;;; emms-playlist-mode.el --- Playlist mode for Emms.

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

;; Author: Yoni Rabkin <yonirabkin@member.fsf.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; either version 2, 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, write to the Free Software
;; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
;; 02110-1301 USA

;;; Commentary:
;;;
;;; This is a method of displaying and manipulating the different Emms
;;; playlist buffers.
;;;
;;; Emms developer's motto: "When forcer says (require 'jump) we say
;;; (funcall #'jump height)"

;;; Code:

;;; --------------------------------------------------------
;;; Variables
;;; --------------------------------------------------------

(require 'emms)
(eval-when-compile
  (condition-case nil
      (require 'overlay)
    (error nil)))
(require 'emms-source-playlist)

(defvar emms-playlist-mode-hook nil
  "Emms playlist mode hook.")

(defvar emms-playlist-mode-selected-overlay nil
  "Last selected track.  Use for updating the display.")

(defvar emms-playlist-mode-switched-buffer nil
  "Last buffer visited before calling `emms-playlist-mode-switch-buffer'.")

(defvar emms-playlist-mode-window-width -25
  "Width for the emms-playlist-mode pop-up window.")

(make-variable-buffer-local
 'emms-playlist-mode-selected-overlay)

(defgroup emms-playlist-mode nil
  "*The Emacs Multimedia System playlist mode."
  :prefix "emms-playlist-mode-"
  :group 'emms)

(defcustom emms-playlist-mode-open-playlists nil
  "*Determine whether to open playlists in a new EMMS buffer on RET.
This is useful if you have a master playlist buffer that is
composed of other playlists."
  :type 'boolean
  :group 'emms-playlist-mode)

;;; --------------------------------------------------------
;;; Faces
;;; --------------------------------------------------------

(defface emms-playlist-track-face
  '((((class color) (background dark))
     (:foreground "DarkSeaGreen"))
    (((class color) (background light))
     (:foreground "Blue"))
    (((type tty) (class mono))
     (:inverse-video t))
    (t (:background "Blue")))
  "Face for the tracks in a playlist buffer."
  :group 'emms-playlist-mode)

(defface emms-playlist-selected-face
  '((((class color) (background dark))
     (:foreground "SteelBlue3"))
    (((class color) (background light))
     (:background "blue3" :foreground "white"))
    (((type tty) (class mono))
     (:inverse-video t))
    (t (:background "blue3")))
  "Face for highlighting the selected track."
  :group 'emms-playlist-mode)

;;; --------------------------------------------------------
;;; Keys
;;; --------------------------------------------------------

(defconst emms-playlist-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map text-mode-map)
    (define-key map (kbd "C-x C-s") 'emms-playlist-save)
    (define-key map (kbd "C-y") 'emms-playlist-mode-yank)
    (define-key map (kbd "C-k") 'emms-playlist-mode-kill-track)
    (define-key map (kbd "C-w") 'emms-playlist-mode-kill)
    (define-key map (kbd "C-_") 'emms-playlist-mode-undo)
    (define-key map (kbd "C-n") 'next-line)
    (define-key map (kbd "C-p") 'previous-line)
    (define-key map (kbd "C-j") 'emms-playlist-mode-insert-newline)
    (define-key map (kbd "M-y") 'emms-playlist-mode-yank-pop)
    (define-key map (kbd "M-<") 'emms-playlist-mode-first)
    (define-key map (kbd "M->") 'emms-playlist-mode-last)
    (define-key map (kbd "d") 'emms-playlist-mode-kill-entire-track)
    (define-key map (kbd "n") 'emms-next)
    (define-key map (kbd "p") 'emms-previous)
    (define-key map (kbd "s") 'emms-stop)
    (define-key map (kbd "f") 'emms-show)
    (define-key map (kbd "c") 'emms-playlist-mode-center-current)
    (define-key map (kbd "q") 'bury-buffer)
    (define-key map (kbd "k") 'emms-playlist-current-kill)
    (define-key map (kbd "?") 'describe-mode)
    (define-key map (kbd "r") 'emms-random)
    (define-key map (kbd "<mouse-2>") 'emms-playlist-mode-play-current-track)
    (define-key map (kbd "RET") 'emms-playlist-mode-play-dtrt)
    map)
  "Keymap for `emms-playlist-mode'.")

(defmacro emms-playlist-mode-move-wrapper (name fun)
  "Create a function NAME which is an `interactive' version of FUN.

NAME should be a symbol.
FUN should be a function."
  `(defun ,name ()
     ,(format "Interactive wrapper around `%s' for playlist-mode."
	      fun)
     (interactive)
     (,fun)))

(emms-playlist-mode-move-wrapper emms-playlist-mode-first
				 emms-playlist-first)

(emms-playlist-mode-move-wrapper emms-playlist-mode-last
				 emms-playlist-last)

(emms-playlist-mode-move-wrapper emms-playlist-mode-select-next
				 emms-playlist-next)

(emms-playlist-mode-move-wrapper emms-playlist-mode-select-previous
				 emms-playlist-previous)

(defun emms-playlist-mode-center-current ()
  "Move point to the currently selected track."
  (interactive)
  (goto-char (if emms-playlist-mode-selected-overlay
                 (overlay-start emms-playlist-mode-selected-overlay)
		 (point-min))))

(defun emms-playlist-mode-play-current-track ()
  "Start playing track at point."
  (interactive)
  (emms-playlist-set-playlist-buffer)
  (emms-playlist-select (point))
  (when emms-player-playing-p
    (emms-stop))
  (emms-start))

(defun emms-playlist-mode-play-dtrt ()
  "Determine the best operation to take on the current track.

If on a playlist, and `emms-playlist-mode-open-playlists' is
non-nil, load the playlist at point into a new buffer.

Otherwise play the track immediately."
  (interactive)
  (if (not emms-playlist-mode-open-playlists)
      (emms-playlist-mode-play-current-track)
    (let* ((track (emms-playlist-track-at))
           (name (emms-track-get track 'name))
           (type (emms-track-get track 'type)))
      (if (or (eq type 'playlist)
              (and (eq type 'file)
                   (string-match "\\.\\(m3u\\|pls\\)\\'" name)))
          (emms-playlist-mode-load-playlist)
        (emms-playlist-mode-play-current-track)))))

(defun emms-playlist-mode-switch-buffer ()
  "Switch to the playlist buffer and then switch back if called again.

This function switches to the current Emms playlist buffer and
remembers the buffer switched from. When called again the
function switches back to the remembered buffer."
  (interactive)
  (if (eq (current-buffer)
	  emms-playlist-buffer)
      (switch-to-buffer emms-playlist-mode-switched-buffer)
    (setq emms-playlist-mode-switched-buffer (current-buffer))
    (switch-to-buffer emms-playlist-buffer)))

(defmacro emms-with-inhibit-read-only-t (&rest body)
  "Simple wrapper around `inhibit-read-only'."
  `(let ((inhibit-read-only t))
     ,@body))
(put 'emms-with-inhibit-read-only-t 'edebug-form-spec '(body))

(defun emms-playlist-mode-insert-newline ()
  "Insert a newline at point."
  (interactive)
  (emms-with-inhibit-read-only-t
   (newline)))

(defun emms-playlist-mode-undo ()
  "Wrapper around `undo'."
  (interactive)
  (emms-with-inhibit-read-only-t
   (undo)))

;;; --------------------------------------------------------
;;; Killing and yanking
;;; --------------------------------------------------------

(defun emms-playlist-mode-between-p (p a b)
  "Return t if P is a point between points A and B."
  (and (<= a p)
       (<= p b)))

;; d
(defun emms-playlist-mode-kill-entire-track ()
  "Kill track at point, including newline."
  (interactive)
  (let ((kill-whole-line t))
    (emms-playlist-mode-kill-track)))

;; C-k
;;
;; Currently this kills as regular GNU/Emacs would and not like a
;; typical music player would.
(defun emms-playlist-mode-kill-track ()
  "Kill track at point."
  (interactive)
  (emms-with-inhibit-read-only-t
   (let ((track (emms-playlist-track-at)))
     (if track
	 (let ((track-region (emms-property-region (point)
						   'emms-track)))
	   (when (and emms-player-playing-p
		      (emms-playlist-selected-track-at-p))
	     (emms-stop)
             (delete-overlay emms-playlist-mode-selected-overlay)
             (setq emms-playlist-mode-selected-overlay nil))
	   (kill-line))
       (kill-line)))))

;; C-w
(defun emms-playlist-mode-kill ()
  "Kill from mark to point."
  (interactive)
  (emms-with-inhibit-read-only-t
   ;; Are we killing the playing/selected track?
   (when (emms-playlist-mode-between-p
          (marker-position emms-playlist-selected-marker)
          (region-beginning)
          (region-end))
     (emms-stop)
     (delete-overlay emms-playlist-mode-selected-overlay)
     (setq emms-playlist-mode-selected-overlay nil))
   (kill-region (region-beginning)
                (region-end))))

;; C-y
(defun emms-playlist-mode-yank ()
  "Yank into the playlist buffer."
  (interactive)
  (emms-with-inhibit-read-only-t
   (goto-char (point-at-bol))
   (yank)))

;; M-y
(defun emms-playlist-mode-yank-pop ()
  "Cycle through the kill-ring."
  (interactive)
  (emms-with-inhibit-read-only-t
   (yank-pop nil)))

;;; --------------------------------------------------------
;;; Overlay
;;; --------------------------------------------------------

(defun emms-playlist-mode-overlay-selected ()
  "Place an overlay over the currently selected track."
  (when emms-playlist-selected-marker
    (save-excursion
      (goto-char emms-playlist-selected-marker)
      (let ((reg (emms-property-region (point) 'emms-track)))
        (if emms-playlist-mode-selected-overlay
            (move-overlay emms-playlist-mode-selected-overlay
                          (car reg)
                          (cdr reg))
          (setq emms-playlist-mode-selected-overlay
                (make-overlay (car reg)
                              (cdr reg)
                              nil t nil))
          (overlay-put emms-playlist-mode-selected-overlay
                       'face 'emms-playlist-selected-face)
          (overlay-put emms-playlist-mode-selected-overlay
                       'evaporate t))))))

;;; --------------------------------------------------------
;;; Saving/Restoring
;;; --------------------------------------------------------

(defun emms-playlist-mode-open-buffer (filename)
  "Opens a previously saved playlist buffer.

It creates a buffer called \"filename\", and restore the contents
of the saved playlist inside."
  (interactive "fFile: ")
  (let* ((s)
	 (buffer (find-file-noselect filename))
	 (name   (buffer-name buffer)))
    (with-current-buffer buffer
      (setq s (read (buffer-string))))
    (kill-buffer buffer)
    (with-current-buffer (emms-playlist-new name)
      (emms-with-inhibit-read-only-t
       (insert s)
       (condition-case nil
	   (progn
	     (emms-playlist-first)
	     (emms-playlist-update-track)
	     (while t
	       (emms-playlist-next)
	       (emms-playlist-update-track)))
	 (error
	  nil)))
      (emms-playlist-first)
      (emms-playlist-select (point))
      (switch-to-buffer (current-buffer)))))

(defun emms-playlist-mode-load-playlist ()
  "Load the playlist into a new EMMS buffer.
This preserves the current EMMS buffer."
  (interactive)
  (let* ((track (emms-playlist-track-at))
         (name (emms-track-get track 'name))
         (type (emms-track-get track 'type)))
    (emms-playlist-select (point))
    (run-hooks 'emms-player-stopped-hook)
    (switch-to-buffer
     (emms-playlist-set-playlist-buffer (emms-playlist-new)))
    (emms-add-playlist name)))

;;; --------------------------------------------------------
;;; Local functions
;;; --------------------------------------------------------

(defun emms-playlist-mode-insert-track (track &optional no-newline)
  "Insert the description of TRACK at point.
When NO-NEWLINE is non-nil, do not insert a newline after the track."
  (emms-playlist-ensure-playlist-buffer)
  (emms-with-inhibit-read-only-t
   (insert (emms-propertize (emms-track-force-description track)
                            'emms-track track
                            'face 'emms-playlist-track-face))
   (when (emms-playlist-selected-track-at-p)
     (emms-playlist-mode-overlay-selected))
   (unless no-newline
     (insert "\n"))))

(defun emms-playlist-mode-update-track-function ()
  "Update the track display at point."
  (emms-playlist-ensure-playlist-buffer)
  (emms-with-inhibit-read-only-t
   (let ((track-region (emms-property-region (point)
					     'emms-track))
	 (track (get-text-property (point)
				   'emms-track)))
     (save-excursion
       (delete-region (car track-region)
		      (cdr track-region))
       (emms-playlist-mode-insert-track track t)))))

;;; --------------------------------------------------------
;;; Entry
;;; --------------------------------------------------------

(defun emms-playlist-mode-go ()
  "Switch to the current emms-playlist buffer and use emms-playlist-mode."
  (interactive)
  (if (or (null emms-playlist-buffer)
	  (not (buffer-live-p emms-playlist-buffer)))
      (error "No current Emms buffer")
    (switch-to-buffer emms-playlist-buffer)
    (when (and (not (eq major-mode 'emms-playlist-mode))
	       emms-playlist-buffer-p)
      (emms-playlist-mode))))

(defun emms-playlist-mode-go-popup (&optional window-width)
  "Popup emms-playlist buffer as a side window. Default value for
WINDOW-WIDTH is `emms-playlist-mode-window-width'."
  (interactive)
  (setq emms-playlist-mode-window-width
	(or window-width emms-playlist-mode-window-width))
  (split-window-horizontally emms-playlist-mode-window-width)
  (other-window 1)
  (emms-playlist-mode-go))

(defun emms-playlist-mode-startup ()
  "Instigate emms-playlist-mode on the current buffer."
  ;; when there is neither a current emms track or a playing one...
  (when (not (or emms-playlist-selected-marker
		 emms-player-playing-p))
    ;; ...then stop the player.
    (emms-stop)
    ;; why select the first track?
    (when emms-playlist-buffer-p
      (emms-playlist-select-first)))
  ;; when there is a selected track.
  (when emms-playlist-selected-marker
    (emms-playlist-mode-overlay-selected))
  (emms-with-inhibit-read-only-t
   (add-text-properties (point-min)
                        (point-max)
                        '(face emms-playlist-track-face)))
  (setq buffer-read-only t))

;;;###autoload
(defun emms-playlist-mode ()
  "A major mode for Emms playlists.
\\{emms-playlist-mode-map}"
  (interactive)
  (let ((val emms-playlist-buffer-p))
    (kill-all-local-variables)
    (setq emms-playlist-buffer-p val))

  (use-local-map emms-playlist-mode-map)
  (setq major-mode 'emms-playlist-mode
	mode-name "Emms-Playlist")

  (setq emms-playlist-insert-track-function
	'emms-playlist-mode-insert-track)
  (setq emms-playlist-update-track-function
	'emms-playlist-mode-update-track-function)
  ;; Not used yet
  ;; (setq emms-playlist-delete-track-function
  ;;       ...)
  (add-hook 'emms-playlist-selection-changed-hook
	    'emms-playlist-mode-overlay-selected)

  (emms-playlist-mode-startup)

  (run-hooks 'emms-playlist-mode-hooks))

(provide 'emms-playlist-mode)

;;; emms-playlist-mode.el ends here