#!/bin/sh
# vim:set ft=sh:

set -e

IFACE_CFG="$ROOT/etc/network/interfaces"
IFACE_DIR="${IFACE_CFG}.d"

cd "$IFACE_DIR"

cat > "$IFACE_CFG.new" <<EOT
# NOTE: $0 rewrites this file.  Edit files in
#      /etc/network/interfaces.d/ to persist any customizations.

EOT

# existing loopback and eths
for i in $ROOT/sys/class/net/*; do
	IFACE="$(basename "$i")"
	case $IFACE in
		lo|eth*)
			[ ! -f "$IFACE" ] && sed -e "s/%%/$IFACE/g" DEFAULT > "$IFACE"
			printf "%s\n\n" "$(cat "$IFACE")" >> "$IFACE_CFG.new"
			;;
		*) continue ;;
	esac
done

# all the rest
for i in "$IFACE_DIR"/*; do
	IFACE="$(basename "$i")"
	case $IFACE in
		DEFAULT|lo|eth*)
			continue
			;;
		*)
			printf "%s\n\n" "$(cat "$IFACE")" >> "$IFACE_CFG.new"
			;;
	esac
done

# install new interfaces config
[ -f "$IFACE_CFG" ] && cp -a "$IFACE_CFG" "$IFACE_CFG.bak"
mv "$IFACE_CFG.new" "$IFACE_CFG"