#!/bin/sh -e
#
# Copyright (c) 2013 Baptiste Daroussin <bapt@FreeBSD.org>
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.

err() {
	out=$1
	shift
	echo "$@" >&2
	exit $out
}


usage() {
	echo "Usage: $0 cmd

Available cmds:
ls      - display all stashed patshes
show    - view a given patch
save    - save a new patch
apply   - apply a given patch
rm      - delete a given patch from the queue
pop     - apply a patch and delete it
help    - show help" >&2
}

export LC_ALL=C

[ -x `which svn` ] || err 1 "svn is not installed on this system"
svnrp=$(svn info 2>&1 | sed -n 's/Working Copy Root Path: \(.*\)/\1/p')
[ -d "${svnrp}" ] || err 1 "should be used inside a working copy"
[ -w "${svnrp}/.svn" ] || err 1 "no write access to ${svnrp}/.svn"
patchdir=${svnrp}/.svn/patches
mkdir -p "${patchdir}" || err 1 "Impossible to create the patch directory"

save() {
	[ $# -ge 1 ] || err 1 "Usage: svnstash save <name> [files...]"
	patch="${patchdir}/$1.patch"
	[ ! -f "${patch}" ] || err 1 "A patch named $1 already exists"
	shift
	files="$@"
	changes=$(svn st -q)
	[ "${changes}" != "" ] || err 1 "No changes to save"
	svn diff --git ${files:-.} > "${patch}"
	svn revert --depth=infinity ${files:-.}
	echo "stashed"
	exit 0
}

list() {
	for p in ${patchdir}/*.patch; do
		[ "$p" = "${patchdir}/*.patch" ] && break
		p=${p##*/}
		echo ${p%.*}
	done
	exit 0
}

show() {
	[ $# -eq 1 ] || err 1 "Usage: svnstash show <name>"
	patch="${patchdir}/$1.patch"
	[ -f "${patch}" ] || err 1 "$1: no such patch"
	less "${patch}"
	exit 0
}

apply() {
	[ $# -eq 1 ] || err 1 "Usage: svnstash apply <name>"
	patch="${patchdir}/$1.patch"
	[ -f "${patch}" ] || err 1 "$1: no such patch"
	cd ${svnrp}
	svn patch --strip 1 "${patch}"
	exit 0
}

remove() {
	[ $# -eq 1 ] || err 1 "Usage: svnstash rm <name>"
	patch="${patchdir}/$1.patch"
	[ -f "${patch}" ] || err 1 "$1: no such patch"
	rm -f "${patch}"
	exit 0
}

pop() {
	[ $# -eq 1 ] || err 1 "Usage: svnstash pop <name>"
	patch="${patchdir}/$1.patch"
	[ -f "${patch}" ] || err 1 "$1: no such patch"
	cd ${svnrp}
	svn patch --strip 1 "${patch}"
	rm -f "${patch}"
	exit 0
}

case $1 in
ls)
	shift
	list "$@"
	;;
show)
	shift
	show "$@"
	;;
save)
	shift
	save "$@"
	;;
apply)
	shift
	apply "$@"
	;;
rm)
	shift
	remove "$@"
	;;
pop)
	shift
	pop "$@"
	;;
*)
	usage
	exit 1
	;;
esac