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

let
  inherit (lib) types;

  cfg = config.plusultra.services.minecraft;
in
{
  options.plusultra.services.minecraft = {
    enable = lib.mkEnableOption "Minecraft server";

    eula = lib.mkOption {
      type = types.bool;
      default = false;
      description = lib.mdDoc ''
        Whether you agree to
        [Mojang's EULA](https://account.mojang.com/documents/minecraft_eula).
        This option must be set to `true` to run Minecraft server.
      '';
    };

    infrared = {
      enable = lib.mkEnableOption "Infrared";
    };

    servers = lib.mkOption {
      default = { };
      description = "The Minecraft servers to run.";
      example = lib.literalExpression ''
        {
          # A default vanilla server.
          vanilla-1 = {};

          # A vanilla server with a custom port.
          vanilla-2 = {
            port = 4000;
          };

          # A vanilla server proxied by Infrared (when enabled).
          vanilla-3 = {
            domain = "minecraft.example.com";
          };

          # A Forge server.
          forge-1 = {
            type = "forge";
          };

          # Use a custom Minecraft server version.
          custom-vanilla = {
            package = pkgs.minecraft-server_1_12_2;
          };

          # Use a custom Forge server version.
          custom-forge = {
            type = "forge";
            package = pkgs.minecraft-forge_1_19_2-43_1_25;
          };
        }
      '';

      type = types.attrsOf (types.submodule ({ config, name, ... }: {
        options = {
          type = lib.mkOption {
            type = types.enum [ "vanilla" "forge" ];
            default = "vanilla";
            description = "The kind of Minecraft server to create.";
          };

          package = lib.mkOption {
            type = types.package;
            default =
              if config.type == "vanilla" then
                pkgs.minecraft-server
              else
                pkgs.plusultra.minecraft-forge;
            defaultText = lib.literalExpression ''
              pkgs.minecraft-server
            '';
          };

          dataDir = lib.mkOption {
            type = types.path;
            default = "/var/lib/minecraft/${name}";
            defaultText = "/var/lib/minecraft/<name>";
            description = "The datrectory where data for the server is stored.";
          };

          port = lib.mkOption {
            type = types.port;
            default = 25565;
            description = "The port for the server to listen on.";
          };

          domain = lib.mkOption {
            type = types.str;
            default = "";
            description = "The domain to pass to Infrared (if enabled).";
          };

          jvmOpts = lib.mkOption {
            type = types.separatedString " ";
            default = "-Xmx2048M -Xms2048M";
            # Example options from https://minecraft.gamepedia.com/Tutorials/Server_startup_script
            example = "-Xms4092M -Xmx4092M -XX:+UseG1GC -XX:+CMSIncrementalPacing "
              + "-XX:+CMSClassUnloadingEnabled -XX:ParallelGCThreads=2 "
              + "-XX:MinHeapFreeRatio=5 -XX:MaxHeapFreeRatio=10";
            description = lib.mdDoc "JVM options for the Minecraft server.";
          };

          serverProperties = lib.mkOption {
            type = types.attrsOf (types.oneOf [ types.bool types.int types.str ]);
            default = { };
            example = lib.literalExpression ''
              {
                server-port = 43000;
                difficulty = 3;
                gamemode = 1;
                max-players = 5;
                motd = "NixOS Minecraft server!";
                white-list = true;
                enable-rcon = true;
                "rcon.password" = "hunter2";
              }
            '';
            description = lib.mdDoc ''
              Minecraft server properties for the server.properties file. Only has
              an effect when {option}`services.minecraft-server.declarative`
              is set to `true`. See
              <https://minecraft.gamepedia.com/Server.properties#Java_Edition_3>
              for documentation on these values.
            '';
          };

          whitelist = lib.mkOption {
            type =
              let
                minecraftUUID = lib.types.strMatching
                  "[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}" // {
                  description = "Minecraft UUID";
                };
              in
              lib.types.attrsOf minecraftUUID;
            default = { };
            description = lib.mdDoc ''
              Whitelisted players, only has an effect when
              {option}`services.minecraft-server.declarative` is
              `true` and the whitelist is enabled
              via {option}`services.minecraft-server.serverProperties` by
              setting `white-list` to `true`.
              This is a mapping from Minecraft usernames to UUIDs.
              You can use <https://mcuuid.net/> to get a
              Minecraft UUID for a username.
            '';
            example = lib.literalExpression ''
              {
                username1 = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
                username2 = "yyyyyyyy-yyyy-yyyy-yyyy-yyyyyyyyyyyy";
              };
            '';
          };

          openFirewall = lib.mkOption {
            type = types.bool;
            default = false;
            description = lib.mdDoc ''
              Whether to open ports in the firewall for the server.
            '';
          };

          declarative = lib.mkOption {
            type = types.bool;
            default = false;
            description = lib.mdDoc ''
              Whether to use a declarative Minecraft server configuration.
              Only if set to `true`, the options
              {option}`plusultra.services.minecraft.servers.<name>.whitelist` and
              {option}`plusultra.services.minecraft.servers.<name>.serverProperties` will be
              applied.
            '';
          };

          extraInfraredOptions = lib.mkOption {
            type = types.attrs;
            default = { };

            description = lib.mdDoc ''
              Extra options passed to Infrared (if enabled) when configuring this server.
            '';
          };
        };
      }));
    };
  };
}