{ lib, pkgs, config, ... }:
{
  grafanaAlertRuleDefinitions = [
    # S.M.A.R.T. overall health failed - critical
    {
      uid = "smart-health-failed-uid";
      title = "DiskSmartHealthFailed";
      condition = "D";
      data = [
        {
          refId = "A";
          datasourceUid = "vm-datasource-uid";
          relativeTimeRange = { from = 300; to = 0; };
          model = {
            expr = ''smart_health_passed == 0'';
            instant = false;
          };
        }
        {
          refId = "C";
          datasourceUid = "__expr__";
          model = {
            type = "reduce";
            expression = "A";
            reducer = "last";
          };
        }
        {
          refId = "D";
          datasourceUid = "__expr__";
          model = {
            type = "math";
            expression = "$C == 0";
          };
        }
      ];
      for = "0s";
      noDataState = "NoData";
      execErrState = "Error";
      annotations = {
        summary = "S.M.A.R.T. health check FAILED on {{ $labels.device }}";
        description = ''
          Disk {{ $labels.device }} ({{ $labels.serial }}) on {{ $labels.instance }} has failed its S.M.A.R.T. health check.
          This indicates imminent disk failure. Replace the disk immediately!
        '';
      };
      labels = {
        severity = "critical";
        category = "storage";
      };
    }

    # Reallocated sectors - warning (any count > 0 is concerning)
    {
      uid = "smart-reallocated-sectors-uid";
      title = "DiskReallocatedSectors";
      condition = "D";
      data = [
        {
          refId = "A";
          datasourceUid = "vm-datasource-uid";
          relativeTimeRange = { from = 300; to = 0; };
          model = {
            expr = ''smart_reallocated_sector_ct > 0'';
            instant = false;
          };
        }
        {
          refId = "C";
          datasourceUid = "__expr__";
          model = {
            type = "reduce";
            expression = "A";
            reducer = "last";
          };
        }
        {
          refId = "D";
          datasourceUid = "__expr__";
          model = {
            type = "math";
            expression = "$C > 0";
          };
        }
      ];
      for = "0s";
      noDataState = "NoData";
      execErrState = "Error";
      annotations = {
        summary = "Reallocated sectors detected on {{ $labels.device }}";
        description = ''
          Disk {{ $labels.device }} ({{ $labels.serial }}) on {{ $labels.instance }} has reallocated sectors.
          This indicates disk surface damage. Monitor closely and plan replacement.
        '';
      };
      labels = {
        severity = "warning";
        category = "storage";
      };
    }

    # Current pending sectors
    {
      uid = "smart-pending-sectors-uid";
      title = "DiskPendingSectors";
      condition = "D";
      data = [
        {
          refId = "A";
          datasourceUid = "vm-datasource-uid";
          relativeTimeRange = { from = 300; to = 0; };
          model = {
            expr = ''smart_current_pending_sector > 0'';
            instant = false;
          };
        }
        {
          refId = "C";
          datasourceUid = "__expr__";
          model = {
            type = "reduce";
            expression = "A";
            reducer = "last";
          };
        }
        {
          refId = "D";
          datasourceUid = "__expr__";
          model = {
            type = "math";
            expression = "$C > 0";
          };
        }
      ];
      for = "0s";
      noDataState = "NoData";
      execErrState = "Error";
      annotations = {
        summary = "Pending sectors detected on {{ $labels.device }}";
        description = ''
          Disk {{ $labels.device }} ({{ $labels.serial }}) on {{ $labels.instance }} has pending sectors.
          These sectors could not be read and may be reallocated. Monitor for increase.
        '';
      };
      labels = {
        severity = "warning";
        category = "storage";
      };
    }

    # Offline uncorrectable errors
    {
      uid = "smart-offline-uncorrectable-uid";
      title = "DiskOfflineUncorrectable";
      condition = "D";
      data = [
        {
          refId = "A";
          datasourceUid = "vm-datasource-uid";
          relativeTimeRange = { from = 300; to = 0; };
          model = {
            expr = ''smart_offline_uncorrectable > 0'';
            instant = false;
          };
        }
        {
          refId = "C";
          datasourceUid = "__expr__";
          model = {
            type = "reduce";
            expression = "A";
            reducer = "last";
          };
        }
        {
          refId = "D";
          datasourceUid = "__expr__";
          model = {
            type = "math";
            expression = "$C > 0";
          };
        }
      ];
      for = "0s";
      noDataState = "NoData";
      execErrState = "Error";
      annotations = {
        summary = "Offline uncorrectable errors on {{ $labels.device }}";
        description = ''
          Disk {{ $labels.device }} ({{ $labels.serial }}) on {{ $labels.instance }} has offline uncorrectable errors.
          This indicates data integrity issues. Consider replacement.
        '';
      };
      labels = {
        severity = "warning";
        category = "storage";
      };
    }

    # High temperature (Seagate enterprise: warning at 50C)
    {
      uid = "smart-high-temperature-uid";
      title = "DiskHighTemperature";
      condition = "D";
      data = [
        {
          refId = "A";
          datasourceUid = "vm-datasource-uid";
          relativeTimeRange = { from = 600; to = 0; };
          model = {
            expr = ''smart_temperature_celsius > 50'';
            instant = false;
          };
        }
        {
          refId = "C";
          datasourceUid = "__expr__";
          model = {
            type = "reduce";
            expression = "A";
            reducer = "last";
          };
        }
        {
          refId = "D";
          datasourceUid = "__expr__";
          model = {
            type = "math";
            expression = "$C > 0";
          };
        }
      ];
      for = "10m";
      noDataState = "NoData";
      execErrState = "Error";
      annotations = {
        summary = "High temperature on {{ $labels.device }}";
        description = ''
          Disk {{ $labels.device }} ({{ $labels.serial }}) on {{ $labels.instance }} temperature exceeds 50°C.
          Check cooling and ventilation.
        '';
      };
      labels = {
        severity = "warning";
        category = "storage";
      };
    }

    # UDMA CRC errors (cable/connection issues)
    {
      uid = "smart-udma-crc-errors-uid";
      title = "DiskUDMACRCErrors";
      condition = "D";
      data = [
        {
          refId = "A";
          datasourceUid = "vm-datasource-uid";
          relativeTimeRange = { from = 86400; to = 0; };
          model = {
            expr = ''increase(smart_udma_crc_error_count[24h]) > 0'';
            instant = false;
          };
        }
        {
          refId = "C";
          datasourceUid = "__expr__";
          model = {
            type = "reduce";
            expression = "A";
            reducer = "last";
          };
        }
        {
          refId = "D";
          datasourceUid = "__expr__";
          model = {
            type = "math";
            expression = "$C > 0";
          };
        }
      ];
      for = "0s";
      noDataState = "NoData";
      execErrState = "Error";
      annotations = {
        summary = "UDMA CRC errors on {{ $labels.device }}";
        description = ''
          Disk {{ $labels.device }} ({{ $labels.serial }}) on {{ $labels.instance }} has new CRC errors.
          This typically indicates SATA cable or connection issues. Check cables.
        '';
      };
      labels = {
        severity = "warning";
        category = "storage";
      };
    }
  ];
}