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

{
  options.services.backrest = {
    enable = lib.mkEnableOption "Backrest web UI for restic backup";

    port = lib.mkOption {
      type = lib.types.port;
      default = 9898;
      description = "Port for the Backrest web UI";
    };

    host = lib.mkOption {
      type = lib.types.str;
      default = "127.0.0.1";
      description = "Address to bind Backrest to";
    };

    dataDir = lib.mkOption {
      type = lib.types.path;
      default = "/var/lib/backrest";
      description = "Directory for Backrest config and data";
    };

    openFirewall = lib.mkOption {
      type = lib.types.bool;
      default = false;
      description = "Open the firewall for the Backrest web UI";
    };
  };

  config = lib.mkIf config.services.backrest.enable {
    systemd.tmpfiles.rules = [
      "d ${config.services.backrest.dataDir} 0700 backrest backrest -"
    ];

    users.users.backrest = {
      isSystemUser = true;
      group = "backrest";
      home = config.services.backrest.dataDir;
      createHome = true;
    };

    users.groups.backrest = { };

    systemd.services.backrest = {
      description = "Backrest web UI for restic backup";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" ];
      serviceConfig = {
        Type = "simple";
        User = "backrest";
        Group = "backrest";
        ExecStart = ''
          ${pkgs.backrest}/bin/backrest \
            -bind-address ${config.services.backrest.host}:${toString config.services.backrest.port} \
            -data-dir ${config.services.backrest.dataDir} \
            -restic-cmd ${pkgs.restic}/bin/restic
        '';
        Restart = "on-failure";
      };
    };

    networking.firewall.allowedTCPPorts = lib.mkIf config.services.backrest.openFirewall [
      config.services.backrest.port
    ];
  };
}