# SPDX-FileCopyrightText: 2024 Lubin Bailly <lubin.bailly@dgnum.eu>
#
# SPDX-License-Identifier: EUPL-1.2

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

let
  inherit (lib) mapAttrs' mkOption nameValuePair;
  inherit (lib.types) listOf attrs;

  uplink = {
    ip = "10.120.33.250";
    prefix = 30;

    router = "10.120.33.249";
  };

  mkNetwork =
    name:
    {
      address ? [ ],
      extraNetwork ? { },
      ...
    }:
    nameValuePair "10-${name}" ({ inherit name address; } // extraNetwork);

  mkNetdev =
    name:
    { Id, ... }:
    nameValuePair "10-${name}" {
      netdevConfig = {
        Name = name;
        Kind = "vlan";
      };
      vlanConfig.Id = Id;
    };

  mkUserVlan =
    {
      vlan,
      netIP,
      servIP,
      interfaceName,
      ...
    }:
    {
      name = interfaceName;
      value = {
        Id = vlan;
        extraNetwork = {
          networkConfig = {
            LinkLocalAddressing = "no";
            DHCPServer = "yes";
          };
          linkConfig = {
            Promiscuous = true;
            MTUBytes = 1500;
          };
          addresses = [
            {
              Address = "${servIP}/27";
              AddPrefixRoute = false;
            }
          ];
          routes = [
            {
              Destination = "${netIP}/27";
              Table = "user";
            }
          ];
        };
      };
    };

  userVlans = builtins.genList (id: rec {
    vlan = 4094 - id;
    prefix24nb = (id + 1) / 8;
    prefix27nb = (id + 1 - prefix24nb * 8) * 32;
    netIP = "10.0.${toString prefix24nb}.${toString prefix27nb}";
    servIP = "10.0.${toString prefix24nb}.${toString (prefix27nb + 1)}";
    interfaceName = "vlan-user-${toString vlan}";
    prefixLen = 27;
  }) 850;

  vlans = {
    vlan-uplink-cri = {
      Id = 223;
      address = with uplink; [ "${ip}/${builtins.toString prefix}" ];

      extraNetwork = {
        routes = [
          {
            # Get the public ip from the metadata
            PreferredSource = builtins.head meta.network.${name}.addresses.ipv4;
            Gateway = uplink.router;
          }
        ];
        linkConfig.MTUBytes = 1500;
      };
    };

    vlan-admin = {
      Id = 3000;
      address = [ "fd26:baf9:d250:8000::1/64" ];
    };

    vlan-admin-ap = {
      Id = 3001;
      address = [
        "fd26:baf9:d250:8001::1/64"
        # FIXME: ipv4 is temporary for APs in production
        "10.0.253.1/24"
      ];
      extraNetwork = {
        networkConfig = {
          IPv6SendRA = true;
          DHCPServer = "yes";
        };
        ipv6Prefixes = [
          {
            AddressAutoconfiguration = false;
            OnLink = false;
            Prefix = "fd26:baf9:d250:8001::/64";
          }
        ];
      };
    };

    vlan-apro = {
      Id = 2000;
      address = [ "10.0.255.1/24" ];

      extraNetwork = {
        networkConfig.DHCPServer = "yes";
        linkConfig.MTUBytes = 1500;
      };
    };

    vlan-hypervisor = {
      Id = 2001;
      address = [ "10.0.254.1/24" ];

      extraNetwork = {
        networkConfig.DHCPServer = "yes";
        linkConfig.MTUBytes = 1500;
      };
    };
  } // builtins.listToAttrs (map mkUserVlan userVlans);
in
{
  options.networking.vlans-info = mkOption {
    type = listOf attrs;
    description = ''
      Information about vlans for log analysis.
    '';
    readOnly = true;
  };
  config = {
    systemd = {
      network = {
        config.routeTables."user" = 1000;
        networks = {
          "10-lo" = {
            name = "lo";
            address = [
              "::1/128"
              "127.0.0.1/8"
              "10.0.0.1/27"
            ];
            routes = [
              {
                Destination = "10.0.0.0/27";
                Table = "user";
              }
            ];
            routingPolicyRules = [
              {
                To = "10.0.0.0/16";
                Table = "user";
              }
            ];
          };
          "10-enp67s0f0np0" = {
            name = "enp67s0f0np0";
            linkConfig.Promiscuous = true;
            networkConfig = {
              Bridge = "br0";

              LinkLocalAddressing = false;
              LLDP = false;
              EmitLLDP = false;
              IPv6AcceptRA = false;
              IPv6SendRA = false;
            };
            linkConfig.MTUBytes = 1504;
          };
          "50-gretap1" = {
            name = "gretap1";
            networkConfig = {
              Bridge = "br0";

              LinkLocalAddressing = false;
              LLDP = false;
              EmitLLDP = false;
              IPv6AcceptRA = false;
              IPv6SendRA = false;
            };
            linkConfig.MTUBytes = 1504;
          };
          "50-br0" = {
            name = "br0";
            networkConfig = {
              VLAN = builtins.attrNames vlans;

              LinkLocalAddressing = false;
              LLDP = false;
              EmitLLDP = false;
              IPv6AcceptRA = false;
              IPv6SendRA = false;
            };
            linkConfig.MTUBytes = 1504;
          };
          "50-wg0" = {
            name = "wg0";
            address = [ "10.10.17.1/30" ];
            networkConfig.Tunnel = "gretap1";
          };
        } // (mapAttrs' mkNetwork vlans);

        netdevs = {
          "50-gretap1" = {
            netdevConfig = {
              Name = "gretap1";
              Kind = "gretap";
            };
            tunnelConfig = {
              Local = "10.10.17.1";
              Remote = "10.10.17.2";
            };
          };
          "50-br0" = {
            netdevConfig = {
              Name = "br0";
              Kind = "bridge";
            };
            bridgeConfig = {
              VLANFiltering = false;
              STP = false;
            };
          };
          "50-wg0" = {
            netdevConfig = {
              Name = "wg0";
              Kind = "wireguard";
            };
            wireguardConfig = {
              ListenPort = 1194;
              PrivateKeyFile = config.age.secrets."wg-key".path;
            };

            wireguardPeers = [
              {
                AllowedIPs = [
                  "10.10.17.0/30"
                ];
                PublicKey = "g6S3gBx1Hf2iX41tokD+m8WfzJJTTcsKifOkn+Wcd00=";
              }
            ];
          };
        } // mapAttrs' mkNetdev vlans;
      };

      services = {
        ethtoolConfig = {
          wantedBy = [ "systemd-networkd.service" ];
          after = [ "sys-subsystem-net-devices-enp67s0f0np0.device" ];
          bindsTo = [ "sys-subsystem-net-devices-enp67s0f0np0.device" ];
          script = builtins.concatStringsSep "\n" (
            builtins.map (name: "${lib.getExe pkgs.ethtool} -K enp67s0f0np0 ${name} off") [
              "rxvlan"
              "txvlan"
              "rx-vlan-filter"
              "rx-vlan-offload"
              "tx-vlan-offload"
              "tx-vlan-stag-hw-insert"
            ]
          );
        };

        systemd-networkd.serviceConfig.LimitNOFILE = 4096;

        net-checker = {
          path = [
            pkgs.iputils
            pkgs.systemd
          ];
          script = ''
            if ping -c 1 8.8.8.8 > /dev/null || ping -c 1 1.1.1.1 > /dev/null; then
              ${lib.concatMapStringsSep "\n  " (
                { interfaceName, ... }: "networkctl up ${interfaceName}"
              ) userVlans}
            else
              ${lib.concatMapStringsSep "\n  " (
                { interfaceName, ... }: "networkctl down ${interfaceName}"
              ) userVlans}
            fi
          '';
        };
      };

      timers.net-checker = {
        wantedBy = [ "timers.target" ];
        timerConfig.OnCalendar = "*-*-* *:*:42";
      };
    };

    networking = {
      vlans-info = [
        {
          vlan = 2001;
          netIP = "10.0.254.0";
          prefixLen = 24;
        }
        {
          vlan = 3001;
          netIP = "10.0.253.0";
          prefixLen = 24;
        }
      ] ++ userVlans;
      nftables = {
        enable = true;
        tables = {
          nat = {
            family = "ip";
            content = ''
              chain postrouting {
                type nat hook postrouting priority 100;
                ip saddr 10.0.0.0/16 ip daddr != 10.0.0.0/16 snat ip to 129.199.195.130-129.199.195.157
              }
            '';
          };
          filter = {
            family = "inet";
            content = ''
              chain forward {
                type filter hook forward priority filter; policy accept;
                ct state vmap {
                  invalid: drop,
                  established: accept,
                  related: accept,
                  new: jump forward_decide,
                  untracked: jump forward_decide,
                };
              }
              chain forward_decide {
                # Block access to vpn
                ip daddr {
                  10.10.17.0/30,
                  100.80.0.0/16,
                } jump forward_reject;

                # And administrative vlans
                ip6 daddr {
                  fd26:baf9:d250::/48,
                } jump forward_reject;

                # These are being deployed, and so are not trusted
                ip saddr 10.0.255.0/24 jump forward_reject;

                # We only forward for ISP clients and our stuff
                ip saddr != 10.0.0.0/16 jump forward_reject;

                # Can talk to us
                ip daddr 10.0.0.0/27 accept;

                # Not others nor CRI
                ip daddr 10.0.0.0/8 jump forward_reject;
              }
              chain forward_reject {
                reject with icmpx type admin-prohibited;
              }
            '';
          };
        };
      };
      firewall = {
        allowedUDPPorts = [
          67
          1194
        ];
        # FIXME: I dont't remember why it's here, and it doesn't seems right
        # comes from https://git.dgnum.eu/DGNum/infrastructure/commit/411795c664374549e5e831722a80180b51fbf0d5
        # checkReversePath = false;
      };
    };

    age.secrets."wg-key".owner = "systemd-network";
    users.users."systemd-network".extraGroups = [ "keys" ];

    boot.kernel.sysctl."net.ipv4.ip_forward" = true;
  };
}