#!/bin/sh
[ "$(id | awk '{print $1}')" != 'uid=0(root)' ] && exec sudo "$0" "$@"

dir="$(realpath "$(dirname "$0")/../alpine")"
aports="$(realpath "$dir/../aports")"
if [ $# -gt 0 ]; then
	cmd="$@"
else
	cmd='/bin/ash -i'
fi

um=0
uma() {
	: $((++um))
	eval "um$um='$1'"
}
m() {
	src="$1"; shift
	dst="$1"; shift
	mkdir -p "$dst"
	mount $@ "$src" "$dst"
	uma "$dst"
}
mb() {
	src="$1"; shift
	if [ $# -gt 0 -a "x$(echo "$1" | cut -c 1)" = x/ ]; then
		dst="$dir$1"; shift
	else
		dst="$dir$src"
	fi
	src="$(realpath $src)"
	[ ! -e "$src" ] && return
	m "$src" "$dst" --bind --slave $@
}

mb /dev -oro
mb /dev/pts
mb /dev/shm
mb /dev/mqueue
m none "$dir/proc" -t proc
mb /sys
ln -f /etc/resolv.conf "$dir/etc/resolv.conf"
mb "$aports" /home/abuild/aports
mb /srv/alpine/edge /home/abuild/packages
mb /var/cache/distfiles
mb /etc/apk/cache

f="$(chroot "$dir" mktemp -p/tmp/)"

chrdir="$PWD/"
chrdir="${chrdir%/aports/*}"
if [ "$chrdir" != "$PWD/" ]; then
	cmd="cd \"/home/abuild${PWD#$chrdir}\" && $cmd"
fi

echo "$cmd" | tee "$dir/$f"
chmod ugo+r "$dir/$f"
chroot "$dir" /bin/su abuild -l "$f"

rm -f "$dir/$f"

for x in $(seq $um -1 1); do
	eval "umount \$um$x"
done