#!/bin/bash
# Sync time via network

. /etc/openslx

month_num() {
	case "$1" in
		Jan) echo 01 ;;
		Feb) echo 02 ;;
		Mar) echo 03 ;;
		Apr) echo 04 ;;
		May) echo 05 ;;
		Jun) echo 06 ;;
		Jul) echo 07 ;;
		Aug) echo 08 ;;
		Sep) echo 09 ;;
		Oct) echo 10 ;;
		Nov) echo 11 ;;
		Dec) echo 12 ;;
		*) echo "INVALID MONTH NAME '$1'" >&2 ;;
	esac
}

adjust_rtc() {
	if [ "$SLX_BIOS_CLOCK" = "local" ]; then
		usleep 100000
		hwclock -l -w || echo "... but could not set BIOS clock to localtime"
	elif [ "$SLX_BIOS_CLOCK" = "utc" ]; then
		usleep 100000
		hwclock -u -w || echo "... but could not set BIOS clock to UTC"
	else
		local rtc sys diff arg re out mon
		for arg in "-l" "-u"; do
			rtc=
			out=$( LC_ALL=C hwclock "$arg" )
			re="([A-Za-z]{3})\\s+([0-9]{1,2})\\s+([0-9:]{8})\\s+([0-9]{4})"
			if [[ $out =~ $re ]]; then
				mon=$( month_num "${BASH_REMATCH[1]}" )
				[ -n "$mon" ] && rtc="${BASH_REMATCH[4]}-${mon}-${BASH_REMATCH[2]} ${BASH_REMATCH[3]}"
			fi
			re="[0-9-]{10}\\s+[0-9:]{8}"
			if [[ $out =~ $re ]]; then
				rtc="${BASH_REMATCH[0]}"
			fi
			if [ -z "$rtc" ]; then
				echo "Error parsing hwclock output" 
				break
			fi
			rtc=$( date -d "$rtc" +%s )
			sys=$( date +%s )
			if [ -z "$rtc" ] || [ -z "$sys" ]; then
				echo "Error converting date/time to unix timestamp"
				break
			fi
			diff=$(( sys - rtc ))
			if [ "$diff" -gt -900 ] && [ "$diff" -lt 900 ]; then
				# Less than 15 minutes off, assume it's the correct mode
				hwclock "$arg" -w || echo "... but could not set BIOS clock ($arg)"
				break
			fi
		done
	fi
}

# Try to merge with servers from DHCP. Prefer DHCP, skip duplicates
for SERVER in $SLX_NTP_SERVER; do
	if ! echo "$SLX_DHCP_NTP" | grep -wq "$SERVER"; then
		SLX_DHCP_NTP="$SLX_DHCP_NTP $SERVER"
	fi
done
SUCCESS=
for SERVER in $SLX_DHCP_NTP; do
	if timeout 3 ntpd -q -n -p "$SERVER"; then
		echo "Successfully queried $SERVER for time."
		adjust_rtc
		SUCCESS=1
		break
	fi
	echo "Error querying $SERVER for current time."
done
if [ -z "$SUCCESS" ]; then
	echo "No NTP server reachable"
	# See if we have a timestamp in our server-config - should only be a few seconds off by now
	if [ -n "$SLX_NOW" ] && [ "$SLX_NOW" -gt 1234567890 ]; then
		TTS="$SLX_NOW"
		CONFIG_DOWNLOAD_TIME=$( cat /tmp/config-download-time 2> /dev/null )
		if [ -n "$CONFIG_DOWNLOAD_TIME" ]; then
			# times are in centiseconds
			NOW_TIME=$(sed -r 's/^([0-9]+)\.([0-9][0-9]).*$/\1\2/' /proc/uptime)
			if [ "$CONFIG_DOWNLOAD_TIME" -gt 0 ] && [ "$NOW_TIME" -gt 0 ]; then
				TTS=$(( TTS + ( NOW_TIME - CONFIG_DOWNLOAD_TIME ) / 100 ))
			fi
		fi
		echo "Setting time to SLX_NOW ($SLX_NOW, corrected $TTS)"
		date -s "@$TTS"
		adjust_rtc
	else
		echo "No fallback option for timesync available, relying on correct RTC setup"
		if [ "$SLX_BIOS_CLOCK" = "local" ]; then
			# Linux defaults to RTC = UTC, so read again in this case
			hwclock -l -s
		fi
	fi
fi

echo "Timesync finished"
exit 0