let
  sources = import ./npins;

  lib = import (sources.nix-lib + "/src/trivial.nix");

  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"
    ];
  };

  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;

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

  # Instanciate a specialized version of nixpkgs
  mkSystemNixpkgs =
    system: version:
    let
      args =
        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.
              ];
            };
          };
    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 = {
    liminix = {
      evalConfig = import "${sources.liminix}/lib/eval-config.nix" { nixpkgs = sources.nixos-unstable; };
    };
  };

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

    specialArgs = {
      inherit sources;
    };

    nodeSpecialArgs = lib.mapSingleFuse mkArgs nodes;
  };

  registry.nixos.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;
      };
    };

  ap01 =
    let
      device = import "${sources.liminix}/devices/zyxel-nwa50ax";
    in
    {
      deployment.systemType = "liminix";
      nixpkgs.hostPlatform = {
        config = "mipsel-unknown-linux-musl";
        gcc = {
          abi = "32";
          arch = "mips32"; # mips32r2?
        };
      };
      nixpkgs.buildPlatform = "x86_64-linux";
      imports = [
        ./machines/ap/configuration.nix
        device.module
      ];
    };
}
// (lib.mapSingleFuse mkNode nodes)