# Shamelessly copied from github.com/orual/flake because they basically nailed
# it and I can't be assed to do this myself.
let
  inherit (builtins) readDir hasAttr attrNames filter concatMap listToAttrs;

  loadHosts = dir: inputs:
    let
      loadConf = dir: n: (import "${dir}/${n}" inputs) // { hostname = n; };

      hosts' =
        let contents = readDir dir;
        in filter (n: contents."${n}" == "directory") (attrNames contents);
    in
    concatMap
      (n:
        let
          contents = readDir "${dir}/${n}";
          hasDefault = (hasAttr "default.nix" contents)
            && (contents."default.nix" == "regular");
        in
        if hasDefault then [ (loadConf dir n) ] else [ ])
      hosts';
in
{
  # Discover NixOS configurations.
  # It will find all sub-directories in `directory` and
  # include it if it has a default.nix.
  genNixOSHosts =
    { inputs
    , self
    , directory ? "${inputs.self}/hosts"
    , nixpkgs ? inputs.nixpkgs
    , builder ? nixpkgs.lib.nixosSystem
    , specialArgs ? { }
    , baseModules ? [ ]
    , overlays ? [ ]
    , config ? { allowUnfree = true; }
    }:
    let
      mkHost = { system, modules, hostname, }:
        builder {
          inherit system;

          specialArgs = { inherit inputs self; } // specialArgs;

          modules = [
            ({ ... }: {
              networking.hostName = hostname;

              nixpkgs = { inherit overlays config; };
            })
          ] ++ baseModules ++ modules;
        };
    in
    listToAttrs (map
      (conf: {
        name = conf.hostname;
        value = mkHost (removeAttrs conf [ "home" ]);
      })
      (loadHosts directory inputs));

  # Discover home-manager configurations.
  # It will find all sub-directories in `directory` and
  # include it if it has a default.nix.
  genHomeHosts =
    { inputs
    , user
    , directory ? "${inputs.self}/hosts"
    , nixpkgs ? inputs.nixpkgs
    , home ? inputs.home
    , builder ? home.lib.homeManagerConfiguration
    , specialArgs ? { }
    , baseModules ? [ ]
    , overlays ? [ ]
    , config ? { allowUnfree = true; }
    ,
    }:
    let
      homeHosts = concatMap
        (h:
          if (hasAttr "home" h) then
            [ ((removeAttrs h [ "home" "modules" ]) // h.home) ]
          else
            [ ])
        (loadHosts directory inputs);

      mkHost = { system, modules, hostname, }:
        let pkgs = import nixpkgs { inherit system config overlays; };
        in builder {
          inherit pkgs;
          extraSpecialArgs = { inherit inputs; } // specialArgs;

          modules = [
            ({ lib, ... }: {
              home.username = lib.mkDefault user;
              home.homeDirectory = lib.mkDefault "/home/${user}";
            })
          ] ++ baseModules ++ modules;
        };
    in
    listToAttrs (map
      (conf: {
        name = "${user}@${conf.hostname}";
        value = mkHost conf;
      })
      homeHosts);
}