matrix-notifications.el

;;; matrix-notifications.el --- Notifications support  -*- lexical-binding: t; -*-

;;; Commentary:

;; This file is not part of GNU Emacs.

;; This file 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.
;;
;; This file 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 file.  If not, see <http://www.gnu.org/licenses/>.

;; FIXME: This system is flexible, but a bit complicated and
;; redundant, e.g. there should be a more central dispatch function
;; that dispatches only to the appropriate handlers, rather than
;; having each handler decide what to do by calling `-notify-p'
;; itself.  Or, the dispatcher could pass the result of `-notify-p' to
;; each handler so the value could be computed only once.

;; TODO: Factor out code from here and -room.el that's duplicated/modified here.

;;; Code:

;;;; Requirements

(require 'notifications)

(require 'anaphora)

;;;; Customization

(defgroup matrix-client-notifications nil
  "Notifications settings."
  :group 'matrix-client)

(defcustom matrix-client-notifications t
  "Enable notifications."
  ;; This variable may be let-bound to nil to disable notifications, e.g. when loading old messages.
  :type 'boolean)

(defcustom matrix-client-room-notification-rules nil
  "Per-room notification rules.
An alist mapping room IDs to nil (meaning to never notify),
t (meaning to always notify), or a predicate function which takes
two arguments, the room object and the event, and returns non-nil
when a notification should fire."
  :type '(alist :key-type (string :tag "Room ID")
                :value-type (choice (const :tag "Never" nil)
                                    (const :tag "Always" t)
                                    (function :tag "Predicate function"))))

;;;; Variables

(defvar matrix-client-notify-hook nil
  "List of functions called for events.
Each is called with the event-type and the event data.")

(defvar matrix-client-notifications-ring nil
  "Alist of recent notifications mapping notification ID to related buffer.
Automatically trimmed to last 20 notifications.")

(defvar matrix-client-notification-rules
  (a-list "always" t
          "never" nil
          "mention" #'matrix-client-event-mentions-user-p
          "silent" 'silent
          ;; "silent-unless-mention" only shows in the notifications
          ;; buffer, unless the user is mentioned, in which case it
          ;; also does a normal notification.  FIXME: Find a way to document/explain this.
          "silent-unless-mention" #'matrix-client-notify-event-silent-unless-mention)
  "Alist mapping friendly string names to notification rules.")

(defvar matrix-client-notifications-buffer-map
  (let ((map (make-sparse-keymap))
        (mappings `(
                    "C-c C-r" matrix-client-room-list
                    "r" matrix-client-reply-or-insert
                    "R" (lambda () (interactive) (matrix-client-reply-or-insert t))
                    "RET" matrix-client-notifications-buffer-RET
                    "DEL "matrix-client-delete-backward-char
                    "C-k" matrix-client-kill-line-or-unsent-message
                    "TAB" matrix-client-tab
                    "<backtab>" (lambda ()
                                  (interactive)
                                  (matrix-client-tab :backward t))
                    ;; This seems to work properly, to get the binding from `org-mode-map'.
                    ,(key-description (where-is-internal 'org-edit-special org-mode-map 'first-only)) matrix-client-room-outorg)))
    (cl-loop for (key fn) on mappings by #'cddr
             do (define-key map (cl-typecase key
                                  (string (kbd key))
                                  (otherwise key))
                  fn))
    map)
  "Keymap for `matrix-client-mode' notification buffers.")

;;;; Commands

(matrix-client-def-room-command notify
  :docstring "Set room notification setting.
Without argument, displays help and current setting."
  :insert (aif (map-elt matrix-client-notification-rules input nil #'equal)
              (progn
                (matrix-client-set-notification-rule room it)
                (format "Notification rule set: %s." input))
            (pcase-let* (((eieio client-data) room)
                         ((eieio notification-rules) client-data)
                         (current-rule notification-rules)
                         (current-rule-name (car (cl-rassoc current-rule matrix-client-notification-rules :test #'equal)))
                         (available-rules (s-join ", " (-map #'car matrix-client-notification-rules))))
              (format "Current notification rule: %s.  Available rules: %s." current-rule-name available-rules))))

(defun matrix-client-switch-to-notifications-buffer (&rest _ignore)
  "Show notifications buffer, if it exists."
  (interactive)
  ;; FIXME: This is messy.
  (switch-to-buffer (oref* (matrix-client--notifications-buffer) client-data buffer)))

(defun matrix-client-notifications-buffer-pop ()
  "Pop to room buffer for event at point."
  (interactive)
  (let* ((properties (text-properties-at (point)))
         (buffer (lax-plist-get properties 'buffer))
         (event-id (lax-plist-get properties 'event_id)))
    (matrix-client-update-last-seen (matrix-client--notifications-buffer))
    (when buffer
      (pop-to-buffer buffer)
      (when event-id
        (awhen (matrix-client--find-propertized-string (list 'event_id event-id))
          (goto-char (car it)))))))

(defun matrix-client-notifications-buffer-send-input ()
  "Send message to room from notification buffer.
This only works for replies."
  (interactive)
  (if-let* ((input (matrix-client--room-input :delete t))
            (room (get-text-property 0 'room input)))
      (progn
        (with-room-buffer room
          (matrix-client-send-input :input input))
        (matrix-client-notify--add-to-notifications-buffer "m.room.message"
          (a-list 'sender (oref* room session user)
                  'content (a-list 'body input)
                  ;; Generate a fake, local event ID so `matrix-client--this-message' can work with it.
                  'event_id (concat "local--" (oref* room session user) "--" (format-time-string "%s")))
          (list :room room))
        (matrix-client-update-last-seen (matrix-client--notifications-buffer)))
    (goto-char (matrix-client--prompt-position))
    (when (s-present? input)
      (insert input)
      (message "Only replies may be sent from the notification buffer"))))

(defun matrix-client-notifications-buffer-RET ()
  "Act appropriately for RET keypress in notifications buffer.
If point is on a message, pop to it in its room buffer.
Otherwise, try to send input.  Then update last-seen line."
  (interactive)
  (cond ((< (point) (matrix-client--prompt-position))
         (matrix-client-notifications-buffer-pop))
        (t (matrix-client-notifications-buffer-send-input)))
  (matrix-client-update-last-seen (matrix-client--notifications-buffer)))

;;;; Functions

(defun matrix-client-notifications-buffer--typing ()
  "Send typing notification to room being replied to, when appropriate."
  (awhen (get-text-property (matrix-client--prompt-position) 'room)
    (matrix-client-room-typing it t)))

(defun matrix-client-set-notification-rule (room rule)
  "Set notification RULE for ROOM.
See `matrix-client-notification-rules' for rules."
  (with-slots* (((client-data id) room)
                ((notification-rules) client-data))
    (setq notification-rules rule)
    (map-put matrix-client-room-notification-rules id rule)
    ;; MAYBE: Persist the variable at a different time (or even use a different system for
    ;; persistence), because calling `customize-save-variable' is a bit slow.
    (customize-save-variable 'matrix-client-room-notification-rules matrix-client-room-notification-rules)))

(defun matrix-client-notify (event-type data &rest rest)
  "Run notify hooks and built-in notificataion for an event of EVENT-TYPE with DATA.
Optional REST of args are also applied to hooks and function."
  ;; FIXME: Pass session so we can get its initial-sync-p.  Probably should be a method specialized
  ;; on session.
  (when matrix-client-notifications
    (unless (oref (car matrix-client-sessions) initial-sync-p)
      (ignore-errors
        ;; Ignore errors so notification problems don't interrupt the processing of events, which would also prevent the next sync.
        (run-hook-with-args 'matrix-client-notify-hook event-type data rest))
      ;; Run built-in notification for this event type
      ;; TODO: Use `if-fn-apply' here.
      (let ((fn (intern-soft (concat "matrix-client-notify-" event-type))))
        (when (functionp fn)
          (apply #'funcall fn data rest))))))

(defun matrix-client-notify--add-to-notifications-buffer (event-type data rest)
  "Add event with DATA to notifications buffer."
  (declare (indent defun))
  ;; FIXME: Handle other event types.
  (pcase (matrix-client-notify-p (plist-get rest :room) data)
    ('nil nil)
    (_ (pcase event-type
         ("m.room.message"
          (let-alist data
            ;; FIXME: Should probably rework a lot of code in this file to pass event arguments in a better way.
            (let* ((room (plist-get rest :room))
                   (room-name (propertize (oref room display-name)
                                          'face 'font-lock-keyword-face))
                   (room-buffer (oref* room client-data buffer))
                   (sender (propertize (concat (matrix-user-displayname room .sender) ">")
                                       'face 'font-lock-function-name-face))
                   (body .content.body)
                   (event-id .event_id)
                   (timestamp (matrix-client-event-timestamp data))
                   (message (propertize (format$ "$room-name: $sender $body")
                                        'buffer room-buffer
                                        'event_id event-id
                                        'sender .sender
                                        'room room
                                        'timestamp timestamp)))
              ;; Using notification buffer pseudo room
              (matrix-client-insert (matrix-client--notifications-buffer) message
                                    :timestamp-prefix t))))))))

(add-hook 'matrix-client-notify-hook #'matrix-client-notify--add-to-notifications-buffer)

(defun matrix-client--notifications-buffer ()
  "Return `matrix-room' object whose buffer is the special notifications buffer.
This function exists to allow the use of `with-room-buffer'."
  (let ((buffer (or (get-buffer "*Matrix Notifications*")
                    (aprog1 (get-buffer-create "*Matrix Notifications*")
                      (with-current-buffer it
                        (setf header-line-format (propertize " Notifications"
                                                             'face '(:inherit font-lock-keyword-face :weight bold
                                                                              :height 1.25))
                              mode-line-format nil)
                        (visual-line-mode)
                        (use-local-map matrix-client-notifications-buffer-map)
                        (add-hook 'post-self-insert-hook #'matrix-client-notifications-buffer--typing nil t)
                        (matrix-client-insert-prompt)
                        (matrix-client-insert-last-seen))))))
    (matrix-room :client-data (matrix-room-client-data :buffer buffer))))

;; MAYBE: Use a macro to define the handlers, because they have to
;; define their arg lists in a certain way, and the macro would take
;; care of that automatically.

(cl-defun matrix-client-notify-m.room.message (event &key room &allow-other-keys)
  "Show notification for m.room.message events.
EVENT should be the `event' variable from the
`defmatrix-client-handler'.  ROOM should be the room object."
  ;; NOTE: Adding notification rule suport
  (pcase (matrix-client-notify-p room event)
    ((or 'nil 'silent) nil)
    (_ (pcase-let* (((map content sender event_id) event)
                    ((map body) content)
                    ((eieio client-data) room)
                    ((eieio buffer) client-data)
                    (display-name (matrix-user-displayname room sender))
                    (id (notifications-notify :title (format$ "<b>$display-name</b>")
                                              ;; Encode the message as ASCII because dbus-notify
                                              ;; can't handle some Unicode chars.  And
                                              ;; `ignore-errors' doesn't work to ignore errors
                                              ;; from it.  Don't ask me why.
                                              :body (encode-coding-string body 'us-ascii)
                                              :category "im.received"
                                              :timeout 5000
                                              :app-icon nil
                                              :actions '("default" "Show")
                                              :on-action #'matrix-client-notification-show)))
         (map-put matrix-client-notifications-ring id (a-list 'buffer buffer
                                                              'event_id event_id))
         ;; Trim the list
         (setq matrix-client-notifications-ring (-take 20 matrix-client-notifications-ring))))))

(defun matrix-client-notification-show (id _key)
  "Show the buffer for a notification.
This function is called by `notifications-notify' when the user
activates a notification."
  (pcase-let* (((map (id notification)) matrix-client-notifications-ring)
               ((map buffer event_id) notification)
               (window (get-buffer-window buffer)))
    (raise-frame)
    (if window
        (select-window window)
      (switch-to-buffer buffer))
    ;; Go to relevant event
    (or (cl-loop initially do (goto-char (point-max))
                 for value = (get-text-property (point) 'event_id)
                 thereis (equal value event_id)
                 while (when-let (pos (previous-single-property-change (point) 'event_id))
                         (goto-char pos)))
        ;; Not found: go to last line
        (goto-char (point-max)))))

;;;;; Predicates

(defun matrix-client-notify-p (room event)
  "Return non-nil if notification should be displayed for EVENT in ROOM."
  ;; FIXME: Initialize to a user-defined default.
  (pcase (oref* room client-data notification-rules)
    ((and fn (pred functionp)) (funcall fn room event))
    ('silent 'silent)
    ('nil nil)
    ('t t)))

(defun matrix-client-notify-event-silent-unless-mention (room event)
  "Return t if EVENT in ROOM mentions user, otherwise `silent'."
  (or (matrix-client-event-mentions-user-p room event)
      'silent))

(defun matrix-client-event-mentions-user-p (room event)
  "Return non-nil if EVENT mentions logged-in user in ROOM.
Uses user's displayname in ROOM."
  (pcase-let* (((map content) event)
               ((map body) content)
               ((eieio session) room)
               ((eieio user) session)
               (displayname (matrix-user-displayname room user))
               (regexp (rx-to-string `(seq (or ,user ,displayname)))))
    (string-match-p regexp body)))

;; MAYBE: Define these rules with a macro.

;;;; Footer

(provide 'matrix-notifications)

;;; matrix-notifications.el ends here