#!/usr/bin/env bash

# make system configuration vars available
source /etc/os-release

# set invocation settings for this script:
# -e: Exit immediately if a command exits with a non-zero status.
# -u: Treat unset variables as an error when substituting.
# -o pipefail: the return value of a pipeline is the status of the last command to exit with a non-zero status, or zero if no command exited with a non-zero status
set -eu -o pipefail

# save the current directory silently
pushd . > /dev/null

# make a temporary directory, save the name, and move into it
dir="$(mktemp -d)"
cd "${dir}"

echo -n "Installing Tailscale: Getting version..."

# get info for the latest version of Tailscale
tarball="$(curl -s 'https://pkgs.tailscale.com/stable/?mode=json' | jq -r .Tarballs.amd64)"
version="$(echo ${tarball} | cut -d_ -f2)"

echo -n "got ${version}. Downloading..."

# download the Tailscale package itself
curl -s "https://pkgs.tailscale.com/stable/${tarball}" -o tailscale.tgz

echo -n "done. Installing..."

# extract the tailscale binaries
tar xzf tailscale.tgz
tar_dir="$(echo ${tarball} | cut -d. -f1-3)"
test -d $tar_dir

# create our target directory structure
mkdir -p tailscale/usr/{bin,sbin,lib/{systemd/system,extension-release.d}}

# pull things into the right place in the target dir structure
cp -rf $tar_dir/tailscale tailscale/usr/bin/tailscale
cp -rf $tar_dir/tailscaled tailscale/usr/sbin/tailscaled

# write a systemd extension-release file
echo -e "SYSEXT_LEVEL=1.0\nID=steamos\nVERSION_ID=${VERSION_ID}" >> tailscale/usr/lib/extension-release.d/extension-release.tailscale

# create the system extension folder if it doesn't already exist, remove the old version of our tailscale extension, and install our new one
mkdir -p /var/lib/extensions
rm -rf /var/lib/extensions/tailscale
cp -rf tailscale /var/lib/extensions/

# return to our original directory (silently) and clean up
popd > /dev/null
rm -rf "${dir}"

systemd-sysext refresh > /dev/null 2>&1
systemctl daemon-reload > /dev/null

systemctl enable systemd-sysext --now
systemctl enable tailscaled --now

echo "done."
echo "If updating, reboot or run the following to finish the process: sudo systemctl restart tailscaled"