{ config, pkgs, lib, ... }:
{
  imports = [
    ./rules/cpu_usage.nix
    ./rules/disk_usage.nix
    ./rules/host_down.nix
    ./rules/inode_usage.nix
    ./rules/ram_usage.nix
  ];

  # Standard vmalert service configuration
  services.vmalert = {
    enable = true;
    settings = {
      "datasource.url" = "http://localhost:8428"; # VictoriaMetrics address
      "notifier.url" = [ "http://localhost:3001/api/alertmanager/grafana/api/v2/alerts" ]; # Must be a list of strings
    };
    # 'rules' is now set by the mkMerge block above.
  };

  # Override the User and Group for the systemd service managed by the official vmalert module.
  systemd.services.vmalert = {
    serviceConfig = {
      User = "victoriametrics";
      Group = "victoriametrics";
    };
  };

  # Ensure the user/group itself exists on the system.
  users.users.victoriametrics = lib.mkIf (config.services.victoriametrics.enable || config.services.vmalert.enable) {
    isSystemUser = true;
    group = "victoriametrics"; # Primary group for the user
    home = "/var/lib/victoriametrics"; # Standard home for VictoriaMetrics components
  };
  users.groups.victoriametrics = lib.mkIf (config.services.victoriametrics.enable || config.services.vmalert.enable) {
    # Ensures the group exists.
  };
}