;; jao-random-album.el -- play random albums  -*- lexical-binding: t; -*-

;; Copyright (C) 2009, 2010, 2017-2019, 2021-2022, 2024, 2026 Jose Antonio Ortega Ruiz

;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
;; Start date: Sat Jul 04, 2009 13:06

;; This file 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 file 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/>.

(require 'multisession)

(defvar jao-random-album-active t)
(defvar jao-random-album-notify nil)
(defvar jao-random-album-skip-lines 2)

(define-multisession-variable jao-random-lines nil)

(defun jao-random-album--buffer-lines ()
  (let ((lines nil))
    (dotimes (n (1- (line-number-at-pos (point-max))) lines)
      (when (> n jao-random-album-skip-lines)
        (push (1+ n) lines)))))

(defun jao-random-lines ()
  (or (multisession-value jao-random-lines)
      (jao-random-lines-save (jao-random-album--buffer-lines))))

(defun jao-random-lines-save (v)
  (setf (multisession-value jao-random-lines) v))

(defun jao-goto-random-album ()
  (let* ((lines (jao-random-lines))
         (pos (random (length lines)))
         (line (nth pos lines)))
    (jao-random-lines-save (remove line lines))
    (goto-line line)))


;; User interface
(defvar jao-random-album-buffer)
(defvar jao-random-album-add-tracks-and-play)
(defvar jao-random-album-stop)

(defun jao-random-album-start ()
  (interactive)
  (setq jao-random-album-active t)
  (jao-random-album-next))

(defun jao-random-album-stop ()
  (interactive)
  (setq jao-random-album-active nil)
  (funcall jao-random-album-stop))

(defun jao-random-album-toggle ()
  (interactive)
  (setq jao-random-album-active (not jao-random-album-active))
  (message "Random album %s"
           (if jao-random-album-active "enabled" "disabled")))

(defun jao-random-album-next ()
  (interactive)
  (with-current-buffer (get-buffer (funcall jao-random-album-buffer))
    (jao-goto-random-album)
    (let ((album (string-trim (thing-at-point 'line))))
      (funcall jao-random-album-add-tracks-and-play album)
      (when jao-random-album-notify
        (funcall jao-random-album-notify album)))))

(defun jao-random-album-reset ()
  (interactive)
  (jao-random-lines-save nil))

(defun jao-random-album-setup (album-buffer add-and-play stop)
  (setq jao-random-album-buffer album-buffer
        jao-random-album-add-tracks-and-play add-and-play
        jao-random-album-stop stop))


(provide 'jao-random-album)
;;; jao-random-album.el ends here
