#!/usr/bin/env bash
# Prepare a host for Hnefatafl. The host may be shared with other games of
# Kestrel's Hall: each keeps its own Caddy site file in /etc/caddy/sites, its
# own port, service user, data directory and access log, and this script
# touches nothing that belongs to another game. Copy it and Caddyfile.tmpl
# to the host and run ON it as root; safe to run again.
#   bash setup-droplet.sh 'tafl.kestrelsnest.social, hnefatafl.<host-ip>.sslip.io'
# The argument is this game's Caddy site address line: one name, or several
# separated by commas. Every name must already resolve to this host.
set -euo pipefail
HOST="${1:?usage: setup-droplet.sh <site address line>}"

apt-get update -q
apt-get install -qy curl rsync

# Caddy (auto-HTTPS), once per host.
if ! command -v caddy >/dev/null; then
  apt-get install -qy debian-keyring debian-archive-keyring apt-transport-https
  curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/gpg.key' \
    | gpg --dearmor -o /usr/share/keyrings/caddy-stable-archive-keyring.gpg
  curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/debian.deb.txt' \
    | tee /etc/apt/sources.list.d/caddy-stable.list
  apt-get update -q && apt-get install -qy caddy
fi

# Node 22, once per host; every game runs its server on it.
if ! command -v node >/dev/null || [[ "$(node -v)" != v22* ]]; then
  curl -fsSL https://deb.nodesource.com/setup_22.x | bash -
  apt-get install -qy nodejs
fi

# The host's Caddyfile only gathers the games' site files. A Caddyfile that
# is neither Caddy's stock one nor this is a single-game host from before the
# shared layout: stop rather than overwrite it.
ROOT_CADDY='# Kestrel'"'"'s Hall: every game on this host brings its own site file.
import sites/*.caddy'
mkdir -p /etc/caddy/sites
if ! grep -q '^import sites/\*.caddy' /etc/caddy/Caddyfile 2>/dev/null; then
  if [ -s /etc/caddy/Caddyfile ] && ! grep -q 'root \* /usr/share/caddy' /etc/caddy/Caddyfile; then
    echo "/etc/caddy/Caddyfile holds another site; move it into /etc/caddy/sites/ first" >&2
    exit 1
  fi
  printf '%s\n' "$ROOT_CADDY" > /etc/caddy/Caddyfile
fi

# This game: its user, its directories, its site.
# The service user shares the slug. A slug that is already a system group
# (Ubuntu ships "dip", "games", "audio" and others) cannot also be a user:
# stop and say so, and choose another user name in this script and the unit.
if ! id -u hnefatafl &>/dev/null; then
  if getent group hnefatafl >/dev/null; then
    echo "a system group is already called hnefatafl; pick another service user name" >&2
    exit 1
  fi
  useradd -r -m -d /opt/hnefatafl-home hnefatafl
fi
mkdir -p /opt/hnefatafl/build /opt/hnefatafl/app /var/lib/hnefatafl/rooms /var/log/hnefatafl
chown -R root:caddy /opt/hnefatafl/build
chmod -R g+rX /opt/hnefatafl/build
chown -R hnefatafl:hnefatafl /var/lib/hnefatafl
sed "s|__HOST__|$HOST|" "$(dirname "$0")/Caddyfile.tmpl" > /etc/caddy/sites/hnefatafl.caddy

caddy validate --config /etc/caddy/Caddyfile
# Validation as root touches the access logs; Caddy runs as caddy and must own them.
chown -R caddy:caddy /var/lib/caddy
systemctl reload-or-restart caddy

# Firewall: ssh + web only.
ufw allow OpenSSH
ufw allow 80/tcp
ufw allow 443/tcp
ufw --force enable

echo "host ready for hnefatafl: now run deploy/deploy.sh <ip> from your machine"