prop/flake.nix

{
  description = "Prop — Microwave propagation prediction for NTMS";

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

    flake-parts = {
      url = "github:hercules-ci/flake-parts";
      inputs.nixpkgs-lib.follows = "nixpkgs";
    };

    systems.url = "github:nix-systems/default";

    pre-commit-hooks = {
      url = "github:cachix/pre-commit-hooks.nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs =
    inputs@{
      self,
      nixpkgs,
      flake-parts,
      systems,
      pre-commit-hooks,
    }:
    flake-parts.lib.mkFlake { inherit inputs; } {
      systems = builtins.filter (s: s != "x86_64-darwin") (import systems);

      perSystem =
        {
          config,
          self',
          inputs',
          pkgs,
          system,
          ...
        }:
        let
          pkgs' = import nixpkgs {
            inherit system;
            config = {
              allowUnfree = true;
            };
            overlays = [
              # Pin Erlang 29.0.3 and Elixir 1.20.2 (matches .tool-versions)
              (final: prev: {
                erlang = prev.beam.interpreters.erlang_29;
                elixir = prev.beam.packages.erlang_29.elixir_1_20;
                beamPackages = prev.beam.packages.erlang_29.extend (
                  self: super: {
                    elixir = super.elixir_1_20;
                  }
                );
              })
            ];
          };

          # wgrib2 is compiled from source — not in nixpkgs
          wgrib2 = pkgs'.callPackage ./nix/wgrib2.nix { };
        in
        {
          _module.args.pkgs = pkgs';

          # Development shell with PostgreSQL, Rust, Elixir LSP
          devShells.default = pkgs'.callPackage ./nix/shell.nix {
            pre-commit-hooks = inputs.pre-commit-hooks.lib.${system};
            inherit wgrib2;
          };

          # Nix formatter for flake files
          formatter = pkgs.nixfmt;
        };
    };
}