#!/usr/bin/env bash
set -e

FILE="dns/db.10.127"
TUN30_TEMP="$(mktemp)"
PP_TEMP="$(mktemp)"
LO_TEMP="$(mktemp)"

if [[ "$(uname)" = *BSD ]]; then
	TAC=gtac
else
	TAC=tac
fi

print_record()
{
	printf "%s\tIN\tPTR\t%s\n" "$1" "$2"
}

ipcalc()
{
	local subnet="$1"
	local add="$2"

	REV="$(echo -n "${subnet%,*}." | "$TAC" -s .)"
	REV="${REV%.*.*.}"

	echo "$[ ${REV%.*} + $add ].${REV#*.}"
}

# PROGRAM BEGIN

sed -i '/AUTOGENERATED/,$d' "$FILE"
echo '; AUTOGENERATED' >> "$FILE"

(
cd route
for i in *; do
	source "$i"
	if [ "$TYPE" = "TUN30" ]; then
		upstream_ip=$(ipcalc "$i" 1)
		downstream_ip=$(ipcalc "$i" 2)

		(
		print_record "$upstream_ip" "$DOWNSTREAM.$UPSTREAM.tun30.neo."
		print_record "$downstream_ip" "$UPSTREAM.$DOWNSTREAM.tun30.neo."
		) >> "$TUN30_TEMP"
	elif [ "$TYPE" = "PTP" ]; then
		i="${i/PP,/}"
		upstream_ip="${i%~*}"
		downstream_ip="${i#*~}"

		(
		print_record "$(ipcalc "$upstream_ip" 0)" "$UPSTREAM.ptp.neo."
		print_record "$(ipcalc "$downstream_ip" 0)" "$DOWNSTREAM.ptp.neo."
		) >> "$PP_TEMP"
	elif [ "$TYPE" = "LO" ]; then
		ip="${i/,32/}"

		print_record "$(ipcalc "$ip" 0)" "$NAME.neo" >> "$LO_TEMP"
	fi
done
)

{
	echo -e "\n; Tunnel /30 Addresses"
	sort -n < "$TUN30_TEMP"
	echo -e "\n; Point to Point Addresses"
	sort -n < "$PP_TEMP"
	echo -e "\n; Loopback Addresses"
	sort -n < "$LO_TEMP"
} >> "$FILE"

rm -f "$TUN30_TEMP" "$PP_TEMP" "$LO_TEMP"