \
	hxnormalize -x | \
	hxselect -c 'a' -s '\n' | \
	grep "html-xml-utils" | \
	sed -e "s/html-xml-utils-//g" -e "s/.tar.gz//g" | \
	sort -n | \
	tail -n 1

exit 0