#!/usr/bin/bash
set -e

# check dependencies
count=0
for dependency in curl tr cut 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="ftp://ftp.gnu.org/gnu/time/"

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

curl "${CURL_OPTS[@]}" "$UPSTREAM_URL" | \
	tr -s ' ' | \
	cut -d ' ' -f 9 | \
	grep ".tar.gz$" | \
	sort -n | \
	tail -n 1 | \
	sed -e "s/^time-//" -e "s/.tar.gz$//"

exit 0