;;; emms-browser.el --- provide a buffer to browse files

;; Copyright (C) 2006  Damien Elmes <emacs@repose.cx>

;; Author: Damien Elmes <emacs@repose.cx>
;; Keywords: emms, mp3, mpeg, multimedia

;; 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; This code allows you to browse the metadata cache and add tracks to
;; your playlist. To be properly useful, you should M-x
;; emms-add-directory-tree to all the files you own at least once so
;; that the cache is fully populated.

;; To use, run (emms-devel) and then bind emms-smart-browse to a key,
;; like:

;; (global-set-key (kbd "<f2>") 'emms-smart-browse)

;; The 'smart browsing' code attempts to link the browser and playlist
;; windows together, so that closing one will close both. Activating
;; it will toggle between three states:

;; a) both windows displayed, with the browser focused
;; b) focus switched to the playlist window
;; c) the extra window closed, and both buffers buried

;; Some useful keybindings in the browser buffer:

;; SPC      - expand/contract current item
;; RET      - add current artist/album/title/etc
;; C-RET    - as above, but select the first added file and play
;; /        - isearch through the available items
;; q        - bury both buffers (if you use emms-smart-browse)

;; If you just want access to the browser, try M-x
;; emms-browse-by-TYPE, where TYPE is one of artist, album, genre or
;; year. These commands can also be used while smart browsing to
;; change the browsing category.

;; If you don't want to activate the code with (emms-devel), you can
;; activate it manually with:

;; (require 'emms-browser)

;; Note this code is very new and is still prone to big changes in the
;; API and breakage. Bug reports are welcome.

;;; Code:

(require 'emms)
(require 'emms-cache)
(require 'emms-source-file)

(eval-when-compile
  (require 'cl))

;; --------------------------------------------------
;; Variables and configuration
;; --------------------------------------------------

(defgroup emms-browser nil
  "*The Emacs Multimedia System browser"
  :prefix "emms-browser-"
  :group 'multimedia
  :group 'applications)

(defcustom emms-browser-default-browsing-function
  'emms-browse-by-artist
  "The default browsing mode."
  :group 'emms-browser
  :type 'function)

(defcustom emms-browser-make-name-function
  'emms-browser-make-name-standard
  "A function to make names for entries and subentries.
Overriding this function allows you to customise how various elements
are displayed. It is called with two arguments - track and type."
  :group 'emms-browser
  :type 'function)

(defcustom emms-browser-insert-track-function
  'emms-browser-insert-track-standard
  "A function to insert a track into the playlist.
The default behaviour indents tracks depending on whether you're
adding an album, artist, etc."
  :group 'emms-browser
  :type 'function)

(defcustom emms-browser-comparison-test
  'case-fold
  "A method for comparing entries in the cache.
The default is to compare case-insensitively."
  :group 'emms-browser
  :type 'symbol)

(defcustom emms-browser-track-sort-function
  'emms-sort-natural-order-less-p
  "How to sort tracks in the browser.
Ues nil for no sorting."
  :group 'emms-browser
  :type 'function)

(defcustom emms-browser-alpha-sort-function
  'string<
  "How to sort artists/albums/etc. in the browser.
Use nil for no sorting."
  :group 'emms-browser
  :type 'function)

(defcustom emms-browser-show-display-hook nil
  "Hooks to run when starting or switching to a browser buffer."
  :group 'emms-browser
  :type 'hook)

(defcustom emms-browser-hide-display-hook nil
  "Hooks to run when burying or removing a browser buffer."
  :group 'emms-browser
  :type 'hook)

(defcustom emms-browser-tracks-added-hook nil
  "Hooks to run when tracks are added to the playlist."
  :group 'emms-browser
  :type 'hook)

(defvar emms-browser-buffer nil
  "The current browser buffer, if any.")

(defvar emms-browser-buffer-name "*EMMS Browser*"
  "The default buffer name.")

(defvar emms-browser-top-level-hash nil
  "The current mapping db, eg. artist -> track.")
(make-variable-buffer-local 'emms-browser-top-level-hash)

(defconst emms-browser-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map text-mode-map)
    (define-key map (kbd "q") 'emms-browser-bury-buffer)
    (define-key map (kbd "/") 'emms-isearch-buffer)
    (define-key map (kbd "?") 'describe-mode)
    (define-key map (kbd "C-/") 'emms-playlist-mode-undo)
    (define-key map (kbd "SPC") 'emms-browser-toggle-subitems)
    (define-key map (kbd "RET") 'emms-browser-add-tracks)
    (define-key map (kbd "<C-return>") 'emms-browser-add-tracks-and-play)
    map)
  "Keymap for `emms-browser-mode'.")

(defface emms-browser-tracks-face
  '((((class color) (background dark))
     (:foreground "#aaaaff"))
    (((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-browser-mode)

(defface emms-browser-tracks-sub-face-1
  '((((class color) (background dark))
     (:foreground "#7777ff"))
    (((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-browser-mode)

(defface emms-browser-tracks-sub-face-2
  '((((class color) (background dark))
     (:foreground "#4444ff"))
    (((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-browser-mode)

(defface emms-browser-tracks-sub-face-3
  '((((class color) (background dark))
     (:foreground "#3333ff"))
    (((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-browser-mode)

;; --------------------------------------------------
;; General mode setup
;; --------------------------------------------------

(defun emms-browser ()
  "Launch or switch to the EMMS Browser."
  (interactive)
  (emms-browser-create-or-focus
   emms-browser-default-browsing-function))

(defun emms-browser-create-or-focus (browse-func)
  "Create a new browser buffer with BROWSE-FUNC, or switch.
BROWSE-FUNC should fill the buffer with something of interest. An
example function is `emms-browse-by-artist'."
  (let ((buf (emms-browser-get-buffer))
        wind)
    (if buf
        ;; if the buffer is displayed, switch the window instead
        (progn
          (setq wind (get-buffer-window buf))
          (if wind
              (select-window wind)
            (switch-to-buffer buf))
          (run-mode-hooks 'emms-browser-show-display-hook))
      ;; if there's no buffer, create a new window
      (emms-browser-create)
      (funcall browse-func))))

(defun emms-browser-create ()
  "Create a new emms-browser buffer and start emms-browser-mode."
  (emms-browser-new-buffer)
  (emms-browser-mode)
  (run-mode-hooks 'emms-browser-show-display-hook))

(defun emms-browser-mode ()
  "A major mode for the Emms browser.
\\{emms-browser-mode-map}"
      ;; create a new buffer
  (interactive)

  (use-local-map emms-browser-mode-map)
  (setq major-mode 'emms-browser-mode
        mode-name "Emms-Browser")

  (setq buffer-read-only t)
  (setq emms-browser-buffer (current-buffer)))

(defun emms-browser-new-buffer ()
  "Create a new browser buffer, and switch to it."
  (switch-to-buffer (generate-new-buffer
                     emms-browser-buffer-name)))

(defun emms-browser-clear ()
  "Create or switch to a browser buffer, clearing it."
  (let ((buf (emms-browser-get-buffer)))
    (if buf
        (progn
          (switch-to-buffer buf)
          (emms-with-inhibit-read-only-t
           (delete-region (point-min) (point-max))))
      (emms-browser-create))))

(defun emms-browser-get-buffer ()
  "Return the current buffer if it exists, or nil."
  (unless (or (null emms-browser-buffer)
              (not (buffer-live-p emms-browser-buffer)))
    emms-browser-buffer))

(defun emms-browser-ensure-browser-buffer ()
  (unless (eq major-mode 'emms-browser-mode)
    (error "Current buffer is not an emms-browser buffer")))

(defun emms-browser-bury-buffer ()
  "Bury the browser buffer, running hooks."
  (interactive)
  (run-mode-hooks 'emms-browser-hide-display-hook)
  (bury-buffer))

;; --------------------------------------------------
;; Top-level browsing methods - by artist/album/etc
;; --------------------------------------------------

;; Since the number of tracks may be rather large, we use a hash to
;; sort the top level elements into various categories. All
;; subelements will be stored in a bdata alist structure.

(defmacro emms-browser-add-category (name type)
  "Create an interactive function emms-browse-by-NAME."
  (let ((funname (intern (concat "emms-browse-by-" name)))
        (modedesc (concat "Browsing by: " name))
        (funcdesc (concat "Browse by " name ".")))
  `(defun ,funname ()
     ,funcdesc
     (interactive)
     (let ((hash (emms-browser-make-hash-by ,type)))
       (emms-browser-clear)
       (rename-buffer ,modedesc)
       (emms-browser-render-hash hash ,type)
       (setq emms-browser-top-level-hash hash)
       (goto-char (point-min))))))

(emms-browser-add-category "artist" 'info-artist)
(emms-browser-add-category "album" 'info-album)
(emms-browser-add-category "genre" 'info-genre)
(emms-browser-add-category "year" 'info-year)

(defun emms-browser-make-hash-by (type)
  "Make a hash, mapping with TYPE, eg artist -> tracks."
  (let ((hash (make-hash-table
             :test emms-browser-comparison-test))
        field existing-entry)
    (maphash (lambda (path track)
               (setq field (emms-track-get track type "misc"))
               (setq existing-entry (gethash field hash))
               (if existing-entry
                   (puthash field (cons track existing-entry) hash)
                 (puthash field (list track) hash)))
             emms-cache-db)
    hash))

(defun emms-browser-render-hash (db type)
  "Render a mapping (DB) into a browser buffer."
  (maphash (lambda (desc data)
             ;; reverse the entries so that unsorted tracks are displayed in
             ;; ascending order
             (emms-browser-insert-top-level-entry desc (nreverse data) type))
           db)
  (emms-with-inhibit-read-only-t
   (let ((sort-fold-case t))
     (sort-lines nil (point-min) (point-max)))))

(defun case-fold-string= (a b)
  (compare-strings a nil nil b nil nil t))

(defun case-fold-string-hash (a)
  (sxhash (upcase a)))

(define-hash-table-test 'case-fold
  'case-fold-string= 'case-fold-string-hash)

(defun emms-browser-insert-top-level-entry (entry tracks type)
  "Insert a single top level entry into the buffer."
  (emms-browser-ensure-browser-buffer)
  (emms-with-inhibit-read-only-t
   (insert (emms-propertize
            entry
            'emms-browser-bdata
            (emms-browser-make-bdata-tree
             type 1 tracks)
            'face 'emms-browser-tracks-face) "\n")))

;; --------------------------------------------------
;; Building a subitem tree
;; --------------------------------------------------

(defun emms-browser-next-mapping-type (current-mapping)
  "Return the next sensible mapping.
Eg. if current-mapping is currently 'info-artist, return 'info-album."
  (cond
   ((eq current-mapping 'info-artist) 'info-album)
   ((eq current-mapping 'info-album) 'info-title)
   ((eq current-mapping 'info-genre) 'info-artist)
   ((eq current-mapping 'info-year) 'info-artist)))

(defun emms-browser-make-bdata-tree (type level tracks)
  "Build a tree of browser DB elements for tracks."
  (emms-browser-make-bdata
   (emms-browser-make-bdata-tree-recurse
    type level tracks)
   ;; with the current hash code, we're guaranteed to have only one
   ;; element at the top
   (emms-track-get (car tracks) type)
   type level))

(defun emms-browser-make-bdata-tree-recurse (type level tracks)
  "Build a tree of alists based on a list of tracks, TRACKS.
For example, if TYPE is 'info-year, return an alist like:
artist1 -> album1 -> *track* 1.."
  (let* ((next-type (emms-browser-next-mapping-type type))
         (next-level (1+ level))
         alist name new-db new-tracks)
    ;; if we're at a leaf, the db data is a list of tracks
    (if (eq type 'info-title)
        tracks
      ;; otherwise, make DBs from the sub elements
      (setq alist
            (emms-browser-make-sorted-alist
             next-type tracks))
      (mapcar (lambda (entry)
                (setq name (emms-browser-make-name
                            entry next-type))
                (setq new-tracks (cdr entry))
                (emms-browser-make-bdata
                 (emms-browser-make-bdata-tree-recurse
                  next-type next-level new-tracks)
                 name next-type next-level))
              alist))))

(defun emms-browser-make-name (entry type)
  "Return a name for ENTRY, used for making a bdata object.
This uses `emms-browser-make-name-function'"
  ;; we use cadr because we are guaranteed only one track in entry.
  (funcall emms-browser-make-name-function entry type))

(defun emms-browser-make-name-standard (entry type)
  "Add track numbers to track names.
Apart from tracks, names are displayed without modification."
  (if (eq type 'info-title)
      (emms-browser-make-name-with-track-number (cadr entry))
    (car entry)))

(defun emms-browser-make-name-with-track-number (track)
  "Concat a track number to the name of track, if one exists."
  (let ((tracknum (emms-track-get track 'info-tracknumber)))
    (concat
     (if (string= tracknum "0")
         ""
       (concat
        (if (eq (length tracknum) 1)
            (concat "0" tracknum)
          tracknum)
        ". "))
     (emms-track-get track 'info-title))))

(defun emms-browser-make-bdata (data name type level)
  "Return a browser data item from ALIST.
DATA should be a list of DB items, or a list of tracks.
NAME is a name for the DB item.
TYPE is a category the data is organised by, such as 'info-artist.
LEVEL is the number of the sublevel the db item will be placed in."
  (list (cons 'type type)
        (cons 'level level)
        (cons 'name name)
        (cons 'data data)))

(defun emms-browser-make-alist (type tracks)
  "Make an alist mapping of TYPE -> TRACKS.
Items with no metadata for TYPE will be placed in 'misc'"
  (let (db key existing)
    (dolist (track tracks)
      (setq key (emms-track-get track type "misc"))
      (setq existing (assoc key db))
      (if existing
          (setcdr existing (cons track (cdr existing)))
        (push (cons key (list track)) db)))
    ;; sort the entries we've built
    (dolist (item db)
      (setcdr item (nreverse (cdr item))))
    db))

(defun emms-browser-make-sorted-alist (type tracks)
  "Return a sorted alist of TRACKS.
TYPE is the metadata to make the alist by - eg. if it's
'info-artist, an alist of artists will be made."
  (emms-browser-sort-alist
   (emms-browser-make-alist type tracks)
   type))

;; --------------------------------------------------
;; BDATA accessors and predicates
;; --------------------------------------------------

(defun emms-browser-bdata-level (bdata)
  (cdr (assq 'level bdata)))

(defun emms-browser-bdata-name (bdata)
  (cdr (assq 'name bdata)))

(defun emms-browser-bdata-type (bdata)
  (cdr (assq 'type bdata)))

(defun emms-browser-bdata-data (bdata)
  (cdr (assq 'data bdata)))

(defun emms-browser-bdata-p (obj)
  "True if obj is a BDATA object."
  (consp (assq 'data obj)))

;; --------------------------------------------------
;; Sorting expanded entries
;; --------------------------------------------------

(defmacro emms-browser-sort-cadr (sort-func)
  "Return a function to sort an alist using SORT-FUNC.
This sorting predicate will compare the cadr of each entry.
SORT-FUNC should be a playlist sorting predicate like
`emms-playlist-sort-by-natural-order'."
  `(lambda (a b)
     (funcall ,sort-func (cadr a) (cadr b))))

(defmacro emms-browser-sort-car (sort-func)
  "Return a function to sort an alist using SORT-FUNC.
This sorting predicate will compare the car of each entry.
SORT-FUNC should be a playlist sorting predicate like
`emms-playlist-sort-by-natural-order'."
  `(lambda (a b)
     (funcall ,sort-func (car a) (car b))))

(defun emms-browser-sort-by-track (alist)
  "Sort an ALIST by the tracks in each entry.
Uses `emms-browser-track-sort-function'."
  (if emms-browser-track-sort-function
      (sort alist (emms-browser-sort-cadr
                  emms-browser-track-sort-function))
    alist))

(defun emms-browser-sort-by-name (alist)
  "Sort ALIST by keys alphabetically.
Uses `emms-browser-alpha-sort-function'."
  (if emms-browser-alpha-sort-function
      (sort alist (emms-browser-sort-car
                  emms-browser-alpha-sort-function))
    alist))

(defun emms-browser-sort-alist (alist type)
  "Sort ALIST using the sorting function for TYPE."
  (let ((sort-func
         (cond
          ((or
            (eq type 'info-album)
            (eq type 'info-artist)
            (eq type 'info-year)
            (eq type 'info-genre))
           'emms-browser-sort-by-name)
          ((eq type 'info-title)
           'emms-browser-sort-by-track)
          (t (message "Can't sort unknown mapping!")))))
    (funcall sort-func alist)))

;; --------------------------------------------------
;; Subitem operations on the buffer
;; --------------------------------------------------

(defun emms-browser-bdata-at-point ()
  "Return the bdata object at point.
Includes information at point (such as album name), and metadata."
  (get-text-property (line-beginning-position)
                     'emms-browser-bdata))

(defun emms-browser-data-at-point ()
  "Return the data stored under point.
This will be a list of DB items."
  (emms-browser-bdata-data (emms-browser-bdata-at-point)))

(defun emms-browser-level-at-point ()
  "Return the current level at point."
  (emms-browser-bdata-level (emms-browser-bdata-at-point)))

(defun emms-browser-expand-one-level ()
  "Expand the current line by one sublevel."
  (interactive)
  (let* ((data (emms-browser-data-at-point)))
    (save-excursion
      (next-line)
      (beginning-of-line)
      (dolist (data-item data)
        (emms-browser-insert-data-item data-item)))))

(defun emms-browser-insert-data-item (data-item)
  "Insert DATA-ITEM into the buffer.
This checks DATA-ITEM's level to determine how much to indent.
The line will have a property emms-browser-bdata storing subitem
information."
  (let* ((level (emms-browser-bdata-level data-item))
         (name (emms-browser-bdata-name data-item))
         (indent (emms-browser-make-indent-for-level level)))
    (emms-with-inhibit-read-only-t
     (insert
      (emms-propertize
       (concat indent name)
       'emms-browser-bdata data-item
       'face (emms-browser-face-from-level level))
      "\n"))))

(defun emms-browser-make-indent-for-level (level)
  (make-string (* 2 (1- level)) ?\  ))

(defun emms-browser-face-from-level (level)
  "Return a face appropriate for LEVEL."
  (intern
   (concat "emms-browser-tracks-sub-face-"
           (int-to-string (1- level)))))

(defun emms-browser-find-entry-more-than-level (level)
  "Move point to next entry more than LEVEL and return point.
If no entry exits, return nil.
Returns point if currently on a an entry more than LEVEL."
  (let ((old-pos (point))
        level-at-point)
    (forward-line 1)
    (setq level-at-point (emms-browser-level-at-point))
    (if (and level-at-point
             (> level-at-point level))
        (point)
      (goto-char old-pos)
      nil)))

(defun emms-browser-subitems-visible ()
  "True if there are any subentries visible point."
  (let ((current-level (emms-browser-level-at-point))
        new-level)
    (save-excursion
      (re-search-forward "\n" nil t)
      (when (setq new-level (emms-browser-level-at-point))
        (> new-level current-level)))))

(defun emms-browser-subitems-exist ()
  "True if it's possible to expand the current line."
  (not (eq (emms-browser-bdata-type
            (emms-browser-bdata-at-point))
           'info-title)))

(defun emms-browser-move-up-level ()
  "Move up one level if possible.
Return true if we were able to move up."
  (let ((moved nil)
        (continue t)
        (current-level (emms-browser-level-at-point)))
    (while (and
            continue
            (zerop (forward-line -1)))
      (when (> current-level (emms-browser-level-at-point))
        (setq moved t)
        (setq continue nil)))
    moved))

(defun emms-browser-toggle-subitems ()
  "Show or hide (kill) subitems under the current line."
  (interactive)
  (if (emms-browser-subitems-visible)
      (emms-browser-kill-subitems)
    (if (emms-browser-subitems-exist)
        (emms-browser-show-subitems)
      (assert (emms-browser-move-up-level))
      (emms-browser-kill-subitems))))

(defun emms-browser-show-subitems ()
  "Show subitems under the current line."
  (emms-browser-expand-one-level))

(defun emms-browser-kill-subitems ()
  "Remove all subitems under the current line.
Stops at the next line at the same level, or EOF."
  (let ((current-level (emms-browser-level-at-point))
        (next-line (line-beginning-position 2)))
    (emms-with-inhibit-read-only-t
     (delete-region next-line
                    (save-excursion
                      (while
                          (emms-browser-find-entry-more-than-level
                           current-level))
                      (line-beginning-position 2))))))


;; --------------------------------------------------
;; Dealing with the playlist (queuing songs, etc)
;; --------------------------------------------------

(defun emms-browser-insert-playlist-group (type group level)
  "Insert a group description into the playlist buffer.
Eg. [album] foo bar"
  (let ((short-type (substring (symbol-name type) 5)))
    (with-current-emms-playlist
      (goto-char (point-max))
      (insert
       (emms-browser-make-indent-for-level level)
       (format "[%s] %s\n" short-type group)))))

(defun emms-browser-insert-track (track name level)
  "Insert a track into the playlist buffer, called NAME.
LEVEL is used to control indentation."
  (funcall emms-browser-insert-track-function track name level))

(defun emms-browser-insert-track-standard (track name level)
  (with-current-emms-playlist
    (goto-char (point-max))
    (insert  (emms-propertize
              (concat
               (emms-browser-make-indent-for-level level)
               name)
              'face 'emms-playlist-track-face
              'emms-track track)
            "\n")))

(defun emms-browser-add-tracks ()
  "Add all tracks at point."
  (interactive)
  (let ((bdata (emms-browser-bdata-at-point)))
    (emms-browser-add-bdata-to-playlist
     bdata (emms-browser-bdata-level bdata)))
  (run-hooks 'emms-browser-tracks-added-hook))

(defun emms-browser-add-tracks-and-play ()
  "Add all tracks at point, and play the first added track."
  (interactive)
  (let (old-pos)
    (with-current-emms-playlist
      (setq old-pos (point-max)))
    (emms-browser-add-tracks)
    (with-current-emms-playlist
      (goto-char old-pos)
      (emms-playlist-next)
      (emms-playlist-select (point)))
    ;; FIXME: is there a better way of doing this?
    (emms-stop)
    (emms-start)))

(defun emms-browser-add-bdata-to-playlist (bdata starting-level)
  "Add all tracks in BDATA to the playlist."
  (let ((type (emms-browser-bdata-type bdata))
        (name (emms-browser-bdata-name bdata))
        (level (emms-browser-bdata-level bdata)))

    ;; adjust the indentation relative to the starting level
    (when starting-level
      (setq level (- level (1- starting-level))))

    (unless (eq type 'info-title)
      (emms-browser-insert-playlist-group
       type name level))

    (dolist (item (emms-browser-bdata-data bdata))
      (if (not (eq type 'info-title))
          (emms-browser-add-bdata-to-playlist item starting-level)
        ;; add full track name as there may not be enough context
        (setq name (concat (emms-track-get item 'info-artist)
                           " - "
                           ;; track numbers don't make much sense
                           ;; for individual files
                           (or (and (> level 1)
                                    name)
                               (emms-track-get item 'info-title))))
        (emms-browser-insert-track
         item name level)))))

(defun emms-isearch-buffer ()
  "Isearch through the buffer."
  (interactive)
  (goto-char (point-min))
  (when (isearch-forward)
    (unless (emms-browser-subitems-visible)
      (emms-browser-show-subitems))))

;; --------------------------------------------------
;; Linked browser and playlist windows
;; --------------------------------------------------

(defcustom emms-browser-switch-to-playlist-on-add
  nil
  "Whether to switch to to the playlist after adding files."
  :group 'emms-browser
  :type 'boolean)

(defun emms-smart-browse ()
  "Display browser and playlist.
Toggle between selecting browser, playlist or hiding both. Tries
to behave sanely if the user has manually changed the window
configuration."
  (interactive)
  (add-to-list 'emms-browser-show-display-hook
               'emms-browser-display-playlist)
  (add-to-list 'emms-browser-hide-display-hook
               'emms-browser-hide-linked-window)
  ;; switch to the playlist window when adding tracks?
  (add-to-list 'emms-browser-tracks-added-hook
               (lambda () (interactive)
                 (let (playlist-window)
                   (when emms-browser-switch-to-playlist-on-add
                     (emms-smart-browse))
                   ;; recenter
                   (when
                       (setq playlist-window
                             (emms-browser-get-linked-window))
                     (with-selected-window
                         playlist-window
                       ;; FIXME: how do we achieve the same behaviour as
                       ;; c-u when calling interactively?
                       (recenter))))))
  (let (wind buf)
  (cond
   ((eq major-mode 'emms-browser-mode)
    (setq buf (emms-browser-get-linked-buffer))
    (setq wind (emms-browser-get-linked-window))
    ;; if the playlist window is visible, select it
    (if wind
        (select-window wind)
      ;; otherwise display and select it
      (select-window (emms-browser-display-playlist))))
   ((eq major-mode 'emms-playlist-mode)
    (setq wind (emms-browser-get-linked-window))
    ;; if the playlist window is selected, and the browser is visible,
    ;; hide both
    (if wind
        (progn
          (select-window wind)
          (emms-browser-bury-buffer))
      ;; otherwise bury both
      (bury-buffer)
      (emms-browser-hide-linked-window)))
   (t
    ;; show both
    (emms-browser)))))

(defun emms-browser-get-linked-buffer ()
  "Return linked buffer (eg browser if playlist is selected."
  (cond
   ((eq major-mode 'emms-browser-mode)
    (car (emms-playlist-buffer-list)))
   ((eq major-mode 'emms-playlist-mode)
    emms-browser-buffer)))

(defun emms-browser-get-linked-window ()
  "Return linked window (eg browser if playlist is selected."
  (let ((buf (emms-browser-get-linked-buffer)))
    (when buf
      (get-buffer-window buf))))

(defun emms-browser-display-playlist ()
  "A hook to show the playlist when the browser is displayed.
Returns the playlist window."
  (interactive)
  (let ((pbuf (emms-browser-get-linked-buffer))
        (pwin (emms-browser-get-linked-window)))
    ;; if the window isn't alive..
    (unless (window-live-p pwin)
      (save-selected-window
        (split-window-horizontally)
        (other-window 1)
        (if pbuf
            (switch-to-buffer pbuf)
          ;; there's no playlist - create one
          (setq pbuf (emms-playlist-current-clear))
          (switch-to-buffer pbuf))
        ;; make q in the playlist window hide the linked browser
        (when (boundp 'emms-playlist-mode-map)
          (define-key emms-playlist-mode-map (kbd "q")
            (lambda ()
              (interactive)
              (emms-browser-hide-linked-window)
              (bury-buffer))))
        (setq pwin (get-buffer-window pbuf))
        (goto-char (point-max))))
    pwin))

(defun emms-browser-hide-linked-window ()
  "Delete a playlist or browser window when the other is hidden."
  (interactive)
  (let ((other-buf (emms-browser-get-linked-buffer))
        (other-win (emms-browser-get-linked-window)))
    (when (and other-win
               (window-live-p other-win))
      (delete-window other-win))
    ;; bury the buffer, or it becomes visible when we hide the
    ;; linked buffer
    (bury-buffer other-buf)))

(provide 'emms-browser)
;;; emms-browser.el ends here