flake.nix

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    rust-overlay.url = "github:oxalica/rust-overlay";

    # crane = {
    #   url = "github:ipetkov/crane";
    #   inputs.nixpkgs.follows = "nixpkgs";
    # };

    systems.url = "github:nix-systems/default";
    treefmt-nix = {
      url = "github:numtide/treefmt-nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs =
    { self
    , systems
    , nixpkgs
    , treefmt-nix
    , ...
    } @ inputs:
    let
      eachSystem = f:
        nixpkgs.lib.genAttrs (import systems) (
          system:
          f (import nixpkgs {
            inherit system;
            overlays = [ inputs.rust-overlay.overlays.default ];
          })
        );

      rustToolchain = eachSystem (pkgs: (pkgs.rust-bin.stable.latest.default.override {
        extensions = [ "rust-src" ];
      }));

      treefmtEval = eachSystem (pkgs: treefmt-nix.lib.evalModule pkgs ./treefmt.nix);
    in
    {
      # You can use crane to build the Rust application with Nix

      # packages = eachSystem (pkgs: let
      #   craneLib = inputs.crane.lib.${pkgs.system};
      # in {
      #   default = craneLib.buildPackage {
      #     src = craneLib.cleanCargoSource (craneLib.path ./.);
      #   };
      # });

      devShells = eachSystem (pkgs: {
        # Based on a discussion at https://github.com/oxalica/rust-overlay/issues/129
        default = pkgs.mkShell (with pkgs; {
          nativeBuildInputs = [
            clang
            gdb
            # Use mold when we are runnning in Linux
            (lib.optionals stdenv.isLinux mold)
          ];
          buildInputs = [
            rustToolchain.${pkgs.system}
            rust-analyzer-unwrapped
            cargo
            cargo-insta
            cargo-hack
            cargo-expand
            # pkg-config
            # openssl
          ];
          RUST_SRC_PATH = rustPlatform.rustLibSrc;
        });
      });

      formatter = eachSystem (pkgs: treefmtEval.${pkgs.system}.config.build.wrapper);

      checks = eachSystem (pkgs: {
        formatting = treefmtEval.${pkgs.system}.config.build.check self;
      });
    };
}