#!/usr/bin/env bash

# Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# Print the version tailscale repository corresponding
# to the version listed in go.mod.

set -euo pipefail

# printversion prints the tailscale version in the standard tailscale format.
printversion() {
	if [[ ! -f ./build_dist.sh ]]; then
		echo >&2 "printversion must be run from the tailscale repository root"
		exit 1
	fi
	eval $(./build_dist.sh shellvars)
	git_hash=$(git rev-parse HEAD)
	short_hash=$(echo "$git_hash" | cut -c1-9)
	echo ${VERSION_SHORT}-t${short_hash}
}

go_list=$(go list -m tailscale.com)
# go list outputs `tailscale.com <version>`. Extract the version.
mod_version=${go_list#tailscale.com}

if [ -z "$mod_version" ]; then

	# test for a workspace, if found, try to resolve the version from there
	tailscale_path=$(go work edit -json | jq -r '.Use[] | select(.ModPath=="tailscale.com")|.DiskPath')
	if [ -n "$tailscale_path" ]; then
		(
			cd "$tailscale_path"
			printversion
		) && exit 0
	fi

	echo >&2 "no version reported by go list -m tailscale.com: $go_list"
	exit 1
fi

case "$mod_version" in
	*-*-*)
		# A pseudo-version such as "v1.1.1-0.20201030135043-eab6e9ea4e45"
		# includes the commit hash.
		mod_version=${mod_version##*-*-}
		;;
esac

tailscale_clone=$(mktemp -d -t tailscale-clone-XXXXXXXXXX)
git clone -q https://github.com/tailscale/tailscale.git "$tailscale_clone"

cd $tailscale_clone
git reset --hard -q
git clean -d -x -f
git fetch -q --all --tags
git checkout -q "$mod_version"

printversion

cd /tmp
rm -rf "$tailscale_clone"