flake.nix

{
  description = "A Nix-flake-based Rust development environment";

  inputs = {
    nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.*.tar.gz";
    rust-overlay = {
      url = "github:oxalica/rust-overlay";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs =
    {
      self,
      nixpkgs,
      rust-overlay,
    }:
    let
      supportedSystems = [
        "x86_64-linux"
        "aarch64-linux"
        "x86_64-darwin"
        "aarch64-darwin"
      ];
      forEachSupportedSystem =
        f:
        nixpkgs.lib.genAttrs supportedSystems (
          system:
          f {
            pkgs = import nixpkgs {
              inherit system;
              overlays = [
                rust-overlay.overlays.default
                self.overlays.default
              ];
            };
          }
        );
    in
    {
      overlays.default = final: prev: {
        rustToolchain =
          let
            rust = prev.rust-bin;
          in
          if builtins.pathExists ./rust-toolchain.toml then
            rust.fromRustupToolchainFile ./rust-toolchain.toml
          else if builtins.pathExists ./rust-toolchain then
            rust.fromRustupToolchainFile ./rust-toolchain
          else
            rust.stable.latest.default.override {
              extensions = [
                "rust-src"
                "rustfmt"
              ];
            };
      };

      devShells = forEachSupportedSystem (
        { pkgs }:
        {
          default = pkgs.mkShell {
            packages = with pkgs; [
              rustToolchain
              openssl
              pkg-config
              cargo-deny
              cargo-edit
              cargo-watch
              rust-analyzer
              cmake
              opusTools
              opusfile
              rustup
              cargo-cross
              gcc
            ];

            env = {
              # Required by rust-analyzer
              RUST_SRC_PATH = "${pkgs.rustToolchain}/lib/rustlib/src/rust/library";
            };
          };
        }
      );
    };
}