# flakelight -- Framework for simplifying flake setup
# Copyright (C) 2023 Archit Gupta <archit@accelbread.com>
# SPDX-License-Identifier: MIT

{ config, src, lib, flakelight, genSystems, ... }:
let
  inherit (lib) isFunction last mapAttrs mergeDefinitions mkIf mkOption
    mkOptionType;
  inherit (lib.types) lazyAttrsOf optionDescriptionPhrase;
  inherit (flakelight.types) coercedTo' drv nullable optFunctionTo stringLike;

  mkCheck = name: pkgs: cmd:
    pkgs.runCommand "check-${name}" { } ''
      cp --no-preserve=mode -r ${src} src
      cd src
      ${cmd}
      touch $out
    '';

  checkType = mkOptionType {
    name = "checkType";
    description =
      let
        targetDesc = optionDescriptionPhrase
          (class: class == "noun" || class == "composite")
          (coercedTo' stringLike (abort "") drv);
      in
      "${targetDesc} or function that evaluates to it";
    descriptionClass = "composite";
    check = x: isFunction x || drv.check x || stringLike.check x;
    merge = loc: defs: pkgs:
      let
        targetType = coercedTo' stringLike (mkCheck (last loc) pkgs) drv;
      in
      (mergeDefinitions loc targetType (map
        (fn: {
          inherit (fn) file;
          value = if isFunction fn.value then fn.value pkgs else fn.value;
        })
        defs)).mergedValue;
  };
in
{
  options.checks = mkOption {
    type = nullable (optFunctionTo (lazyAttrsOf checkType));
    default = null;
  };

  config.outputs = mkIf (config.checks != null) {
    checks = genSystems (pkgs: mapAttrs (_: v: v pkgs) (config.checks pkgs));
  };
}