# packwiz2nix

packwiz2nix brings all of the benefits of Nix to [packwiz](https://packwiz.infra.link/), helping you create
[fixed-output derivations](https://nixos.org/manual/nix/stable/language/advanced-attributes.html#adv-attr-outputHash) from
your already existing packwiz modpack!

## Getting started

### For users

It is recommended to use [Infinidoge's](https://github.com/Infinidoge) [nix-minecraft](https://github.com/Infinidoge/nix-minecraft)
module as it allows you to symlink packages into a minecraft server's directory.

There is a convenience function called `mkModLinks` that can automate the creation of symlinks for a server like so:

```nix
{
  nix-minecraft,
  packwiz2nix,
  pkgs,
  yourModpack,
  ...
}: let
  inherit (packwiz2nix.lib) mkPackwizPackages mkModLinks;
  # replace "/checksums.json" with the path to the modpack's checksums file
  mods = mkPackwizPackages pkgs (yourModpack + "/checksums.json");
in {
  imports = [
    nix-minecraft.nixosModules.minecraft-servers
  ];

  nixpkgs.overlays = [nix-minecraft.overlay];

  services.minecraft-servers = {
    enable = true;
    eula = true;

    servers.my_server = {
      enable = true;
      package = pkgs.quiltServers.quilt-1_19_4-0_18_10;
      symlinks = mkModLinks mods;
    };
  };
}
```

### For modpack developers

packwiz2nix is quick to set up, all you have to do is add this to the `apps` attribute of a flake:

```nix
{
  inputs = {
    nixpkgs.url = "nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
    packwiz2nix.url = "github:getchoo/packwiz2nix";
  };

  outputs = {
    nixpkgs,
    flake-utils,
    packwiz2nix,
    ...
  }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = import nixpkgs {inherit system;};
    in {
      apps = {
        # replace ./mods with the path to your .pw.toml files
        generate-checksums = packwiz2nix.lib.mkChecksumsApp pkgs ./mods;
      };
    });
}
```

An example of this can be found in my [personal modpack](https://github.com/getchoo/modpack/blob/main/flake.nix)

## Maintainer Guide

packwiz2nix also offers some more advanced features if maintainers wish to integrate
this project further into their distribution.

### Create traditional modpacks

One of these features is the ability to create traditional modpacks anyone can use. So far,
only modpacks for MultiMC and Prism Launcher are supported.

#### MultiMC/Prism Launcher

`mkMultiMCPack` allows you to create a package attribute that will result in a zipfile any user of
Prism Launcher and MultiMC can import. For example:

```nix
{
  packages = let
    inherit (packwiz2nix.lib) mkMultiMCPack mkPackwizPackages;
    mods = mkPackwizPackages pkgs ./checksums.json;
  in rec {
    myModpack = mkMultiMCPack {
      inherit pkgs mods;
      # optionally include external
      # files in modpack
      filesDir = ./files;
      name = "myModpack";
    };

    default = myModpack;
  };
}
```

## Gotchas!

There are two main things you should keep in mind with this project currently:

- No Curseforge support

  - Packwiz does not keep the download URL for Curseforge mods in it's TOML files
    due to Curseforge's ToS, which is not acceptable in the current method used to 
    generate checksums and create the final derivations for mods.

  - This is the biggest concern as it affects end users the most

- Checksums must be generated (**modpack developers, make sure you read this**)
  - Packwiz uses SHA1 by default to verify mod files, which fetchers in nix such as `builtins.fetchurl`
    and `pkgs.fetchurl` do not support. This prevents us from using them, and requires a separate
    checksum file (using SHA256) to be generated and updated along with the modpack.
    
  - There are [plans](https://github.com/packwiz/packwiz/issues/156) to change this in the future,
    which would allow for this process to be removed

## Related Projects

- [Infinidoge/nix-minecraft](https://github.com/Infinidoge/nix-minecraft)
- [nix-community/mineflake](https://github.com/nix-community/mineflake)