#!/bin/bash
# Copyright (C) 2022 Miquel Sabaté Solà <mikisabate@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

set -e

# This script adds the `default` subcommand, which simply switches to the
# default branch of the current repository. Note that this is done locally.
# Hence, if you have changed your default branch just on your server, make sure
# to update the git repository before running this command. That being said,
# this should be a minor corner case.
#
# Moreover, this subcommand does not do *magical stuff*. That is, it won't try
# to stash whatever you currently have before jumping or anything like that.
# Consider this as an alias of `git checkout <my-default-branch>`, with all its
# consequences. The entire point of this subcommand is to jump into the default
# branch when you are so lost in your life that you no longer know if the
# repository you are working on is using `main`, `master`, `development`, or
# whatever.
#
# Last but not least, you can optionally pass an argument if your upstream is
# not named "origin". Thus, the usage of this is:
#
#   $ git default           # equivalent to `git checkout main`
#   $ git default upstream  # as before but your upstream is not `origin`.

upstream="origin"
if [ -n "$1" ]; then
    upstream="$1"
fi

branch=$(git rev-parse --abbrev-ref "$upstream"/HEAD | cut -c8-)
git checkout "$branch"