#!/bin/execlineb

elgetopt "be:u:c:"

multisubstitute {
	importas -D "0" build ELGETOPT_b
	importas -D "" extra_mounts ELGETOPT_e
	importas -D "" user_arg ELGETOPT_u
	importas -D "" command_arg ELGETOPT_c
	importas -D "" dest 1
	importas -i USER USER
	importas -i HOME HOME
}

shift
elgetpositionals
emptyenv -oP

backtick -D "ash -l" command {
	ifelse { test -n $command_arg } {
		echo $command_arg
	}

	ifelse { test $# -gt 0 } {
		echo $@
	}

	echo ash -l
}
importas -ui command command
# TODO: add -s to that when not using `su` later

backtick -D "" -E user { ifelse { test -n $user_arg } { echo $user_arg } echo $USER }

backtick -D "" -E build_mounts {
	if { test $build = 1 }
		echo "
			${HOME}/aports
			${HOME}/packages
			${HOME}/.abuild
		"
}

define -s -C bindpoints "/etc/resolv.conf ${build_mounts} ${extra_mounts}"

ifelse -n { test -d $dest } {
	foreground { echo "no such file or directory: $dest" }
	exit 1
}

ifelse -n { test -x ${dest}/bin/sh } {
	foreground { echo "$dest does not contain executable /bin/sh" }
	exit 1
}

backtick -E uid { id -u }
backtick -E -D "exec" sucmd { if { test $uid != 0 } echo doas }
$sucmd

unshare -m

foreground { mount -t devtmpfs devtmpfs ${dest}/dev }
foreground { mount -t tmpfs shm ${dest}/dev/shm }
foreground { mount -t devpts devpts ${dest}/dev/pts }
foreground { mount -t sysfs sysfs ${dest}/sys }
foreground { mount -t proc proc ${dest}/proc }
foreground { mount -t tmpfs tmpfs ${dest}/tmp }
foreground {
	forx -E point { $bindpoints }

	# ensure $point exists in destination
	ifthenelse { test -f $point } {
		touch ${dest}${point}
	} {
		mkdir -p ${dest}${point}
	}

	mount --bind $point ${dest}${point}
}

chroot ${dest}

su $user -c "$command"