;;; gnus-srvr.el --- virtual server support for Gnus

;; Copyright (C) 1995-2016 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: news

;; 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:

;;; Code:

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

(require 'gnus)
(require 'gnus-start)
(require 'gnus-spec)
(require 'gnus-group)
(require 'gnus-int)
(require 'gnus-range)

(autoload 'gnus-group-make-nnir-group "nnir")

(defcustom gnus-server-mode-hook nil
  "Hook run in `gnus-server-mode' buffers."
  :group 'gnus-server
  :type 'hook)

(defcustom gnus-server-exit-hook nil
  "Hook run when exiting the server buffer."
  :group 'gnus-server
  :type 'hook)

(defcustom gnus-server-line-format "     {%(%h:%w%)} %s%a%c\n"
  "Format of server lines.
It works along the same lines as a normal formatting string,
with some simple extensions.

The following specs are understood:

%h back end
%n name
%w address
%s status
%a agent covered

General format specifiers can also be used.
See Info node `(gnus)Formatting Variables'."
  :link '(custom-manual "(gnus)Formatting Variables")
  :group 'gnus-server-visual
  :type 'string)

(defcustom gnus-server-mode-line-format "Gnus: %%b"
  "The format specification for the server mode line."
  :group 'gnus-server-visual
  :type 'string)

(defcustom gnus-server-browse-in-group-buffer nil
  "Whether server browsing should take place in the group buffer.
If nil, a faster, but more primitive, buffer is used instead."
  :version "22.1"
  :group 'gnus-server-visual
  :type 'boolean)

;;; Internal variables.

(defvar gnus-tmp-how)
(defvar gnus-tmp-name)
(defvar gnus-tmp-where)
(defvar gnus-tmp-status)
(defvar gnus-tmp-agent)
(defvar gnus-tmp-cloud)
(defvar gnus-tmp-news-server)
(defvar gnus-tmp-news-method)
(defvar gnus-tmp-user-defined)

(defvar gnus-inserted-opened-servers nil)

(defvar gnus-server-line-format-alist
  `((?h gnus-tmp-how ?s)
    (?n gnus-tmp-name ?s)
    (?w gnus-tmp-where ?s)
    (?s gnus-tmp-status ?s)
    (?a gnus-tmp-agent ?s)
    (?c gnus-tmp-cloud ?s)))

(defvar gnus-server-mode-line-format-alist
  `((?S gnus-tmp-news-server ?s)
    (?M gnus-tmp-news-method ?s)
    (?u gnus-tmp-user-defined ?s)))

(defvar gnus-server-line-format-spec nil)
(defvar gnus-server-mode-line-format-spec nil)
(defvar gnus-server-killed-servers nil)

(defvar gnus-server-mode-map)

(defvar gnus-server-menu-hook nil
  "*Hook run after the creation of the server mode menu.")

(defun gnus-server-make-menu-bar ()
  (gnus-turn-off-edit-menu 'server)
  (unless (boundp 'gnus-server-server-menu)
    (easy-menu-define
     gnus-server-server-menu gnus-server-mode-map ""
     '("Server"
       ["Add..." gnus-server-add-server t]
       ["Browse" gnus-server-read-server t]
       ["Scan" gnus-server-scan-server t]
       ["List" gnus-server-list-servers t]
       ["Kill" gnus-server-kill-server t]
       ["Yank" gnus-server-yank-server t]
       ["Copy" gnus-server-copy-server t]
       ["Show" gnus-server-show-server t]
       ["Edit" gnus-server-edit-server t]
       ["Regenerate" gnus-server-regenerate-server t]
       ["Compact" gnus-server-compact-server t]
       ["Exit" gnus-server-exit t]))

    (easy-menu-define
     gnus-server-connections-menu gnus-server-mode-map ""
     '("Connections"
       ["Open" gnus-server-open-server t]
       ["Close" gnus-server-close-server t]
       ["Offline" gnus-server-offline-server t]
       ["Deny" gnus-server-deny-server t]
       ["Toggle Cloud" gnus-server-toggle-cloud-server t]
       "---"
       ["Open All" gnus-server-open-all-servers t]
       ["Close All" gnus-server-close-all-servers t]
       ["Reset All" gnus-server-remove-denials t]))

    (gnus-run-hooks 'gnus-server-menu-hook)))

(defvar gnus-server-mode-map nil)
(put 'gnus-server-mode 'mode-class 'special)

(unless gnus-server-mode-map
  (setq gnus-server-mode-map (make-sparse-keymap))
  (suppress-keymap gnus-server-mode-map)

  (gnus-define-keys gnus-server-mode-map
    " " gnus-server-read-server-in-server-buffer
    "\r" gnus-server-read-server
    gnus-mouse-2 gnus-server-pick-server
    "q" gnus-server-exit
    "l" gnus-server-list-servers
    "k" gnus-server-kill-server
    "y" gnus-server-yank-server
    "c" gnus-server-copy-server
    "a" gnus-server-add-server
    "e" gnus-server-edit-server
    "S" gnus-server-show-server
    "s" gnus-server-scan-server

    "O" gnus-server-open-server
    "\M-o" gnus-server-open-all-servers
    "C" gnus-server-close-server
    "\M-c" gnus-server-close-all-servers
    "D" gnus-server-deny-server
    "L" gnus-server-offline-server
    "R" gnus-server-remove-denials

    "n" next-line
    "p" previous-line

    "g" gnus-server-regenerate-server

    "G" gnus-group-make-nnir-group

    "z" gnus-server-compact-server

    "i" gnus-server-toggle-cloud-server

    "\C-c\C-i" gnus-info-find-node
    "\C-c\C-b" gnus-bug))

(defface gnus-server-agent
  '((((class color) (background light)) (:foreground "PaleTurquoise" :bold t))
    (((class color) (background dark)) (:foreground "PaleTurquoise" :bold t))
    (t (:bold t)))
  "Face used for displaying AGENTIZED servers"
  :group 'gnus-server-visual)
;; backward-compatibility alias
(put 'gnus-server-agent-face 'face-alias 'gnus-server-agent)
(put 'gnus-server-agent-face 'obsolete-face "22.1")

(defface gnus-server-cloud
  '((((class color) (background light)) (:foreground "ForestGreen" :bold t))
    (((class color) (background dark)) (:foreground "PaleGreen" :bold t))
    (t (:bold t)))
  "Face used for displaying AGENTIZED servers"
  :group 'gnus-server-visual)

(defface gnus-server-opened
  '((((class color) (background light)) (:foreground "Green3" :bold t))
    (((class color) (background dark)) (:foreground "Green1" :bold t))
    (t (:bold t)))
  "Face used for displaying OPENED servers"
  :group 'gnus-server-visual)
;; backward-compatibility alias
(put 'gnus-server-opened-face 'face-alias 'gnus-server-opened)
(put 'gnus-server-opened-face 'obsolete-face "22.1")

(defface gnus-server-closed
  '((((class color) (background light)) (:foreground "Steel Blue" :italic t))
    (((class color) (background dark))
     (:foreground "LightBlue" :italic t))
    (t (:italic t)))
  "Face used for displaying CLOSED servers"
  :group 'gnus-server-visual)
;; backward-compatibility alias
(put 'gnus-server-closed-face 'face-alias 'gnus-server-closed)
(put 'gnus-server-closed-face 'obsolete-face "22.1")

(defface gnus-server-denied
  '((((class color) (background light)) (:foreground "Red" :bold t))
    (((class color) (background dark)) (:foreground "Pink" :bold t))
    (t (:inverse-video t :bold t)))
  "Face used for displaying DENIED servers"
  :group 'gnus-server-visual)
;; backward-compatibility alias
(put 'gnus-server-denied-face 'face-alias 'gnus-server-denied)
(put 'gnus-server-denied-face 'obsolete-face "22.1")

(defface gnus-server-offline
  '((((class color) (background light)) (:foreground "Orange" :bold t))
    (((class color) (background dark)) (:foreground "Yellow" :bold t))
    (t (:inverse-video t :bold t)))
  "Face used for displaying OFFLINE servers"
  :group 'gnus-server-visual)
;; backward-compatibility alias
(put 'gnus-server-offline-face 'face-alias 'gnus-server-offline)
(put 'gnus-server-offline-face 'obsolete-face "22.1")

(defvar gnus-server-font-lock-keywords
  '(("(\\(agent\\))" 1 'gnus-server-agent)
    ("(\\(cloud\\))" 1 'gnus-server-cloud)
    ("(\\(opened\\))" 1 'gnus-server-opened)
    ("(\\(closed\\))" 1 'gnus-server-closed)
    ("(\\(offline\\))" 1 'gnus-server-offline)
    ("(\\(denied\\))" 1 'gnus-server-denied)))

(defun gnus-server-mode ()
  "Major mode for listing and editing servers.

All normal editing commands are switched off.
\\<gnus-server-mode-map>
For more in-depth information on this mode, read the manual
\(`\\[gnus-info-find-node]').

The following commands are available:

\\{gnus-server-mode-map}"
  ;; FIXME: Use define-derived-mode.
  (interactive)
  (when (gnus-visual-p 'server-menu 'menu)
    (gnus-server-make-menu-bar))
  (kill-all-local-variables)
  (gnus-simplify-mode-line)
  (setq major-mode 'gnus-server-mode)
  (setq mode-name "Server")
  (gnus-set-default-directory)
  (setq mode-line-process nil)
  (use-local-map gnus-server-mode-map)
  (buffer-disable-undo)
  (setq truncate-lines t)
  (setq buffer-read-only t)
  (if (featurep 'xemacs)
      (put 'gnus-server-mode 'font-lock-defaults '(gnus-server-font-lock-keywords t))
    (set (make-local-variable 'font-lock-defaults)
	 '(gnus-server-font-lock-keywords t)))
  (gnus-run-mode-hooks 'gnus-server-mode-hook))

(defun gnus-server-insert-server-line (name method)
  (let* ((gnus-tmp-name name)
         (gnus-tmp-how (car method))
	 (gnus-tmp-where (nth 1 method))
	 (elem (assoc method gnus-opened-servers))
	 (gnus-tmp-status
	  (cond
	   ((eq (nth 1 elem) 'denied) "(denied)")
	   ((eq (nth 1 elem) 'offline) "(offline)")
	   (t
	    (condition-case nil
		(if (or (gnus-server-opened method)
			(eq (nth 1 elem) 'ok))
		    "(opened)"
		  "(closed)")
	      ((error) "(error)")))))
	 (gnus-tmp-agent (if (and gnus-agent
				  (gnus-agent-method-p method))
			     " (agent)"
			   ""))
	 (gnus-tmp-cloud (if (gnus-cloud-server-p gnus-tmp-name)
			     " (cloud)"
			   "")))
    (beginning-of-line)
    (gnus-add-text-properties
     (point)
     (prog1 (1+ (point))
       ;; Insert the text.
       (eval gnus-server-line-format-spec))
     (list 'gnus-server (intern gnus-tmp-name)
           'gnus-named-server (intern (gnus-method-to-server method t))))))

(defun gnus-enter-server-buffer ()
  "Set up the server buffer."
  (gnus-server-setup-buffer)
  (gnus-configure-windows 'server)
  ;; Usually `gnus-configure-windows' will finish with the
  ;; `gnus-server-buffer' selected as the current buffer, but not always (I
  ;; bumped into it when starting from a dedicated *Group* frame, and
  ;; gnus-configure-windows opened *Server* into its own dedicated frame).
  (with-current-buffer (get-buffer gnus-server-buffer)
    (gnus-server-prepare)))

(defun gnus-server-setup-buffer ()
  "Initialize the server buffer."
  (unless (get-buffer gnus-server-buffer)
    (with-current-buffer (gnus-get-buffer-create gnus-server-buffer)
      (gnus-server-mode))))

(defun gnus-server-prepare ()
  (gnus-set-format 'server-mode)
  (gnus-set-format 'server t)
  (let ((alist gnus-server-alist)
	(buffer-read-only nil)
	done server op-ser)
    (erase-buffer)
    (setq gnus-inserted-opened-servers nil)
    ;; First we do the real list of servers.
    (while alist
      (unless (member (cdar alist) done)
	(push (cdar alist) done)
	(setq server (pop alist))
	(when (and server (car server) (cdr server))
	  (gnus-server-insert-server-line (car server) (cdr server))))
      (when (member (cdar alist) done)
	(pop alist)))
    ;; Then we insert the list of servers that have been opened in
    ;; this session.
    (dolist (open gnus-opened-servers)
      (when (and (not (member (car open) done))
		 ;; Just ignore ephemeral servers.
		 (not (gnus-method-ephemeral-p (car open))))
	(push (car open) done)
	(gnus-server-insert-server-line
	 (setq op-ser (format "%s:%s" (caar open) (nth 1 (car open))))
	 (car open))
	(push (list op-ser (car open)) gnus-inserted-opened-servers))))
  (goto-char (point-min))
  (gnus-server-position-point))

(defun gnus-server-server-name ()
  (let ((server (get-text-property (point-at-bol) 'gnus-server)))
    (and server (symbol-name server))))

(defun gnus-server-named-server ()
  "Return a server name that matches one of the names returned by
`gnus-method-to-server'."
  (let ((server (get-text-property (point-at-bol) 'gnus-named-server)))
    (and server (symbol-name server))))

(defalias 'gnus-server-position-point 'gnus-goto-colon)

(defconst gnus-server-edit-buffer "*Gnus edit server*")

(defun gnus-server-update-server (server)
  (with-current-buffer gnus-server-buffer
    (let* ((buffer-read-only nil)
	   (entry (assoc server gnus-server-alist))
	   (oentry (assoc (gnus-server-to-method server)
			  gnus-opened-servers)))
      (when entry
	(gnus-dribble-enter
	 (concat "(gnus-server-set-info \"" server "\" '"
		 (gnus-prin1-to-string (cdr entry)) ")\n")
	 (concat "^(gnus-server-set-info \"" (regexp-quote server) "\"")))
      (when (or entry oentry)
	;; Buffer may be narrowed.
	(save-restriction
	  (widen)
	  (when (gnus-server-goto-server server)
	    (gnus-delete-line))
	  (if entry
	      (gnus-server-insert-server-line (car entry) (cdr entry))
	    (gnus-server-insert-server-line
	     (format "%s:%s" (caar oentry) (nth 1 (car oentry)))
	     (car oentry)))
	  (gnus-server-position-point))))))

(defun gnus-server-set-info (server info)
  ;; Enter a select method into the virtual server alist.
  (when (and server info)
    (gnus-dribble-enter
     (concat "(gnus-server-set-info \"" server "\" '"
	     (gnus-prin1-to-string info) ")")
     (concat "^(gnus-server-set-info \"" (regexp-quote server) "\""))
    (let* ((server (nth 1 info))
	   (entry (assoc server gnus-server-alist))
	   (cached (assoc server gnus-server-method-cache)))
      (if cached
	  (setq gnus-server-method-cache
		(delq cached gnus-server-method-cache)))
      (if entry
	  (progn
	    ;; Remove the server from `gnus-opened-servers' since
	    ;; it has never been opened with the new `info' yet.
	    (gnus-opened-servers-remove (cdr entry))
	    ;; Don't make a new Lisp object.
	    (setcar (cdr entry) (car info))
	    (setcdr (cdr entry) (cdr info)))
	(setq gnus-server-alist
	      (nconc gnus-server-alist (list (cons server info))))))))

;;; Interactive server functions.

(defun gnus-server-kill-server (server)
  "Kill the server on the current line."
  (interactive (list (gnus-server-server-name)))
  (unless (gnus-server-goto-server server)
    (if server (error "No such server: %s" server)
      (error "No server on the current line")))
  (unless (assoc server gnus-server-alist)
    (error "Read-only server %s" server))
  (gnus-dribble-touch)
  (let ((buffer-read-only nil))
    (gnus-delete-line))
  (push (assoc server gnus-server-alist) gnus-server-killed-servers)
  (setq gnus-server-alist (delq (car gnus-server-killed-servers)
				gnus-server-alist))
  (let ((groups (gnus-groups-from-server server)))
    (when (and groups
	       (gnus-yes-or-no-p
		(format "Kill all %s groups from this server? "
			(length groups))))
      (dolist (group groups)
	(setq gnus-newsrc-alist
	      (delq (assoc group gnus-newsrc-alist)
		    gnus-newsrc-alist))
	(when gnus-group-change-level-function
	  (funcall gnus-group-change-level-function
		   group gnus-level-killed 3)))))
  (gnus-server-position-point))

(defun gnus-server-yank-server ()
  "Yank the previously killed server."
  (interactive)
  (unless gnus-server-killed-servers
    (error "No killed servers to be yanked"))
  (let ((alist gnus-server-alist)
	(server (gnus-server-server-name))
	(killed (car gnus-server-killed-servers)))
    (if (not server)
	(setq gnus-server-alist (nconc gnus-server-alist (list killed)))
      (if (string= server (caar gnus-server-alist))
	  (push killed gnus-server-alist)
	(while (and (cdr alist)
		    (not (string= server (caadr alist))))
	  (setq alist (cdr alist)))
	(if alist
	    (setcdr alist (cons killed (cdr alist)))
	  (setq gnus-server-alist (list killed)))))
    (gnus-server-update-server (car killed))
    (setq gnus-server-killed-servers (cdr gnus-server-killed-servers))
    (gnus-server-position-point)))

(defun gnus-server-exit ()
  "Return to the group buffer."
  (interactive)
  (gnus-run-hooks 'gnus-server-exit-hook)
  (gnus-kill-buffer (current-buffer))
  (gnus-configure-windows 'group t))

(defun gnus-server-list-servers ()
  "List all available servers."
  (interactive)
  (let ((cur (gnus-server-server-name)))
    (gnus-server-prepare)
    (if cur (gnus-server-goto-server cur)
      (goto-char (point-max))
      (forward-line -1))
    (gnus-server-position-point)))

(defun gnus-server-set-status (method status)
  "Make METHOD have STATUS."
  (let ((entry (assoc method gnus-opened-servers)))
    (if entry
	(setcar (cdr entry) status)
      (push (list method status) gnus-opened-servers))))

(defun gnus-opened-servers-remove (method)
  "Remove METHOD from the list of opened servers."
  (setq gnus-opened-servers (delq (assoc method gnus-opened-servers)
				  gnus-opened-servers)))

(defun gnus-server-open-server (server)
  "Force an open of SERVER."
  (interactive (list (gnus-server-server-name)))
  (let ((method (gnus-server-to-method server)))
    (unless method
      (error "No such server: %s" server))
    (gnus-server-set-status method 'ok)
    (prog1
	(gnus-open-server method)
      (gnus-server-update-server server)
      (gnus-server-position-point))))

(defun gnus-server-open-all-servers ()
  "Open all servers."
  (interactive)
  (dolist (server gnus-inserted-opened-servers)
    (gnus-server-open-server (car server))))

(defun gnus-server-close-server (server)
  "Close SERVER."
  (interactive (list (gnus-server-server-name)))
  (let ((method (gnus-server-to-method server)))
    (unless method
      (error "No such server: %s" server))
    (gnus-server-set-status method 'closed)
    (prog1
	(gnus-close-server method)
      (gnus-server-update-server server)
      (gnus-server-position-point))))

(defun gnus-server-offline-server (server)
  "Set SERVER to offline."
  (interactive (list (gnus-server-server-name)))
  (let ((method (gnus-server-to-method server)))
    (unless method
      (error "No such server: %s" server))
    (prog1
	(gnus-close-server method)
      (gnus-server-set-status method 'offline)
      (gnus-server-update-server server)
      (gnus-server-position-point))))

(defun gnus-server-close-all-servers ()
  "Close all servers."
  (interactive)
  (dolist (server gnus-inserted-opened-servers)
    (gnus-server-close-server (car server)))
  (dolist (server gnus-server-alist)
    (gnus-server-close-server (car server))))

(defun gnus-server-deny-server (server)
  "Make sure SERVER will never be attempted opened."
  (interactive (list (gnus-server-server-name)))
  (let ((method (gnus-server-to-method server)))
    (unless method
      (error "No such server: %s" server))
    (gnus-server-set-status method 'denied))
  (gnus-server-update-server server)
  (gnus-server-position-point)
  t)

(defun gnus-server-remove-denials ()
  "Make all denied servers into closed servers."
  (interactive)
  (dolist (server gnus-opened-servers)
    (when (eq (nth 1 server) 'denied)
      (setcar (nthcdr 1 server) 'closed)))
  (gnus-server-list-servers))

(defun gnus-server-copy-server (from to)
  "Copy a server definition to a new name."
  (interactive
   (list
    (or (gnus-server-server-name)
	(error "No server on the current line"))
    (read-string "Copy to: ")))
  (unless from
    (error "No server on current line"))
  (unless (and to (not (string= to "")))
    (error "No name to copy to"))
  (when (assoc to gnus-server-alist)
    (error "%s already exists" to))
  (unless (gnus-server-to-method from)
    (error "%s: no such server" from))
  (let ((to-entry (cons from (gnus-copy-sequence
			      (gnus-server-to-method from)))))
    (setcar to-entry to)
    (setcar (nthcdr 2 to-entry) to)
    (push to-entry gnus-server-killed-servers)
    (gnus-server-yank-server)))

(defun gnus-server-add-server (how where)
  (interactive
   (list (intern (gnus-completing-read "Server method"
                                       (mapcar 'car gnus-valid-select-methods)
                                       t))
	 (read-string "Server name: ")))
  (when (assq where gnus-server-alist)
    (error "Server with that name already defined"))
  (push (list where how where) gnus-server-killed-servers)
  (gnus-server-yank-server))

(defun gnus-server-goto-server (server)
  "Jump to a server line."
  (interactive
   (list (gnus-completing-read "Goto server" (mapcar 'car gnus-server-alist) t)))
  (let ((to (text-property-any (point-min) (point-max)
			       'gnus-server (intern server))))
    (when to
      (goto-char to)
      (gnus-server-position-point))))

(defun gnus-server-edit-server (server)
  "Edit the server on the current line."
  (interactive (list (gnus-server-server-name)))
  (unless server
    (error "No server on current line"))
  (unless (assoc server gnus-server-alist)
    (error "This server can't be edited"))
  (let ((info (cdr (assoc server gnus-server-alist))))
    (gnus-close-server info)
    (gnus-edit-form
     info "Editing the server."
     `(lambda (form)
	(gnus-server-set-info ,server form)
	(gnus-server-list-servers)
	(gnus-server-position-point))
     'edit-server)))

(defun gnus-server-show-server (server)
  "Show the definition of the server on the current line."
  (interactive (list (gnus-server-server-name)))
  (unless server
    (error "No server on current line"))
  (let ((info (gnus-server-to-method server)))
    (gnus-edit-form
     info "Showing the server."
     `(lambda (form)
	(gnus-server-position-point))
     'edit-server)))

(defun gnus-server-scan-server (server)
  "Request a scan from the current server."
  (interactive (list (gnus-server-server-name)))
  (let ((method (gnus-server-to-method server)))
    (if (not (gnus-get-function method 'request-scan))
	(error "Server %s can't scan" (car method))
      (gnus-message 3 "Scanning %s..." server)
      (gnus-request-scan nil method)
      (gnus-message 3 "Scanning %s...done" server))))

(defun gnus-server-read-server-in-server-buffer (server)
  "Browse a server in server buffer."
  (interactive (list (gnus-server-server-name)))
  (let (gnus-server-browse-in-group-buffer)
    (gnus-server-read-server server)))

(defun gnus-server-read-server (server)
  "Browse a server."
  (interactive (list (gnus-server-server-name)))
  (let ((buf (current-buffer)))
    (prog1
	(gnus-browse-foreign-server server buf)
      (with-current-buffer buf
	(gnus-server-update-server (gnus-server-server-name))
	(gnus-server-position-point)))))

(defun gnus-server-pick-server (e)
  (interactive "e")
  (mouse-set-point e)
  (gnus-server-read-server (gnus-server-server-name)))


;;;
;;; Browse Server Mode
;;;

(defvar gnus-browse-menu-hook nil
  "*Hook run after the creation of the browse mode menu.")

(defcustom gnus-browse-subscribe-newsgroup-method
  'gnus-subscribe-alphabetically
  "Function(s) called when subscribing groups in the Browse Server Buffer
A few pre-made functions are supplied: `gnus-subscribe-randomly'
inserts new groups at the beginning of the list of groups;
`gnus-subscribe-alphabetically' inserts new groups in strict
alphabetic order; `gnus-subscribe-hierarchically' inserts new groups
in hierarchical newsgroup order; `gnus-subscribe-interactively' asks
for your decision; `gnus-subscribe-killed' kills all new groups;
`gnus-subscribe-zombies' will make all new groups into zombies;
`gnus-subscribe-topics' will enter groups into the topics that
claim them."
  :version "24.1"
  :group 'gnus-server
  :type '(radio (function-item gnus-subscribe-randomly)
		(function-item gnus-subscribe-alphabetically)
		(function-item gnus-subscribe-hierarchically)
		(function-item gnus-subscribe-interactively)
		(function-item gnus-subscribe-killed)
		(function-item gnus-subscribe-zombies)
		(function-item gnus-subscribe-topics)
		function
		(repeat function)))

(defvar gnus-browse-mode-hook nil)
(defvar gnus-browse-mode-map nil)
(put 'gnus-browse-mode 'mode-class 'special)

(unless gnus-browse-mode-map
  (setq gnus-browse-mode-map (make-keymap))
  (suppress-keymap gnus-browse-mode-map)

  (gnus-define-keys
      gnus-browse-mode-map
    " " gnus-browse-read-group
    "=" gnus-browse-select-group
    "n" gnus-browse-next-group
    "p" gnus-browse-prev-group
    "\177" gnus-browse-prev-group
    [delete] gnus-browse-prev-group
    "N" gnus-browse-next-group
    "P" gnus-browse-prev-group
    "\M-n" gnus-browse-next-group
    "\M-p" gnus-browse-prev-group
    "\r" gnus-browse-select-group
    "u" gnus-browse-unsubscribe-current-group
    "l" gnus-browse-exit
    "L" gnus-browse-exit
    "q" gnus-browse-exit
    "Q" gnus-browse-exit
    "d" gnus-browse-describe-group
    [delete] gnus-browse-delete-group
    "\C-c\C-c" gnus-browse-exit
    "?" gnus-browse-describe-briefly

    "\C-c\C-i" gnus-info-find-node
    "\C-c\C-b" gnus-bug))

(defun gnus-browse-make-menu-bar ()
  (gnus-turn-off-edit-menu 'browse)
  (unless (boundp 'gnus-browse-menu)
    (easy-menu-define
     gnus-browse-menu gnus-browse-mode-map ""
     '("Browse"
       ["Subscribe" gnus-browse-unsubscribe-current-group t]
       ["Read" gnus-browse-read-group t]
       ["Select" gnus-browse-select-group t]
       ["Describe" gnus-browse-describe-group t]
       ["Next" gnus-browse-next-group t]
       ["Prev" gnus-browse-prev-group t]
       ["Exit" gnus-browse-exit t]))
    (gnus-run-hooks 'gnus-browse-menu-hook)))

(defvar gnus-browse-current-method nil)
(defvar gnus-browse-return-buffer nil)

(defvar gnus-browse-buffer "*Gnus Browse Server*")

(defun gnus-browse-foreign-server (server &optional return-buffer)
  "Browse the server SERVER."
  (setq gnus-browse-current-method (gnus-server-to-method server))
  (setq gnus-browse-return-buffer return-buffer)
  (let* ((method gnus-browse-current-method)
	 (orig-select-method gnus-select-method)
	 (gnus-select-method method)
	 groups group)
    (gnus-message 5 "Connecting to %s..." (nth 1 method))
    (cond
     ((not (gnus-check-server method))
      (gnus-message
       1 "Unable to contact server %s: %s" (nth 1 method)
       (gnus-status-message method))
      nil)
     ((not
       (prog2
	   (gnus-message 6 "Reading active file...")
	   (gnus-request-list method)
	 (gnus-message 6 "Reading active file...done")))
      (gnus-message
       1 "Couldn't request list: %s" (gnus-status-message method))
      nil)
     (t
      (with-current-buffer nntp-server-buffer
	(let ((cur (current-buffer)))
	  (goto-char (point-min))
         (unless (or (null gnus-ignored-newsgroups)
                     (string= gnus-ignored-newsgroups ""))
	    (delete-matching-lines gnus-ignored-newsgroups))
	  ;; We treat NNTP as a special case to avoid problems with
	  ;; garbage group names like `"foo' that appear in some badly
	  ;; managed active files. -jh.
	  (if (eq (car method) 'nntp)
	      (while (not (eobp))
		(ignore-errors
		  (push (cons
			 (mm-string-as-unibyte
			  (buffer-substring
			   (point)
			   (progn
			     (skip-chars-forward "^ \t")
			     (point))))
			 (let ((last (read cur)))
			   (cons (read cur) last)))
			groups))
		(forward-line))
	    (while (not (eobp))
	      (ignore-errors
		(push (cons
		       (mm-string-as-unibyte
			(if (eq (char-after) ?\")
			    (read cur)
			  (let ((p (point)) (name ""))
			    (skip-chars-forward "^ \t\\\\")
			    (setq name (buffer-substring p (point)))
			    (while (eq (char-after) ?\\)
			      (setq p (1+ (point)))
			      (forward-char 2)
			      (skip-chars-forward "^ \t\\\\")
			      (setq name (concat name (buffer-substring
						       p (point)))))
			    name)))
		       (let ((last (read cur)))
			 (cons (read cur) last)))
		      groups))
	      (forward-line)))))
      (setq groups (sort groups
			 (lambda (l1 l2)
			   (string< (car l1) (car l2)))))
      (if gnus-server-browse-in-group-buffer
	  (let* ((gnus-select-method orig-select-method)
		 (gnus-group-listed-groups
		  (mapcar (lambda (group)
			    (let ((name
				   (gnus-group-prefixed-name
				    (car group) method)))
			      (gnus-set-active name (cdr group))
			      name))
			  groups)))
	    (gnus-configure-windows 'group)
	    (funcall gnus-group-prepare-function
		     gnus-level-killed 'ignore 1 'ignore))
	(gnus-get-buffer-create gnus-browse-buffer)
	(gnus-configure-windows 'browse)
	(buffer-disable-undo)
	(let ((buffer-read-only nil))
	  (erase-buffer))
	(gnus-browse-mode)
	(setq mode-line-buffer-identification
	      (list
	       (format
		"Gnus: %%b {%s:%s}" (car method) (cadr method))))
	(let ((buffer-read-only nil)
	      name
	      (prefix (let ((gnus-select-method orig-select-method))
			(gnus-group-prefixed-name "" method))))
	  (while (setq group (pop groups))
	    (gnus-add-text-properties
	     (point)
	     (prog1 (1+ (point))
	       (insert
		(format "%c%7d: %s\n"
			(let ((level
			       (if (string= prefix "")
				   (gnus-group-level (setq name (car group)))
				 (gnus-group-level
				  (concat prefix (setq name (car group)))))))
			  (cond
			   ((<= level gnus-level-subscribed) ? )
			   ((<= level gnus-level-unsubscribed) ?U)
			   ((= level gnus-level-zombie) ?Z)
			   (t ?K)))
			(max 0 (- (1+ (cddr group)) (cadr group)))
			;; Don't decode if name is ASCII
			(if (and (fboundp 'detect-coding-string)
				 (eq (detect-coding-string name t) 'undecided))
			    name
			  (mm-decode-coding-string
			   name
			   (inline (gnus-group-name-charset method name)))))))
	     (list 'gnus-group name)
	     )))
	(switch-to-buffer (current-buffer)))
      (goto-char (point-min))
      (gnus-group-position-point)
      (gnus-message 5 "Connecting to %s...done" (nth 1 method))
      t))))

(define-derived-mode gnus-browse-mode fundamental-mode "Browse Server"
  "Major mode for browsing a foreign server.

All normal editing commands are switched off.

\\<gnus-browse-mode-map>
The only things you can do in this buffer is

1) `\\[gnus-browse-unsubscribe-current-group]' to subscribe to a group.
The group will be inserted into the group buffer upon exit from this
buffer.

2) `\\[gnus-browse-read-group]' to read a group ephemerally.

3) `\\[gnus-browse-exit]' to return to the group buffer."
  (when (gnus-visual-p 'browse-menu 'menu)
    (gnus-browse-make-menu-bar))
  (gnus-simplify-mode-line)
  (setq mode-line-process nil)
  (buffer-disable-undo)
  (setq truncate-lines t)
  (gnus-set-default-directory)
  (setq buffer-read-only t))

(defun gnus-browse-read-group (&optional no-article number)
  "Enter the group at the current line.
If NUMBER, fetch this number of articles."
  (interactive "P")
  (let ((group (gnus-browse-group-name)))
    (if (or (not (gnus-get-info group))
	    (gnus-ephemeral-group-p group))
	(unless (gnus-group-read-ephemeral-group
		 group gnus-browse-current-method nil
		 (cons (current-buffer) 'browse)
		 nil nil nil number)
	  (error "Couldn't enter %s" group))
      (unless (gnus-group-read-group nil no-article group)
	(error "Couldn't enter %s" group)))))

(defun gnus-browse-select-group (&optional number)
  "Select the current group.
If NUMBER, fetch this number of articles."
  (interactive "P")
  (gnus-browse-read-group 'no number))

(defun gnus-browse-next-group (n)
  "Go to the next group."
  (interactive "p")
  (prog1
      (forward-line n)
    (gnus-group-position-point)))

(defun gnus-browse-prev-group (n)
  "Go to the next group."
  (interactive "p")
  (gnus-browse-next-group (- n)))

(defun gnus-browse-unsubscribe-current-group (arg)
  "(Un)subscribe to the next ARG groups.
The variable `gnus-browse-subscribe-newsgroup-method' determines
how new groups will be entered into the group buffer."
  (interactive "p")
  (when (eobp)
    (error "No group at current line"))
  (let ((ward (if (< arg 0) -1 1))
	(arg (abs arg)))
    (while (and (> arg 0)
		(not (eobp))
		(gnus-browse-unsubscribe-group)
		(zerop (gnus-browse-next-group ward)))
      (decf arg))
    (gnus-group-position-point)
    (when (/= 0 arg)
      (gnus-message 7 "No more newsgroups"))
    arg))

(defun gnus-browse-group-name ()
  (save-excursion
    (beginning-of-line)
    (let ((name (get-text-property (point) 'gnus-group)))
      (when (re-search-forward ": \\(.*\\)$" (point-at-eol) t)
	(concat (gnus-method-to-server-name gnus-browse-current-method) ":"
		(or name
		    (match-string-no-properties 1)))))))

(defun gnus-browse-describe-group (group)
  "Describe the current group."
  (interactive (list (gnus-browse-group-name)))
  (gnus-group-describe-group nil group))

(defun gnus-browse-delete-group (group force)
  "Delete the current group.  Only meaningful with editable groups.
If FORCE (the prefix) is non-nil, all the articles in the group will
be deleted.  This is \"deleted\" as in \"removed forever from the face
of the Earth\".  There is no undo.  The user will be prompted before
doing the deletion."
  (interactive (list (gnus-browse-group-name)
		     current-prefix-arg))
  (gnus-group-delete-group group force))

(defun gnus-browse-unsubscribe-group ()
  "Toggle subscription of the current group in the browse buffer."
  (let ((sub nil)
	(buffer-read-only nil)
	group)
    (save-excursion
      (beginning-of-line)
      ;; If this group it killed, then we want to subscribe it.
      (unless (eq (char-after) ? )
	(setq sub t))
      (setq group (gnus-browse-group-name))
      (when (gnus-server-equal gnus-browse-current-method "native")
	(setq group (gnus-group-real-name group)))
      (if sub
	  (progn
	    ;; Make sure the group has been properly removed before we
	    ;; subscribe to it.
 	    (if (gnus-ephemeral-group-p group)
		(gnus-kill-ephemeral-group group))
	    (let ((entry (gnus-group-entry group)))
	      (if entry
		  ;; Just change the subscription level if it is an
		  ;; unsubscribed group.
		  (gnus-group-change-level entry
					   gnus-level-default-subscribed)
		;; If it is a killed group or a zombie, feed it to the
		;; mechanism for new group subscription.
		(gnus-call-subscribe-functions
		 gnus-browse-subscribe-newsgroup-method
		 group)
		(gnus-request-update-group-status group 'subscribe)))
	    (delete-char 1)
	    (insert (let ((lvl (gnus-group-level group)))
		      (cond
		       ((< lvl gnus-level-unsubscribed) ? )
		       ((< lvl gnus-level-zombie) ?U)
		       ((< lvl gnus-level-killed) ?Z)
		       (t ?K)))))
	(gnus-group-change-level
	 group gnus-level-unsubscribed gnus-level-default-subscribed)
	(delete-char 1)
	(insert ?U)))
    t))

(defun gnus-browse-exit ()
  "Quit browsing and return to the group buffer."
  (interactive)
  (when (derived-mode-p 'gnus-browse-mode)
    (gnus-kill-buffer (current-buffer)))
  ;; Insert the newly subscribed groups in the group buffer.
  (with-current-buffer gnus-group-buffer
    (gnus-group-list-groups nil))
  (if gnus-browse-return-buffer
      (gnus-configure-windows 'server 'force)
    (gnus-configure-windows 'group 'force)))

(defun gnus-browse-describe-briefly ()
  "Give a one line description of the group mode commands."
  (interactive)
  (gnus-message 6 "%s"
		(substitute-command-keys "\\<gnus-browse-mode-map>\\[gnus-group-next-group]:Forward  \\[gnus-group-prev-group]:Backward  \\[gnus-browse-exit]:Exit  \\[gnus-info-find-node]:Run Info  \\[gnus-browse-describe-briefly]:This help")))

(defun gnus-server-regenerate-server ()
  "Issue a command to the server to regenerate all its data structures."
  (interactive)
  (let ((server (gnus-server-server-name)))
    (unless server
      (error "No server on the current line"))
    (condition-case ()
	(gnus-get-function (gnus-server-to-method server)
			   'request-regenerate)
      (error
	(error "This back end doesn't support regeneration")))
    (gnus-message 5 "Requesting regeneration of %s..." server)
    (unless (gnus-open-server server)
      (error "Couldn't open server"))
    (if (gnus-request-regenerate server)
	(gnus-message 5 "Requesting regeneration of %s...done" server)
      (gnus-message 5 "Couldn't regenerate %s" server))))


;;;
;;; Server compaction. -- dvl
;;;

;; #### FIXME: this function currently fails to update the Group buffer's
;; #### appearance.
(defun gnus-server-compact-server ()
  "Issue a command to the server to compact all its groups.

Note: currently only implemented in nnml."
  (interactive)
  (let ((server (gnus-server-server-name)))
    (unless server
      (error "No server on the current line"))
    (condition-case ()
	(gnus-get-function (gnus-server-to-method server)
			   'request-compact)
      (error
       (error "This back end doesn't support compaction")))
    (gnus-message 5 "\
Requesting compaction of %s... (this may take a long time)"
		  server)
    (unless (gnus-open-server server)
      (error "Couldn't open server"))
    (if (not (gnus-request-compact server))
	(gnus-message 5 "Couldn't compact %s" server)
      (gnus-message 5 "Requesting compaction of %s...done" server)
      ;; Invalidate the original article buffer which might be out of date.
      ;; #### NOTE: Yes, this might be a bit rude, but since compaction
      ;; #### will not happen very often, I think this is acceptable.
      (let ((original (get-buffer gnus-original-article-buffer)))
	(and original (gnus-kill-buffer original))))))

(defun gnus-server-toggle-cloud-server ()
  "Make the server under point be replicated in the Emacs Cloud."
  (interactive)
  (let ((server (gnus-server-server-name)))
    (unless server
      (error "No server on the current line"))

    (unless (gnus-method-option-p server 'cloud)
      (error "The server under point doesn't support cloudiness"))

    (if (gnus-cloud-server-p server)
	(setq gnus-cloud-covered-servers
	      (delete server gnus-cloud-covered-servers))
      (push server gnus-cloud-covered-servers))

    (gnus-server-update-server server)
    (gnus-message 1 (if (gnus-cloud-server-p server)
			"Replication of %s in the cloud will start"
		      "Replication of %s in the cloud will stop")
		  server)))

(provide 'gnus-srvr)

;;; gnus-srvr.el ends here
