{
  config,
  pkgs,
  lib,
  ...
}:
let
  cfg = config.services.matrix-synapse;
  federationSenders = lib.range 0 (cfg.federationSenders - 1);
in
{
  services.matrix-synapse = lib.mkIf (cfg.federationSenders > 0) {
    settings = {
      instance_map = lib.listToAttrs (
        lib.map (index: {
          name = "federation_sender-${toString index}";
          value = {
            path = "/run/matrix-synapse/federation_sender-${toString index}.sock";
          };
        }) federationSenders
      );
      send_federation = false;
      federation_sender_instances = lib.map (index: "federation_sender-${toString index}") federationSenders;
      outbound_federation_restricted_to = lib.map (index: "federation_sender-${toString index}") federationSenders;
      worker_replication_secret = "federation_sender_secret";
    };

    workers = lib.listToAttrs (
      lib.map (index: {
        name = "federation_sender-${toString index}";
        value = {
          worker_app = "synapse.app.generic_worker";
          worker_listeners = [
            {
              type = "http";
              path = "/run/matrix-synapse/federation_sender-${toString index}.sock";
              resources = [
                {
                  names = [ "replication" ];
                  compress = false;
                }
              ];
            }
          ];
        };
      }) federationSenders
    );
  };
}