{ config, lib, ... }:

let
  cfg = config.home.ensureDirs;

  enabledDirs = lib.filterAttrs (_: opts: opts.enable) cfg;

  dirType = lib.types.submodule (
    { name, ... }:
    {
      options = {
        enable = lib.mkEnableOption "this directory" // {
          default = true;
        };

        path = lib.mkOption {
          type = lib.types.str;
          default = name;
          description = "Directory path relative to $HOME. Defaults to the attribute name.";
        };

        mode = lib.mkOption {
          type = lib.types.str;
          default = "755";
          description = "Octal permissions to set on the directory.";
        };
      };
    }
  );

  activationScript = builtins.concatStringsSep "\n" (
    lib.mapAttrsToList (_: opts: ''
      run mkdir -p "$HOME/${opts.path}"
      run chmod ${opts.mode} "$HOME/${opts.path}"
    '') enabledDirs
  );

in
{
  options.home.ensureDirs = lib.mkOption {
    type = lib.types.attrsOf dirType;
    default = { };
    description = ''
      Set of directories (relative to $HOME) to create with specific
      permissions on every home-manager activation. Works on both
      Linux and Darwin. The attribute name defaults as the directory
      path but can be overridden via the `path` option.
    '';
    example = lib.literalExpression ''
      {
        ".ssh"               = { mode = "700"; };
        ".gnupg"             = { mode = "700"; };
        ".local/share/myapp" = { mode = "700"; };
        "projects"           = {};
        "my-workspace" = {
          path = "work/projects";
          mode = "750";
        };
      }
    '';
  };

  config = lib.mkIf (enabledDirs != { }) {
    home.activation.ensureDirs = lib.hm.dag.entryAfter [ "writeBoundary" ] activationScript;
  };
}