;;; notifications.el --- Client interface to desktop notifications.

;; Copyright (C) 2010 Free Software Foundation, Inc.

;; Author: Julien Danjou <julien@danjou.info>
;; Keywords: comm desktop notifications

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This package provides an implementation of the Desktop Notifications
;; <http://www.galago-project.org/specs/notification/>.

;; In order to activate this package, you must add the following code
;; into your .emacs:
;;
;;   (require 'notifications)

;;; Code:
(eval-when-compile
  (require 'cl))

;; Pacify byte-compiler.  D-Bus support in the Emacs core can be
;; disabled with configuration option "--without-dbus".  Declare used
;; subroutines and variables of `dbus' therefore.
(declare-function dbus-call-method "dbusbind.c")
(declare-function dbus-register-signal "dbusbind.c")

(require 'dbus)

(defconst notifications-application-name "Emacs"
  "Default application name.")

(defconst notifications-application-icon
  (expand-file-name
   "images/icons/hicolor/scalable/apps/emacs.svg"
   data-directory)
  "Default application icon.")

(defconst notifications-service "org.freedesktop.Notifications"
  "D-Bus notifications service name.")

(defconst notifications-path "/org/freedesktop/Notifications"
  "D-Bus notifications service path.")

(defconst notifications-interface "org.freedesktop.Notifications"
  "D-Bus notifications service path.")

(defconst notifications-notify-method "Notify"
  "D-Bus notifications service path.")

(defconst notifications-close-notification-method "CloseNotification"
  "D-Bus notifications service path.")

(defconst notifications-action-signal "ActionInvoked"
  "D-Bus notifications action signal.")

(defconst notifications-closed-signal "NotificationClosed"
  "D-Bus notifications closed signal.")

(defconst notifications-closed-reason
  '((1 expired)
    (2 dismissed)
    (3 close-notification)
    (4 undefined))
  "List of reasons why a notification has been closed.")

(defvar notifications-on-action-map nil
  "Mapping between notification and action callback functions.")

(defvar notifications-on-close-map nil
  "Mapping between notification and close callback functions.")

(defun notifications-on-action-signal (id action)
  (let ((entry (assoc id notifications-on-action-map)))
    (when entry
      (funcall (cadr entry) action)
      (remove entry 'notifications-on-action-map))))

(dbus-register-signal
 :session
 notifications-service
 notifications-path
 notifications-interface
 notifications-action-signal
 'notifications-on-action-signal)

(defun notifications-on-closed-signal (id reason)
  (let ((entry (assoc id notifications-on-close-map)))
    (when entry
      (funcall (cadr entry) (cadr (assoc reason notifications-closed-reason)))
      (remove entry 'notifications-on-close-map))))

(dbus-register-signal
 :session
 notifications-service
 notifications-path
 notifications-interface
 notifications-closed-signal
 'notifications-on-closed-signal)

(defun notifications-notify (&rest params)
  "Send notification via D-Bus using the Freedesktop notification protocol.
Various PARAMS can be set:

 :title          The notification title.
 :body           The notification body text.
 :app-name       The name of the application sending the notification.
                 Default to `notifications-application-name'.
 :replaces-id    The notification ID that this notification replaces.
 :app-icon       The notification icon.
                 Default is `notifications-application-icon'.
                 Set to nil if you do not want any icon displayed.
 :actions        A list of actions in the form:
                   (KEY TITLE KEY TITLE ...)
                 where KEY and TITLE are both strings.
                 The default action (usually invoked by clicking the
                 notification) should have a key named \"default\".
                 The title can be anything, though implementations are free
                 not to display it.
 :timeout        The timeout time in milliseconds since the display
                 of the notification at which the notification should
                 automatically close.
                 If -1, the notification's expiration time is dependent
                 on the notification server's settings, and may vary for
                 the type of notification.
                 If 0, the notification never expires.
                 Default value is -1.
 :urgency        The urgency level.
                 Either `low', `normal' or `critical'.
 :category       The type of notification this is.
 :desktop-entry  This specifies the name of the desktop filename representing
                 the calling program.
 :image-data     This is a raw data image format which describes the width,
                 height, rowstride, has alpha, bits per sample, channels and
                 image data respectively.
 :sound-file     The path to a sound file to play when the notification pops up.
 :suppress-sound Causes the server to suppress playing any sounds, if it has
                 that ability.
 :x              Specifies the X location on the screen that the notification
                 should point to.  The \"y\" hint must also be specified.
 :y              Specifies the Y location on the screen that the notification
                 should point to.  The \"x\" hint must also be specified.
 :on-action      Function to call when an action is invoked.  The key of the
                 action is passed as argument to the function.
 :on-close       Function to call when the notification has been closed
                 by timeout or by the user.
                 The function receives the closing reason as argument:
                   - `expired' if the notification has expired
                   - `dismissed' if the notification was dismissed by the user
                   - `close-notification' if the notification was closed
                     by a call to CloseNotification

This function returns a notification id, an integer, which can be
used to manipulate the notification item with
`notifications-close'."
  (let ((title (plist-get params :title))
        (body (plist-get params :body))
        (app-name (plist-get params :app-name))
        (replaces-id (plist-get params :replaces-id))
        (app-icon (plist-get params :app-icon))
        (actions (plist-get params :actions))
        (timeout (plist-get params :timeout))
        ;; Hints
        (hints '())
        (urgency (plist-get params :urgency))
        (category (plist-get params :category))
        (desktop-entry (plist-get params :desktop-entry))
        (image-data (plist-get params :image-data))
        (sound-file (plist-get params :sound-file))
        (suppress-sound (plist-get params :suppress-sound))
        (x (plist-get params :x))
        (y (plist-get params :y))
        id)
    ;; Build hints array
    (when urgency
      (add-to-list 'hints `(:dict-entry
                            "urgency"
                            (:variant :byte ,(case urgency
                                               ('low 0)
                                               ('critical 2)
                                               (t 1)))) t))
    (when category
      (add-to-list 'hints `(:dict-entry
                            "category"
                            (:variant :string ,category)) t))
    (when desktop-entry
      (add-to-list 'hints `(:dict-entry
                            "desktop-entry"
                            (:variant :string ,desktop-entry)) t))
    (when image-data
      (add-to-list 'hints `(:dict-entry
                            "image_data"
                            (:variant :struct ,image-data)) t))
    (when sound-file
      (add-to-list 'hints `(:dict-entry
                            "sound-file"
                            (:variant :string ,sound-file)) t))
    (when suppress-sound
      (add-to-list 'hints `(:dict-entry
                            "suppress-sound"
                            (:variant :boolean ,suppress-sound)) t))
    (when x
      (add-to-list 'hints `(:dict-entry "x" (:variant :int32 ,x)) t))
    (when y
      (add-to-list 'hints `(:dict-entry "y" (:variant :int32 ,y)) t))

    ;; Call Notify method
    (setq id
          (dbus-call-method :session
                            notifications-service
                            notifications-path
                            notifications-interface
                            notifications-notify-method
                            :string (or app-name
                                        notifications-application-name)
                            :uint32 (or replaces-id 0)
                            :string (if app-icon
                                        (expand-file-name app-icon)
                                      ;; If app-icon is nil because user
                                      ;; requested it to be so, send the
                                      ;; empty string
                                      (if (plist-member params :app-icon)
                                          ""
                                        ;; Otherwise send the default icon path
                                        notifications-application-icon))
                            :string (or title "")
                            :string (or body "")
                            `(:array ,@actions)
                            (or hints '(:array :signature "{sv}"))
                            :int32 (or timeout -1)))

    ;; Register close/action callback function
    (let ((on-action (plist-get params :on-action))
          (on-close (plist-get params :on-close)))
      (when on-action
        (add-to-list 'notifications-on-action-map (list id on-action)))
      (when on-close
        (add-to-list 'notifications-on-close-map (list id on-close))))

    ;; Return notification id
    id))

(defun notifications-close-notification (id)
  "Close a notification with identifier ID."
  (dbus-call-method :session
                    notifications-service
                    notifications-path
                    notifications-interface
                    notifications-close-notification-method
                    :int32 id))

(provide 'notifications)