nixos-config/shell.nix

let
  sources = import ./nix/sources.nix;
  pkgs = import sources.nixpkgs { };

  nix-pre-commit-hooks = import sources."pre-commit-hooks.nix";

  pre-commit-check = nix-pre-commit-hooks.run {
    src = ./.;
    hooks = {
      nixpkgs-fmt.enable = true;
    };
  };

  update-sources = pkgs.writeShellScriptBin "update-sources" ''
    set -e
    git diff --exit-code -s nix/sources.json || (echo "File nix/sources.json has unstaged changes, refusing to update." >&2 && exit 1)
    git diff --cached --exit-code -s nix/sources.json || (echo "File nix/sources.json has staged changes, refusing to update." >&2 && exit 1)
    niv update
    git diff --exit-code -s nix/sources.json && echo "Already up to date." && exit 0
    git commit -m "Update sources" nix/sources.json
  '';
in
pkgs.mkShell {
  nativeBuildInputs = (with pkgs; [
    git
    niv
    nixpkgs-fmt
  ]) ++ [
    update-sources
  ];
  shellHook = ''
    ${pre-commit-check.shellHook}
  '';
}