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

{ config, lib, flakelight, genSystems, ... }:
let
  inherit (builtins) match storeDir;
  inherit (lib) defaultFunctor fix isFunction last mapAttrs mergeDefinitions
    mkIf mkMerge mkOption mkOptionType;
  inherit (lib.types) coercedTo enum lazyAttrsOf
    optionDescriptionPhrase pathInStore submoduleWith;
  inherit (flakelight.types) nullable optFunctionTo stringLike;

  isStorePath = s: match "${storeDir}/[^.][^ \n]*" s != null;

  app = submoduleWith {
    modules = [{
      options = {
        type = mkOption { type = enum [ "app" ]; default = "app"; };
        program = mkOption { type = pathInStore // { check = isStorePath; }; };
      };
    }];
  };

  mkApp = name: pkgs: s:
    let s' = "${s}"; in {
      program =
        if isStorePath s' then s'
        else "${pkgs.writeShellScript "app-${name}" s'}";
    };

  parameterize = value: fn: fix fn value;

  appType = parameterize app (self': app: (mkOptionType rec {
    name = "appType";
    description =
      let
        targetDesc = optionDescriptionPhrase
          (class: class == "noun" || class == "composite")
          (coercedTo stringLike (abort "") app);
      in
      "${targetDesc} or function that evaluates to it";
    descriptionClass = "composite";
    check = x: isFunction x || app.check x || stringLike.check x;
    merge = loc: defs: pkgs:
      let
        targetType = coercedTo stringLike (mkApp (last loc) pkgs) app;
      in
      (mergeDefinitions loc targetType (map
        (fn: {
          inherit (fn) file;
          value = if isFunction fn.value then fn.value pkgs else fn.value;
        })
        defs)).mergedValue;
    inherit (app) getSubOptions getSubModules;
    substSubModules = m: self' (app.substSubModules m);
    functor = (defaultFunctor name) // { wrapped = app; };
    nestedTypes.coercedType = stringLike;
    nestedTypes.finalType = app;
  }));
in
{
  options = {
    app = mkOption {
      type = nullable appType;
      default = null;
    };

    apps = mkOption {
      type = nullable (optFunctionTo (lazyAttrsOf appType));
      default = null;
    };
  };

  config = mkMerge [
    (mkIf (config.app != null) {
      apps.default = config.app;
    })

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