;; -*- lexical-binding: t; -*-
;;; yekneb-set-source-directory.el --- Sets the `source-directory' variable for GNU Emacs.

;; Copyright © 2021 - 2025 Ben Key

;; This file is part of the yekneb package.
;;
;; The yekneb package 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, either version 3 of the License, or (at your option) any
;; later version.
;;
;; The yekneb package 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
;; the yekneb package. If not, see <http://www.gnu.org/licenses/>.

(require 'cl-lib)
(require 'find-func)
(require 'yekneb-file-utilities)

;;;###autoload
(defconst
  yekneb-source-directory-candidates
  (list
   (format "/usr/local/share/emacs/%d.%d" emacs-major-version emacs-minor-version)
   (expand-file-name (format "~/src/packages/emacs%d-%d.%d+1" emacs-major-version emacs-major-version emacs-minor-version))
   (expand-file-name (format "~/src/packages/emacs-%d.%d" emacs-major-version emacs-minor-version))
   (expand-file-name (format "~/src/emacs-%d.%d" emacs-major-version emacs-minor-version))
   (expand-file-name "../src" invocation-directory)
   (expand-file-name (format "../src/emacs-%d.%d" emacs-major-version emacs-minor-version) invocation-directory)
   (expand-file-name (format "../../src/emacs-%d.%d" emacs-major-version emacs-minor-version) invocation-directory)
   (expand-file-name (format "../../../src/emacs-%d.%d" emacs-major-version emacs-minor-version) invocation-directory)
   (format "${USERPROFILE}/src/emacs-%d.%d" emacs-major-version emacs-minor-version)
   (format "${SOURCE_ROOT}/emacs-%d.%d" emacs-major-version emacs-minor-version)
   (format "${SystemDrive}/src/emacs-%d.%d" emacs-major-version emacs-minor-version)
   )
  "A list of possible candidates for the source directory."
  )

(defun yekneb-source-directory-is-valid ()
  "Determines if the `source-directory' variable set and is valid."
  (and source-directory (file-directory-p source-directory))
  )

(defun yekneb-find-function-C-source-directory-is-valid ()
  "Determines if the `source-directory' variable set and is valid."
  (and find-function-C-source-directory (file-directory-p find-function-C-source-directory))
  )

;;;###autoload
(defun yekneb-set-source-directory ()
  "Sets the `source-directory' and `find-function-C-source-directory' variables."
  (when (not (yekneb-source-directory-is-valid))
    (cl-dolist (candidate yekneb-source-directory-candidates)
      (setq candidate (yekneb-convert-slash-in-file-name (substitute-env-vars candidate)))
      (when
        (and
         (file-directory-p candidate)
         (file-directory-p (expand-file-name "nt" candidate))
         (file-directory-p (expand-file-name "src" candidate))
         (file-exists-p (expand-file-name "src/emacs.c" candidate))
         (file-directory-p (expand-file-name "site-lisp" candidate))
         )
        (setq source-directory candidate)
        (let ((dir (expand-file-name "src" source-directory)))
          (when (file-accessible-directory-p dir)
            (setq find-function-C-source-directory dir)
            )
          )
        (cl-return)
        )
      )
    )
  )

(provide 'yekneb-set-source-directory)