{ config, lib, ... }:
let
  inherit (lib)
    mkOption
    mkEnableOption
    types;

  cfg = config.microvm;

  intToHex = int:
    {
      "0" = "00";
      "1" = "01";
      "2" = "02";
      "3" = "03";
      "4" = "04";
      "5" = "05";
      "6" = "06";
      "7" = "07";
      "8" = "08";
      "9" = "09";
      "10" = "0a";
      "11" = "0b";
      "12" = "0c";
      "13" = "0d";
      "14" = "0e";
      "15" = "0f";
      "16" = "10";
      "17" = "11";
      "18" = "12";
      "19" = "13";
      "20" = "14";
      "21" = "15";
      "22" = "16";
      "23" = "17";
      "24" = "18";
      "25" = "19";
      "26" = "1a";
      "27" = "1b";
      "28" = "1c";
      "29" = "1d";
      "30" = "1e";
      "31" = "1f";
      "32" = "20";
      "33" = "21";
      "34" = "22";
      "35" = "23";
      "36" = "24";
      "37" = "25";
      "38" = "26";
      "39" = "27";
      "40" = "28";
      "41" = "29";
      "42" = "2a";
      "43" = "2b";
      "44" = "2c";
      "45" = "2d";
      "46" = "2e";
      "47" = "2f";
      "48" = "30";
      "49" = "31";
      "50" = "32";
      "51" = "33";
      "52" = "34";
      "53" = "35";
      "54" = "36";
      "55" = "37";
      "56" = "38";
      "57" = "39";
      "58" = "3a";
      "59" = "3b";
      "60" = "3c";
      "61" = "3d";
      "62" = "3e";
      "63" = "3f";
      "64" = "40";
      "65" = "41";
      "66" = "42";
      "67" = "43";
      "68" = "44";
      "69" = "45";
      "70" = "46";
      "71" = "47";
      "72" = "48";
      "73" = "49";
      "74" = "4a";
      "75" = "4b";
      "76" = "4c";
      "77" = "4d";
      "78" = "4e";
      "79" = "4f";
      "80" = "50";
      "81" = "51";
      "82" = "52";
      "83" = "53";
      "84" = "54";
      "85" = "55";
      "86" = "56";
      "87" = "57";
      "88" = "58";
      "89" = "59";
      "90" = "5a";
      "91" = "5b";
      "92" = "5c";
      "93" = "5d";
      "94" = "5e";
      "95" = "5f";
      "96" = "60";
      "97" = "61";
      "98" = "62";
      "99" = "63";
      "100" = "64";
      "101" = "65";
      "102" = "66";
      "103" = "67";
      "104" = "68";
      "105" = "69";
      "106" = "6a";
      "107" = "6b";
      "108" = "6c";
      "109" = "6d";
      "110" = "6e";
      "111" = "6f";
      "112" = "70";
      "113" = "71";
      "114" = "72";
      "115" = "73";
      "116" = "74";
      "117" = "75";
      "118" = "76";
      "119" = "77";
      "120" = "78";
      "121" = "79";
      "122" = "7a";
      "123" = "7b";
      "124" = "7c";
      "125" = "7d";
      "126" = "7e";
      "127" = "7f";
      "128" = "80";
      "129" = "81";
      "130" = "82";
      "131" = "83";
      "132" = "84";
      "133" = "85";
      "134" = "86";
      "135" = "87";
      "136" = "88";
      "137" = "89";
      "138" = "8a";
      "139" = "8b";
      "140" = "8c";
      "141" = "8d";
      "142" = "8e";
      "143" = "8f";
      "144" = "90";
      "145" = "91";
      "146" = "92";
      "147" = "93";
      "148" = "94";
      "149" = "95";
      "150" = "96";
      "151" = "97";
      "152" = "98";
      "153" = "99";
      "154" = "9a";
      "155" = "9b";
      "156" = "9c";
      "157" = "9d";
      "158" = "9e";
      "159" = "9f";
      "160" = "a0";
      "161" = "a1";
      "162" = "a2";
      "163" = "a3";
      "164" = "a4";
      "165" = "a5";
      "166" = "a6";
      "167" = "a7";
      "168" = "a8";
      "169" = "a9";
      "170" = "aa";
      "171" = "ab";
      "172" = "ac";
      "173" = "ad";
      "174" = "ae";
      "175" = "af";
      "176" = "b0";
      "177" = "b1";
      "178" = "b2";
      "179" = "b3";
      "180" = "b4";
      "181" = "b5";
      "182" = "b6";
      "183" = "b7";
      "184" = "b8";
      "185" = "b9";
      "186" = "ba";
      "187" = "bb";
      "188" = "bc";
      "189" = "bd";
      "190" = "be";
      "191" = "bf";
      "192" = "c0";
      "193" = "c1";
      "194" = "c2";
      "195" = "c3";
      "196" = "c4";
      "197" = "c5";
      "198" = "c6";
      "199" = "c7";
      "200" = "c8";
      "201" = "c9";
      "202" = "ca";
      "203" = "cb";
      "204" = "cc";
      "205" = "cd";
      "206" = "ce";
      "207" = "cf";
      "208" = "d0";
      "209" = "d1";
      "210" = "d2";
      "211" = "d3";
      "212" = "d4";
      "213" = "d5";
      "214" = "d6";
      "215" = "d7";
      "216" = "d8";
      "217" = "d9";
      "218" = "da";
      "219" = "db";
      "220" = "dc";
      "221" = "dd";
      "222" = "de";
      "223" = "df";
      "224" = "e0";
      "225" = "e1";
      "226" = "e2";
      "227" = "e3";
      "228" = "e4";
      "229" = "e5";
      "230" = "e6";
      "231" = "e7";
      "232" = "e8";
      "233" = "e9";
      "234" = "ea";
      "235" = "eb";
      "236" = "ec";
      "237" = "ed";
      "238" = "ee";
      "239" = "ef";
      "240" = "f0";
      "241" = "f1";
      "242" = "f2";
      "243" = "f3";
      "244" = "f4";
      "245" = "f5";
      "246" = "f6";
      "247" = "f7";
      "248" = "f8";
      "249" = "f9";
      "250" = "fa";
      "251" = "fb";
      "252" = "fc";
      "253" = "fd";
      "254" = "fe";
      "255" = "ff";
    }.${toString int};

  groupIdOption = mkOption {
    type = types.int;
    default = config.microvm.groupId;
  };

  taskIdOption = mkOption {
    type = types.int;
  };

  tcpUdpConnectionOptions.options = {
    target = mkOption {
      type = types.str;
    };
  };

  icmpConnectionOptions.options = {
    target = mkOption {
      type = types.str;
    };
  };
in
{
  options.microvm = {
    enableExtras = mkEnableOption "Extras";
    groupId = mkOption {
      type = types.int;
    };
    taskId = mkOption {
      type = types.int;
    };
    hostsHostName = mkOption {
      type = types.str;
    };
    hostName = mkOption {
      type = types.str;
    };

    connections = {
      tcpUdp = mkOption {
        type = with types;
          listOf (submodule tcpUdpConnectionOptions);
        default = [];
      };

      icmp = mkOption {
        type = with types;
          listOf (submodule icmpConnectionOptions);
        default = [];
      };
    };
  };

  config = {
    networking.hostName = "${cfg.hostName}-${cfg.hostsHostName}";

    microvm.interfaces = [
      {
        type = "tap";

        # interface name on the host
        id = "mvm-${cfg.hostName}";

        # Ethernet address of the MicroVM's interface, not the host's
        #
        # Locally administered have one of 2/6/A/E in the second nibble.
        mac = "02:00:00:00:${intToHex cfg.groupId}:${intToHex cfg.taskId}";
      }
    ];

  services.udev.extraRules = ''
    ATTR{address}=="02:00:00:00:${intToHex cfg.groupId}:${intToHex cfg.taskId}", NAME="eth0"
  '';

    networking.interfaces."eth0" = {
      ipv4.addresses = [
        {
          address = "10.80.${toString cfg.groupId}.${toString cfg.taskId}";
          prefixLength = 24;
        }
      ];
    };
  };
}