# Heavily based on https://fasterthanli.me/series/building-a-rust-service-with-nix
{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
    rust-overlay = {
      url = "github:oxalica/rust-overlay";
      inputs = {
        nixpkgs.follows = "nixpkgs";
        flake-utils.follows = "flake-utils";
      };
    };
    crane = {
      url = "github:ipetkov/crane";
      inputs = {
        nixpkgs.follows = "nixpkgs";
        rust-overlay.follows = "rust-overlay";
        flake-utils.follows = "flake-utils";
      };
    };
  };
  outputs = {
    self,
    nixpkgs,
    flake-utils,
    rust-overlay,
    crane,
  }:
    flake-utils.lib.eachDefaultSystem
    (
      system: let
        overlays = [(import rust-overlay)];
        pkgs = import nixpkgs {
          inherit system overlays;
        };
        rustToolchain = pkgs.rust-bin.stable.latest.default;
        craneLib = (crane.mkLib pkgs).overrideToolchain rustToolchain;
        src = craneLib.cleanCargoSource ./.;
        nativeBuildInputs = with pkgs; [rustToolchain pkg-config];
        buildInputs = with pkgs; [];
        commonArgs = {
          inherit src buildInputs nativeBuildInputs;
        };
        cargoArtifacts = craneLib.buildDepsOnly commonArgs;
        bin = craneLib.buildPackage (commonArgs
          // {
            inherit cargoArtifacts;
          });
      in
        with pkgs; {
          packages = {
            # that way we can build `bin` specifically,
            # but it's also the default.
            inherit bin;
            default = bin;
          };
          devShells.default = mkShell {
            # instead of passing `buildInputs` / `nativeBuildInputs`,
            # we refer to an existing derivation here
            inputsFrom = [bin];
          };
        }
    );
}