digga/flake.nix

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

  inputs =
    {
      master.url = "nixpkgs/master";
      nixos.url = "nixpkgs/release-20.09";
      home.url = "github:nix-community/home-manager/release-20.09";
      flake-utils.url = "github:numtide/flake-utils";
    };

  outputs = inputs@{ self, home, nixos, master, flake-utils, nur }:
    let
      inherit (builtins) attrNames attrValues readDir elem;
      inherit (flake-utils.lib) eachDefaultSystem;
      inherit (nixos) lib;
      inherit (lib) all removeSuffix recursiveUpdate genAttrs filterAttrs;
      inherit (utils) pathsToImportedAttrs genPkgset overlayPaths modules
        genPackages pkgImport;

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

      system = "x86_64-linux";

      externOverlays = [ nur.overlay ];
      externModules = [ home.nixosModules.home-manager ];

      pkgset =
        let overlays = (attrValues self.overlays) ++ externOverlays; in
        genPkgset {
          inherit master nixos overlays system;
        };

      outputs = {
        nixosConfigurations =
          import ./hosts (recursiveUpdate inputs {
            inherit lib pkgset system utils externModules;
          });

        overlay = import ./pkgs;

        overlays = pathsToImportedAttrs overlayPaths;

        nixosModules = modules;

        templates.flk.path = ./.;

        templates.flk.description = "flk template";

        defaultTemplate = self.templates.flk;
      };
    in
    (eachDefaultSystem (system':
      let
        pkgs' = pkgImport {
          pkgs = nixos;
          system = system';
          overlays = [ ];
        };
      in
      {
        devShell = import ./shell.nix {
          pkgs = pkgs';
        };

        packages =
          let
            packages' = genPackages {
              overlay = self.overlay;
              overlays = self.overlays;
              pkgs = pkgs';
            };

            filtered = filterAttrs
              (_: v:
                (v.meta ? platforms)
                && (elem system' v.meta.platforms)
                && (
                  (all (dev: dev.meta ? platforms) v.buildInputs)
                  && (all (dev: elem system' dev.meta.platforms) v.buildInputs)
                ))
              packages';
          in
          filtered;
      })) // outputs;
}