#!/usr/bin/env bash
# Copyright 2016-2018 Luke Shumaker
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
set -e

branch=$(git name-rev --name-only HEAD)
if [[ $branch == master ]]; then
	gitdir="$(git rev-parse --git-dir)"
	workdir="${gitdir}/release"
	exec 8>"${workdir}.lock"
	flock 8

	rm -rf -- "$workdir"
	git worktree prune
	git branch -D release.tmp &>/dev/null || true

	unset GIT_INDEX_FILE
	git worktree add -b release.tmp "${gitdir}/release" master
	(
		unset GIT_DIR GIT_WORK_TREE
		cd "$workdir"

		go generate ./...
		git ls-files -z '*/.gitignore' | xargs -0r rm -f --

		git add .
		git commit -m "Generate artifacts"

		git checkout release # Ensure it exists locally
		git pull --no-edit -s ours # Avoid conflicts

		# What we want is
		#
		#    git merge --no-edit -s theirs release.tmp
		#
		# Unfortunately, there is no 'theirs' strategy; so we
		# have to switch branches and do it backward with the
		# 'ours' strategry, switch back, then merge the merge
		# commit.
		git checkout release.tmp
		git merge --no-edit -s ours release
		git checkout release
		git merge release.tmp

		git branch -d release.tmp
	)
	rm -rf -- "$workdir"
	git worktree prune
fi