{ config, lib, pkgs, ... }:

let
  cfg = config.services.flashdns;
in
{
  options.services.flashdns = {
    enable = lib.mkEnableOption "flashdns service";

    port = lib.mkOption {
      type = lib.types.port;
      default = 6000;
      description = "Port for flashdns API";
    };

    dnsPort = lib.mkOption {
      type = lib.types.port;
      default = 53;
      description = "Port for flashdns DNS service";
    };

    dataDir = lib.mkOption {
      type = lib.types.path;
      default = "/var/lib/flashdns";
      description = "Data directory for flashdns";
    };

    settings = lib.mkOption {
      type = lib.types.attrs;
      default = {};
      description = "Additional configuration settings";
    };

    package = lib.mkOption {
      type = lib.types.package;
      default = pkgs.flashdns-server or (throw "flashdns-server package not found");
      description = "Package to use for flashdns";
    };
  };

  config = lib.mkIf cfg.enable {
    # Create system user
    users.users.flashdns = {
      isSystemUser = true;
      group = "flashdns";
      description = "FlashDNS service user";
      home = cfg.dataDir;
    };

    users.groups.flashdns = {};

    # Create systemd service
    systemd.services.flashdns = {
      description = "FlashDNS Distributed DNS Service";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" "iam.service" "flaredb.service" ];
      requires = [ "iam.service" "flaredb.service" ];

      serviceConfig = {
        Type = "simple";
        User = "flashdns";
        Group = "flashdns";
        Restart = "on-failure";
        RestartSec = "10s";

        # State directory management
        StateDirectory = "flashdns";
        StateDirectoryMode = "0750";

        # Security hardening
        NoNewPrivileges = true;
        PrivateTmp = true;
        ProtectSystem = "strict";
        ProtectHome = true;
        ReadWritePaths = [ cfg.dataDir ];

        # DNS requires binding to privileged port 53
        AmbientCapabilities = [ "CAP_NET_BIND_SERVICE" ];

        # Start command
        ExecStart = "${cfg.package}/bin/flashdns-server --grpc-addr 0.0.0.0:${toString cfg.port} --dns-addr 0.0.0.0:${toString cfg.dnsPort}";
      };
    };
  };
}