# Fg42 - Emacs Editor for advance users
#
# Copyright (c) 2010-2024 Sameer Rahmani <lxsameer@gnu.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 2.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

{ pkgs, lib }:
let
  isStrEmpty = s: (builtins.replaceStrings [ " " ] [ "" ] s) == "";

  splitString = _sep: _s: builtins.filter
    (x: builtins.typeOf x == "string")
    (builtins.split _sep _s);

in {
  elispStr
, alwaysEnsure ? false
}:
  let
    inherit (import ./elisp_reader.nix { inherit lib; }) fromElisp;

    readFunction = fromElisp;
    find = item: list:
      if list == [] then [] else
        if builtins.head list == item then
          list
        else
          find item (builtins.tail list);

    getKeywordValue = keyword: list:
      let
        keywordList = find keyword list;
      in
        if keywordList != [] then
          let
            keywordValue = builtins.tail keywordList;
          in
            if keywordValue != [] then
              builtins.head keywordValue
            else
              true
        else
          null;

    isDisabled = item:
      let
        disabledValue = getKeywordValue ":disabled" item;
      in
        if disabledValue == [] then
          false
        else if builtins.isBool disabledValue then
          disabledValue
        else if builtins.isString disabledValue then
          true
        else
          false;

    getName = item:
      let
        ensureValue = getKeywordValue ":ensure" item;
        usePackageName = builtins.head (builtins.tail item);
      in
        if builtins.isString ensureValue then
          if lib.hasPrefix ":" ensureValue then
            usePackageName
          else
            ensureValue
        else if ensureValue == true || (ensureValue == null && alwaysEnsure) then
          usePackageName
        else
          [];

    recurse = item:
      if builtins.isList item && item != [] then
        let
          packageManager = builtins.head item;
        in
          if builtins.elem packageManager [ "depends-on" ] then
            if !(isDisabled item) then
              [ packageManager (getName item) ] ++ map recurse item
            else
              []
          else
            map recurse item
      else
        [];
  in lib.flatten (map recurse (readFunction elispStr))