#!/bin/sh
# git-local <--upload|--download|--remove|--list> [remote] [prefix]
#
# Upload (backup) and download (restore) the state of local branches to a remote
# repository.  This feature is useful at the end of a work session to push
# changes not ready to publish to others for the purposes of backup, and to
# provide some desktop independence for the developer.
#
# Default remote is 'origin', default prefix is current username.
#
# --upload
#	upload all local branches to remote repository with a namespace prefix
#	of prefix/.
#
# --download
#	download local branches on remote repository with a namespace prefix of
#	prefix/.
#
# --remove
#	remove all branches on remote repository with a namespace prefix of
#	prefix/.
#
# --list
#	list all branches on remote repository with a namespace prefix of
#	prefix/.
#

usage()
{
    cat <<+EOF+ >&2
usage: $0 <--upload|--download> [remote] [prefix]

    Back up and restore local branches to a remote repository

    --upload local branches to remote, using prefix prefix
    --download branches on remote using prefix prefix as local branches
    --remove remote branches on remote having prefix prefix (CAREFUL!)
    --list remote branches on remote having prefix prefix (CAREFUL!)

    Default remote is 'origin', default prefix is user's username.
+EOF+
}

upload()
{
    git push "$remote" "+refs/heads/*:refs/$prefix/*"
}

download()
{
    git fetch -uf "$remote" "+refs/$prefix/*:refs/heads/*"
    git reset --hard
}

remove()
{
    for b in $(git ls-remote $remote refs/$prefix/* | awk '{ print $2 }'); do
	git push "$remote" ":$b"
    done
}

list()
{
    git ls-remote $remote "refs/$prefix/*"
}

# MAIN

unset op
case "$1" in
    --upload) op=upload
	;;

    --download) op=download
	;;

    --remove) op=remove
	;;

    --list) op=list
	;;

    *)	usage
	exit 1
	;;
esac

unset remote
unset prefix

shift
if [ $# -eq 1 ]; then
    remote=$1
elif [ $# -eq 2 ]; then
    remote=$1
    prefix=$2
elif [ $# -gt 2 ]; then
    usage
    exit 1
fi

if [ -z "$remote" ]; then
    remote=origin
fi

if [ -z "$prefix" ]; then
    prefix=$(whoami)
fi

case $op in
    upload)
	upload
	;;

    download)
	download
	;;

    remove)
	remove
	;;

    list)
	list
	;;

    *)
	usage
	exit 1
	;;
esac