#!/bin/bash

set -e # bail on errors

REMOTE="${1:-origin}"
ORIG_BRANCH="$(git rev-parse --abbrev-ref HEAD)"
if [[ "$ORIG_BRANCH" = "HEAD" ]]; then
  echo "Cannot update in a detached HEAD state"
  exit 1
fi
if [[ -z "$2" ]]; then
  BRANCHES="$ORIG_BRANCH"
else
  shift
  BRANCHES="$@"
fi

STASH_OUTPUT=$(git stash)
if [[ "$STASH_OUTPUT" = "No local changes to save" ]]; then
    POP_STASH=0
else
    POP_STASH=1
fi

git fetch --prune --tags "$REMOTE"

for BRANCH in $BRANCHES; do
  echo "* Updating $BRANCH from $REMOTE/$BRANCH"
  git checkout "$BRANCH"
  git rebase "$REMOTE/$BRANCH"
done

git checkout "$ORIG_BRANCH"

if [[ $POP_STASH -eq 1 ]]; then
  git stash pop
fi