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

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

    port = lib.mkOption {
      type = lib.types.port;
      default = 3010;
      description = "Port for creditservice gRPC API";
    };

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

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

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

  config = lib.mkIf cfg.enable {
    # Create system user
    users.users.creditservice = {
      isSystemUser = true;
      group = "creditservice";
      description = "CreditService quota/billing user";
      home = cfg.dataDir;
    };

    users.groups.creditservice = {};

    # Create systemd service
    systemd.services.creditservice = {
      description = "CreditService Quota and Billing Management";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" "chainfire.service" "nightlight.service" ];
      wants = [ "chainfire.service" "nightlight.service" ];

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

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

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

        # Start command
        ExecStart = "${cfg.package}/bin/creditservice-server --port ${toString cfg.port} --data-dir ${cfg.dataDir}";
      };
    };
  };
}