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

let
  cfg = config.services.otf;
in
{
  options.services.otf = {
    enable = lib.mkEnableOption "Open Terraform Framework";
    # It is important to expose the datadirectory to the user so we make it a reusable option
    dataDir = lib.mkOption {
      type = lib.types.str;
      default = "/var/lib/otf";
      description = "Directory to store OTF data.";
    };
    package = lib.mkPackageOption pkgs "otf" { };
    pgPackage = lib.mkPackageOption pkgs "postgresql_16" { };
    environmentFile = lib.mkOption {
      type = with lib.types; nullOr path;
      default = lib.types.null;
    };
    # this application is configured entirely by environment variables and needs to be exposed
    environment = lib.mkOption {
      type =
        with lib.types;
        attrsOf (
          nullOr (oneOf [
            str
            path
            package
          ])
        );
      default = {
        OTF_ADDRESS = "localhost:9000";
        # OTF_SITE_TOKEN = "my-token";
        # OTF_SSL = "false";
        # OTF_SECRET = "";
        # OTF_CERT_FILE = "";
        # OTF_KEY_FILE = "";
      };
      description = "Environment variables for the OTF service.";
    };
  };

  config = lib.mkIf cfg.enable {
    # it is best for this project to have a dedicated user for database access
    users.groups.otf = { };
    users.users.otf = {
      isSystemUser = true;
      home = cfg.dataDir;
      createHome = true;
      group = "otf";
    };

    services.postgresql = {
      enable = true;
      # this lets us set the package
      # TODO: expose to end user
      package = cfg.pgPackage;
      # This enabled autoconfig of both a database and a user of the same name
      ensureDatabases = [ "otf" ];
      ensureUsers = [
        {
          name = "otf";
          ensureDBOwnership = true;
        }
      ];
    };

    systemd.services.otf = {
      description = "Open Terraform Framework";
      after = [
        "network.target"
        "postgresql.service"
      ];
      requires = [ "postgresql.service" ];
      wantedBy = [ "multi-user.target" ];
      inherit (cfg) environment;
      serviceConfig = {
        User = "otf";
        Group = "otf";
        WorkingDirectory = cfg.dataDir;
        ExecStart = "${cfg.package}/bin/otfd";
        Restart = "on-failure";
        EnvironmentFile = lib.mkIf (cfg.environmentFile != null) cfg.environmentFile;
      };
    };
  };
}