# Grafana dashboards, built into a form file-provisioning can actually use.
#
# Returns an attrset of { name = derivation; }, where each derivation is a single
# dashboard JSON file. modules/server.nix drops these into /etc/grafana-dashboards.
{ lib, runCommand, fetchurl, jq, dsUid }:

let
  # Dashboards exported from grafana.com carry an `__inputs` block and reference their
  # datasource as "''${DS_PROMETHEUS}". That placeholder is only substituted by Grafana's
  # interactive *import* flow -- file provisioning never runs it, so the uid stays
  # literal and every panel fails to resolve a datasource. Substitute at build time.
  #
  # A dashboard-level `datasource`-type template variable (lowercase, e.g.
  # "''${ds_prometheus}") is a different mechanism and resolves fine on its own; this
  # only touches names declared in __inputs.
  fixupProgram = ''
    def dsuid($pluginId):
      if   $pluginId == "prometheus" then $prom
      elif $pluginId == "loki"       then $loki
      else "" end;

    def subst($name; $uid):
      walk(if type == "string" then gsub("\\$\\{" + $name + "\\}"; $uid) else . end);

    reduce (.__inputs // [])[] as $i (.; subst($i.name; dsuid($i.pluginId)))
    | del(.__inputs, .__requires)
    # Provisioned dashboards must not carry an id, or Grafana rejects them on collision
    # with whatever already occupies that id in its database.
    | .id = null
  '';

  fixup = name: src: runCommand "grafana-dashboard-${name}.json"
    { nativeBuildInputs = [ jq ]; }
    ''
      jq --arg prom ${lib.escapeShellArg dsUid.prometheus} \
         --arg loki ${lib.escapeShellArg dsUid.loki} \
         ${lib.escapeShellArg fixupProgram} < ${src} > "$out"
    '';

  fromGrafanaCom = { name, id, rev, hash }:
    fixup name (fetchurl {
      url = "https://grafana.com/api/dashboards/${toString id}/revisions/${toString rev}/download";
      inherit hash;
    });
in
{
  # https://grafana.com/grafana/dashboards/1860
  node-exporter-full = fromGrafanaCom {
    name = "node-exporter-full";
    id = 1860;
    rev = 45;
    hash = "sha256-GExrdAnzBtp1Ul13cvcZRbEM6iOtFrXXjEaY6g6lGYY=";
  };

  # https://grafana.com/grafana/dashboards/22604
  smartctl-exporter = fromGrafanaCom {
    name = "smartctl-exporter";
    id = 22604;
    rev = 2;
    hash = "sha256-ci8WE23fZ+ltEKFoUdNNVXsUIV0jqtas79ia2lYIo88=";
  };

  # Dashboard 15362 ("ZFS Pool Metrics") used to fill this slot. It is an *InfluxDB*
  # dashboard -- its queries are InfluxQL against a `zpool_stats` measurement -- so it
  # can never render against Prometheus, however it is provisioned. This is a
  # Prometheus-native replacement built on the metrics we actually export: node
  # exporter's zfs collector plus the ZFS textfile collector.
  # Generated by dashboards/gen_zfs.py.
  zfs-pools = fixup "zfs-pools" ../dashboards/zfs-pools.json;

  # CrystalDiskInfo-style per-drive SMART view. Generated by dashboards/gen_smart.py.
  # The Good/Caution/Bad verdict and the per-drive row titles both come from the
  # recording rules in rules/smartctl.yml, so this one needs those loaded to be useful.
  drive-health = fixup "drive-health" ../dashboards/smart.json;
}