{ lib, pkgs, config, ... }:
{
  grafanaAlertRuleDefinitions = [
    {
      uid = "host-down-alert-uid";
      title = "HostDown";
      condition = "C";

      data = [
        {
          refId = "A";
          datasourceUid = "vm-datasource-uid";
          queryType = "prometheus";
          relativeTimeRange = { from = 60; to = 0; }; # Query over the last minute
          model = {
            expr = ''up'';
            legendFormat = "{{instance}} ({{job}})";
            instant = false; # Changed from true, as relativeTimeRange is used
          };
        }
        { # New Expression B: Reduce Query A
          refId = "B";
          datasourceUid = "__expr__";
          model = {
            type = "reduce";
            expression = "A"; # Input is Query A
            reducer = "last"; # Get the last value of each series in A
          };
        }
        { # Modified Expression C: Math condition based on B
          refId = "C";
          datasourceUid = "__expr__";
          model = {
            type = "math";
            expression = "$B == 0"; # Check if the last value from B is 0
          };
        }
      ];

      for = "2m";
      noDataState = "Alerting";
      execErrState = "Error";

      annotations = {
        summary = "Host {{ $labels.instance }} is down";
        description = ''Host {{ $labels.instance }} (job: {{ $labels.job }}) has been down for more than 2 minutes.'';
      };
      labels = {
        severity = "critical";
        category = "availability";
      };
    }
  ];
}