#!/bin/bash
#
# Move the "bump to <version>" commit to the HEAD of the branch
#

set -e


function usage() {
    >&2 cat << EOM
Move the "bump to <version>" commit to the HEAD of the branch

This script requires that 'git config branch.${BRANCH}.release' is set to the
release version for the release branch.

EOM
    exit 1
}


BRANCH="$(git rev-parse --abbrev-ref HEAD)"
VERSION="$(git config "branch.${BRANCH}.release")" || usage


COMMIT_MSG="Bump $VERSION"
sha=$(git log --grep $COMMIT_MSG --format="%H")
if [ -z "$sha" ]; then
    >&2 echo "No commit with message \"$COMMIT_MSG\""
    exit 2
fi
if [[ "$sha" == "$(git rev-parse HEAD)" ]]; then
    >&2 echo "Bump commit already at HEAD"
    exit 0
fi

commits=$(git log --format="%H" HEAD..$sha | wc -l)

git rebase --onto $sha~1 HEAD~$commits $BRANCH
git cherry-pick $sha