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

with lib;
let

in {
  options = {
    enable = mkEnableOption "Enable Fudo Paris user server.";

    state-directory = mkOption {
      type = str;
      description = "Directory at which to store server state.";
    };

    networking = {
      interface = mkOption {
        type = str;
        description = "Parent host interface on which to listen.";
      };

      ipv4 = mkOption {
        type = nullOr (submodule {
          options = {
            address = mkOption {
              type = str;
              description = "IP address.";
            };
            prefixLength = mkOption {
              type = int;
              description = "Significant bits in the address.";
            };
          };
        });
        default = null;
      };

      ipv6 = mkOption {
        type = nullOr (submodule {
          options = {
            address = mkOption {
              type = str;
              description = "IP address.";
            };
            prefixLength = mkOption {
              type = int;
              description = "Significant bits in the address.";
            };
          };
        });
        default = null;
      };
    };
  };

  config = {
    systemd.tmpfiles.rules =
      [ "d ${cfg.state-directory}/home 0700 root root - -" ];

    containers.paris = {
      tmpfs = true;
      macvlans = [ cfg.networking.interface ];
      bindMounts = {
        "/home" = {
          hostPath = "${cfg.state-directory}/home";
          isReadOnly = false;
        };
      };
      additionalCapabilities = [ "CAP_NET_ADMIN" ];
      config = {
        nixpkgs.pkgs = pkgs;

        environment.systemPackages = with pkgs; [ rtorrent ];

        networking = {
          defaultGateway = {
            address = getSiteGatewayV4 siteName;
            interface = "mv-${cfg.networking.interface}";
          };
          enableIPv6 = !isNull cfg.networking.ipv6;
          nameservers = config.networking.nameservers;
          firewall = {
            enable = true;
            allowedTCPPorts = [ 22 ] ++ cfg.ports;
          };
          interfaces."mv-${cfg.networking.interface}" = {
            ipv4.addresses = optional (!isNull cfg.networking.ipv4) {
              address = cfg.networking.ipv4.address;
              prefixLength = cfg.networking.ipv4.prefixLength;
            };
            ipv6.addresses = optional (!isNull cfg.networking.ipv6) {
              address = cfg.networking.ipv6.address;
              prefixLength = cfg.networking.ipv6.prefixLength;
            };
          };
        };
      };
    };
  };
}