flake.nix

{
  description = "Customized dwm";

  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05";

  outputs = { self, nixpkgs }:
    let
      system = "x86_64-linux";

      overlay = final: prev: {
        dwm = prev.dwm.overrideAttrs (old: {
          version = "6.5";
          src = builtins.path { path = ./.; name = "dwm"; };
        });
      };

      dwm = (
        import nixpkgs {
          inherit system;
          overlays = [ overlay ];
        }
      ).dwm;
    in
    {
      overlays.default = overlay;

      packages.${system}.default = dwm;

      checks.${system} = {
        build = dwm;

        version = nixpkgs.legacyPackages.${system}.runCommand "version-check" { } ''
          dwm_version="$(${dwm}/bin/dwm -v 2>&1 || :)"

          echo "package version: ${dwm.name}"
          echo "dwm version:     $dwm_version"

          [[ "${dwm.name}" == "$dwm_version" ]]
          touch ${placeholder "out"}
        '';
      };
    };
}