;;; togetherly.el --- allow multiple clients to edit a single buffer online

;; Copyright (C) 2015 zk_phi

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2 of the License, or
;; (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program; if not, write to the Free Software
;; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

;; Author: zk_phi
;; URL: http://hins11.yu-yake.com/
;; Version: 0.1.1
;; Package-Requires: ((cl-lib "0.3"))

;;; Commentary:

;; Server:
;;   1. Open a buffer you want to share.
;;   2. `M-x togetherly-server-start' to start a server.
;;   3. `M-x togetherly-server-close' when finished.
;;
;; Client:
;;   1. `M-x togetherly-client-start' to request access to the server.
;;   2. Kill `*Togetherly*' buffer when finished.
;;
;; See Readme.org for more information.

;;; Change Log:

;; 0.1.0 test release
;; 0.1.1 add `togetherly-server-comehere' command

;;; Code:

(defconst togetherly-version "0.1.1")

(require 'cl-lib)
(require 'ido)

;; todos
;; -----
;; - クライアントを複数立ち上げられるように
;;   - ポートを切り替えてサーバーも複数立ち上がると楽しい
;;   - *Togetherly*の代わりにプロセスバッファを作って、各変数をバッファローカルにすればおｋ？
;; - チャットができるといい？
;; - 画面をシェアしつつ編集を許可しないということができてもいいかも
;;   - client ごとに read-only かどうかの属性を持てばいい？
;; - 認証機能やっぱほしい？
;; - 色を同期する必要はないかも

;; + customs

(defvar togetherly-cursor-sync-rate 0.5
  "Interval in seconds to sync cursor positions.")

(defvar togetherly-cursor-colors
  ;; (defun color-hsl-to-hex (h s l) (apply 'color-rgb-to-hex (color-hsl-to-rgb h s l)))
  ;; (mapcar (lambda (h) (color-hsl-to-hex h 0.6 0.3))
  ;;         '(0.0 0.125 0.25 0.375 0.5 0.625 0.75 0.875))
  ;; (mapcar (lambda (h) (color-hsl-to-hex h 0.6 0.8))
  ;;         '(0.0 0.125 0.25 0.375 0.5 0.625 0.75 0.875))
  (let ((lst (if (eq (frame-parameter nil 'background-mode) 'dark)
                 '("#7a1e1e" "#7a631e" "#4c7a1e" "#1e7a35"
                   "#1e7a7a" "#1e357a" "#4c1e7a" "#7a1e63")
               '("#eaadad" "#eadbad" "#cceaad" "#adeabc"
                 "#adeaea" "#adbcea" "#cbadea" "#eaaddb"))))
    (setcdr (last lst) lst))
  "(Possivly infinite) list of cursor colors.")

(defvar togetherly-region-colors
  ;; (mapcar (lambda (h) (color-hsl-to-hex h 0.6 0.2))
  ;;         '(0.0 0.125 0.25 0.375 0.5 0.625 0.75 0.875))
  ;; (mapcar (lambda (h) (color-hsl-to-hex h 0.6 0.9))
  ;;         '(0.0 0.125 0.25 0.375 0.5 0.625 0.75 0.875))
  (let ((lst (if (eq (frame-parameter nil 'background-mode) 'dark)
                 '("#511414" "#514214" "#335114" "#145123"
                   "#145151" "#142351" "#321451" "#511442")
               '("#f4d6d6" "#f4edd6" "#e5f4d6" "#d6f4dd"
                 "#d6f4f4" "#d6ddf4" "#e5d6f4" "#f4d6ed"))))
    (setcdr (last lst) lst))
  "(Possively infinite) list of region colors.")

;; + utilities

(defun togetherly--make-overlay (beg end bgcolor &optional priority omit-eol)
  "Make cursor/region overlays."
  (let ((ov (make-overlay 1 1)))
    (overlay-put ov 'face `(:background ,bgcolor))
    (overlay-put ov 'bgcolor bgcolor)
    (overlay-put ov 'priority (or priority 0))
    (togetherly--move-overlay ov beg end omit-eol)
    ov))

(defun togetherly--move-overlay (ov beg end &optional omit-eol)
  "Move cursor/region overlays."
  (let* ((eol (eql (char-before end) ?\n))
         (end (if eol (1- end) end))
         (after-str (when (and eol (not omit-eol))
                      (propertize " " 'face `(:background ,(overlay-get ov 'bgcolor))))))
    (move-overlay ov beg end (current-buffer))
    (overlay-put ov 'after-string after-str)))

(defun togetherly--buffer-string ()
  "Like `buffer-string' but NOT aware of narrowing and
text-properties."
  (save-restriction
    (widen)
    (buffer-substring-no-properties (point-min) (point-max))))

(defvar togetherly--last-display-name nil)
(defun togetherly--read-display-name ()
  "Read displayname with the minibuffer."
  (let ((name (read-string
               (if (null togetherly--last-display-name)
                   "Displayname : "
                 (format "Displayname (default:%s) : " togetherly--last-display-name)))))
    (if (and (string= name "") togetherly--last-display-name)
        togetherly--last-display-name
      (setq togetherly--last-display-name name))))

(defvar togetherly--last-host-address "localhost")
(defun togetherly--read-host-address ()
  "Read host address with the minibuffer."
  (let* ((addrs (when (and (fboundp 'network-interface-list)
                           (fboundp 'network-interface-info))
                  (mapcar (lambda (x)
                            (format-network-address
                             (car (network-interface-info (car x))) t))
                          (network-interface-list))))
         (addr (cl-case (length addrs)
                 ((0) (read-string
                       (format "Address (default:%s) : " togetherly--last-host-address)))
                 ((1) (car addrs))
                 (t   (ido-completing-read "Address: " addrs nil t)))))
    (if (string= addr "")
        togetherly--last-host-address
      (setq togetherly--last-host-address addr))))

(defvar togetherly--last-target-address "localhost")
(defun togetherly--read-target-address ()
  "Read target address with the minibuffer."
  (let ((addr (read-string
               (format "Address (default:%s) : " togetherly--last-target-address))))
    (if (string= addr "")
        togetherly--last-target-address
      (setq togetherly--last-target-address addr))))

(defvar togetherly--last-port 10000)
(defun togetherly--read-port ()
  "Read port number with the minibuffer."
  (let ((port (read-string (format "Port (default:%s) : " togetherly--last-port))))
    (if (string= port "")
        togetherly--last-port
      (setq togetherly--last-port (read port)))))

;; + the protocol

;; login
;; - (login . ID) [Client->Server]
;; - (error . MESSAGE) [Server->Client]

;; share buffer-string
;; - (refresh) [Client->Server]
;; - (welcome BUFFER_STRING . MAJOR_MODE) [Server->Client]
;; * `refresh' tells the server to send `welcome' message immediately.
;; * note that `welcome' can also be sent before `refresh' request, as needed.

;; share modifications
;; - (changed NAME BEG BEFORE_STRING . AFTER_STRING) [Server<->Client]
;; * When `changed' message sent to the server, the message is
;;   broadcasted for ALL clients, including the client who actually
;;   made the change. Thus clients must be aware if the message is the
;;   one sent by himself or not.

;; share members / cursor-positions
;; - (moved MARK . POINT) [Client->Server]
;; - (cursors (NAME1 RCOLOR1 PCOLOR1 MARK1 . POINT1) ...) [Server->Client]
;; * `cursors' is broadcasted every `togetherly-cursor-sync-rate' seconds.

;; other commands
;; - (comehere . POINT) [Server->Client]

;; + server
;;   + vars

(defvar togetherly--server nil)         ; (PROC NAME RCOLOR . PCOLOR)
(defvar togetherly--server-buffer nil)
(defvar togetherly--server-timer-object nil)
(defvar togetherly--server-clients nil) ; list of (PROC NAME RCOLOR PCOLOR REGION_OV . POINT_OV)

;;   + utils

(defun togetherly--server-send (client obj)
  "Send OBJ to CLIENT."
  (process-send-string (car client) (prin1-to-string obj)))

(defun togetherly--server-broadcast (obj)
  "Send OBJ to all clients."
  (dolist (client togetherly--server-clients)
    (togetherly--server-send client obj)))

;;   + API

(defun togetherly--server-broadcast-cursor-positions ()
  "Broadcast all clients' cursor positions."
  (togetherly--server-broadcast
   (cons 'cursors
         (nconc
          (mapcar
           (lambda (c) (cl-destructuring-bind (_ name rcolor pcolor region-ov . ___) c
                         `(,name ,rcolor ,pcolor
                                 ,(overlay-start region-ov)
                                 . ,(1- (overlay-end region-ov)))))
           togetherly--server-clients)
          (with-current-buffer togetherly--server-buffer
            (cl-destructuring-bind (_ name rcolor . pcolor) togetherly--server
              `((,name ,rcolor ,pcolor ,(when mark-active (mark)) . ,(point)))))))))

;; Sync modifications on change.
(defvar togetherly--server-last-change nil)
(defun togetherly--server-before-change (beg end)
  (setq togetherly--server-last-change
        ;; store 2 extra characters to make it easier to detect confliction
        ;;                                            vvvvvvvvvvvvvvvvvvvvvvvvvvv
        (cons beg (buffer-substring-no-properties beg (min (+ end 2) (point-max))))))
(defun togetherly--server-after-change (beg end _)
  (togetherly--server-broadcast
   `(changed ,(cadr togetherly--server)
             ,(car togetherly--server-last-change)
             ,(cdr togetherly--server-last-change)
             . ,(buffer-substring-no-properties beg (min (+ end 2) (point-max))))))

(defun togetherly-server-comehere ()
  (interactive)
  (togetherly--server-broadcast `(comehere . ,(point))))

(defun togetherly--server-process-message (proc message)
  "Process MESSAGE from client process PROC."
  (cl-case (car message)

    ((login)
     (let ((name (cdr message)))
       (cond
        ((or (string= name (cadr togetherly--server))
             (member name (mapcar 'cadr togetherly--server-clients)))
         (process-send-string proc "(error . \"Duplicate Displayname\")")
         (delete-process proc))
        (t
         (set-process-query-on-exit-flag proc nil)
         (with-current-buffer togetherly--server-buffer
           (let* ((pcolor (car togetherly-cursor-colors))
                  (rcolor (car togetherly-region-colors))
                  (client `(,proc ,name ,rcolor ,pcolor
                                  ,(togetherly--make-overlay 1 2 rcolor 0)
                                  . ,(togetherly--make-overlay 1 2 pcolor 1))))
             (setq togetherly-region-colors (cdr togetherly-region-colors)
                   togetherly-cursor-colors (cdr togetherly-cursor-colors))
             (push client togetherly--server-clients)
             (setq header-line-format
                   (concat " " (propertize name 'face `(:background ,pcolor))
                           " " header-line-format))))
         (togetherly--server-send
          (car togetherly--server-clients)
          (with-current-buffer togetherly--server-buffer
            `(welcome ,(togetherly--buffer-string) . ,major-mode)))
         (message "Togetherly: %s logged in." name)))))

    ((changed)
     (let ((client (assoc proc togetherly--server-clients))
           (inhibit-modification-hooks t))
       (when client
         (cl-destructuring-bind (_ beg before-string . after-string) (cdr message)
           (condition-case nil
               (with-current-buffer togetherly--server-buffer
                 (save-excursion
                   (goto-char beg)
                   (unless (looking-at (regexp-quote before-string)) (error ""))
                   (replace-match after-string t t))
                 (togetherly--server-broadcast message))
             ;; confliction detected
             (error
              (with-current-buffer togetherly--server-buffer
                (togetherly--server-send
                 client `(welcome ,(togetherly--buffer-string) . ,major-mode)))))))))

    ((moved)
     (let ((client (assoc proc togetherly--server-clients)))
       (when client
         (cl-destructuring-bind (mark . point) (cdr message)
           (condition-case nil
               (cl-destructuring-bind (_ __ ___ ____ region-ov . point-ov) client
                 (with-current-buffer togetherly--server-buffer
                   (togetherly--move-overlay point-ov point (1+ point))
                   (if mark
                       (togetherly--move-overlay region-ov mark (1+ point) t)
                     (togetherly--move-overlay region-ov 0 0 t))))
             ;; confliction detected
             (error
              (with-current-buffer togetherly--server-buffer
                (togetherly--server-send
                 client `(welcome ,(togetherly--buffer-string) . ,major-mode)))))))))

    ((refresh)
     (let ((client (assoc proc togetherly--server-clients)))
       (with-current-buffer togetherly--server-buffer
         (togetherly--server-send
          client `(welcome ,(togetherly--buffer-string) . ,major-mode)))))))

;;   + server process

(defun togetherly-server-start ()
  "Start a Togetherly server with this buffer."
  (interactive)
  (cond ((null togetherly--server)
         (let* ((addr (togetherly--read-host-address))
                (server-port (togetherly--read-port))
                (server-name (togetherly--read-display-name))
                (server-proc (make-network-process
                              :name "togetherly-server" :server t
                              :service server-port :noquery t :host addr
                              :sentinel 'togetherly--server-sentinel-function
                              :filter 'togetherly--server-filter-function))
                (rcolor (car togetherly-region-colors))
                (pcolor (car togetherly-cursor-colors)))
           (setq togetherly-region-colors   (cdr togetherly-region-colors)
                 togetherly-cursor-colors   (cdr togetherly-cursor-colors)
                 togetherly--server         `(,server-proc ,server-name ,rcolor . ,pcolor)
                 togetherly--server-buffer  (current-buffer)
                 togetherly--server-clients nil
                 togetherly--server-timer-object
                 (run-with-timer nil togetherly-cursor-sync-rate
                                 'togetherly--server-broadcast-cursor-positions))
           (set (make-local-variable 'header-line-format)
                (concat " " (propertize server-name 'face `(:background ,pcolor)))))
         (add-hook 'before-change-functions 'togetherly--server-before-change nil t)
         (add-hook 'after-change-functions 'togetherly--server-after-change nil t)
         (add-hook 'kill-buffer-query-functions 'togetherly--server-kill-buffer-query))
        ((y-or-n-p "Togetherly server already started. Migrate to this buffer ? ")
         (set (make-local-variable 'header-line-format)
              (buffer-local-value 'header-line-format togetherly--server-buffer))
         (add-hook 'before-change-functions 'togetherly--server-before-change nil t)
         (add-hook 'after-change-functions 'togetherly--server-after-change nil t)
         (with-current-buffer togetherly--server-buffer
           (remove-hook 'before-change-functions 'togetherly--server-before-change t)
           (remove-hook 'after-change-functions 'togetherly--server-after-change t)
           (kill-local-variable 'header-line-format))
         (setq togetherly--server-buffer (current-buffer))
         (togetherly--server-broadcast `(welcome ,(togetherly--buffer-string) . ,major-mode)))
        (t
         (message "Togetherly: Canceled."))))

(defun togetherly--server-filter-function (proc str)
  (with-current-buffer (get-buffer-create " *togetherly-server-tmp*")
    (save-excursion
      (goto-char (point-max))
      (insert str))
    (let (message)
      (while (setq message (ignore-errors (read (current-buffer))))
        (togetherly--server-process-message proc message)
        (delete-region (point) (point-min)))
      (goto-char (point-min)))))

(defun togetherly--server-sentinel-function (proc message)
  (unless (string-match "^open" message)
    (let ((client (assoc proc togetherly--server-clients)))
      (cond (client                     ; client process is killed
             (cl-destructuring-bind (proc name _ __ region-ov . point-ov) client
               (with-current-buffer togetherly--server-buffer
                 (let* ((old-header header-line-format)
                        (new-header (with-temp-buffer
                                      (insert old-header)
                                      (search-backward (regexp-quote (concat " " name " ")))
                                      (replace-match "")
                                      (buffer-string))))
                   (setq header-line-format new-header)
                   (delete-overlay region-ov)
                   (delete-overlay point-ov)))
               (setq togetherly--server-clients (delq client togetherly--server-clients))
               (unless (string-match "^delete" message)
                 (message "Togetherly: %s logged out." name))))
            ((eq proc (car togetherly--server)) ; server process is killed
             (mapc (lambda (c) (delete-process (car c))) togetherly--server-clients)
             (setq togetherly--server nil)
             (cancel-timer togetherly--server-timer-object)
             (with-current-buffer togetherly--server-buffer
               (kill-local-variable 'header-line-format))
             (remove-hook 'kill-buffer-query-functions 'togetherly--server-kill-buffer-query)
             (remove-hook 'before-change-functions 'togetherly--server-before-change t)
             (remove-hook 'after-change-functions 'togetherly--server-after-change t))))))

(defun togetherly--server-kill-buffer-query ()
  (or (not (eq (current-buffer) togetherly--server-buffer))
      (when (y-or-n-p "This buffer is running the Togetherly server. Really continue ? ")
        (delete-process (car togetherly--server))
        t)))

(defun togetherly-server-close ()
  "Close the Togetherly server."
  (interactive)
  (delete-process (car togetherly--server)))

;; + client
;;   + vars

(defvar togetherly--client-name nil)
(defvar togetherly--client-process nil)
(defvar togetherly--client-overlays nil)
(defvar togetherly--client-timer-object nil)

;;   + utils

(defun togetherly--client-send (obj)
  "Send OBJ to the server."
  (process-send-string togetherly--client-process (prin1-to-string obj)))

;;   + API

(defun togetherly--client-report-cursor-position ()
  "Report the cursor position to the server."
  (with-current-buffer "*Togetherly*"
    (togetherly--client-send `(moved ,(when (use-region-p) (mark)) . ,(point)))))

(defvar togetherly--client-last-change nil)
(defun togetherly--client-before-change (beg end)
  (setq togetherly--client-last-change
        (cons beg (buffer-substring-no-properties beg (min (+ end 2) (point-max))))))
(defun togetherly--client-after-change (beg end _)
  (togetherly--client-send
   `(changed ,togetherly--client-name
             ,(car togetherly--client-last-change)
             ,(cdr togetherly--client-last-change)
             . ,(buffer-substring-no-properties beg (min (+ end 2) (point-max))))))

(defun togetherly--client-process-message (proc message)
  "Process MESSAGE from server process PROC."
  (cl-case (car message)

    ((welcome)
     (with-current-buffer "*Togetherly*"
       (let ((inhibit-modification-hooks t)
             (original-pos (point))
             (mode (cddr message)))
         (erase-buffer)
         (insert (cadr message))
         (unless (eq major-mode mode)
           (funcall (or (and (fboundp mode) mode) 'fundamental-mode)))
         (goto-char (max (min original-pos (point-max)) (point-min)))
         ;; local hooks must be set after changing major-mode
         (add-hook 'before-change-functions 'togetherly--client-before-change nil t)
         (add-hook 'after-change-functions 'togetherly--client-after-change nil t)))
     (message "Togetherly: Buffer refreshed."))

    ((error)
     (delete-process proc)
     (message "Togetherly Error: %s." (cdr message)))

    ((changed)
     (cl-destructuring-bind (name beg before-string . after-string) (cdr message)
       (unless (string= name togetherly--client-name)
         (condition-case nil
             (with-current-buffer "*Togetherly*"
               (save-excursion
                 (goto-char beg)
                 (unless (looking-at (regexp-quote before-string)) (error ""))
                 (let ((inhibit-modification-hooks t))
                   (replace-match after-string t t))))
           ;; confliction detected
           (error (togetherly--client-send '(refresh)))))))

    ((cursors)
     (mapc 'delete-overlay togetherly--client-overlays)
     (with-current-buffer "*Togetherly*"
       (setq header-line-format
             (mapconcat (lambda (c)
                          (cl-destructuring-bind (n _ p  . __) c
                            (concat " " (propertize n 'face `(:background ,p)))))
                        (cdr message) " "))
       (dolist (cursor (cdr message))
         (cl-destructuring-bind (name rcolor pcolor mark . point) cursor
           (unless (string= name togetherly--client-name)
             (when mark
               (push (togetherly--make-overlay mark (1+ point) rcolor 0 t)
                     togetherly--client-overlays))
             (push (togetherly--make-overlay point (1+ point) pcolor 1)
                   togetherly--client-overlays))))))

    ((comehere)
     (let* ((buf (get-buffer "*Togetherly*"))
            (windows (mapcar (lambda (w) (cons (window-buffer w) w)) (window-list)))
            (windows (cl-remove-if-not (lambda (p) (eq buf (car p))) windows)))
       (condition-case nil
           (if windows
               (dolist (window (mapcar 'cdr windows))
                 (with-selected-window window
                   (goto-char (cdr message))
                   (recenter)))
             (with-current-buffer "*Togetherly*"
               (goto-char (cdr message))
               (recenter)))
         (error (togetherly--client-send '(refresh))))))))

;;   + client process

(defun togetherly--client-filter-function (proc str)
  (with-current-buffer (get-buffer-create " *togetherly-client-tmp*")
    (save-excursion
      (goto-char (point-max))
      (insert str))
    (let (message)
      (while (setq message (ignore-errors (read (current-buffer))))
        (togetherly--client-process-message proc message)
        (delete-region (point) (point-min)))
      (goto-char (point-min)))))

(defun togetherly-client-start ()
  (interactive)
  (when (or (null togetherly--client-process)
            (when (y-or-n-p "Already running Togetherly client. Kill the client first ? ")
              (delete-process togetherly--client-process)
              t))
    (let* ((host (togetherly--read-target-address))
           (port (togetherly--read-port))
           (name (setq togetherly--client-name (togetherly--read-display-name))))
      (setq togetherly--client-process
            (make-network-process
             :name "togetherly" :host host :service port :noquery t
             :buffer (get-buffer-create "*Togetherly*")
             :sentinel 'togetherly--client-sentinel-function
             :filter 'togetherly--client-filter-function))
      (switch-to-buffer "*Togetherly*")
      (setq togetherly--client-timer-object
            (run-with-timer nil togetherly-cursor-sync-rate
                            'togetherly--client-report-cursor-position))
      (add-hook 'kill-buffer-query-functions 'togetherly--client-kill-buffer-query)
      (togetherly--client-send `(login . ,name)))))

(defun togetherly--client-sentinel-function (proc message)
  (setq togetherly--client-process nil)
  (cancel-timer togetherly--client-timer-object)
  (remove-hook 'kill-buffer-query-functions 'togetherly--client-kill-buffer-query)
  (when (get-buffer "*Togetherly*")
    (kill-buffer "*Togetherly*")))

(defun togetherly--client-kill-buffer-query ()
  (or (not (string= (buffer-name) "*Togetherly*"))
      (y-or-n-p "Really logout from Togetherly server ? ")))

;; + provide

(provide 'togetherly)

;;; togetherly.el ends here