#!/usr/bin/env bash
set -e

# Assert there is at least one branch provided
test -z "$1" && echo "new branch name required." 1>&2 && exit 1

if [ -z "$2" ]; then
    new_branch="$1"
    old_branch="$(git symbolic-ref --short -q HEAD)"
else
    new_branch="$2"
    old_branch="$1"
fi

remote=$(git config branch."$old_branch".remote; true)

git branch -m "$old_branch" "$new_branch"
# check if the branch is tracking a remote branch
if [[ -n "$remote" && "$remote" != "." ]]
then
    git push "$remote" :"$old_branch"
    git push --set-upstream "$remote" "$new_branch"
fi