#!/bin/sh
set -e

check_divert() {
	distrib=${4:-$2.distrib}
	sh_diverter=$(dpkg-divert --listpackage $2)
	sh_truename=$(dpkg-divert --truename $2)
	case "$1" in
	true)
		if [ "$sh_diverter" != "dash" ]; then
			dpkg-divert --remove $2
			dpkg-divert --package dash --divert $distrib --add $2
			if [ -n "$sh_truename" ]; then
				rm -f $sh_truename
			fi
			cp -dp $2 $distrib
			ln -sf $3 $2
		fi
		;;
	false)
		if [ "$sh_diverter" = "dash" ]; then
			bash=$(echo "$3"|sed 's/dash/bash/')
			dpkg-divert --remove $2
			dpkg-divert --package bash --divert $distrib --add $2
			if [ -n "$sh_truename" ]; then
				rm -f $sh_truename
			fi
			cp -dp $2 $distrib
			ln -sf $bash $2
		fi
		;;
	ash)
		div=$(dpkg-divert --list $2)
		case $div in
		'')
			;;
		*by\ ash)
			dst=${div% by ash}
			dst=${dst##* to }

			# Work around dpkg-divert bug.
			if [ -e "$dst" ]; then
				mv "$dst" "$dst.dash-tmp"
			fi
			dpkg-divert --remove $2
			if [ -e "$dst.dash-tmp" ]; then
				mv "$dst.dash-tmp" "$dst"
			fi

			dpkg-divert --package dash --divert $distrib --add $2
			if [ "$dst" != $distrib ] && [ -e "$dst" ]; then
				mv "$dst" $distrib
			fi
			ln -sf $3 $2
			;;
		*)
			d=${2%/*}
			if
				[ -h $2 ] && [ -f $2 ] && [ -f $d/$5 ] &&
				cmp $2 $d/$5
			then
				ln -sf $3 $2
			fi
			;;
		esac
	esac
}

add_shell() {
	if ! type add-shell > /dev/null 2>&1; then
		return
	fi

	add-shell /bin/dash
}

reset_default() {
	db_fget dash/sh seen
	if [ "$RET" = false ]; then
		db_reset dash/sh
	fi
}

debconf=
if [ -f /usr/share/debconf/confmodule ]; then
	. /usr/share/debconf/confmodule
	debconf=yes
fi

if [ "$1" = configure ] && [ -z "$2" ]; then
	check_divert ash /bin/sh dash '' ash
	check_divert ash /usr/share/man/man1/sh.1.gz dash.1.gz \
		/usr/share/man/man1/sh.distrib.1.gz ash.1.gz
	add_shell
elif [ "$1" = configure ] && dpkg --compare-versions "$2" lt 0.4.18; then
	add_shell
fi

if [ $debconf ]; then
	reset_default

	db_get dash/sh
	check_divert "$RET" /bin/sh dash
	check_divert "$RET" /usr/share/man/man1/sh.1.gz dash.1.gz \
		/usr/share/man/man1/sh.distrib.1.gz
fi

test "$1" = 'configure' || exit 0
test -x /usr/bin/update-menus || exit 0
test -z "$2" || dpkg --compare-versions "$2" lt 0.5.2-3 || exit 0
exec update-menus