{ config, lib, ... }:
with lib;
with types;
let
  cfg = config.components.monitor.promtail;
in
{
  options.components.monitor.promtail = {
    enable = mkOption {
      type = lib.types.bool;
      default = config.components.monitor.enable;
    };
    port = mkOption {
      type = int;
      default = 3500;
      description = "port to provide promtail export";
    };
  };

  config = mkMerge [

    (mkIf config.components.monitor.promtail.enable {

      services.opentelemetry-collector.settings = {
        receivers.loki = {
          protocols.http.endpoint = "127.0.0.1:${toString cfg.port}";
          use_incoming_timestamp = true;
        };
        service.pipelines.logs.receivers = [ "loki" ];
      };

      services.promtail = {
        enable = true;
        configuration = {
          server = {
            http_listen_port = 28183;
            grpc_listen_port = 0;
          };

          positions.filename = "/tmp/positions.yaml";
          clients = [
            { url = "http://127.0.0.1:${toString cfg.port}/loki/api/v1/push"; }
          ];

          scrape_configs = [
            {
              job_name = "journal";
              journal = {
                max_age = "12h";
              };
              relabel_configs = [
                {
                  source_labels = [ "__journal__systemd_unit" ];
                  target_label = "unit";
                }
                {
                  source_labels = [ "__journal__transport" ];
                  target_label = "transport";
                }
              ];
            }
          ];
        };
      };
    })
  ];
}