flake-hub/flake.nix

{
  description = "oleks's personal Flake hub – a place to publish custom packages and overlays";

  inputs = {
    fleet-pins.url = "git+https://git.oleks.space/oleks/fleet-pins?ref=main";
    nixpkgs.follows = "fleet-pins/nixpkgs-projects";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs =
    {
      self,
      nixpkgs,
      fleet-pins,
      flake-utils,
      ...
    }:
    let
      # Systems that have native builders
      buildSystems = [
        "x86_64-linux"
        "aarch64-linux"
      ];

      # Cross-compilation targets from x86_64-linux
      crossTargets = {
        "s390x-linux" = "s390x-linux";
      };

      mkPackages = pkgs: {
        hello-world = pkgs.callPackage ./packages/hello-world.nix { };
        xonsh = pkgs.callPackage ./packages/xonsh.nix {
          xonsh-unwrapped = import ./packages/xonsh-unwrapped.nix {
            inherit (pkgs) lib python3Packages fetchFromGitHub;
          };
        };
      };

      # Native builds
      native = flake-utils.lib.eachSystem buildSystems (
        system:
        let
          pkgs = import nixpkgs { inherit system; };
          packages = mkPackages pkgs;
        in
        {
          packages = packages // {
            default = packages.hello-world;
          };

          overlays.default = final: prev: mkPackages final;

          devShells.default = pkgs.mkShell {
            name = "oleks-hub-shell";
            buildInputs = [ self.packages.${system}.default ];
            nativeBuildInputs = with pkgs; [
              nix
              fmt
            ];
            shellHook = ''
              echo "Welcome to the oleks Flake hub development shell."
            '';
          };
        }
      );

      # Cross-compiled builds (built from x86_64-linux)
      cross = builtins.listToAttrs (
        builtins.map (
          target:
          let
            pkgs = import nixpkgs {
              system = "x86_64-linux";
              crossSystem.config =
                nixpkgs.lib.systems.examples.${
                  {
                    "s390x-linux" = "s390x";
                  }
                  .${target}
                }.config;
            };
            packages = mkPackages pkgs;
          in
          {
            name = target;
            value = packages // {
              default = packages.hello-world;
            };
          }
        ) (builtins.attrNames crossTargets)
      );
    in
    native
    // {
      packages = (native.packages or { }) // cross;
    };
}