;;; emms-player-mpd.el --- MusicPD support for EMMS

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

;; Author: Michael Olson (mwolson AT gnu DOT org)

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

;;; Commentary:

;;; Benefits

;; MusicPD features crossfade, very little skipping, minor CPU usage,
;; many clients, many supported output formats, fast manipulation via
;; network processes, and good abstraction of client and server.

;;; MusicPD setup

;; If you want to set up a local MusicPD server, you'll need to have
;; mpd installed.  If you want to use a remote server instance, no
;; installation is needed.

;; The website is at http://musicpd.org/.  Debian packages are
;; available.  I recommend getting the latest development version; see
;; http://mpd.wikicities.com/wiki/Subversion for nightly Debian
;; packages and the svn repo.
;;
;; Copy the example configuration for mpd into ~/.mpdconf and edit it
;; to your needs.  Use your top level music directory for
;; music_directory.  If your playlists use absolute file names, be
;; certain that music_directory has the leading directory part.
;;
;; Before you try to play anything, but after setting up the above,
;; run `mkdir ~/.mpd && mpd --create-db' to create MusicPD's track
;; database.
;;
;; Check to see if mpd is running.  It must be running as a daemon for
;; you to be able to play anything.  Launch it by executing "mpd".  It
;; can be killed later with "mpd --kill" (or just "killall mpd" if
;; you're not using the latest development version).

;;; EMMS setup

;; Add the following to your config.
;;
;; (require 'emms-player-mpd)

;; Adjust `emms-player-mpd-server-name' and
;; `emms-player-mpd-server-port' to match the location and port of
;; your MusicPD server.
;;
;; (setq emms-player-mpd-server-name "localhost")
;; (setq emms-player-mpd-server-port "6600")

;; To get track info from MusicPD, do the following.
;;
;; (add-to-list 'emms-info-functions 'emms-info-mpd)

;; Add 'emms-player-mpd to the top of `emms-player-list'.
;;
;; (add-to-list 'emms-player-list 'emms-player-mpd)

;; If you use absolute file names in your m3u playlists (which is most
;; likely), make sure you set `emms-player-mpd-music-directory' to the
;; value of "music_directory" from your MusicPD config.  There are
;; additional options available as well, but the defaults should be
;; sufficient for most uses.

;; You can set `emms-player-mpd-sync-playlist' to nil if your master
;; EMMS playlist contains only stored playlists.

;; If at any time you wish to replace the current EMMS playlist buffer
;; with the contents of the MusicPD playlist, type
;; M-x emms-player-mpd-connect.
;;
;; This will also run the relevant seek functions, so that if you use
;; emms-playing-time, the displayed time will be accurate.

;;; Contributors

;; Adam Sjøgren implemented support for changing the volume.

(require 'emms-player-simple)
(require 'emms-source-playlist)  ; for emms-source-file-parse-playlist

(defun emms-player-mpd-get-supported-regexp ()
  "Returns a regexp of file extensions that MusicPD supports,
or nil if we cannot figure it out."
  (let ((out (split-string (shell-command-to-string "mpd --version")
                           "\n"))
        (found-start nil)
        (supported nil))
    ;; Get supported formats
    (while (car out)
      (cond ((string= (car out) "Supported formats:")
             (setq found-start t))
            ((and found-start
                  (not (string= (car out) "")))
             (setq supported (concat supported (car out)))))
      (setq out (cdr out)))
    ;; Create regexp
    (when (and (stringp supported)
               (not (string= supported "")))
      (concat "\\`http://\\|\\.\\(m3u\\|pls\\|"
              (mapconcat 'identity (delq nil (split-string supported))
                         "\\|")
              "\\)\\'"))))

(defvar emms-player-mpd-supported-regexp
  ;; Use a sane default, just in case
  (or (emms-player-mpd-get-supported-regexp)
      (concat "\\`http://\\|"
              "\\.\\(m3u\\|ogg\\|flac\\|mp3\\|wav\\|mod\\|au\\|aiff\\)\\'"))
  "Formats supported by MusicPD Client.")

(defgroup emms-player-mpd nil
  "EMMS player for MusicPD."
  :group 'emms-player
  :prefix "emms-player-mpd-")

(defcustom emms-player-mpd (emms-player 'emms-player-mpd-start
                                        'emms-player-mpd-stop
                                        'emms-player-mpd-playable-p)
 "*Parameters for the MusicPD player."
 :type '(cons symbol alist)
 :group 'emms-player-mpd)

(defcustom emms-player-mpd-music-directory nil
  "The value of 'music_directory' in your MusicPD configuration file.
You need this if your playlists use absolute file names, otherwise
leave it set to nil."
  ;; The :format part ensures that entering directories happens on the
  ;; next line, where there is more space to work with
  :type '(choice :format "%{%t%}:\n   %[Value Menu%] %v"
                 (const nil)
                 directory)
  :group 'emms-player-mpd)

(defcustom emms-player-mpd-connect-function 'open-network-stream
  "Function used to initiate the connection to MusicPD.
It should take same arguments as `open-network-stream' does."
  :type 'function
  :group 'emms-player-mpd)

(defcustom emms-player-mpd-server-name (or (getenv "MPD_HOST") "localhost")
  "The MusicPD server that we should connect to."
  :type 'string
  :group 'emms-player-mpd)

(defcustom emms-player-mpd-server-port (or (getenv "MPD_PORT") "6600")
  "The port of the MusicPD server that we should connect to."
  :type '(choice number string)
  :group 'emms-player-mpd)

(defcustom emms-player-mpd-check-interval 1
  "How often to check to see whether MusicPD has advanced to the
next song.  This may be an integer or a floating point number.

This is used only if `emms-player-mpd-sync-playlist' is non-nil"
  :type 'integer
  :group 'emms-player-mpd)

(defcustom emms-player-mpd-verbose nil
  "Whether to provide notifications for server connection events
and errors."
  :type 'boolean
  :group 'emms-player-mpd)

(defcustom emms-player-mpd-sync-playlist t
  "Whether to syncronize the EMMS playlist with the MusicPD playlist.

If your EMMS playlist contains music files rather than playlists,
leave this set to non-nil.

If your EMMS playlist contains stored playlists, set this to nil."
  :type 'boolean
  :group 'emms-player-mpd)

(emms-player-set emms-player-mpd
                 'regex
                 emms-player-mpd-supported-regexp)

(emms-player-set emms-player-mpd
                 'pause
                 'emms-player-mpd-pause)

(emms-player-set emms-player-mpd
                 'resume
                 'emms-player-mpd-pause)

(emms-player-set emms-player-mpd
                 'seek
                 'emms-player-mpd-seek)

;;; Transaction Queue (with some improvements) based on tq.el

(defun emms-player-mpd-tq-create (process)
  "Create and return a transaction queue communicating with PROCESS.
PROCESS should be a subprocess capable of sending and receiving
streams of bytes.  It may be a local process, or it may be connected
to a tcp server on another machine."
  (let ((tq (cons nil (cons process
                            (generate-new-buffer
                             (concat " emms-player-mpd-tq-temp-"
                                     (process-name process)))))))
    (set-process-filter process
                        `(lambda (proc string)
                           (emms-player-mpd-tq-filter ',tq string)))
    tq))

;; accessors
(defun emms-player-mpd-tq-queue (tq)
  (car tq))
(defun emms-player-mpd-tq-process (tq)
  (car (cdr tq)))
(defun emms-player-mpd-tq-buffer (tq)
  (cdr (cdr tq)))
(defun emms-player-mpd-tq-queue-head-question (tq)
  (car (car (emms-player-mpd-tq-queue tq))))
(defun emms-player-mpd-tq-queue-head-regexp (tq)
  (car (cdr (car (emms-player-mpd-tq-queue tq)))))
(defun emms-player-mpd-tq-queue-head-closure (tq)
  (car (cdr (cdr (car (emms-player-mpd-tq-queue tq))))))
(defun emms-player-mpd-tq-queue-head-fn (tq)
  (cdr (cdr (cdr (car (emms-player-mpd-tq-queue tq))))))

(defun emms-player-mpd-tq-queue-empty (tq)
  (not (emms-player-mpd-tq-queue tq)))

(defun emms-player-mpd-tq-queue-add (tq question re closure fn)
  (setcar tq (nconc (emms-player-mpd-tq-queue tq)
                    (cons (cons question (cons re (cons closure fn))) nil)))
  'ok)

(defun emms-player-mpd-tq-queue-pop (tq)
  (setcar tq (cdr (car tq)))
  (let ((question (emms-player-mpd-tq-queue-head-question tq)))
    (when question
      (process-send-string (emms-player-mpd-tq-process tq) question)))
  (null (car tq)))

(defun emms-player-mpd-tq-enqueue (tq question regexp closure fn)
  "Add a transaction to transaction queue TQ.
This sends the string QUESTION to the process that TQ communicates with.
When the corresponding answer comes back, we call FN
with two arguments: CLOSURE, and the answer to the question.
REGEXP is a regular expression to match the entire answer;
that's how we tell where the answer ends."
  (let ((sendp (not (emms-player-mpd-tq-queue-head-question tq))))
    (emms-player-mpd-tq-queue-add tq question regexp closure fn)
    (when sendp
      (process-send-string (emms-player-mpd-tq-process tq) question))))

(defun emms-player-mpd-tq-close (tq)
  "Shut down transaction queue TQ, terminating the process."
  (delete-process (emms-player-mpd-tq-process tq))
  (kill-buffer (emms-player-mpd-tq-buffer tq)))

(defun emms-player-mpd-tq-filter (tq string)
  "Append STRING to the TQ's buffer; then process the new data."
  (with-current-buffer (emms-player-mpd-tq-buffer tq)
    (goto-char (point-max))
    (insert string)
    (emms-player-mpd-tq-process-buffer tq)))

(defun emms-player-mpd-tq-process-buffer (tq)
  "Check TQ's buffer for the regexp at the head of the queue."
  (set-buffer (emms-player-mpd-tq-buffer tq))
  (if (= 0 (buffer-size)) ()
    (if (emms-player-mpd-tq-queue-empty tq)
        (let ((buf (generate-new-buffer "*spurious*")))
          (copy-to-buffer buf (point-min) (point-max))
          (delete-region (point-min) (point))
          (pop-to-buffer buf nil)
          (error "Spurious communication from process %s, see buffer %s"
                 (process-name (emms-player-mpd-tq-process tq))
                 (buffer-name buf)))
      (goto-char (point-min))
      (if (re-search-forward (emms-player-mpd-tq-queue-head-regexp tq) nil t)
          (let ((answer (buffer-substring (point-min) (point))))
            (delete-region (point-min) (point))
            (unwind-protect
                (condition-case nil
                    (funcall (emms-player-mpd-tq-queue-head-fn tq)
                             (emms-player-mpd-tq-queue-head-closure tq)
                             answer)
                  (error nil))
              (emms-player-mpd-tq-queue-pop tq))
            (emms-player-mpd-tq-process-buffer tq))))))

;;; Dealing with the MusicPD network process

(defvar emms-player-mpd-process nil)
(defvar emms-player-mpd-queue nil)

(defvar emms-player-mpd-playlist-id nil)
(defvar emms-player-mpd-current-song nil)
(defvar emms-player-mpd-status-timer nil)

(defvar emms-player-mpd-status-regexp
  "^\\(OK\\( MPD \\)?\\|ACK \\[\\([0-9]+\\)@[0-9]+\\] \\(.+\\)\\)\n+\\'"
  "Regexp that matches the valid status strings that MusicPD can
return at the end of a request.")

(defun emms-player-mpd-sentinel (proc str)
  "The process sentinel for MusicPD."
  (let ((status (process-status proc)))
    (cond ((memq status '(exit signal closed))
           (when emms-player-mpd-verbose
             (message "Closed MusicPD process"))
           (emms-player-mpd-tq-close emms-player-mpd-queue)
           (setq emms-player-mpd-queue nil)
           (setq emms-player-mpd-process nil))
          ((memq status '(run open))
           (when emms-player-mpd-verbose
             (message "MusicPD process started successfully")))
          (t
           (when emms-player-mpd-verbose
             (message "Other MusicPD status change: %s" status))))))

;; Ignore a useless byte-compile warning
(eval-when-compile
  (put 'process-kill-without-query 'byte-compile nil))

(defun emms-player-mpd-ensure-process ()
  "Make sure that a MusicPD process is currently active."
  (unless (and emms-player-mpd-process
               (processp emms-player-mpd-process)
               (memq (process-status emms-player-mpd-process) '(run open)))
    (setq emms-player-mpd-process
          (funcall emms-player-mpd-connect-function "mpd"
                   nil
                   emms-player-mpd-server-name
                   emms-player-mpd-server-port))
    (set-process-sentinel emms-player-mpd-process
                          'emms-player-mpd-sentinel)
    (setq emms-player-mpd-queue
          (emms-player-mpd-tq-create emms-player-mpd-process))
    (if (fboundp 'set-process-query-on-exit-flag)
        (set-process-query-on-exit-flag emms-player-mpd-process nil)
      (process-kill-without-query emms-player-mpd-process))))

(defun emms-player-mpd-send (question closure fn)
  "Send the given QUESTION to the MusicPD server.
When a reply comes, call FN with CLOSURE and the result."
  (emms-player-mpd-ensure-process)
  (unless (string= (substring question -1) "\n")
    (setq question (concat question "\n")))
  (emms-player-mpd-tq-enqueue emms-player-mpd-queue question
                              emms-player-mpd-status-regexp
                              closure fn))

;;; Helper functions

(defun emms-player-mpd-parse-response (response)
  "Convert the given MusicPD response into a list.
The car of the list is special:
If an error has occurred, it will contain a cons cell whose car is
an error number and whose cdr is the corresponding message.
Otherwise, it will be nil."
  (when (stringp response)
    (save-match-data
      (let* ((data (split-string response "\n"))
             (cruft (last data 3))
             (status (if (string= (cadr cruft) "")
                         (car cruft)
                       (cadr cruft))))
        (setcdr cruft nil)
        (when (and (stringp (car data))
                   (string-match "^OK\\( MPD \\)?" (car data)))
          (setq data (cdr data)))
        (if (and (stringp status)
                 (string-match "^ACK \\[\\([0-9]+\\)@[0-9]+\\] \\(.+\\)"
                               status))
            (cons (cons (match-string 1 status)
                        (match-string 2 status))
                  data)
          (cons nil data))))))

(defun emms-player-mpd-parse-line (line)
  "Turn the given LINE from MusicPD into a cons cell.
The format of the cell is (name . value)."
  (when (string-match "\\`\\([^:\n]+\\):\\s-*\\(.+\\)" line)
    (let ((name (match-string 1 line))
          (value (match-string 2 line)))
      (if (and name value)
          (progn
            (setq name (downcase name))
            (cons name value))
        nil))))

(defun emms-player-mpd-get-alist (info)
  "Turn the given parsed INFO from MusicPD into an alist.
The format of the alist is (name . value)."
  (when (and info
             (null (car info))          ; no error has occurred
             (cdr info))                ; data exists
    (let ((alist nil)
          cell old-cell)
      (dolist (line (cdr info))
        (when (setq cell (emms-player-mpd-parse-line line))
          (if (setq old-cell (assoc (car cell) alist))
              (setcdr old-cell (cdr cell))
            (setq alist (cons cell alist)))))
      alist)))

(defun emms-player-mpd-get-alists (info)
  "Turn the given parsed INFO from MusicPD into an list of alists.
The format of the alist is (name . value).

The list will be in reverse order."
  (when (and info
             (null (car info))          ; no error has occurred
             (cdr info))                ; data exists
    (let ((alists nil)
          (alist nil)
          cell)
      (dolist (line (cdr info))
        (when (setq cell (emms-player-mpd-parse-line line))
          (if (assoc (car cell) alist)
              (setq alists (cons alist alists)
                    alist (list cell))
            (setq alist (cons cell alist)))))
      (when alist
        (setq alists (cons alist alists)))
      alists)))

(defun emms-player-mpd-get-tracks-1 (closure response)
  (let ((songs (emms-player-mpd-get-alists
                (emms-player-mpd-parse-response response)))
        (tracks nil))
    (when songs
      (dolist (song-info songs)
        (let (cell)
          (when (setq cell (assoc "file" song-info))
            (let ((track (emms-track 'file (cdr cell))))
              (emms-info-mpd track song-info)
              (setq tracks (cons track tracks)))))))
    (funcall (car closure) (cdr closure) tracks)))

(defun emms-player-mpd-get-tracks (closure callback)
  "Get the current playlist from MusicPD in the form of a list of
EMMS tracks.
Call CALLBACK with CLOSURE and result when the request is complete."
  (emms-player-mpd-send "playlistinfo" (cons callback closure)
                        #'emms-player-mpd-get-tracks-1))

(defun emms-player-mpd-get-status-1 (closure response)
  (funcall (car closure)
           (cdr closure)
           (emms-player-mpd-get-alist
            (emms-player-mpd-parse-response response))))

(defun emms-player-mpd-get-status (closure callback)
  "Get status information from MusicPD.
It will be returned in the form of an alist by calling CALLBACK
with CLOSURE as its first argument, and the status as the
second."
  (emms-player-mpd-send "status" (cons callback closure)
                        #'emms-player-mpd-get-status-1))

(defun emms-player-mpd-get-status-part (closure callback item &optional info)
  "Get ITEM from the current MusicPD status.
Call CALLBACK with CLOSURE and result when the request is complete.
If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (if info
      (funcall callback closure (cdr (assoc item info)))
    (emms-player-mpd-get-status
     (cons callback (cons closure item))
     (lambda (closure info)
       (let ((fn (car closure))
             (close (cadr closure))
             (item (cddr closure)))
         (funcall fn close (cdr (assoc item info))))))))

(defun emms-player-mpd-get-playlist-id (closure callback &optional info)
  "Get the current playlist ID from MusicPD.
Call CALLBACK with CLOSURE and result when the request is complete.
If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (when info
    (setq callback (lambda (closure id) id)))
  (emms-player-mpd-get-status-part closure callback "playlist" info))

(defun emms-player-mpd-get-volume (closure callback &optional info)
  "Get the current volume from MusicPD.
Call CALLBACK with CLOSURE and result when the request is complete.
If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (when info
    (setq callback (lambda (closure volume) volume)))
  (emms-player-mpd-get-status-part closure callback "volume" info))

(defun emms-player-mpd-get-current-song (closure callback &optional info)
  "Get the current song from MusicPD.
This is in the form of a number that indicates the position of
the song on the current playlist.

Call CALLBACK with CLOSURE and result when the request is complete.
If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (when info
    (setq callback (lambda (closure id) id)))
  (emms-player-mpd-get-status-part closure callback "song" info))

(defun emms-player-mpd-get-mpd-state (closure callback &optional info)
  "Get the current state of the MusicPD server.
This is either \"play\", \"stop\", or \"pause\".

Call CALLBACK with CLOSURE and result when the request is complete.
If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (when info
    (setq callback (lambda (closure id) id)))
  (emms-player-mpd-get-status-part closure callback "state" info))

(defun emms-player-mpd-get-playing-time (closure callback &optional info)
  "Get the number of seconds that the current song has been playing,
or nil if we cannot obtain this information.

Call CALLBACK with CLOSURE and result when the request is complete.
If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (if info
      (emms-player-mpd-get-status-part
       nil
       (lambda (closure time)
         (and time
              (string-match "\\`\\([0-9]+\\):" time)
              (string-to-number (match-string 1 time))))
       "time" info)
    (emms-player-mpd-get-status-part
     (cons callback closure)
     (lambda (closure time)
       (funcall (car closure)
                (cdr closure)
                (and time
                     (string-match "\\`\\([0-9]+\\):" time)
                     (string-to-number (match-string 1 time)))))
     "time" info)))

(defun emms-player-mpd-sync-from-emms-1 (closure)
  (emms-player-mpd-get-playlist-id
   closure
   (lambda (closure id)
     (let ((buffer (car closure))
           (fn (cdr closure)))
       (funcall fn buffer id)))))

(defun emms-player-mpd-sync-from-emms (callback)
  "Synchronize the MusicPD playlist with the contents of the
current EMMS playlist.

If CALLBACK is provided, call it with the current EMMS playlist
buffer and MusicPD playlist ID when we are done, if there were no
errors."
  (emms-player-mpd-clear)
  (with-current-emms-playlist
    (let (tracks)
      (save-excursion
        (setq tracks (nreverse
                      (emms-playlist-tracks-in-region
                       (point-min) (point-max)))))
      (emms-player-mpd-add-several-tracks
       tracks
       (cons (current-buffer) callback)
       #'emms-player-mpd-sync-from-emms-1))))

(defun emms-player-mpd-sync-from-mpd-2 (closure info)
  (let ((buffer (car closure))
        (fn (cadr closure))
        (close (cddr closure))
        (id (emms-player-mpd-get-playlist-id nil #'ignore info))
        (song (emms-player-mpd-get-current-song nil #'ignore info)))
    (when (buffer-live-p buffer)
      (let ((emms-playlist-buffer buffer))
        (with-current-emms-playlist
          (setq emms-player-mpd-playlist-id id)
          (if song
              (progn
                (goto-line (1+ (string-to-number song)))
                (emms-playlist-select (point)))
            (goto-char (point-min)))))
      (when (functionp fn)
        (funcall fn close info)))))

(defun emms-player-mpd-sync-from-mpd-1 (closure tracks)
  (let ((buffer (car closure)))
    (when (and tracks
               (buffer-live-p buffer))
      (let ((emms-playlist-buffer buffer))
        (with-current-emms-playlist
          (emms-playlist-clear)
          (mapc #'emms-playlist-insert-track tracks)))
      (emms-player-mpd-get-status closure
                                  #'emms-player-mpd-sync-from-mpd-2))))

(defun emms-player-mpd-sync-from-mpd (&optional closure callback)
  "Synchronize the EMMS playlist with the contents of the current
MusicPD playlist."
  (with-current-emms-playlist
    (emms-player-mpd-get-tracks
     (cons emms-playlist-buffer (cons callback closure))
     #'emms-player-mpd-sync-from-mpd-1)))

(defun emms-player-mpd-detect-song-change-1 (closure info)
  (let ((song (emms-player-mpd-get-current-song nil #'ignore info))
        (status (emms-player-mpd-get-mpd-state nil #'ignore info))
        (time (emms-player-mpd-get-playing-time nil #'ignore info)))
    (cond ((string= status "stop")
           (emms-player-mpd-disconnect t)
           (if (with-current-emms-playlist
                 (save-excursion
                   (forward-line 1)
                   (emms-playlist-track-at (point))))
               ;; a track remains, so use the conservative stop method
               (let ((emms-player-stopped-p t))
                 (emms-player-stopped))
             ;; at the last track: we probably ran out of stuff to
             ;; play, so let EMMS do something further if it wants to
             (emms-player-stopped)))
          ((string= status "pause")
           nil)
          ((string= status "play")
           (unless (or (null song)
                       (and (stringp emms-player-mpd-current-song)
                            (string= song emms-player-mpd-current-song)))
             (setq emms-player-mpd-current-song song)
             (let ((emms-player-stopped-p t))
               (emms-player-stopped))
             (with-current-emms-playlist
               (emms-playlist-select (progn
                                       (goto-line (1+ (string-to-number song)))
                                       (point))))
             (emms-player-started 'emms-player-mpd)
             (when time
               (run-hook-with-args 'emms-player-seeked-functions time)))))))

(defun emms-player-mpd-detect-song-change (&optional info)
  "Detect whether a song change has occurred.
This is usually called by a timer.

If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (if info
      (emms-player-mpd-detect-song-change-1 nil info)
    (emms-player-mpd-get-status nil #'emms-player-mpd-detect-song-change-1)))

(defun emms-player-mpd-get-filename (file)
  "Turn FILE into something that MusicPD can understand.
This usually means removing a prefix."
  (if (or (not emms-player-mpd-music-directory)
          (not (eq (aref file 0) ?/))
          (string-match "\\`http://" file))
      file
    (file-relative-name file emms-player-mpd-music-directory)))

(defun emms-player-mpd-quote-file (file)
  "Escape special characters in FILE and surround in double-quotes."
  (concat "\""
          (emms-replace-regexp-in-string
           "\"" "\\\\\""
           (emms-replace-regexp-in-string "\\\\" "\\\\\\\\" file))
          "\""))

(defun emms-player-mpd-clear ()
  "Clear the playlist."
  (when emms-player-mpd-status-timer
    (emms-cancel-timer emms-player-mpd-status-timer)
    (setq emms-player-mpd-status-timer nil))
  (emms-player-mpd-send "clear" nil #'ignore))

;;; Adding to the MusicPD playlist

(defun emms-player-mpd-add-file (file closure callback)
  "Add FILE to the current MusicPD playlist.
If an error occurs, display a relevant message.

Execute CALLBACK with CLOSURE as its first argument when done."
  (setq file (emms-player-mpd-get-filename file))
  (emms-player-mpd-send
   (concat "add " (emms-player-mpd-quote-file file))
   (cons file (cons callback closure))
   (lambda (closure response)
     (let ((output (emms-player-mpd-parse-response response))
           (file (car closure))
           (callback (cadr closure))
           (close (cddr closure)))
       (if (car output)
           (message "MusicPD error: %s: %s" file (cdar output))
         (when (functionp callback)
           (funcall callback close)))))))

(defun emms-player-mpd-add-buffer-contents (closure callback)
  "Load contents of the current buffer into MusicPD by adding each line.
This handles both m3u and pls type playlists.

Execute CALLBACK with CLOSURE as its first argument when done."
  (goto-char (point-min))
  (let ((format (emms-source-playlist-determine-format)))
    (when format
      (emms-player-mpd-add-several-files
       (emms-source-playlist-files format)
       closure callback))))

(defun emms-player-mpd-add-playlist (playlist closure callback)
  "Load contents of PLAYLIST into MusicPD by adding each line.
This handles both m3u and pls type playlists.

Execute CALLBACK with CLOSURE as its first argument when done."
  ;; This is useful for playlists of playlists
  (with-temp-buffer
    (insert-file-contents playlist)
    (emms-player-mpd-add-buffer-contents closure callback)))

(defun emms-player-mpd-add-streamlist (url closure callback)
  "Download contents of URL and then add its feeds into MusicPD.

Execute CALLBACK with CLOSURE as its first argument when done."
  ;; This is useful with emms-streams.el
  (condition-case nil
      (progn
        (require 'url)
        (with-temp-buffer
          (url-insert-file-contents url)
          (emms-player-mpd-add-buffer-contents closure callback)))
    (error (message (concat "You need to install url.el so that"
                            " Emms can retrieve this stream")))))

(defun emms-player-mpd-add (track closure callback)
  "Add TRACK to the MusicPD playlist.

Execute CALLBACK with CLOSURE as its first argument when done."
  (let ((name (emms-track-get track 'name))
        (type (emms-track-get track 'type)))
    (cond ((eq type 'url)
           (emms-player-mpd-add-file name closure callback))
          ((eq type 'streamlist)
           (emms-player-mpd-add-streamlist name closure callback))
          ((or (eq type 'playlist)
               (string-match "\\.\\(m3u\\|pls\\)\\'" name))
           (emms-player-mpd-add-playlist name closure callback))
          ((eq type 'file)
           (emms-player-mpd-add-file name closure callback)))))

(defun emms-player-mpd-add-several-tracks (tracks closure callback)
  "Add TRACKS to the MusicPD playlist.

Execute CALLBACK with CLOSURE as its first argument when done."
  (when (consp tracks)
    (while (cdr tracks)
      (emms-player-mpd-add (car tracks) nil #'ignore)
      (setq tracks (cdr tracks)))
    ;; only execute callback on last track
    (emms-player-mpd-add (car tracks) closure callback)))

(defun emms-player-mpd-add-several-files (files closure callback)
  "Add FILES to the MusicPD playlist.

Execute CALLBACK with CLOSURE as its first argument when done."
  (when (consp files)
    (while (cdr files)
      (emms-player-mpd-add-file (car files) nil #'ignore)
      (setq files (cdr files)))
    ;; only execute callback on last file
    (emms-player-mpd-add-file (car files) closure callback)))

;;; EMMS API

(defun emms-player-mpd-playable-p (track)
  "Return non-nil when we can play this track."
  (and (memq (emms-track-type track) '(file url playlist streamlist))
       (string-match (emms-player-get emms-player-mpd 'regex)
                     (emms-track-name track))))

(defun emms-player-mpd-play (&optional id)
  "Play whatever is in the current MusicPD playlist.
If ID is specified, play the song at that position in the MusicPD
playlist."
  (if id
      (progn
        (unless (stringp id)
          (setq id (number-to-string id)))
        (emms-player-mpd-send
         (concat "play " id)
         nil
         (lambda (closure response)
           (setq emms-player-mpd-current-song nil)
           (setq emms-player-mpd-status-timer
                 (run-at-time t emms-player-mpd-check-interval
                              'emms-player-mpd-detect-song-change)))))
    ;; we only want to play one track, so don't start the timer
    (emms-player-mpd-send
     "play"
     nil
     (lambda (closure response)
       (emms-player-started 'emms-player-mpd)))))

(defun emms-player-mpd-start-and-sync-1 (buffer id)
  (when emms-player-mpd-status-timer
    (emms-cancel-timer emms-player-mpd-status-timer)
    (setq emms-player-mpd-status-timer nil))
  (when (buffer-live-p buffer)
    (let ((emms-playlist-buffer buffer))
      (with-current-emms-playlist
        (setq emms-player-mpd-playlist-id id)
        (emms-player-mpd-play (1- (emms-line-number-at-pos
                                   emms-playlist-selected-marker)))))))

(defun emms-player-mpd-start-and-sync ()
  "Ensure that MusicPD's playlist is up-to-date with EMMS's
playlist, and then play the current track.

This is called if `emms-player-mpd-sync-playlist' is non-nil."
  (emms-player-mpd-get-playlist-id
   nil
   (lambda (closure id)
     (if (and (stringp emms-player-mpd-playlist-id)
              (string= emms-player-mpd-playlist-id id))
         (emms-player-mpd-start-and-sync-1 emms-playlist-buffer id)
       (emms-player-mpd-sync-from-emms
        #'emms-player-mpd-start-and-sync-1)))))

(defun emms-player-mpd-connect-1 (closure info)
  (setq emms-player-mpd-current-song nil)
  (let* ((state (emms-player-mpd-get-mpd-state nil #'ignore info)))
    (unless (string= state "stop")
      (setq emms-player-playing-p 'emms-player-mpd))
    (when (string= state "pause")
      (setq emms-player-paused-p t))
    (unless (string= state "stop")
      (emms-player-mpd-detect-song-change info)
      (setq emms-player-mpd-status-timer
            (run-at-time t emms-player-mpd-check-interval
                         'emms-player-mpd-detect-song-change)))))

;;;###autoload
(defun emms-player-mpd-connect ()
  "Connect to MusicPD and retrieve its current playlist.
Afterward, the status of MusicPD will be tracked."
  (interactive)
  (when emms-player-mpd-status-timer
    (emms-cancel-timer emms-player-mpd-status-timer)
    (setq emms-player-mpd-status-timer nil))
  (emms-player-mpd-sync-from-mpd
   nil #'emms-player-mpd-connect-1))

(defun emms-player-mpd-start (track)
  "Starts a process playing TRACK."
  (interactive)
  (if (and emms-player-mpd-sync-playlist
           (not (memq (emms-track-get track 'type) '(streamlist playlist)))
           (not (string-match "\\`http://" (emms-track-get track 'name))))
      (emms-player-mpd-start-and-sync)
    (emms-player-mpd-clear)
    ;; if we have loaded the item successfully, play it
    (emms-player-mpd-add track nil #'emms-player-mpd-play)))

(defun emms-player-mpd-disconnect (&optional no-stop)
  "Terminate the MusicPD client process and disconnect from MusicPD.

If NO-STOP is non-nil, do not indicate to EMMS that we are
stopped.  This argument is meant to be used when calling this
from other functions."
  (interactive)
  (emms-cancel-timer emms-player-mpd-status-timer)
  (setq emms-player-mpd-status-timer nil)
  (setq emms-player-mpd-playlist-id nil)
  (setq emms-player-mpd-current-song nil)
  (unless no-stop
    (let ((emms-player-stopped-p t))
      (emms-player-stopped))))

(defun emms-player-mpd-stop ()
  "Stop the currently playing song."
  (interactive)
  (emms-player-mpd-disconnect t)
  (condition-case nil
      (emms-player-mpd-send "stop" nil #'ignore)
    (error nil))
  (let ((emms-player-stopped-p t))
    (emms-player-stopped)))

(defun emms-player-mpd-pause ()
  "Pause the currently playing song."
  (interactive)
  (emms-player-mpd-send "pause" nil #'ignore))

(defun emms-player-mpd-seek (sec)
  "Seek backward or forward by SEC seconds, depending on sign of SEC."
  (interactive)
  (emms-player-mpd-send (format "seek %s%d"
                                (if (> sec 0) "+" "")
                                sec)
                        nil #'ignore))

(defun emms-player-mpd-next ()
  "Move forward by one track in MusicPD's internal playlist."
  (interactive)
  (emms-player-mpd-send "next" nil #'ignore))

(defun emms-player-mpd-previous ()
  "Move backward by one track in MusicPD's internal playlist."
  (interactive)
  (emms-player-mpd-send "previous" nil #'ignore))

(defun emms-player-mpd-volume-change (amount)
  "Change volume up or down by AMOUNT, depending on whether it is
positive or negative."
  (interactive "MVolume change amount (+ increase, - decrease): ")
  (emms-player-mpd-get-volume
   amount
   (lambda (change volume)
     (let ((new-volume (+ (string-to-number volume) change)))
       (emms-player-mpd-send
        (concat "setvol \"" (number-to-string new-volume) "\"")
        nil #'ignore)))))

(defun emms-player-mpd-volume-up ()
  "Increase the volume."
  (interactive)
  (emms-player-mpd-volume-change 5))

(defun emms-player-mpd-volume-down ()
  "Decrease the volume."
  (interactive)
  (emms-player-mpd-volume-change -5))

(defun emms-player-mpd-show-1 (closure response)
  (let* ((info (emms-player-mpd-get-alist
                (emms-player-mpd-parse-response response)))
         (track (emms-dictionary '*track*))
         (insertp (car closure))
         (callback (cadr closure))
         (buffer (cddr closure))
         (name (cdr (assoc "name" info)))
         (desc nil))
    (when info
      (if name
          (setq desc name)
        (emms-track-set track 'type 'file)
        (emms-track-set track 'name (cdr (assoc "file" info)))
        (emms-info-mpd track info)
        (setq desc (emms-track-description track))))
    (if (not desc)
        (message "Nothing playing right now")
      (setq desc (format emms-show-format desc))
      (cond ((functionp callback)
             (funcall callback buffer desc))
            (insertp
             (when (buffer-live-p buffer)
               (with-current-buffer buffer
                 (insert desc))))
            (t
             (message "%s" desc))))))

;;;###autoload
(defun emms-player-mpd-show (&optional insertp callback)
  "Describe the current EMMS track in the minibuffer.
If INSERTP is non-nil, insert the description into the current buffer instead.
If CALLBACK is a function, call it with the current buffer and description.
This function uses `emms-show-format' to format the current track.
It differs from `emms-show' in that it asks MusicPD for the current track,
rather than EMMS."
  (interactive "P")
  (emms-player-mpd-send "currentsong"
                        (cons insertp (cons callback (current-buffer)))
                        #'emms-player-mpd-show-1))

;;; Track info

(defun emms-info-mpd-process (track info)
  (dolist (data info)
    (let ((name (car data))
          (value (cdr data)))
      (setq name (cond ((string= name "artist") 'info-artist)
                       ((string= name "title") 'info-title)
                       ((string= name "album") 'info-album)
                       ((string= name "track") 'info-tracknumber)
                       ((string= name "date") 'info-year)
                       ((string= name "genre") 'info-genre)
                       ((string= name "time")
                        (setq value (string-to-number value))
                        'info-playing-time)
                       (t nil)))
      (when name
        (emms-track-set track name value)))))

(defun emms-info-mpd-1 (track response)
  (let ((info (emms-player-mpd-get-alist
               (emms-player-mpd-parse-response response))))
    (when info
      (emms-info-mpd-process track info)
      (emms-track-updated track))))

(defun emms-info-mpd (track &optional info)
  "Add track information to TRACK.
This is a useful addition to `emms-info-functions'.
If INFO is specified, use that instead of acquiring the necessary
info from MusicPD."
  (if info
      (emms-info-mpd-process track info)
    (let (file)
      (when (and (eq 'file (emms-track-type track))
                 emms-player-mpd-music-directory
                 (setq file (emms-player-mpd-get-filename
                             (emms-track-name track)))
                 (string-match emms-player-mpd-supported-regexp file)
                 (not (string-match "\\`http://" file)))
        (condition-case nil
            (emms-player-mpd-send
             (concat "find filename "
                     (emms-player-mpd-quote-file file))
             track
             #'emms-info-mpd-1)
          (error nil))))))

(provide 'emms-player-mpd)

;;; emms-player-mpd.el ends here