#!/usr/bin/env bash
# Usage: script/release
#
# - checks out the master branch
# - changes version in `bin/ruby-build` to current date
# - commits and tags the change
# - pushes master & the new tag to GitHub
# - creates a new Release on GitHub
# - [automated] a GitHub Action will create a Homebrew PR for the new release

set -e

git fetch -q --tags origin master
git checkout -q master
git merge --ff-only '@{upstream}'

existing="$(git tag --points-at HEAD)"
if [ -n "$existing" ]; then
  echo "Aborting: HEAD is already tagged as '${existing}'" >&2
  exit 1
fi

binfile="bin/ruby-build"
new_version="$(date '+%Y%m%d')"

version_suffix=""
while git show-ref --verify --quiet -- "refs/tags/v${new_version}${version_suffix}"; do
  version_suffix=".$(( ${version_suffix#.} + 1 ))"
done

new_version="${new_version}${version_suffix}"
version_tag="v${new_version}"
previous_tag="$(git describe --tags HEAD --abbrev=0)"

if git diff --quiet "${previous_tag}..HEAD" -- bin share; then
  echo "Aborting: No features to release since '${previous_tag}'" >&2
  exit 1
fi

sed -i.bak -E "s!^(RUBY_BUILD_VERSION=).+!\\1\"${new_version}\"!" "$binfile"
rm -f "${binfile}.bak"
make share/man/man1/ruby-build.1

git commit -m "ruby-build ${new_version}" -- "$binfile" share/man/man1/ruby-build.1

git tag "$version_tag"
git push origin master "${version_tag}"

gh release create "$version_tag" --title "ruby-build ${new_version}" --generate-notes