#!/usr/bin/env bash
#
# install.sh — install nuntius as a systemd service.
#
# nuntius ships as a single static binary. Build it on your workstation, upload
# the binary, the systemd unit, and the .env template to the server, then run
# this script there as root from that directory:
#
#   scp bin/nuntius nuntius.service .env.example user@host:/tmp/nuntius/
#   ssh user@host
#   cd /tmp/nuntius && sudo bash install.sh
#
# It expects ./nuntius and ./nuntius.service (and optionally ./.env.example) in
# the current working directory. Idempotent: re-running is safe — it skips the
# user, config, and .env when they already exist, and never starts the service.

set -euo pipefail

NUNTIUS_USER="nuntius"
BIN_DEST="/usr/local/bin/nuntius"
CONFIG_DIR="/etc/nuntius"
CONFIG_FILE="${CONFIG_DIR}/config.toml"
ENV_FILE="${CONFIG_DIR}/.env"
DATA_DIR="/var/lib/nuntius"
SERVICE_DEST="/etc/systemd/system/nuntius.service"

log()  { printf '\033[1;34m==>\033[0m %s\n' "$*"; }
warn() { printf '\033[1;33mWARN:\033[0m %s\n' "$*" >&2; }
die()  { printf '\033[1;31mERROR:\033[0m %s\n' "$*" >&2; exit 1; }

usage() {
  cat <<'EOF'
install.sh — install nuntius as a systemd service.

Upload the binary, the systemd unit, and the .env template to the server, then
run this script there as root from that directory:

  scp bin/nuntius nuntius.service .env.example user@host:/tmp/nuntius/
  ssh user@host
  cd /tmp/nuntius && sudo bash install.sh

Idempotent: re-running is safe. The service is enabled but never started.
EOF
  exit 0
}

require_root() {
  [ "$(id -u)" -eq 0 ] || die "Run as root: sudo bash install.sh"
}

require_files() {
  [ -f ./nuntius ] || die "./nuntius binary not found — copy it here first (e.g. rsync bin/nuntius)."
  [ -f ./nuntius.service ] || \
    die "./nuntius.service not found — paste the unit from docs/deployment.md (Option A)."
}

create_user() {
  if id "$NUNTIUS_USER" >/dev/null 2>&1; then
    log "User ${NUNTIUS_USER} already exists."
  else
    log "Creating system user ${NUNTIUS_USER}…"
    useradd --system --shell /usr/sbin/nologin --home-dir "$DATA_DIR" --user-group "$NUNTIUS_USER"
  fi
}

create_data_dir() {
  log "Setting up ${DATA_DIR}…"
  mkdir -p "$DATA_DIR"
  chown "$NUNTIUS_USER:$NUNTIUS_USER" "$DATA_DIR"
  chmod 750 "$DATA_DIR"
}

install_binary() {
  log "Installing binary to ${BIN_DEST}…"
  install -m 0755 ./nuntius "$BIN_DEST"
}

install_service() {
  log "Installing systemd unit ${SERVICE_DEST}…"
  install -m 0644 ./nuntius.service "$SERVICE_DEST"
}

generate_config() {
  if [ -f "$CONFIG_FILE" ]; then
    log "Config ${CONFIG_FILE} already exists; leaving it untouched."
    return
  fi
  log "Generating ${CONFIG_FILE}…"
  mkdir -p "$CONFIG_DIR"
  # nuntius writes the template config on first start; run it briefly, then
  # let `timeout` send SIGTERM (graceful shutdown). No backgrounding or manual
  # kill — the write happens at startup, before the timeout elapses.
  timeout -k 5s 4s "$BIN_DEST" >/dev/null 2>&1 || true
  [ -f "$CONFIG_FILE" ] || warn "nuntius did not create ${CONFIG_FILE}; check the uploaded binary."
  chown -R "$NUNTIUS_USER:$NUNTIUS_USER" "$DATA_DIR"
}

install_env() {
  if [ -f "$ENV_FILE" ]; then
    log "${ENV_FILE} already exists; leaving it untouched."
  elif [ -f ./.env.example ]; then
    log "Creating ${ENV_FILE} from .env.example (edit it!)…"
    install -m 0600 ./.env.example "$ENV_FILE"
    chown "root:$NUNTIUS_USER" "$ENV_FILE"
  else
    warn ".env.example not found; skipping ${ENV_FILE}. Create it before starting."
  fi
}

enable_service() {
  log "Reloading systemd and enabling nuntius…"
  systemctl daemon-reload
  systemctl enable nuntius.service
}

final_notes() {
  cat <<'EOF'

============================================================
✓ nuntius installed and enabled, but NOT started.

Next manual steps:
  1. Set the SMTP password:
       sudo $EDITOR /etc/nuntius/.env
  2. Edit the auto-generated config (smtp.host, smtp.user, allowed_origins):
       sudo $EDITOR /etc/nuntius/config.toml
  3. Start the service:
       sudo systemctl start nuntius
       sudo journalctl -u nuntius -f
  4. Add the nginx location block (see README.md), then:
       sudo nginx -t && sudo systemctl reload nginx
============================================================
EOF
}

main() {
  case "${1:-}" in
    -h | --help) usage ;;
  esac

  require_root
  require_files
  create_user
  create_data_dir
  install_binary
  install_service
  generate_config
  install_env
  enable_service
  final_notes
}

main "$@"