#!/usr/bin/env bash
set -euo pipefail

if [ "$(id -u)" -ne 0 ]; then
  echo "Run this installer with sudo or as root." >&2
  exit 1
fi

MONITOR_URL="${MONITOR_URL:-${1:-}}"
SERVER_ID="${SERVER_ID:-$(hostname -s)}"
SERVER_NAME="${SERVER_NAME:-$(hostname -f 2>/dev/null || hostname)}"
SERVER_ENV="${SERVER_ENV:-production}"
AGENT_TOKEN="${AGENT_TOKEN:-}"
INTERVAL="${INTERVAL:-60}"
INSTALL_BIN="${INSTALL_BIN:-/usr/local/bin/fleet-monitor-agent}"
ENV_FILE="${ENV_FILE:-/etc/fleet-monitor-agent.env}"
SERVICE_FILE="${SERVICE_FILE:-/etc/systemd/system/fleet-monitor-agent.service}"

if [ -z "$MONITOR_URL" ]; then
  echo "Usage: MONITOR_URL=https://watchtower.1exch.app AGENT_TOKEN=your-token sudo -E bash install-agent.sh" >&2
  echo "   or: sudo AGENT_TOKEN=your-token bash install-agent.sh https://watchtower.1exch.app" >&2
  exit 1
fi

require_command() {
  if ! command -v "$1" >/dev/null 2>&1; then
    echo "Missing required command: $1" >&2
    exit 1
  fi
}

escape_env() {
  printf "%s" "$1" | sed "s/'/'\\\\''/g"
}

require_command curl
require_command systemctl

echo "Installing WatchTower agent from $MONITOR_URL"
curl -fsS "$MONITOR_URL/downloads/linux-agent.sh" -o "$INSTALL_BIN"
chmod 0755 "$INSTALL_BIN"

curl -fsS "$MONITOR_URL/downloads/linux-agent.service" -o "$SERVICE_FILE"
chmod 0644 "$SERVICE_FILE"

cat > "$ENV_FILE" <<EOF
MONITOR_URL='$(escape_env "$MONITOR_URL")'
SERVER_ID='$(escape_env "$SERVER_ID")'
SERVER_NAME='$(escape_env "$SERVER_NAME")'
SERVER_ENV='$(escape_env "$SERVER_ENV")'
AGENT_TOKEN='$(escape_env "$AGENT_TOKEN")'
INTERVAL='$(escape_env "$INTERVAL")'
EOF
chmod 0600 "$ENV_FILE"

systemctl daemon-reload
systemctl enable --now fleet-monitor-agent

echo "WatchTower agent installed and started."
echo "Service: systemctl status fleet-monitor-agent"
echo "Logs:    journalctl -u fleet-monitor-agent -f"