dotfiles/nixng/modules/minecraft-forge.nix

{
  pkgs,
  config,
  lib,
  ...
}:
with lib; let
  cfg = config.services.minecraft.forge;
in {
  options.services.minecraft.forge = {
    enable = mkEnableOption "Enable Minecraft server service.";

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

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

    modpacksChHash = mkOption {
      type = types.str;
    };

    javaPackage = mkOption {
      type = types.package;
      default = pkgs.jdk17;
    };

    serverPackage = mkOption {
      type = types.package;
      readOnly = true;
    };

    eulaAccept = mkOption {
      type = with types; bool;
      description = ''
        By changing the setting below to true you are indicating your agreement to Mojang's EULA (https://account.mojang.com/documents/minecraft_eula).
      '';
      default = false;
    };

    extraJavaArguments = mkOption {
      type = with types; listOf str;
      default = [];
    };

    extraFixup = mkOption {
      type = types.lines;
      default = "";
    };
  };

  config = mkIf cfg.enable {
    services.minecraft.forge.serverPackage = let
      forgeFod = pkgs.stdenv.mkDerivation {
        pname = "minecraft";
        version = "unknown";

        outputHashMode = "recursive";
        outputHashAlgo = "sha256";
        outputHash = cfg.modpacksChHash;

        buildInputs = with pkgs; [unzip curl which cacert];

        phases = ["fetchPhase" "installPhase" "fixupPhase "];

        fetchPhase = ''
          curl https://api.modpacks.ch/public/modpack/${toString cfg.modpackId}/${toString cfg.versionId}/server/linux -o modpacks.ch # fuck creeperhost
          chmod +x modpacks.ch
        '';

        installPhase = ''
          mkdir ebin $out

          cat > ebin/java <<EOF
          #!$(which sh)

          echo "cd \$PWD && java \$@" > install-forge
          EOF
          chmod +x ebin/java
          export PATH=$PWD/ebin:$PATH

          ./modpacks.ch ${toString cfg.modpackId} ${toString cfg.versionId} --nojava --path $out --verbose
        '';

        fixupPhase = ''
          # delete useless non-reproducible data that we really don't need. A less "shotgun" cleaning is possible
          rm $out/version.json

          ${cfg.extraFixup}
        '';
      };
    in
      pkgs.stdenv.mkDerivation {
        pname = "minecraft";
        version = "unknown";

        phases = ["installPhase"];

        installPhase = ''
          mkdir -p $out/bin

          cp ${pkgs.writeShellScript "server.sh" ''
            export PATH=${makeBinPath (with pkgs; [coreutils findutils bash cfg.javaPackage])}:$PATH
            export _path=$PWD
            echo $0

            echo $rw_paths
            function linkFile()
            {
              _rw_paths=${"( " + lib.concatMapStringsSep " " (x: ''"${x}"'') ["config" "modpack/gamemodes.json"] + " )"}
              _ignore_paths=${"( " + lib.concatMapStringsSep " " (x: ''"${x}"'') ["start.sh"] + " )"}

              ignore=0
              for ignore_path in ''${_ignore_paths[@]} ; do
                if [ "''${1##ignore_path}" != "$1" ] || [ "$ignore_path" = "$1" ] ; then
                  ignore=1
                  break
                fi
              done

              if [ -f "$1" ] || [ $ignore = 1 ] ; then
                return
              fi
              mkdir -p "$_path/$(dirname "$1")"

              copy=0
              for rw_path in ''${_rw_paths[@]} ; do
                if [ "''${1##$rw_path}" != "$1" ] || [ "$rw_path" = "$1" ] ; then
                  copy=1
                  break
                fi
              done

              if [ "$copy" = 1 ] ; then
                cp --no-preserve=mode,ownership "${forgeFod}/$1" "$_path/$1"
              else
                ln -s "${forgeFod}/$1" "$_path/$1"
              fi
            }
            export -f linkFile

            echo $_path
            if [ "$_path" = "" ] || ! [ -d "$_path" ] ; then
              echo "invalid path"
              exit 1
            fi

            find $_path -type l -lname '/nix/store/*' -delete
            find $_path -type d -empty -delete

            find ${forgeFod} -type f -printf '%P\n' | tr '\n' '\0' | xargs -0 -I {} sh -c 'linkFile "$1"' sh {} # mkdir -p "$_path/$(dirname "$1")" ; ln -s "${forgeFod}/$1" "$_path/$1"

            ln -s ${pkgs.writeShellScript "start.sh" ''
              ${lib.getExe cfg.javaPackage} $(cat ${forgeFod}/start.sh  | grep -e "java" -e jar | sed 's/^"java" \(.*\) -jar .*$/\1/') "$@" -jar forge-*.jar
            ''} $_path/start.sh

            # [ -f $_path/install-forge ] && bash install-forge

            $_path/start.sh
          ''} $out/bin/server
        '';
      };

    init.services.minecraft-forge = {
      script = pkgs.writeShellScript "minecraft-run" ''
        set -xe

        mkdir -p /var/lib/minecraft/forge
        cd /var/lib/minecraft/forge
        echo "eula=true" > eula.txt
        ${pkgs.bash}/bin/bash -x ${cfg.serverPackage}/bin/server ${concatMapStringsSep " " (x: ''"${x}"'') cfg.extraJavaArguments}
      '';
      enabled = true;
    };

    assertions = [
      {
        assertion = cfg.eulaAccept;
        message = "You must accept the EULA";
      }
    ];
  };
}