#!/bin/bash
set -e
print_usage () { cat <<'END'
usage:
  to move repository directory, cd to anywhere and
    cvs-repomove --move local-repo module hostname remote-repo
  to adjust CVS/Root afterwards, in each working directory
    cvs-repomove                automatically update **/CVS/Root
END
}

# We do things in the following order:
#						src		dst
#  0. Check things				@/..moving-to	none/..moved-to
#  1. Rename src repo to prevent commits etc.	..moving-to	none/..moved-to
#  2. Make temporary copy at destination	..moving-to	..tmp
#  3. Install temporary copy at destination	..moving-to	@
#  4. Move aside src repo			..moved-to	@

fail () { echo >&2 "error: $1"; exit 8; }
bad_usage () { echo >&2 "bad usage: $1"; print_usage >&2; exit 12; }

move=false

while [ $# -gt 0 ]; do
	case "$1" in
	--move)		move=true ;;
	--help)		print_usage; exit 0 ;;
	--)		;;
	-*)		bad_usage "unknown option $1" ;;
	*)		break ;;
	esac
	shift
done

mn () { echo " $1"; }

check_module () {
	case "$module" in
	*..*)		fail \
 "moving a module with \`..' in its name is not supported" ;;
	*/*)		fail \
 "moving a subdirectory is not supported" ;;
	-*)		fail \
 "moving a module whose name starts with \`-' is not supported" ;;
	esac
}

check_remote_host () {
	case "$1" in
	/*|.*|-*)	fail "bad hostname $dsthost" ;;
	esac
}

check_remote_path () {
	case "$1" in
	*[^0-9a-zA-Z/._+,-]*) fail \
		"remote pathname may not contain metacharacters, sorry" ;;
	esac
}

do_move () {
	check_module
	check_remote_host "$dsthost"
	check_remote_path "$dstrepo/$module"

	case "$dstrepo" in
	/*)	;;
	*)	bad_usage "destination repo path must be absolute" ;;
	esac

	printf "moving module %s from %s to %s:%s\n" \
		"$module" "$srcrepo" "$dsthost" "$dstrepo"

	mn "checking existing repository"
	ls -d -- "$srcrepo/CVSROOT" >/dev/null

	dstrepotrans="$(printf "%s" "$dstrepo" | tr / :)"
	movingto="moving-to-$dsthost:$dstrepotrans"
	if test -d "$srcrepo/$module..$movingto"; then
		echo "    resuming previous attempt at a move"
		resume=true
		if test -d "$srcrepo/$module"; then
			fail "but $srcrepo/$module exists too"
		fi
	else
		resume=false
		ls -d -- "$srcrepo/$module" >/dev/null
	fi

	set +e
	previously="$(ls -d -- "$srcrepo/$module..moved-to-"* 2>/dev/null)"
	set -e
	if [ "x$previously" != x ]; then
		echo "    btw, module was once before moved away from here"
		mv -- "$previously" \
 "${previously/..moved-to-/..previously-$(date +%s)-moved-to-}"
	fi

	mn "checking dst repository"
 	"$CVS_RSH" "$dsthost" bash -ec "'
 		cd $dstrepo
 		ls -d CVSROOT >/dev/null
 		if test -d $dstrepo/$module; then
 			echo >&2 module already exists in destination repo
 			exit 1
 		fi
 		for f in $module..*; do
 case \"\$f\" in
 *..moved-to-*) echo \"    btw, module was previously at destn repo\" ;;
 *..previously-*) ;;
 *..tmp-*) echo \"    nb: possibly-stale temp/partial copy \$f\" ;;
 *..\*) ;;
 *) echo >&2 \"error: found unexpected subdir \$f\"; exit 8;;
 esac
 		done
 	'"

	if ! $resume; then
		mv -- "$srcrepo/$module" "$srcrepo/$module..$movingto"
	fi

	mn "transferring repo data"
	tmpid="tmp-$(uname -n).$(date +%s)"
	tar -c -C "$srcrepo/$module..$movingto" -f - . | \
	 "$CVS_RSH" "$dsthost" bash -ec "'
		cd $dstrepo
		mkdir $module..$tmpid
		cd $module..$tmpid
		tar --no-same-owner -xf -
	'"
	test "${PIPESTATUS[*]}" = "0 0"

	mn "confirming move at destination repo"
	"$CVS_RSH" "$dsthost" bash -ec "'
		cd $dstrepo
		mv $module..$tmpid $module
	'"

	mn "confirming move at local repo"
	mv -- "$srcrepo/$module..$movingto" \
		"$srcrepo/$module..moved-to-$dsthost:$dstrepotrans"
	echo "module moved successfully"
}

compute_fqdn_data () {
	fqdn_data="$(adnshost -s - "$1" 2>/dev/null || true)"
}

do_furtle () {
	module="$(cat CVS/Repository)"
	oldroot="$(cat CVS/Root)"
	goose="$oldroot"
	check_module
	printf "checking/updating repo for %s\n" "$module"
	compute_fqdn_data "$(uname -n)"
	our_fqdn_data="$fqdn_data"
	searching=true
	while $searching; do
		mn "chasing geese at $goose"
		case "$goose" in
		*[0-9a-zA-Z]:/*)
			remotehost="${goose%%:*}"
			path="${goose#*:}"
			check_remote_host "$remotehost"
			check_remote_path "$remotepath/$module"
			isremote=true
			compute_fqdn_data "$remotehost"
			if [ "x$fqdn_data" = "x$our_fqdn_data" -a \
				"x$fqdn_data" != x ]; then
				isremote=false
				goose="$path"
			fi
			;;
		*:*)
			fail "unknown remote repository string $goose"
			;;
		/*)
			isremote=false
			path="$goose"
			;;
		*)
			fail "unknown repository string $goose"
			;;
		esac
		check="
 cd $path
 if test -d $module; then echo good; exit 0; fi
 if ls -d $module..moved-to-* 2>/dev/null; then exit 0; fi
 echo bad
"
		if $isremote; then
			new_goose_info="$("$CVS_RSH" "$remotehost" \
					bash -ec "'$check'")"
		else
			new_goose_info="$(	bash -ec "$check")"
		fi
		case "$new_goose_info" in
		good)
			searching=false
			;;
		bad)
			echo >&2 "trail went cold at $goose"
			exit 4
			;;
		*..moved-to-*)
			goose="$(printf "%s" \
				"${new_goose_info#*..moved-to-}" | \
				tr : / | sed -e 's,/,:,')"
			;;
		esac
	done
	if [ "x$goose" = "x$oldroot" ]; then
		echo 'repo has not moved - nothing to do'
		exit 0
	fi
	mn "found new repo, adjusting working tree"
	cvs-adjustroot "$oldroot" "$goose"
	echo 'working tree adjustment completed'
}

if $move; then
	[ "$#" = 4 ] || bad_usage "--move needs hostname and path"
	srcrepo="$1"; module="$2"; dsthost="$3"; dstrepo="$4"
	do_move
else
	[ "$#" = 0 ] || bad_usage "without --move, give no arguments"
	do_furtle
fi