{
  description = "A flake to install sTodo";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
  };

  outputs = {
    self,
    nixpkgs,
  }: let
    tarball = fetchTarball {
      url = "https://git.stuce.ch/stuce/sTodo/releases/download/Release1/release1.tar.gz";
      sha256 = "10jyldwmcs5zyz1k8lp3jscn7nhlvn56g0709l5jp91qimw7xiqz";
    };
  in {
    packages.x86_64-linux.sTodo = with nixpkgs.legacyPackages.x86_64-linux;
      stdenv.mkDerivation {
        pname = "sTodo";
        version = "1.0.0";
        src = tarball;
        buildInputs = [zlib gmp libffi openssl];
        installPhase = ''
          mkdir -p $out/bin
          cp $src/sTodo $out/bin
        '';
        mainProgram = "sTodo";
      };
    nixosModules.sTodo = {
      config,
      lib,
      pkgs,
      ...
    }: let
      cfg = config.services.sTodo;
    in {
      options.services.sTodo = {
        # options.programs.sTodo = {
        enable = lib.mkEnableOption "sTodo";
        package = lib.mkOption {
          type = lib.types.package;
          default = self.packages.x86_64-linux.sTodo;
        };
        appRoot = lib.mkOption {
          type = lib.types.str;
          default = "http://localhost:6901";
          description = "Link used to access the webapp";
        };
        clientSessionKey = lib.mkOption {
          type = lib.types.str;
          default = "/etc/sTodo/client_session_key.aes";
          description = "Location of the client session key";
        };

        port = lib.mkOption {
          type = lib.types.int;
          default = 6901;
          description = "Default port of the app";
        };
      };

      # Systemd Service
      config = lib.mkIf cfg.enable {
        environment.etc."sTodo" = {
          source = "${tarball.out}/config";
        };
        environment.systemPackages = [pkgs.openssl];

        systemd.services.sTodo.preStart = ''
          [ -f /etc/sTodo/client_session_key.aes ] || {
            "${pkgs.openssl}/bin/openssl" rand -base64 32 > /etc/sTodo/client_session_key.aes
          }
        '';
        systemd.services.sTodo = {
          description = "Launch a sTodo app to have a online todolist";
          after = ["network.target"];
          wantedBy = ["multi-user.target"];
          serviceConfig = {
            ExecStart = "${cfg.package}/bin/sTodo";
            Restart = "always";
          };
          environment = {
            YESOD_PORT = "${toString cfg.port}";
            YESOD_APPROOT = "${cfg.appRoot}";
            YESOD_SQLITE_DATABASE = "/etc/sTodo/sTodo.sqlite3";
            YESOD_STATIC_DIR = "/etc/sTodo/static";
            YESOD_SESSION_KEY = "/etc/sTodo/client_session_key.aes";
          };
        };
      };
    };
  };
}