;;; background.el ---                                -*- lexical-binding: t; -*-

;; Copyright (C) 2021  Arthur Miller

;; Author: Arthur Miller <arthur.miller@live.com>
;; Keywords: 

;; 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, either version 3 of the License, or
;; (at your option) any later version.

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;; 

;;; Code:

(defvar bg-walpaper-dir (expand-file-name "~/wallpapers"))
(defvar bg-img-list nil)
(defvar bg-frame nil)
(defvar bg-buffer nil)
(defvar bg-curr-image nil)
(defvaralias 'bg-nd 'directory-files-no-dot-files-regexp)

(defun bg-init-buffer ()
  (unless bg-buffer
    (setq bg-buffer (get-buffer-create "  *bg-buffer*")))
  (with-current-buffer bg-buffer
    (with-silent-modifications
      (erase-buffer)
      (setq mode-line-format nil)
      (insert-image (create-image bg-curr-image)))))

(defun bg-init-frame ()
  (if (display-graphic-p)
      (unless bg-frame
        (let ((w (+ (display-pixel-width) 2))
              (h (+ (display-pixel-height) 2)))
          (setq bg-frame (make-frame 
                          `((name . "bg-frame")
                            (width . ,w)
                            (height . ,h)
                            (visibility . t)
                            (auto-raise . nil)
                            (skip-taskbar . t)
                            (no-focus-on-map . t)
                            (no-accept-focus . t)
                            (undecorated . t)
                            (unsplittable . t)
                            (z-group . below)
                            (no-other-frame . t)
                            (minibuffer . nil)
                            (tool-bar-lines . 0)
                            (menu-bar-lines . 0)
                            (left-fringe . 0)
                            (right-fringe . 0)
                            (border-width . 0)
                            (internal-border-width . 0)
                            (vertical-scroll-bars . nil)
                            (horizontal-scroll-bars . nil))))))))

(defun bg-kill-frame ()
  (when bg-frame
    (delete-frame bg-frame)
    (setq bg-frame nil)
    (kill-buffer bg-buffer)
    (setq bg-buffer nil)))

(defun bg-get-random-image ()
  (when bg-walpaper-dir
    (unless bg-img-list
      (setq bg-img-list (directory-files bg-walpaper-dir t bg-nd t)))
    (let ((index (random (length bg-img-list))))
      (if (not (equal (nth index bg-img-list) bg-curr-image))
          (nth index bg-img-list)
        (bg-get-random-image)))))

(defun bg-show-background (&optional image-name)
  (interactive)
  (setq bg-curr-image (or image-name (bg-get-random-image)))
  (bg-init-buffer)
  (unless bg-frame (bg-init-frame))
  (with-selected-frame bg-frame
    (switch-to-buffer bg-buffer))
  (unless (frame-visible-p bg-frame) (make-frame-visible bg-frame)))

(defun bg-hide-background ()
  (interactive)
  (bg-kill-frame))

(provide 'background)
;;; background.el ends here