{ config, lib, pkgs, ... }:

with lib;

let

  cfg = config.graylog.pipeline;

in {

  options.graylog.pipeline = mkOption {
    default = {};
    type = with types; attrsOf (submodule ({ name , ... }: {
      options = {
        name = mkOption {
          type = with types; str;
          default = name;
          description = ''
            name of the pipeline
          '';
        };
        streamId = mkOption {
          type = with types; nullOr str;
          default = null;
          example = "000000000000000001";
          description = ''
            stream id on which this pipeline should operate
            dont use terraform references here.
          '';
        };
        description = mkOption {
          type = with types; str;
          default = "";
          description = ''
            description of the pipeline
          '';
        };
        # todo : create proper module system here
        source = mkOption {
          type = with types; str;
          description = ''
            source of the pipeline (without the header and the end)
          '';
        };
      };
    }));
  };

  config =
    let
      allPipelines = cfg;
      allPipelineConnections = mapAttrsToList (
        name: values:
        {
          "${values.streamId}" = "\${graylog_pipeline.${name}.id}";
        }
      ) (filterAttrs(name: values: values.streamId != null) allPipelines);
      collected = foldAttrs (n: a: [n] ++ a) [] allPipelineConnections;
    in
    mkIf (cfg != {}) {

      # create pipelines
      resource."graylog_pipeline" =
        mapAttrs (
          name: pipelineConfig:
          {
            source = ''
              pipeline "${pipelineConfig.name}"
              ${pipelineConfig.source}
              end
            '';
            description = pipelineConfig.description;
          }
        )
        allPipelines;

        resource."graylog_pipeline_connection" =
          let
            mapping = filter (
              name:
              builtins.match ".*\\$.*" name != null
            ) (builtins.attrNames collected);
          in

          mkAssert ( mapping == [] )
          ''
            graylog.pipeline.<name>.streamId =
              ${concatStringsSep "\n  " mapping}
            is not valid.

            use graylog.stream.<name>.pipelines instead
          ''
          (mapAttrs (
            name: pipelineConfig:
            {
              stream_id = name;
              pipeline_ids = pipelineConfig;
            }
          )
          collected);


    };

}