# SPDX-FileCopyrightText: 2020 Luke Granger-Brown <depot@lukegb.com>
#
# SPDX-License-Identifier: Apache-2.0

{ lib, config, pkgs, ... }:
with lib;
let
  notifyBird = pkgs.writeScript "blade-router-vrrp-bird.sh" ''
    #!${pkgs.runtimeShell}

    ENDSTATE=$3
    NAME=$2
    TYPE=$1

    BIRDC=${pkgs.bird2}/bin/birdc

    case $ENDSTATE in
        "MASTER") $BIRDC enable export4
                  $BIRDC enable export6
                  exit 0
                  ;;
        *)        $BIRDC disable export4
                  $BIRDC disable export6
                  exit 0
                  ;;
    esac
  '';
in {
  imports = [
    ../lib/bgp.nix
  ];

  options.my.blade-router = {
    addresses.linknet.v4 = {
      local = mkOption { type = types.str; };
      remote = mkOption { type = types.str; };
      prefixLength = mkOption { type = types.int; default = 31; };
    };
    addresses.linknet.v6 = {
      local = mkOption { type = types.str; };
      remote = mkOption { type = types.str; };
      prefixLength = mkOption { type = types.int; default = 126; };
    };

    addresses.br-public.v4 = {
      addr = mkOption { type = types.str; };
      prefixLength = mkOption { type = types.int; default = 24; };
    };
    addresses.br-public.v6 = {
      addr = mkOption { type = types.str; };
      prefixLength = mkOption { type = types.int; default = 48; };
    };

    addresses.br-public-vip.v4 = {
      addr = mkOption { type = types.str; default = "92.118.28.1"; };
      prefixLength = mkOption { type = types.int; default = 24; };
    };
    addresses.br-public-vip.v6 = {
      addr = mkOption { type = types.str; default = "2a09:a441::1"; };
      prefixLength = mkOption { type = types.int; default = 48; };
    };
    addresses.br-public-vip.v6-ll = {
      addr = mkOption { type = types.str; default = "fe80::f00f"; };
      prefixLength = mkOption { type = types.int; default = 64; };
    };

    addresses.br-public-radvd-prefix = {
      addr = mkOption { type = types.str; default = "2a09:a441:0:ffff::"; };
      prefixLength = mkOption { type = types.int; default = 64; };
    };

    vrrp.priority = mkOption { type = types.int; };
  };

  config = {
    boot.kernel.sysctl."net.ipv4.ip_forward" = 1;
    boot.kernel.sysctl."net.ipv6.conf.all.forwarding" = 1;

    networking = {
      interfaces.br-public.ipv4.addresses = [{
        address = config.my.blade-router.addresses.br-public.v4.addr;
        prefixLength = config.my.blade-router.addresses.br-public.v4.prefixLength;
      }];
      interfaces.br-public.ipv6.addresses = [{
        address = config.my.blade-router.addresses.br-public.v6.addr;
        prefixLength = config.my.blade-router.addresses.br-public.v6.prefixLength;
      }];
      interfaces.en-internet.ipv4.addresses = [{
        address = config.my.blade-router.addresses.linknet.v4.local;
        prefixLength = config.my.blade-router.addresses.linknet.v4.prefixLength;
      }];
      interfaces.en-internet.ipv6.addresses = [{
        address = config.my.blade-router.addresses.linknet.v6.local;
        prefixLength = config.my.blade-router.addresses.linknet.v6.prefixLength;
      }];
      defaultGateway = config.my.blade-router.addresses.linknet.v4.remote;
      defaultGateway6 = config.my.blade-router.addresses.linknet.v6.remote;
      firewall.extraCommands = ''
        iptables -A INPUT -p vrrp -i br-mgmt -j ACCEPT
        ip6tables -A INPUT -p vrrp -i br-mgmt -j ACCEPT
      '';
    };

    services.lukegbgp = {
      enable = true;
      config = {
        local.routerID = config.my.blade-router.addresses.linknet.v4.local;
        peering.veloxserv = {
          local = {
            asn = 205479;
            v4 = config.my.blade-router.addresses.linknet.v4.local;
            v6 = config.my.blade-router.addresses.linknet.v6.local;
          };
          remote = {
            asn = 3170;
            export_community = 4001;
            routers = [{
              v4 = config.my.blade-router.addresses.linknet.v4.remote;
              v6 = config.my.blade-router.addresses.linknet.v6.remote;
            }];
          };
        };
        export.v4 = [ "92.118.28.0/24" ];
        export.v6 = [ "2a09:a441::/32" ];
      };
    };

    services.keepalived = let
      mgmtBase = {
        interface = "br-mgmt";
        state = "MASTER";
        priority = config.my.blade-router.vrrp.priority;
      };
    in {
      enable = true;
      vrrpInstances.mgmtGateway4 = mgmtBase // {
        virtualIps = [
          { addr = "10.100.0.1/23"; }
          { addr = "${config.my.blade-router.addresses.br-public-vip.v4.addr}/${toString config.my.blade-router.addresses.br-public-vip.v4.prefixLength}"; dev = "br-public"; }
        ];
        virtualRouterId = 1;
      };
      vrrpInstances.mgmtGateway6 = mgmtBase // {
        virtualIps = [
          { addr = "${config.my.blade-router.addresses.br-public-vip.v6-ll.addr}/${toString config.my.blade-router.addresses.br-public-vip.v6-ll.prefixLength}"; dev = "br-public"; }
          { addr = "${config.my.blade-router.addresses.br-public-vip.v6.addr}/${toString config.my.blade-router.addresses.br-public-vip.v6.prefixLength}"; dev = "br-public"; }
        ];
        virtualRouterId = 2;
      };
      extraGlobalDefs = ''
        enable_script_security
        script_user root
      '';
      extraConfig = ''
        vrrp_sync_group mgmtGateway {
          group {
            mgmtGateway4
            mgmtGateway6
          }
          notify ${notifyBird} bird2
        }
      '';
    };
  
    services.radvd = {
      enable = true;
      config = ''
        interface br-public {
          AdvSendAdvert on;
          MinRtrAdvInterval 30;
          MaxRtrAdvInterval 100;
          AdvRASrcAddress {
            ${config.my.blade-router.addresses.br-public-vip.v6-ll.addr};
          };
          prefix ${config.my.blade-router.addresses.br-public-radvd-prefix.addr}/${toString config.my.blade-router.addresses.br-public-radvd-prefix.prefixLength} {
            AdvOnLink on;
            AdvAutonomous on;
            AdvRouterAddr off;
          };
        };
      '';
    };
  };
}