nix-config/modules/nixos/network/default.nix

{
  config,
  lib,
  pkgs,
  namespace,
  ...
}:
with lib;
let
  cfg = config.${namespace}.network;

  profiles =
    let
      make =
        name: profile:
        nameValuePair "${name}" {
          connection = {
            id = name;
            type = profile.type;
            autoconnect = profile.autoconnect;
            autoconnect-retries = profile.autoconnect-retries;
            autoconnect-priority = profile.priority;
            interface-name = profile.interface or cfg.ipv4.interface;
          };
          ipv4 = {
            method = cfg.ipv4.method;
          }
          // (
            if (cfg.ipv4.method == "auto") then
              { }
            else
              {
                address = cfg.ipv4.address;
                gateway = cfg.ipv4.gateway;
                dns = cfg.ipv4.dns;
              }
          );
          ipv6 = {
            addr-gen-mode = "stable-privacy";
            method = "auto";
          };
          wifi = mkIf (profile.type == "wifi") {
            mode = "infrastructure";
            ssid = profile.ssid;
            roaming = "allowed";
          };
          wifi-security = mkIf (profile.type == "wifi") {
            key-mgmt = profile.keyMgmt;
            psk = profile.psk;
          };
        };

      userProfiles = mapAttrs' make cfg.networkmanager.profiles;

      # When using manual IP with NM enabled, auto-generate an ethernet profile
      # so NM actually assigns the static address (not just DHCP).
      ethernetProfile =
        optionalAttrs (cfg.ipv4.method == "manual" && cfg.ipv4.interface != "" && cfg.networkmanager.enable)
          {
            "static-${cfg.ipv4.interface}" = {
              connection = {
                id = "static-${cfg.ipv4.interface}";
                type = "ethernet";
                autoconnect = true;
                interface-name = cfg.ipv4.interface;
              };
              ipv4 = {
                method = "manual";
                address = cfg.ipv4.address;
                gateway = cfg.ipv4.gateway;
                dns = cfg.ipv4.dns;
              };
              ipv6 = {
                addr-gen-mode = "stable-privacy";
                method = "auto";
              };
            };
          };
    in
    userProfiles // ethernetProfile;
in
{
  imports = [
    ./options.nix
  ];

  config = {
    assertions = [
      {
        assertion = cfg.hostName != "";
        message = "mjallen.network.hostName must be set to a non-empty string.";
      }
      {
        assertion = cfg.ipv4.method == "auto" || cfg.ipv4.method == "manual";
        message = "mjallen.network.ipv4.method must be either \"auto\" or \"manual\" (got \"${cfg.ipv4.method}\").";
      }
      {
        assertion = cfg.ipv4.method != "manual" || cfg.ipv4.interface != "";
        message = "mjallen.network.ipv4.interface must be set when ipv4.method is \"manual\".";
      }
      {
        assertion = cfg.ipv4.method != "manual" || cfg.ipv4.address != "";
        message = "mjallen.network.ipv4.address must be set when ipv4.method is \"manual\".";
      }
      {
        assertion = cfg.ipv4.method != "manual" || cfg.ipv4.gateway != "";
        message = "mjallen.network.ipv4.gateway must be set when ipv4.method is \"manual\".";
      }
      {
        assertion = cfg.nat.enable -> cfg.nat.externalInterface != "";
        message = "mjallen.network.nat.externalInterface must be set when NAT is enabled.";
      }
    ];

    systemd = {
      services = {
        NetworkManager-wait-online.enable = false;
        systemd-networkd-wait-online.enable = lib.mkForce false;
        systemd-networkd.stopIfChanged = false;
        systemd-resolved.stopIfChanged = false;
      };
      network.wait-online.enable = false;
    };

    # Restrict Avahi to the configured LAN interface when one is explicitly set.
    # This prevents Avahi from announcing on virtual/container interfaces (veth*,
    # podman0, virbr0, etc.) which causes hostname conflicts and suffix mangling
    # (e.g. "jallen-nas-4.local" instead of "jallen-nas.local").
    services.avahi = lib.mkIf (cfg.ipv4.interface != "") {
      allowInterfaces = [ cfg.ipv4.interface ];
    };

    networking = {
      hostName = lib.mkForce cfg.hostName;

      # Use networkd if enabled
      useNetworkd = lib.mkDefault true;

      # Set default gateway and nameservers if in manual mode
      defaultGateway = lib.mkIf (cfg.ipv4.method == "manual") {
        address = cfg.ipv4.gateway;
        interface = lib.mkIf (cfg.ipv4.interface != "") cfg.ipv4.interface;
      };

      nameservers = lib.mkIf (cfg.ipv4.method == "manual") [ cfg.ipv4.dns ];

      # Set hostId if provided
      hostId = lib.mkIf (cfg.hostId != "") cfg.hostId;

      # Configure NAT if enabled
      nat = lib.mkIf cfg.nat.enable {
        enable = true;
        internalInterfaces = cfg.nat.internalInterfaces;
        externalInterface = cfg.nat.externalInterface;
        enableIPv6 = cfg.nat.enableIPv6;
      };

      # Configure firewall
      firewall = {
        enable = cfg.firewall.enable;
        allowPing = cfg.firewall.allowPing;
        allowedTCPPorts = cfg.firewall.allowedTCPPorts;
        allowedUDPPorts = cfg.firewall.allowedUDPPorts;
        trustedInterfaces = cfg.firewall.trustedInterfaces;

        # Default port ranges for KDE Connect
        allowedTCPPortRanges = lib.mkIf cfg.firewall.kdeConnect.enable [
          {
            from = cfg.firewall.kdeConnect.tcpRange.from;
            to = cfg.firewall.kdeConnect.tcpRange.to;
          }
        ];
        allowedUDPPortRanges = lib.mkIf cfg.firewall.kdeConnect.enable [
          {
            from = cfg.firewall.kdeConnect.udpRange.from;
            to = cfg.firewall.kdeConnect.udpRange.to;
          }
        ];

        # Extra firewall commands
        extraCommands = lib.mkIf (cfg.extraFirewallCommands != "") cfg.extraFirewallCommands;
      };

      # Enable iwd daemon when requested.
      # When iwd is enabled alongside NetworkManager, iwd acts as the WiFi
      # backend for NM (iwd handles scanning/association; NM handles
      # connection management).  They are not mutually exclusive.
      wireless.iwd = lib.mkIf cfg.iwd.enable {
        enable = true;
        settings = cfg.iwd.settings;
      };

      # Configure NetworkManager when enabled
      networkmanager = mkIf cfg.networkmanager.enable {
        enable = true;
        # Use iwd as the WiFi backend when iwd is also enabled
        wifi.backend = mkIf cfg.iwd.enable "iwd";
        wifi.powersave = cfg.networkmanager.powersave;
        settings.connectivity.uri = "http://nmcheck.gnome.org/check_network_status.txt";
        plugins = with pkgs; [
          networkmanager-fortisslvpn
          networkmanager-iodine
          networkmanager-l2tp
          networkmanager-openconnect
          networkmanager-openvpn
          networkmanager-sstp
          networkmanager-strongswan
          networkmanager-vpnc
        ];

        # Configure profiles if any are defined
        ensureProfiles = mkIf (profiles != { }) {
          environmentFiles = lib.optional (config.sops.secrets ? wifi) config.sops.secrets.wifi.path;
          profiles = profiles;
        };
      };
    };
  };
}