let
  sources = import ./npins;

  lib = import (sources.nix-lib + "/src/trivial.nix");
  lib' = (import sources.nixos-unstable { }).lib;

  patch = import sources.nix-patches { patchFile = ./patches; };

  nodes' = import ./meta/nodes.nix;
  nodes = builtins.attrNames nodes';

  mkNode = node: {
    # Import the base configuration for each node
    imports = builtins.map (lib.mkRel (./machines/${node})) [
      "_configuration.nix"
      "_hardware-configuration.nix"
    ];

    deployment.systemType = systemType node;
  };

  nixpkgs' = import ./meta/nixpkgs.nix;

  # All supported nixpkgs versions, instanciated
  nixpkgs = lib.mapSingleFuse (
    s: lib.mapSingleFuse (mkSystemNixpkgs s) nixpkgs'.versions.supported
  ) nixpkgs'.systems.supported;

  # Get the configured nixos version for the node,
  # defaulting to the one defined in meta/nixpkgs
  version = node: nodes'.${node}.nixpkgs or nixpkgs'.versions.default;
  system = node: nodes'.${node}.system or nixpkgs'.systems.default;
  systemType =
    node:
    nodes'.${node}.system
      or (lib'.warn "Not specifying the `deployment.systemType` is deprecated!" "nixos");

  # Builds a patched version of nixpkgs, only as the source
  mkNixpkgs' =
    v:
    let
      version = "nixos-${v}";
    in
    patch.mkNixpkgsSrc {
      src = sources.${version};
      inherit version;
    };

  mkNixpkgsConfigPerSystem =
    system: _:
    if system == "nixos" then
      { }
    else
      (import "${sources.liminix}/devices/${system}").system
      // {
        overlays = [ (import "${sources.liminix}/overlay.nix") ];
        config = {
          allowUnsupportedSystem = true; # mipsel
          permittedInsecurePackages = [
            "python-2.7.18.8" # Python < 3 is needed for kernel backports.
          ];
        };
      };

  # Instanciate a specialized version of nixpkgs
  mkSystemNixpkgs =
    system: version:
    let
      args = mkNixpkgsConfigPerSystem system version;
    in
    import (mkNixpkgs' version) args;

  ###
  # Function to create arguments based on the node
  #
  mkArgs =
    node:
    let
      pkgs = nixpkgs.${system node};
    in
    rec {
      lib = import sources.nix-lib {
        inherit (pkgs.${version node}) lib;

        nixpkgs = pkgs;

        keysRoot = ./keys;
      };

      meta = (import ./meta) lib;

      nodeMeta = meta.nodes.${node};
    };
in

{
  registry = {
    zyxel-nwa50ax = {
      evalConfig = import "${sources.liminix}/lib/eval-config.nix" {
        nixpkgs = sources.nixos-unstable;
      };

      defaults = _: {
        nixpkgs = {
          source = sources.nixos-unstable;
          config = {
            allowUnsupportedSystem = true; # mipsel
            permittedInsecurePackages = [
              "python-2.7.18.8" # Python < 3 is needed for kernel backports.
            ];
          };
          hostPlatform = {
            config = "mipsel-unknown-linux-musl";
            gcc = {
              abi = "32";
              arch = "mips32"; # mips32r2?
            };
          };

          # It's impure, but who cares?
          # Can Flakes do that?
          buildPlatform = builtins.currentSystem;
        };
      };
    };

    nixos = {
      evalConfig = import "${sources.nixos-unstable}/nixos/lib/eval-config.nix";
      defaults =
        { nodeMeta, name, ... }:
        {
          # Import the default modules
          imports = [ ./modules ];

          # Include default secrets
          age-secrets.sources = [ ./machines/${name}/secrets ];

          # Deployment config is specified in meta.nodes.${node}.deployment
          inherit (nodeMeta) deployment;

          nix = {
            # Set NIX_PATH to the patched version of nixpkgs
            nixPath = [ "nixpkgs=${mkNixpkgs' (version name)}" ];
            optimise.automatic = true;

            gc = {
              automatic = true;
              dates = "weekly";
              options = "--delete-older-than 7d";
            };
          };

          # Allow unfree packages
          nixpkgs.config.allowUnfree = true;

          # Use the stateVersion declared in the metadata
          system = {
            inherit (nodeMeta) stateVersion;
          };
        };
    };
  };

  meta = {
    nodeNixpkgs = lib.mapSingleFuse (n: nixpkgs.${system n}.${version n}) nodes;

    specialArgs = {
      inherit sources;
    };

    nodeSpecialArgs = lib.mapSingleFuse mkArgs nodes;
  };
}
// (lib.mapSingleFuse mkNode nodes)