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

let
  endpoint = "116.203.26.228";
in
{
  networking = {
    domain = ".vapor.systems";
    hostName = "mail";
    dhcpcd.enable = false;
    interfaces.eth0 = {
      ipv4 = {
        addresses = [
          {
            address = "116.203.26.228";
            prefixLength = 32;
          }
        ];

        routes = [
          {
            address = "172.31.1.1";
            prefixLength = 32;
          }
        ];
      };
      ipv6 = {
        addresses = [
          {
            address = "2a01:4f8:1c1c:3ce7::1";
            prefixLength = 64;
          }
          {
            address = "fe80::9000:6ff:fe53:14ce";
            prefixLength = 64;
          }
        ];

        routes = [
          {
            address = "fe80::1";
            prefixLength = 128;
          }
        ];
      };
    };

    defaultGateway = "172.31.1.1";
    defaultGateway6 = {
      address = "fe80::1";
      interface = "eth0";
    };
  };

  pubKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPVwt+/sB77NZnjwqgwtkcqKsIYyMnYh5qlqYoY9dLEd";

  wireguard = {
    enable = true;
    inherit endpoint;
    v4 = {
      address = "10.10.0.6";
    };
    v6 = {
      address = "6";
    };
    publicKey = "lk0mN1R5Uf5iwvWe/4mOmrMap7xtsieQaJSHcXQ7+VY=";
    allowedIPs = [ ];
  };

  services.kopia = {
    enable = true;
    instances = {
      b2 = {
        enable = true;
        environmentFile = config.secrets.b2.dest;
        repository.b2.bucket = "mail-vapor-systems";

        snapshots = {
          schedule = "daily";
          paths = [
            "/var/lib/stalwart-mail"
          ];
        };

        policy = [{
          retention = {
            keepLatest = 5;
            keepDaily = 30;
            keepWeekly = 4;
            keepMonthly = 3;
            keepAnnual = 0;
          };
        }];
      };
    };
  };

  secrets = {
    b2 = {
      source = ../../secrets/backup/mail.vapor.systems.env;
      dest = "/etc/secrets/b2.env";
    };
  };

  deploy = {
    host = endpoint;
    sshUser = "audron";
    buildOn = "remote";
    substituteOnTarget = true;
    hermetic = false;
  };

  # System state version
  system.stateVersion = "25.05";
}