os/flake.nix

{
  description = "A highly structured configuration database.";

  inputs.nixpkgs.url = "nixpkgs/release-20.03";
  inputs.unstable.url = "nixpkgs/master";
  inputs.home.url = "github:rycee/home-manager/bqv-flakes";

  outputs = inputs@{ self, home, nixpkgs, unstable }:
    let
      inherit (builtins) attrNames attrValues readDir;
      inherit (nixpkgs) lib;
      inherit (lib) removeSuffix recursiveUpdate;
      inherit (utils) pathsToImportedAttrs;

      utils = import ./lib/utils.nix { inherit lib; };

      system = "x86_64-linux";

      pkgImport = pkgs:
        import pkgs {
          inherit system;
          overlays = attrValues self.overlays;
          config = { allowUnfree = true; };
        };

      pkgs = pkgImport nixpkgs;
      unstablePkgs = pkgImport unstable;

    in
    {
      nixosConfigurations =
        import ./hosts (recursiveUpdate inputs {
          inherit system pkgs
            unstablePkgs utils;
        }
        );

      devShell."${system}" = import ./shell.nix { inherit pkgs; };

      overlay = import ./pkgs;

      overlays =
        let
          overlayDir = ./overlays;
          fullPath = name: overlayDir + "/${name}";
          overlayPaths = map fullPath (attrNames (readDir overlayDir));
        in
        pathsToImportedAttrs overlayPaths;

      packages."${system}" = self.overlay pkgs pkgs;

      nixosModules =
        let
          # binary cache
          cachix = import ./cachix.nix;
          cachixAttrs = { inherit cachix; };

          # modules
          moduleList = import ./modules/list.nix;
          modulesAttrs = pathsToImportedAttrs moduleList;

          # profiles
          profilesList = import ./profiles/list.nix;
          profilesAttrs = { profiles = pathsToImportedAttrs profilesList; };

        in
        recursiveUpdate
          (recursiveUpdate cachixAttrs modulesAttrs)
          profilesAttrs;
    };
}