#!/bin/sh
set -e

[ -e "/dev/net/tun" ] || { echo "/dev/net/tun not found. Is the container running in privileged mode?"; exit 1; }

[ -n "$DISK_FILENAME" ] || DISK_FILENAME="rq0.dsk"

echo -n "Checking for disk... "
if [ -f "/mnt/$DISK_FILENAME" ]; then
	[ -w "/mnt/$DISK_FILENAME" ] || { echo "Disk /mnt/$DISK_FILENAME exists and is not writable"; exit 1; }
	echo "Disk found and is writable."
else
	[ -w "/mnt/" ] || { echo "Disk /mnt/$DISK_FILENAME not found and /mnt not writable"; exit 1; }
	[ -f "/rq0.dsk.gz" ] ||
		{ echo "Disk /mnt/$DISK_FILENAME not found and image was not built with a default disk"; exit 1; }
	echo "Disk not found."
	echo "Extracting default disk image..."
	gzip -cd /rq0.dsk.gz > "/mnt/$DISK_FILENAME" ||
		{ echo "Failed to extract default disk image to /mnt/$DISK_FILENAME"; exit 1; }
fi

# Start CoreDNS as soon as possible after validations done
echo "Starting CoreDNS..."
[ -z "$COREDNS_DEBUG" ] && COREDNS_QUIET="-quiet"
coredns "$COREDNS_QUIET" -conf /Corefile &

# Set exit command only if NOEXIT not set
[ -z "$NOEXIT" ] && EXIT_CMD="exit" || EXIT_CMD=""

echo "Configuring simh..."
# Allow overriding boot.ini.template
[ -f /mnt/boot.ini.template ] && cp -f /mnt/boot.ini.template /mnt/boot.ini.template
sed -e "s/<DISK_FILENAME>/${DISK_FILENAME}/" \
    -e "s/<EXIT>/${EXIT_CMD}/" /boot.ini.template > /boot.ini

echo "Configuring networking..."
[ -z "$CIDR" ] && CIDR=28
[ -z "$HOSTIP" ] && HOSTIP=1.3.3.1
[ -z "$PDPIP" ] && PDPIP=1.3.3.7

ip tuntap add pdp mode tap
ip link set pdp up
ip addr add "${HOSTIP}/${CIDR}" dev pdp
iptables -t nat -A PREROUTING ! -i pdp -p tcp --dport 4000 -j ACCEPT # dz serial device
iptables -t nat -A PREROUTING ! -i pdp -j DNAT --to-destination "$PDPIP"
iptables -t nat -A POSTROUTING ! -o pdp -j MASQUERADE

echo "Booting PDP-11..."
pdp11 /boot.ini