;;; emms-lyrics.el --- Display lyrics synchronically

;; Copyright (C) 2005, 2006 Free Software Foundation, Inc.

;; Author: William Xu <william.xwl@gmail.com>
;; Keywords: emms music lyric

;; This file is part of EMMS.

;; EMMS 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 2, or (at your option)
;; any later version.
;;
;; EMMS 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 EMMS; if not, write to the Free Software Foundation,
;; Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

;;; Commentary:

;; This package enables you to play music files and display lyrics
;; synchronically! :-) Plus, it provides a `emms-lyrics-mode' for
;; making lyric files.

;; Put this file into your load-path and the following into your
;; ~/.emacs:
;;             (require 'emms-lyrics)
;;
;; Then either `M-x emms-lyrics-enable' or add (emms-lyrics 1) in
;; your .emacs to enable.

;;; Known bugs:

;; 1. Sometimes music playing would be blocked by some process, like
;;    startup Gnus, while emms-lyrics still goes on, thus make music and
;;    lyrics asynchronical.

;;; Todo:

;; 1. Maybe the lyric setup should run before `emms-start'.
;; 2. Give a user a chance to choose when finding out multiple lyrics.
;; 3. Search lyrics from internet ?

;;; Code:

(require 'emms)
(require 'emms-player-simple)
(require 'emms-source-file)
(require 'time-date)

;;; User Customization

(defgroup emms-lyrics nil
  "Lyrics module for EMMS."
  :group 'emms)

(defcustom emms-lyrics-display-on-modeline t
  "If non-nil, display lyrics on mode line."
  :type 'boolean
  :group 'emms-lyrics)

(defcustom emms-lyrics-display-on-minibuffer nil
  "If non-nil, display lyrics on minibuffer."
  :type 'boolean
  :group 'emms-lyrics)

(defcustom emms-lyrics-dir ""
  "Local lyrics repository. `emms-lyrics-find-lyric' will look
for lyrics in current directory and this directory."
  :type 'string
  :group 'emms-lyrics)

(defcustom emms-lyrics-display-format " %s "
  "Format for displaying lyrics."
  :type 'string
  :group 'emms-lyrics)

(defcustom emms-lyrics-coding-system 'utf-8
  "Coding system used in the output of lyrics."
  :type 'coding-system
  :group 'emms-lyrics)

(defcustom emms-lyrics-mode-hook nil
  "Normal hook run after entering Emms Lyric mode."
  :type 'hook
  :group 'emms-lyrics)

(defcustom emms-lyrics-find-lyric-function 'emms-lyrics-find-lyric
  "Function for finding lyric files."
  :type 'symbol
  :group 'emms-lyrics)


;;; Emms Lyrics

(defvar emms-lyrics-display-p t
  "If non-nil, will diplay lyrics.")

(defvar emms-lyrics-alist nil
  "a list of the form: '((time0 lyric0) (time1 lyric1)...)). In short,
at time-i, display lyric-i.")

(defvar emms-lyrics-timers nil
  "timers for displaying lyric.")

(defvar emms-lyrics-start-time nil
  "emms lyric start time.")

(defvar emms-lyrics-pause-time nil
  "emms lyric pause time.")

(defvar emms-lyrics-elapsed-time 0
  "How long time has emms lyric played.")

(defvar emms-lyrics-mode-line-string ""
  "Current lyric.")

(defun emms-lyrics-read-file (file &optional catchup)
  "Read a lyric file(LRC format).
Optional CATCHUP is for recognizing `emms-lyrics-catchup'.
FILE should end up with \".lrc\", its content looks like one of the
following:

    [1:39]I love you, Emacs!
    [00:39]I love you, Emacs!
    [00:39.67]I love you, Emacs!

FILE should be under the same directory as the music file, or under
`emms-lyrics-dir'."
  (or catchup
      (setq file (funcall emms-lyrics-find-lyric-function file)))
  (when (and file (file-exists-p file))
    (with-temp-buffer
      (let ((coding-system-for-read emms-lyrics-coding-system))
        (insert-file-contents file)
        (while (search-forward-regexp "\\[[0-9:.]+\\].*" nil t)
          (let ((lyric-string (match-string 0))
                (time 0)
                (lyric ""))
            (setq lyric
                  (emms-replace-regexp-in-string ".*\\]" "" lyric-string))
            (while (string-match "\\[[0-9:.]+\\]" lyric-string)
              (let* ((time-string (match-string 0 lyric-string))
                     (semi-pos (string-match ":" time-string)))
                (setq time
                      (+ (* (string-to-number
                             (substring time-string 1 semi-pos))
                            60)
                         (string-to-number
                          (substring time-string
                                     (1+ semi-pos)
                                     (1- (length time-string))))))
                (setq lyric-string
                      (substring lyric-string (length time-string)))
                (setq emms-lyrics-alist
                      (append emms-lyrics-alist `((,time ,lyric))))
                (setq time 0))))))
      t)))

(defun emms-lyrics-start ()
  "Start displaying lryics."
  (setq emms-lyrics-start-time (current-time)
	emms-lyrics-pause-time nil
	emms-lyrics-elapsed-time 0)
  (when (let ((file
	       (emms-track-get
		(emms-playlist-current-selected-track)
		'name)))
	  (emms-lyrics-read-file
	   (emms-replace-regexp-in-string
	    (concat "\\." (file-name-extension file) "\\'")
            ".lrc"
            (file-name-nondirectory file))))
    (emms-lyrics-set-timer)))

(defun emms-lyrics-catchup (lrc)
  "Catchup with later downloaded LRC file(full path).
If you write some lyrics crawler, which is running asynchronically,
then this function would be useful to call when the crawler finishes its
job."
  (let ((old-start emms-lyrics-start-time))
    (setq emms-lyrics-start-time (current-time)
          emms-lyrics-pause-time nil
          emms-lyrics-elapsed-time 0)
    (emms-lyrics-read-file lrc t)
    (emms-lyrics-set-timer)
    (emms-lyrics-seek
     (time-to-seconds (time-since old-start)))))

(defun emms-lyrics-stop ()
  "Stop displaying lyrics."
  (interactive)
  (when emms-lyrics-alist
    (mapc #'emms-cancel-timer emms-lyrics-timers)
    (if (or (not emms-player-paused-p)
	    emms-player-stopped-p)
	(setq emms-lyrics-alist nil
	      emms-lyrics-timers nil
	      emms-lyrics-mode-line-string ""))))

(defun emms-lyrics-pause ()
  "Pause displaying lyrics."
  (if emms-player-paused-p
      (setq emms-lyrics-pause-time (current-time))
    (when emms-lyrics-pause-time
      (setq emms-lyrics-elapsed-time
	    (+ (time-to-seconds
		(time-subtract emms-lyrics-pause-time
			       emms-lyrics-start-time))
	       emms-lyrics-elapsed-time)))
    (setq emms-lyrics-start-time (current-time)))
  (when emms-lyrics-alist
    (if emms-player-paused-p
	(emms-lyrics-stop)
      (emms-lyrics-set-timer))))

(defun emms-lyrics-seek (sec)
  "Seek forward or backward SEC seconds lyrics."
  (setq emms-lyrics-elapsed-time
	(+ emms-lyrics-elapsed-time
	   (time-to-seconds (time-since emms-lyrics-start-time))
	   sec))
  (when (< emms-lyrics-elapsed-time 0)	; back to start point
    (setq emms-lyrics-elapsed-time 0))
  (setq emms-lyrics-start-time (current-time))
  (when emms-lyrics-alist
    (let ((paused-orig emms-player-paused-p))
      (setq emms-player-paused-p t)
      (emms-lyrics-stop)
      (setq emms-player-paused-p paused-orig))
    (emms-lyrics-set-timer)))

(defun emms-lyrics-sync (sec)
  "Synchronize the lyric display at SEC seconds."
  (setq emms-lyrics-start-time (current-time)
        emms-lyrics-elapsed-time 0)
  (emms-lyrics-seek sec))

(defun emms-lyrics-toggle-display-on-minibuffer ()
  "Toggle display lyrics on minibbufer."
  (interactive)
  (if emms-lyrics-display-on-minibuffer
      (progn
	(setq emms-lyrics-display-on-minibuffer nil)
	(message "Disable lyrics on minibufer."))
    (setq emms-lyrics-display-on-minibuffer t)
    (message "Enable lyrics on minibufer.")))

(defun emms-lyrics-toggle-display-on-modeline ()
  "Toggle display lyrics on mode line."
  (interactive)
  (if emms-lyrics-display-on-modeline
      (progn
	(setq emms-lyrics-display-on-modeline nil
	      emms-lyrics-mode-line-string "")
	(message "Disable lyrics on mode line."))
    (setq emms-lyrics-display-on-modeline t)
    (message "Enable lyrics on mode line.")))

(defun emms-lyrics (arg)
  "Turn on emms lyrics display if ARG is positive, off otherwise."
  (interactive "p")
  (if (and arg (> arg 0))
      (progn
        (setq emms-lyrics-display-p t)
        (add-hook 'emms-player-started-hook     'emms-lyrics-start)
        (add-hook 'emms-player-stopped-hook     'emms-lyrics-stop)
        (add-hook 'emms-player-finished-hook    'emms-lyrics-stop)
        (add-hook 'emms-player-paused-hook      'emms-lyrics-pause)
        (add-hook 'emms-player-seeked-functions 'emms-lyrics-seek)
        (add-hook 'emms-player-time-set-functions 'emms-lyrics-sync))
    (emms-lyrics-stop)
    (setq emms-lyrics-display-p nil)
    (emms-lyrics-restore-mode-line)
    (remove-hook 'emms-player-started-hook     'emms-lyrics-start)
    (remove-hook 'emms-player-stopped-hook     'emms-lyrics-stop)
    (remove-hook 'emms-player-finished-hook    'emms-lyrics-stop)
    (remove-hook 'emms-player-paused-hook      'emms-lyrics-pause)
    (remove-hook 'emms-player-seeked-functions 'emms-lyrics-seek)
    (remove-hook 'emms-player-time-set-functions 'emms-lyrics-sync)))

;;;###autoload
(defun emms-lyrics-enable ()
  "Enable displaying emms lyrics."
  (interactive)
  (emms-lyrics 1)
  (message "emms lyrics enabled."))

;;;###autoload
(defun emms-lyrics-disable ()
  "Disable displaying emms lyrics."
  (interactive)
  (emms-lyrics -1)
  (message "emms lyrics disabled."))

;;;###autoload
(defun emms-lyrics-toggle ()
  "Toggle displaying emms lyrics."
  (interactive)
  (if emms-lyrics-display-p
      (emms-lyrics-disable)
    (emms-lyrics-enable)))

(defun emms-lyrics-set-timer ()
  "Set timers for displaying lyrics."
  (setq emms-lyrics-timers
	(mapcar
	 '(lambda (arg)
	    (let ((time (- (car arg) emms-lyrics-elapsed-time))
		  (lyric (cadr arg)))
	      (when (>= time 0)
		(run-at-time (format "%d sec" time)
			     nil
			     'emms-lyrics-display
			     lyric))))
	 emms-lyrics-alist)))

(defun emms-lyrics-mode-line ()
  "Add lyric to the mode line."
  (or global-mode-string (setq global-mode-string '("")))
  (unless (member 'emms-lyrics-mode-line-string
		  global-mode-string)
    (setq global-mode-string
	  (append global-mode-string
		  '(emms-lyrics-mode-line-string)))))

(defun emms-lyrics-restore-mode-line ()
  "Restore the mode line."
  (setq global-mode-string
	(remove 'emms-lyrics-mode-line-string global-mode-string))
  (force-mode-line-update))

(defun emms-lyrics-display (lyric)
  "Display lyric.

LYRIC is current playing lyric.

See `emms-lyrics-display-on-modeline' and
`emms-lyrics-display-on-minibuffer' on how to config where to
display."
  (when emms-lyrics-alist
    (when emms-lyrics-display-on-modeline
      (emms-lyrics-mode-line)
      (setq emms-lyrics-mode-line-string
	    (format emms-lyrics-display-format lyric))
      (force-mode-line-update))
    (when emms-lyrics-display-on-minibuffer
      (unless (minibuffer-window-active-p (selected-window))
        (message lyric)))))

(defun emms-lyrics-find-lyric (file)
  "Return full path of found lrc FILE, or nil if not found.
Use `emms-source-file-gnu-find' to find lrc FILE under current directory
and `emms-lyrics-dir'.
e.g., (emms-lyrics-find-lyric \"abc.lrc\")"
  (let* ((track (emms-playlist-current-selected-track))
         (dir (file-name-directory (emms-track-get track 'name))))
    (when (eq 'file (emms-track-get track 'type))
      ;; If find two or more lyric files, only return the first one. Good
      ;; luck! :-)
      (if (file-exists-p (concat dir file)) ; same directory?
          (concat dir file)
        (when (not (string= emms-lyrics-dir ""))
          (let* ((ret (car (split-string
                            (shell-command-to-string
                             (concat emms-source-file-gnu-find " "
                                     emms-lyrics-dir " -name "
                                     "'" ; wrap up whitespaces, FIXME, '->\'
                                     (emms-replace-regexp-in-string "'" "*" file)
                                     "'"))
                            "\n"))))
            (unless (equal ret "")
              ret)))))))

(defun emms-lyrics-find-current-lyric ()
  "Visit current selected track's lyric file."
  (interactive)
  (let ((name (emms-track-get (emms-playlist-current-selected-track)
                              'name)))
    (condition-case nil
        (find-file-existing
         (funcall emms-lyrics-find-lyric-function
                  (emms-replace-regexp-in-string
                   (concat "\\." (file-name-extension name) "\\'")
                   ".lrc"
                   (file-name-nondirectory name))))
      (error "lyric file does not exist"))))


;;; emms-lyrics-mode

(defvar emms-lyrics-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map "p" 'emms-lyrics-previous-line)
    (define-key map "n" 'emms-lyrics-next-line)
    (define-key map "i" 'emms-lyrics-insert-time)
    map)
  "Keymap for `emms-lyrics-mode'.")

(defun emms-lyrics-rem* (x y)
  "The remainder of X divided by Y, with the same sign as X."
  (let* ((q (floor x y))
         (rem (- x (* y q))))
    (if (= rem 0)
        0
      (if (eq (>= x 0) (>= y 0))
          rem
        (- rem y)))))

(defun emms-lyrics-insert-time ()
  "Insert lyric time in the form: [01:23.21], then goto the
beginning of next line."
  (interactive)
  (let* ((total (+ (time-to-seconds
		    (time-subtract (current-time)
				   emms-lyrics-start-time))
		   emms-lyrics-elapsed-time))
	 (min (/ (* (floor (/ total 60)) 100) 100))
	 (sec (/ (floor (* (emms-lyrics-rem* total 60) 100)) 100.0)))
    (insert (emms-replace-regexp-in-string
	     " " "0" (format "[%2d:%2d]" min sec))))
  (emms-lyrics-next-line))

(defun emms-lyrics-next-line ()
  "Goto the beginning of next line."
  (interactive)
  (forward-line 1))

(defun emms-lyrics-previous-line ()
  "Goto the beginning of previous line."
  (interactive)
  (forward-line -1))

(define-derived-mode emms-lyrics-mode nil "Emms Lyric"
  "Major mode for creating lyric files.
\\{emms-lyrics-mode-map}"
  (run-hooks 'emms-lyrics-mode-hook))

(provide 'emms-lyrics)

;;; emms-lyrics.el ends here