#!/bin/sh
#
# Usage: modconf [load|save|default|set|vars] <package-name>
#        modconf {merge|diff} <conf-file>
#
# Be aware of concurrent updates!

TMP=/var/tmp
FLASH=$TMP/flash
TMPFILE=$TMP/.conf.tmp.$$

trap "rm -f $TMPFILE" EXIT

case "$1" in
	set|load|save|default|vars)
		cfg=/mod/etc/conf/$2.cfg
		diff=$FLASH/$2.diff
		default=/mod/etc/default.$2/$2.cfg

		if [ ! -r "$default" ]; then
			echo 'Package is not configurable.' 1>&2
			exit 1
		fi
		;;
	diff|merge)
		cat > $TMPFILE

		# . accepts relative filenames only if they start with .
		default="$2"
		case "$default" in
			[^/]*) default="./$default"
		esac
		;;
esac
case "$1" in
	load)
		if [ -r "$diff" ]; then
			cat $diff | $0 merge $default > $cfg
		else
			cp $default $cfg
		fi
		;;
	save)
		if [ -r "$cfg" ]; then
			cat $cfg | $0 diff $default > $diff
			[ -s "$diff" ] || rm -f $diff
		else
			rm -f $diff
		fi
		;;
	default)
		if [ "$2" = "mod" ]; then
			alias export=
			. "$cfg"
			unalias export

			cp $default $cfg
			$0 set mod "MOD_HTTPD_PASSWD=$MOD_HTTPD_PASSWD"
			$0 save mod
		else
			cp $default $cfg
			rm -f $diff
		fi
		;;
	merge)
		env -i sh -s "$default" "$TMPFILE" <<'EOF'
		unset PWD
		# export all variables: perhaps there are some that are 
		# not yet prefixed with 'export'
		set -a 
		. "$1"
		. "$2"
		export -p
EOF
		;;
	diff)
		# remove all exported variables and redefine 'export' as needed
		env -i sh -s "$default" "$TMPFILE" <<'EOF'
		unset PWD
		alias export=
		. "$1"
		unalias export
		diff() {
			name="${1%%=*}" value="${1#*=}"
			if eval '[ "${'$name'+set}" != "" -a "$'$name'" != "$value" -o "${'$name'+set}" = "" ]'; then
				unalias export
				eval "export $name"
				alias export=diff
			fi
		}
		alias export=diff
		. "$2"
		alias export=
		. "$2"
		unalias export
		export -p
EOF
		;;
	set)
		cp $cfg $TMPFILE
		shift 2
		for assignment; do
			case "$assignment" in
				-)
					cat
					;;
				*=*) 
					name="${assignment%%=*}"
					value="${assignment#*=}"
					case "$name" in
						""|[^A-Za-z_]*|*[^A-Za-z0-9_]*)
							echo "Invalid name '$name'" 1>&2
							continue
						;;
					esac
					value="$(echo "${value}_" | sed "s/'/'\"'\"'/g")"
					value="'${value%_}'"
					echo "export $name=$value"
					;;
				*)
					echo "Invalid assignment '$assignment'" 1>&2
					continue
					;;
			esac
		done |
		$0 merge $TMPFILE > $cfg
		;;
	vars)
		list() {
			name="${1%=*}"
			echo "$name"
		}
		alias export=list
		. "$default"
		;;
	*)
		echo "Usage: $0 {load|save|default|set|vars} <package-name>" 1>&2
		echo "       $0 {merge|diff} <conf-file>" 1>&2
		exit 1
esac

exit 0