Delete duplicate server names when getting credentials.

[gnus] / lisp / gnus-agent.el

;;; gnus-agent.el --- unplugged support for Gnus

;; Copyright (C) 1997-2011  Free Software Foundation, Inc.

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

(require 'gnus)
(require 'gnus-cache)
(require 'nnmail)
(require 'nnvirtual)
(require 'gnus-sum)
(require 'gnus-score)
(require 'gnus-srvr)
(require 'gnus-util)
(eval-when-compile
  (if (featurep 'xemacs)
      (require 'itimer)
    (require 'timer))
  (require 'cl))

(autoload 'gnus-server-update-server "gnus-srvr")
(autoload 'gnus-agent-customize-category "gnus-cus")

(defcustom gnus-agent-directory (nnheader-concat gnus-directory "agent/")
  "Where the Gnus agent will store its files."
  :group 'gnus-agent
  :type 'directory)

(defcustom gnus-agent-plugged-hook nil
  "Hook run when plugging into the network."
  :group 'gnus-agent
  :type 'hook)

(defcustom gnus-agent-unplugged-hook nil
  "Hook run when unplugging from the network."
  :group 'gnus-agent
  :type 'hook)

(defcustom gnus-agent-fetched-hook nil
  "Hook run when finished fetching articles."
  :version "22.1"
  :group 'gnus-agent
  :type 'hook)

(defcustom gnus-agent-handle-level gnus-level-subscribed
  "Groups on levels higher than this variable will be ignored by the Agent."
  :group 'gnus-agent
  :type 'integer)

(defcustom gnus-agent-expire-days 7
  "Read articles older than this will be expired.
If you wish to disable Agent expiring, see `gnus-agent-enable-expiration'."
  :group 'gnus-agent
  :type '(number :tag "days"))

(defcustom gnus-agent-expire-all nil
  "If non-nil, also expire unread, ticked and dormant articles.
If nil, only read articles will be expired."
  :group 'gnus-agent
  :type 'boolean)

(defcustom gnus-agent-group-mode-hook nil
  "Hook run in Agent group minor modes."
  :group 'gnus-agent
  :type 'hook)

;; Extracted from gnus-xmas-redefine in order to preserve user settings
(when (featurep 'xemacs)
  (add-hook 'gnus-agent-group-mode-hook 'gnus-xmas-agent-group-menu-add))

(defcustom gnus-agent-summary-mode-hook nil
  "Hook run in Agent summary minor modes."
  :group 'gnus-agent
  :type 'hook)

;; Extracted from gnus-xmas-redefine in order to preserve user settings
(when (featurep 'xemacs)
  (add-hook 'gnus-agent-summary-mode-hook 'gnus-xmas-agent-summary-menu-add))

(defcustom gnus-agent-server-mode-hook nil
  "Hook run in Agent summary minor modes."
  :group 'gnus-agent
  :type 'hook)

;; Extracted from gnus-xmas-redefine in order to preserve user settings
(when (featurep 'xemacs)
  (add-hook 'gnus-agent-server-mode-hook 'gnus-xmas-agent-server-menu-add))

(defcustom gnus-agent-confirmation-function 'y-or-n-p
  "Function to confirm when error happens."
  :version "21.1"
  :group 'gnus-agent
  :type 'function)

(defcustom gnus-agent-synchronize-flags nil
  "Indicate if flags are synchronized when you plug in.
If this is `ask' the hook will query the user."
  ;; If the default switches to something else than nil, then the function
  ;; should be fixed not be exceedingly slow.  See 2005-09-20 ChangeLog entry.
  :version "21.1"
  :type '(choice (const :tag "Always" t)
                 (const :tag "Never" nil)
                 (const :tag "Ask" ask))
  :group 'gnus-agent)

(defcustom gnus-agent-go-online 'ask
  "Indicate if offline servers go online when you plug in.
If this is `ask' the hook will query the user."
  :version "21.3"
  :type '(choice (const :tag "Always" t)
                 (const :tag "Never" nil)
                 (const :tag "Ask" ask))
  :group 'gnus-agent)

(defcustom gnus-agent-mark-unread-after-downloaded t
  "Indicate whether to mark articles unread after downloaded."
  :version "21.1"
  :type 'boolean
  :group 'gnus-agent)

(defcustom gnus-agent-download-marks '(download)
  "Marks for downloading."
  :version "21.1"
  :type '(repeat (symbol :tag "Mark"))
  :group 'gnus-agent)

(defcustom gnus-agent-consider-all-articles nil
  "When non-nil, the agent will let the agent predicate decide
whether articles need to be downloaded or not, for all articles.  When
nil, the default, the agent will only let the predicate decide
whether unread articles are downloaded or not.  If you enable this,
groups with large active ranges may open slower and you may also want
to look into the agent expiry settings to block the expiration of
read articles as they would just be downloaded again."
  :version "22.1"
  :type 'boolean
  :group 'gnus-agent)

(defcustom gnus-agent-max-fetch-size 10000000 ;; 10 Mb
  "Chunk size for `gnus-agent-fetch-session'.
The function will split its article fetches into chunks smaller than
this limit."
  :version "22.1"
  :group 'gnus-agent
  :type 'integer)

(defcustom gnus-agent-enable-expiration 'ENABLE
  "The default expiration state for each group.
When set to ENABLE, the default, `gnus-agent-expire' will expire old
contents from a group's local storage.  This value may be overridden
to disable expiration in specific categories, topics, and groups.  Of
course, you could change gnus-agent-enable-expiration to DISABLE then
enable expiration per categories, topics, and groups."
  :version "22.1"
  :group 'gnus-agent
  :type '(radio (const :format "Enable " ENABLE)
                (const :format "Disable " DISABLE)))

(defcustom gnus-agent-expire-unagentized-dirs t
  "*Whether expiration should expire in unagentized directories.
Have gnus-agent-expire scan the directories under
\(gnus-agent-directory) for groups that are no longer agentized.
When found, offer to remove them."
  :version "22.1"
  :type 'boolean
  :group 'gnus-agent)

(defcustom gnus-agent-auto-agentize-methods nil
  "Initially, all servers from these methods are agentized.
The user may remove or add servers using the Server buffer.
See Info node `(gnus)Server Buffer'."
  :version "22.1"
  :type '(repeat symbol)
  :group 'gnus-agent)

(defcustom gnus-agent-queue-mail t
  "Whether and when outgoing mail should be queued by the agent.
When `always', always queue outgoing mail.  When nil, never
queue.  Otherwise, queue if and only if unplugged."
  :version "22.1"
  :group 'gnus-agent
  :type '(radio (const :format "Always" always)
                (const :format "Never" nil)
                (const :format "When unplugged" t)))

(defcustom gnus-agent-prompt-send-queue nil
  "If non-nil, `gnus-group-send-queue' will prompt if called when unplugged."
  :version "22.1"
  :group 'gnus-agent
  :type 'boolean)

(defcustom gnus-agent-article-alist-save-format 1
  "Indicates whether to use compression(2), versus no
compression(1), when writing agentview files.  The compressed
files do save space but load times are 6-7 times higher.  A group
must be opened then closed for the agentview to be updated using
the new format."
  ;; Wouldn't symbols instead numbers be nicer?  --rsteib
  :version "22.1"
  :group 'gnus-agent
  :type '(radio (const :format "Compressed" 2)
                (const :format "Uncompressed" 1)))

;;; Internal variables

(defvar gnus-agent-history-buffers nil)
(defvar gnus-agent-buffer-alist nil)
(defvar gnus-agent-article-alist nil
  "An assoc list identifying the articles whose headers have been fetched.
If successfully fetched, these headers will be stored in the group's overview
file.  The key of each assoc pair is the article ID, the value of each assoc
pair is a flag indicating whether the identified article has been downloaded
\(gnus-agent-fetch-articles sets the value to the day of the download).
NOTES:
1) The last element of this list can not be expired as some
   routines (for example, get-agent-fetch-headers) use the last
   value to track which articles have had their headers retrieved.
2) The function `gnus-agent-regenerate' may destructively modify the value.")
(defvar gnus-agent-group-alist nil)
(defvar gnus-category-alist nil)
(defvar gnus-agent-current-history nil)
(defvar gnus-agent-overview-buffer nil)
(defvar gnus-category-predicate-cache nil)
(defvar gnus-category-group-cache nil)
(defvar gnus-agent-spam-hashtb nil)
(defvar gnus-agent-file-name nil)
(defvar gnus-agent-send-mail-function nil)
(defvar gnus-agent-file-coding-system 'raw-text)
(defvar gnus-agent-file-loading-cache nil)
(defvar gnus-agent-total-fetched-hashtb nil)
(defvar gnus-agent-inhibit-update-total-fetched-for nil)
(defvar gnus-agent-need-update-total-fetched-for nil)

;; Dynamic variables
(defvar gnus-headers)
(defvar gnus-score)

;; Added to support XEmacs
(eval-and-compile
  (unless (fboundp 'directory-files-and-attributes)
    (defun directory-files-and-attributes (directory
                                           &optional full match nosort)
      (let (result)
        (dolist (file (directory-files directory full match nosort))
          (push (cons file (file-attributes file)) result))
        (nreverse result)))))

;;;
;;; Setup
;;;

(defun gnus-open-agent ()
  (setq gnus-agent t)
  (gnus-agent-read-servers)
  (gnus-category-read)
  (gnus-agent-create-buffer)
  (add-hook 'gnus-group-mode-hook 'gnus-agent-mode)
  (add-hook 'gnus-summary-mode-hook 'gnus-agent-mode)
  (add-hook 'gnus-server-mode-hook 'gnus-agent-mode))

(defun gnus-agent-create-buffer ()
  (if (gnus-buffer-live-p gnus-agent-overview-buffer)
      t
    (setq gnus-agent-overview-buffer
          (gnus-get-buffer-create " *Gnus agent overview*"))
    (with-current-buffer gnus-agent-overview-buffer
      (mm-enable-multibyte))
    nil))

(gnus-add-shutdown 'gnus-close-agent 'gnus)

(defun gnus-close-agent ()
  (setq gnus-category-predicate-cache nil
        gnus-category-group-cache nil
        gnus-agent-spam-hashtb nil)
  (gnus-kill-buffer gnus-agent-overview-buffer))

;;;
;;; Utility functions
;;;

(defmacro gnus-agent-with-refreshed-group (group &rest body)
  "Performs the body then updates the group's line in the group
buffer.  Automatically blocks multiple updates due to recursion."
`(prog1 (let ((gnus-agent-inhibit-update-total-fetched-for t)) ,@body)
     (when (and gnus-agent-need-update-total-fetched-for
                (not gnus-agent-inhibit-update-total-fetched-for))
        (with-current-buffer gnus-group-buffer
          (setq gnus-agent-need-update-total-fetched-for nil)
          (gnus-group-update-group ,group t)))))

(defun gnus-agent-read-file (file)
  "Load FILE and do a `read' there."
  (with-temp-buffer
    (ignore-errors
      (nnheader-insert-file-contents file)
      (goto-char (point-min))
      (read (current-buffer)))))

(defsubst gnus-agent-method ()
  (concat (symbol-name (car gnus-command-method)) "/"
          (if (equal (cadr gnus-command-method) "")
              "unnamed"
            (cadr gnus-command-method))))

(defsubst gnus-agent-directory ()
  "The name of the Gnus agent directory."
  (nnheader-concat gnus-agent-directory
                   (nnheader-translate-file-chars (gnus-agent-method)) "/"))

(defun gnus-agent-lib-file (file)
  "The full name of the Gnus agent library FILE."
  (expand-file-name file
                    (file-name-as-directory
                     (expand-file-name "agent.lib" (gnus-agent-directory)))))

(defun gnus-agent-cat-set-property (category property value)
  (if value
      (setcdr (or (assq property category)
              (let ((cell (cons property nil)))
                    (setcdr category (cons cell (cdr category)))
                    cell)) value)
    (let ((category category))
      (while (cond ((eq property (caadr category))
                    (setcdr category (cddr category))
                    nil)
                   (t
                    (setq category (cdr category)))))))
  category)

(eval-when-compile
  (defmacro gnus-agent-cat-defaccessor (name prop-name)
    "Define accessor and setter methods for manipulating a list of the form
\(NAME (PROPERTY1 VALUE1) ... (PROPERTY_N VALUE_N)).
Given the call (gnus-agent-cat-defaccessor func PROPERTY1), the list may be
manipulated as follows:
  (func LIST): Returns VALUE1
  (setf (func LIST) NEW_VALUE1): Replaces VALUE1 with NEW_VALUE1."
    `(progn (defmacro ,name (category)
              (list (quote cdr) (list (quote assq)
                                      (quote (quote ,prop-name)) category)))

            (define-setf-method ,name (category)
              (let* ((--category--temp-- (make-symbol "--category--"))
                     (--value--temp-- (make-symbol "--value--")))
                (list (list --category--temp--) ; temporary-variables
                      (list category)           ; value-forms
                      (list --value--temp--)    ; store-variables
                      (let* ((category --category--temp--) ; store-form
                             (value --value--temp--))
                        (list (quote gnus-agent-cat-set-property)
                              category
                              (quote (quote ,prop-name))
                              value))
                      (list (quote ,name) --category--temp--) ; access-form
                      )))))
  )

(defmacro gnus-agent-cat-name (category)
  `(car ,category))

(gnus-agent-cat-defaccessor
 gnus-agent-cat-days-until-old             agent-days-until-old)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-enable-expiration          agent-enable-expiration)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-groups                     agent-groups)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-high-score                 agent-high-score)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-length-when-long           agent-long-article)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-length-when-short          agent-short-article)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-low-score                  agent-low-score)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-predicate                  agent-predicate)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-score-file                 agent-score)
(gnus-agent-cat-defaccessor
 gnus-agent-cat-enable-undownloaded-faces  agent-enable-undownloaded-faces)


;; This form is equivalent to defsetf except that it calls make-symbol
;; whereas defsetf calls gensym (Using gensym creates a run-time
;; dependency on the CL library).

(eval-and-compile
  (define-setf-method gnus-agent-cat-groups (category)
    (let* ((--category--temp-- (make-symbol "--category--"))
           (--groups--temp-- (make-symbol "--groups--")))
      (list (list --category--temp--)
            (list category)
            (list --groups--temp--)
            (let* ((category --category--temp--)
                   (groups --groups--temp--))
              (list (quote gnus-agent-set-cat-groups) category groups))
            (list (quote gnus-agent-cat-groups) --category--temp--))))
  )

(defun gnus-agent-set-cat-groups (category groups)
  (unless (eq groups 'ignore)
    (let ((new-g groups)
          (old-g (gnus-agent-cat-groups category)))
      (cond ((eq new-g old-g)
             ;; gnus-agent-add-group is fiddling with the group
             ;; list. Still, Im done.
             nil
             )
            ((eq new-g (cdr old-g))
             ;; gnus-agent-add-group is fiddling with the group list
             (setcdr (or (assq 'agent-groups category)
                         (let ((cell (cons 'agent-groups nil)))
                           (setcdr category (cons cell (cdr category)))
                           cell)) new-g))
            (t
             (let ((groups groups))
               (while groups
                 (let* ((group        (pop groups))
                        (old-category (gnus-group-category group)))
                   (if (eq category old-category)
                       nil
                     (setf (gnus-agent-cat-groups old-category)
                           (delete group (gnus-agent-cat-groups
                                          old-category))))))
               ;; Purge cache as preceeding loop invalidated it.
               (setq gnus-category-group-cache nil))

             (setcdr (or (assq 'agent-groups category)
                         (let ((cell (cons 'agent-groups nil)))
                           (setcdr category (cons cell (cdr category)))
                           cell)) groups))))))

(defsubst gnus-agent-cat-make (name &optional default-agent-predicate)
  (list name `(agent-predicate . ,(or default-agent-predicate 'false))))

(defun gnus-agent-read-group ()
  "Read a group name in the minibuffer, with completion."
  (let ((def (or (gnus-group-group-name) gnus-newsgroup-name)))
    (when def
      (setq def (gnus-group-decoded-name def)))
    (gnus-group-completing-read nil nil t nil nil def)))

;;; Fetching setup functions.

(defun gnus-agent-start-fetch ()
  "Initialize data structures for efficient fetching."
  (gnus-agent-create-buffer))

(defun gnus-agent-stop-fetch ()
  "Save all data structures and clean up."
  (setq gnus-agent-spam-hashtb nil)
  (with-current-buffer nntp-server-buffer
    (widen)))

(defmacro gnus-agent-with-fetch (&rest forms)
  "Do FORMS safely."
  `(unwind-protect
       (let ((gnus-agent-fetching t))
         (gnus-agent-start-fetch)
         ,@forms)
     (gnus-agent-stop-fetch)))

(put 'gnus-agent-with-fetch 'lisp-indent-function 0)
(put 'gnus-agent-with-fetch 'edebug-form-spec '(body))

(defmacro gnus-agent-append-to-list (tail value)
  `(setq ,tail (setcdr ,tail (cons ,value nil))))

(defmacro gnus-agent-message (level &rest args)
  `(if (<= ,level gnus-verbose)
       (message ,@args)))

;;;
;;; Mode infestation
;;;

(defvar gnus-agent-mode-hook nil
  "Hook run when installing agent mode.")

(defvar gnus-agent-mode nil)
(defvar gnus-agent-mode-status '(gnus-agent-mode " Plugged"))

(defun gnus-agent-mode ()
  "Minor mode for providing a agent support in Gnus buffers."
  (let* ((buffer (progn (string-match "^gnus-\\(.*\\)-mode$"
                                      (symbol-name major-mode))
                        (match-string 1 (symbol-name major-mode))))
         (mode (intern (format "gnus-agent-%s-mode" buffer))))
    (set (make-local-variable 'gnus-agent-mode) t)
    (set mode nil)
    (set (make-local-variable mode) t)
    ;; Set up the menu.
    (when (gnus-visual-p 'agent-menu 'menu)
      (funcall (intern (format "gnus-agent-%s-make-menu-bar" buffer))))
    (unless (assq mode minor-mode-alist)
      (push (cons mode (cdr gnus-agent-mode-status)) minor-mode-alist))
    (unless (assq mode minor-mode-map-alist)
      (push (cons mode (symbol-value (intern (format "gnus-agent-%s-mode-map"
                                                     buffer))))
            minor-mode-map-alist))
    (when (eq major-mode 'gnus-group-mode)
      (let ((init-plugged gnus-plugged)
            (gnus-agent-go-online nil))
        ;; g-a-t-p does nothing when gnus-plugged isn't changed.
        ;; Therefore, make certain that the current value does not
        ;; match the desired initial value.
        (setq gnus-plugged :unknown)
        (gnus-agent-toggle-plugged init-plugged)))
    (gnus-run-hooks 'gnus-agent-mode-hook
                    (intern (format "gnus-agent-%s-mode-hook" buffer)))))

(defvar gnus-agent-group-mode-map (make-sparse-keymap))
(gnus-define-keys gnus-agent-group-mode-map
  "Ju" gnus-agent-fetch-groups
  "Jc" gnus-enter-category-buffer
  "Jj" gnus-agent-toggle-plugged
  "Js" gnus-agent-fetch-session
  "JY" gnus-agent-synchronize-flags
  "JS" gnus-group-send-queue
  "Ja" gnus-agent-add-group
  "Jr" gnus-agent-remove-group
  "Jo" gnus-agent-toggle-group-plugged)

(defun gnus-agent-group-make-menu-bar ()
  (unless (boundp 'gnus-agent-group-menu)
    (easy-menu-define
     gnus-agent-group-menu gnus-agent-group-mode-map ""
     '("Agent"
       ["Toggle plugged" gnus-agent-toggle-plugged t]
       ["Toggle group plugged" gnus-agent-toggle-group-plugged t]
       ["List categories" gnus-enter-category-buffer t]
       ["Add (current) group to category" gnus-agent-add-group t]
       ["Remove (current) group from category" gnus-agent-remove-group t]
       ["Send queue" gnus-group-send-queue gnus-plugged]
       ("Fetch"
        ["All" gnus-agent-fetch-session gnus-plugged]
        ["Group" gnus-agent-fetch-group gnus-plugged])
       ["Synchronize flags" gnus-agent-synchronize-flags t]
       ))))

(defvar gnus-agent-summary-mode-map (make-sparse-keymap))
(gnus-define-keys gnus-agent-summary-mode-map
  "Jj" gnus-agent-toggle-plugged
  "Ju" gnus-agent-summary-fetch-group
  "JS" gnus-agent-fetch-group
  "Js" gnus-agent-summary-fetch-series
  "J#" gnus-agent-mark-article
  "J\M-#" gnus-agent-unmark-article
  "@" gnus-agent-toggle-mark
  "Jc" gnus-agent-catchup)

(defun gnus-agent-summary-make-menu-bar ()
  (unless (boundp 'gnus-agent-summary-menu)
    (easy-menu-define
     gnus-agent-summary-menu gnus-agent-summary-mode-map ""
     '("Agent"
       ["Toggle plugged" gnus-agent-toggle-plugged t]
       ["Mark as downloadable" gnus-agent-mark-article t]
       ["Unmark as downloadable" gnus-agent-unmark-article t]
       ["Toggle mark" gnus-agent-toggle-mark t]
       ["Fetch downloadable" gnus-agent-summary-fetch-group t]
       ["Catchup undownloaded" gnus-agent-catchup t]))))

(defvar gnus-agent-server-mode-map (make-sparse-keymap))
(gnus-define-keys gnus-agent-server-mode-map
  "Jj" gnus-agent-toggle-plugged
  "Ja" gnus-agent-add-server
  "Jr" gnus-agent-remove-server)

(defun gnus-agent-server-make-menu-bar ()
  (unless (boundp 'gnus-agent-server-menu)
    (easy-menu-define
     gnus-agent-server-menu gnus-agent-server-mode-map ""
     '("Agent"
       ["Toggle plugged" gnus-agent-toggle-plugged t]
       ["Add" gnus-agent-add-server t]
       ["Remove" gnus-agent-remove-server t]))))

(defun gnus-agent-make-mode-line-string (string mouse-button mouse-func)
  (if (and (fboundp 'propertize)
           (fboundp 'make-mode-line-mouse-map))
      (propertize string 'local-map
                  (make-mode-line-mouse-map mouse-button mouse-func)
                  'mouse-face
                  (if (and (featurep 'xemacs)
                           ;; XEmacs' `facep' only checks for a face
                           ;; object, not for a face name, so it's useless
                           ;; to check with `facep'.
                           (find-face 'modeline))
                      'modeline
                    'mode-line-highlight))
    string))

(defun gnus-agent-toggle-plugged (set-to)
  "Toggle whether Gnus is unplugged or not."
  (interactive (list (not gnus-plugged)))
  (cond ((eq set-to gnus-plugged)
         nil)
        (set-to
         (setq gnus-plugged set-to)
         (gnus-run-hooks 'gnus-agent-plugged-hook)
         (setcar (cdr gnus-agent-mode-status)
                 (gnus-agent-make-mode-line-string " Plugged"
                                                   'mouse-2
                                                   'gnus-agent-toggle-plugged))
         (gnus-agent-go-online gnus-agent-go-online))
        (t
         (gnus-agent-close-connections)
         (setq gnus-plugged set-to)
         (gnus-run-hooks 'gnus-agent-unplugged-hook)
         (setcar (cdr gnus-agent-mode-status)
                 (gnus-agent-make-mode-line-string " Unplugged"
                                                   'mouse-2
                                                   'gnus-agent-toggle-plugged))))
  (set-buffer-modified-p t))

(defmacro gnus-agent-while-plugged (&rest body)
  `(let ((original-gnus-plugged gnus-plugged))
    (unwind-protect
        (progn (gnus-agent-toggle-plugged t)
               ,@body)
      (gnus-agent-toggle-plugged original-gnus-plugged))))

(put 'gnus-agent-while-plugged 'lisp-indent-function 0)
(put 'gnus-agent-while-plugged 'edebug-form-spec '(body))

(defun gnus-agent-close-connections ()
  "Close all methods covered by the Gnus agent."
  (let ((methods (gnus-agent-covered-methods)))
    (while methods
      (gnus-close-server (pop methods)))))

;;;###autoload
(defun gnus-unplugged ()
  "Start Gnus unplugged."
  (interactive)
  (setq gnus-plugged nil)
  (gnus))

;;;###autoload
(defun gnus-plugged ()
  "Start Gnus plugged."
  (interactive)
  (setq gnus-plugged t)
  (gnus))

;;;###autoload
(defun gnus-slave-unplugged (&optional arg)
  "Read news as a slave unplugged."
  (interactive "P")
  (setq gnus-plugged nil)
  (gnus arg nil 'slave))

;;;###autoload
(defun gnus-agentize ()
  "Allow Gnus to be an offline newsreader.

The gnus-agentize function is now called internally by gnus when
gnus-agent is set.  If you wish to avoid calling gnus-agentize,
customize gnus-agent to nil.

This will modify the `gnus-setup-news-hook', and
`message-send-mail-real-function' variables, and install the Gnus agent
minor mode in all Gnus buffers."
  (interactive)
  (gnus-open-agent)
  (unless gnus-agent-send-mail-function
    (setq gnus-agent-send-mail-function
          (or message-send-mail-real-function
              (function (lambda () (funcall message-send-mail-function))))
          message-send-mail-real-function 'gnus-agent-send-mail))

  ;; If the servers file doesn't exist, auto-agentize some servers and
  ;; save the servers file so this auto-agentizing isn't invoked
  ;; again.
  (when (and (not (file-exists-p (nnheader-concat
                                  gnus-agent-directory "lib/servers")))
             gnus-agent-auto-agentize-methods)
    (gnus-message 3 "First time agent user, agentizing remote groups...")
    (mapc
     (lambda (server-or-method)
       (let ((method (gnus-server-to-method server-or-method)))
         (when (memq (car method)
                     gnus-agent-auto-agentize-methods)
           (push (gnus-method-to-server method)
                 gnus-agent-covered-methods)
           (setq gnus-agent-method-p-cache nil))))
     (cons gnus-select-method gnus-secondary-select-methods))
    (gnus-agent-write-servers)))

(defun gnus-agent-queue-setup (&optional group-name)
  "Make sure the queue group exists.
Optional arg GROUP-NAME allows to specify another group."
  (unless (gnus-gethash (format "nndraft:%s" (or group-name "queue"))
                        gnus-newsrc-hashtb)
    (gnus-request-create-group (or group-name "queue") '(nndraft ""))
    (let ((gnus-level-default-subscribed 1))
      (gnus-subscribe-group (format "nndraft:%s" (or group-name "queue"))
                            nil '(nndraft "")))
    (gnus-group-set-parameter
     (format "nndraft:%s" (or group-name "queue"))
     'gnus-dummy '((gnus-draft-mode)))))

(defun gnus-agent-send-mail ()
  (if (or (not gnus-agent-queue-mail)
          (and gnus-plugged (not (eq gnus-agent-queue-mail 'always))))
      (funcall gnus-agent-send-mail-function)
    (goto-char (point-min))
    (re-search-forward
     (concat "^" (regexp-quote mail-header-separator) "\n"))
    (replace-match "\n")
    (gnus-agent-insert-meta-information 'mail)
    (gnus-request-accept-article "nndraft:queue" nil t t)
    (gnus-group-refresh-group "nndraft:queue")))

(defun gnus-agent-insert-meta-information (type &optional method)
  "Insert meta-information into the message that says how it's to be posted.
TYPE can be either `mail' or `news'.  If the latter, then METHOD can
be a select method."
  (save-excursion
    (message-remove-header gnus-agent-meta-information-header)
    (goto-char (point-min))
    (insert gnus-agent-meta-information-header ": "
            (symbol-name type) " " (format "%S" method)
            "\n")
    (forward-char -1)
    (while (search-backward "\n" nil t)
      (replace-match "\\n" t t))))

(defun gnus-agent-restore-gcc ()
  "Restore GCC field from saved header."
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward
            (concat "^" (regexp-quote gnus-agent-gcc-header) ":") nil t)
      (replace-match "Gcc:" 'fixedcase))))

(defun gnus-agent-any-covered-gcc ()
  (save-restriction
    (message-narrow-to-headers)
    (let* ((gcc (mail-fetch-field "gcc" nil t))
           (methods (and gcc
                         (mapcar 'gnus-inews-group-method
                                 (message-unquote-tokens
                                  (message-tokenize-header
                                   gcc " ,")))))
           covered)
      (while (and (not covered) methods)
        (setq covered (gnus-agent-method-p (car methods))
              methods (cdr methods)))
      covered)))

;;;###autoload
(defun gnus-agent-possibly-save-gcc ()
  "Save GCC if Gnus is unplugged."
  (when (and (not gnus-plugged) (gnus-agent-any-covered-gcc))
    (save-excursion
      (goto-char (point-min))
      (let ((case-fold-search t))
        (while (re-search-forward "^gcc:" nil t)
          (replace-match (concat gnus-agent-gcc-header ":") 'fixedcase))))))

(defun gnus-agent-possibly-do-gcc ()
  "Do GCC if Gnus is plugged."
  (when (or gnus-plugged (not (gnus-agent-any-covered-gcc)))
    (gnus-inews-do-gcc)))

;;;
;;; Group mode commands
;;;

(defun gnus-agent-fetch-groups (n)
  "Put all new articles in the current groups into the Agent."
  (interactive "P")
  (unless gnus-plugged
    (error "Groups can't be fetched when Gnus is unplugged"))
  (gnus-group-iterate n 'gnus-agent-fetch-group))

(defun gnus-agent-fetch-group (&optional group)
  "Put all new articles in GROUP into the Agent."
  (interactive (list (gnus-group-group-name)))
  (setq group (or group gnus-newsgroup-name))
  (unless group
    (error "No group on the current line"))
  (if (not (gnus-agent-group-covered-p group))
      (message "%s isn't covered by the agent" group)
    (gnus-agent-while-plugged
      (let ((gnus-command-method (gnus-find-method-for-group group)))
        (gnus-agent-with-fetch
          (gnus-agent-fetch-group-1 group gnus-command-method)
          (gnus-message 5 "Fetching %s...done" group))))))

(defun gnus-agent-add-group (category arg)
  "Add the current group to an agent category."
  (interactive
   (list
    (intern
     (gnus-completing-read
      "Add to category"
      (mapcar (lambda (cat) (symbol-name (car cat)))
              gnus-category-alist)
      t))
    current-prefix-arg))
  (let ((cat (assq category gnus-category-alist))
        c groups)
    (gnus-group-iterate arg
      (lambda (group)
        (when (gnus-agent-cat-groups (setq c (gnus-group-category group)))
          (setf (gnus-agent-cat-groups c)
                (delete group (gnus-agent-cat-groups c))))
        (push group groups)))
    (setf (gnus-agent-cat-groups cat)
          (nconc (gnus-agent-cat-groups cat) groups))
    (gnus-category-write)))

(defun gnus-agent-remove-group (arg)
  "Remove the current group from its agent category, if any."
  (interactive "P")
  (let (c)
    (gnus-group-iterate arg
      (lambda (group)
        (when (gnus-agent-cat-groups (setq c (gnus-group-category group)))
          (setf (gnus-agent-cat-groups c)
                (delete group (gnus-agent-cat-groups c))))))
    (gnus-category-write)))

(defun gnus-agent-synchronize-flags ()
  "Synchronize unplugged flags with servers."
  (interactive)
  (save-excursion
    (dolist (gnus-command-method (gnus-agent-covered-methods))
      (when (file-exists-p (gnus-agent-lib-file "flags"))
        (gnus-agent-synchronize-flags-server gnus-command-method)))))

(defun gnus-agent-possibly-synchronize-flags ()
  "Synchronize flags according to `gnus-agent-synchronize-flags'."
  (interactive)
  (save-excursion
    (dolist (gnus-command-method (gnus-agent-covered-methods))
      (when (eq (gnus-server-status gnus-command-method) 'ok)
        (gnus-agent-possibly-synchronize-flags-server gnus-command-method)))))

(defun gnus-agent-synchronize-flags-server (method)
  "Synchronize flags set when unplugged for server."
  (let ((gnus-command-method method)
        (gnus-agent nil))
    (when (file-exists-p (gnus-agent-lib-file "flags"))
      (set-buffer (get-buffer-create " *Gnus Agent flag synchronize*"))
      (erase-buffer)
      (nnheader-insert-file-contents (gnus-agent-lib-file "flags"))
      (cond ((null gnus-plugged)
             (gnus-message
              1 "You must be plugged to synchronize flags with server %s"
              (nth 1 gnus-command-method)))
            ((null (gnus-check-server gnus-command-method))
             (gnus-message
              1 "Couldn't open server %s" (nth 1 gnus-command-method)))
            (t
             (condition-case err
                 (while t
                   (let ((bgn (point)))
                     (eval (read (current-buffer)))
                     (delete-region bgn (point))))
               (end-of-file
                (delete-file (gnus-agent-lib-file "flags")))
               (error
                (let ((file (gnus-agent-lib-file "flags")))
                  (write-region (point-min) (point-max)
                                (gnus-agent-lib-file "flags") nil 'silent)
                  (error "Couldn't set flags from file %s due to %s"
                         file (error-message-string err)))))))
      (kill-buffer nil))))

(defun gnus-agent-possibly-synchronize-flags-server (method)
  "Synchronize flags for server according to `gnus-agent-synchronize-flags'."
  (when (and (file-exists-p (gnus-agent-lib-file "flags"))
             (or (and gnus-agent-synchronize-flags
                      (not (eq gnus-agent-synchronize-flags 'ask)))
                 (and (eq gnus-agent-synchronize-flags 'ask)
                      (gnus-y-or-n-p
                       (format "Synchronize flags on server `%s'? "
                               (cadr method))))))
    (gnus-agent-synchronize-flags-server method)))

;;;###autoload
(defun gnus-agent-rename-group (old-group new-group)
  "Rename fully-qualified OLD-GROUP as NEW-GROUP.
Always updates the agent, even when disabled, as the old agent
files would corrupt gnus when the agent was next enabled.
Depends upon the caller to determine whether group renaming is
supported."
  (let* ((old-command-method (gnus-find-method-for-group old-group))
         (old-path           (directory-file-name
                              (let (gnus-command-method old-command-method)
                                (gnus-agent-group-pathname old-group))))
         (new-command-method (gnus-find-method-for-group new-group))
         (new-path           (directory-file-name
                              (let (gnus-command-method new-command-method)
                                (gnus-agent-group-pathname new-group))))
         (file-name-coding-system nnmail-pathname-coding-system))
    (gnus-rename-file old-path new-path t)

    (let* ((old-real-group (gnus-group-real-name old-group))
           (new-real-group (gnus-group-real-name new-group))
           (old-active (gnus-agent-get-group-info old-command-method old-real-group)))
      (gnus-agent-save-group-info old-command-method old-real-group nil)
      (gnus-agent-save-group-info new-command-method new-real-group old-active)

      (let ((old-local (gnus-agent-get-local old-group
                                             old-real-group old-command-method)))
        (gnus-agent-set-local old-group
                              nil nil
                              old-real-group old-command-method)
        (gnus-agent-set-local new-group
                              (car old-local) (cdr old-local)
                              new-real-group new-command-method)))))

;;;###autoload
(defun gnus-agent-delete-group (group)
  "Delete fully-qualified GROUP.
Always updates the agent, even when disabled, as the old agent
files would corrupt gnus when the agent was next enabled.
Depends upon the caller to determine whether group deletion is
supported."
  (let* ((command-method (gnus-find-method-for-group group))
         (path           (directory-file-name
                          (let (gnus-command-method command-method)
                            (gnus-agent-group-pathname group))))
         (file-name-coding-system nnmail-pathname-coding-system))
    (gnus-delete-directory path)

    (let* ((real-group (gnus-group-real-name group)))
      (gnus-agent-save-group-info command-method real-group nil)

      (let ((local (gnus-agent-get-local group
                                         real-group command-method)))
        (gnus-agent-set-local group
                              nil nil
                              real-group command-method)))))

;;;
;;; Server mode commands
;;;

(defun gnus-agent-add-server ()
  "Enroll SERVER in the agent program."
  (interactive)
  (let* ((server       (gnus-server-server-name))
         (named-server (gnus-server-named-server))
         (method       (and server
                            (gnus-server-get-method nil server))))
    (unless server
      (error "No server on the current line"))

    (when (gnus-agent-method-p method)
      (error "Server already in the agent program"))

    (push named-server gnus-agent-covered-methods)

    (setq gnus-agent-method-p-cache nil)
    (gnus-server-update-server server)
    (gnus-agent-write-servers)
    (gnus-message 1 "Entered %s into the Agent" server)))

(defun gnus-agent-remove-server ()
  "Remove SERVER from the agent program."
  (interactive)
  (let* ((server       (gnus-server-server-name))
         (named-server (gnus-server-named-server)))
    (unless server
      (error "No server on the current line"))

    (unless (member named-server gnus-agent-covered-methods)
      (error "Server not in the agent program"))

    (setq gnus-agent-covered-methods
          (delete named-server gnus-agent-covered-methods)
          gnus-agent-method-p-cache nil)

    (gnus-server-update-server server)
    (gnus-agent-write-servers)
    (gnus-message 1 "Removed %s from the agent" server)))

(defun gnus-agent-read-servers ()
  "Read the alist of covered servers."
  (setq gnus-agent-covered-methods
        (gnus-agent-read-file
         (nnheader-concat gnus-agent-directory "lib/servers"))
        gnus-agent-method-p-cache nil)

  ;; I am called so early in start-up that I can not validate server
  ;; names.  When that is the case, I skip the validation.  That is
  ;; alright as the gnus startup code calls the validate methods
  ;; directly.
  (if gnus-server-alist
      (gnus-agent-read-servers-validate)))

(defun gnus-agent-read-servers-validate ()
  (mapcar (lambda (server-or-method)
            (let* ((server (if (stringp server-or-method)
                               server-or-method
                             (gnus-method-to-server server-or-method)))
                   (method (gnus-server-to-method server)))
              (if method
                  (unless (member server gnus-agent-covered-methods)
                    (push server gnus-agent-covered-methods)
                    (setq gnus-agent-method-p-cache nil))
                (gnus-message 8 "Ignoring disappeared server `%s'" server))))
          (prog1 gnus-agent-covered-methods
            (setq gnus-agent-covered-methods nil))))

(defun gnus-agent-read-servers-validate-native (native-method)
  (setq gnus-agent-covered-methods
        (mapcar (lambda (method)
                  (if (or (not method)
                          (equal method native-method))
                      "native"
                    method)) gnus-agent-covered-methods)))

(defun gnus-agent-write-servers ()
  "Write the alist of covered servers."
  (gnus-make-directory (nnheader-concat gnus-agent-directory "lib"))
  (let ((coding-system-for-write nnheader-file-coding-system)
        (file-name-coding-system nnmail-pathname-coding-system))
    (with-temp-file (nnheader-concat gnus-agent-directory "lib/servers")
      (prin1 gnus-agent-covered-methods
             (current-buffer)))))

;;;
;;; Summary commands
;;;

(defun gnus-agent-mark-article (n &optional unmark)
  "Mark the next N articles as downloadable.
If N is negative, mark backward instead.  If UNMARK is non-nil, remove
the mark instead.  The difference between N and the actual number of
articles marked is returned."
  (interactive "p")
  (let ((backward (< n 0))
        (n (abs n)))
    (while (and
            (> n 0)
            (progn
              (gnus-summary-set-agent-mark
               (gnus-summary-article-number) unmark)
              (zerop (gnus-summary-next-subject (if backward -1 1) nil t))))
      (setq n (1- n)))
    (when (/= 0 n)
      (gnus-message 7 "No more articles"))
    (gnus-summary-recenter)
    (gnus-summary-position-point)
    n))

(defun gnus-agent-unmark-article (n)
  "Remove the downloadable mark from the next N articles.
If N is negative, unmark backward instead.  The difference between N and
the actual number of articles unmarked is returned."
  (interactive "p")
  (gnus-agent-mark-article n t))

(defun gnus-agent-toggle-mark (n)
  "Toggle the downloadable mark from the next N articles.
If N is negative, toggle backward instead.  The difference between N and
the actual number of articles toggled is returned."
  (interactive "p")
  (gnus-agent-mark-article n 'toggle))

(defun gnus-summary-set-agent-mark (article &optional unmark)
  "Mark ARTICLE as downloadable.  If UNMARK is nil, article is marked.
When UNMARK is t, the article is unmarked.  For any other value, the
article's mark is toggled."
  (let ((unmark (cond ((eq nil unmark)
                       nil)
                      ((eq t unmark)
                       t)
                      (t
                       (memq article gnus-newsgroup-downloadable)))))
    (when (gnus-summary-goto-subject article nil t)
      (gnus-summary-update-mark
       (if unmark
           (progn
             (setq gnus-newsgroup-downloadable
                   (delq article gnus-newsgroup-downloadable))
             (gnus-article-mark article))
         (setq gnus-newsgroup-downloadable
               (gnus-add-to-sorted-list gnus-newsgroup-downloadable article))
         gnus-downloadable-mark)
       'unread))))

;;;###autoload
(defun gnus-agent-get-undownloaded-list ()
  "Construct list of articles that have not been downloaded."
  (let ((gnus-command-method (gnus-find-method-for-group gnus-newsgroup-name)))
    (when (set (make-local-variable 'gnus-newsgroup-agentized)
               (gnus-agent-method-p gnus-command-method))
      (let* ((alist (gnus-agent-load-alist gnus-newsgroup-name))
             (headers (sort (mapcar (lambda (h)
                                      (mail-header-number h))
                                    gnus-newsgroup-headers) '<))
             (cached (and gnus-use-cache gnus-newsgroup-cached))
             (undownloaded (list nil))
             (tail-undownloaded undownloaded)
             (unfetched (list nil))
             (tail-unfetched unfetched))
        (while (and alist headers)
          (let ((a (caar alist))
                (h (car headers)))
            (cond ((< a h)
                   ;; Ignore IDs in the alist that are not being
                   ;; displayed in the summary.
                   (setq alist (cdr alist)))
                  ((> a h)
                   ;; Headers that are not in the alist should be
                   ;; fictious (see nnagent-retrieve-headers); they
                   ;; imply that this article isn't in the agent.
                   (gnus-agent-append-to-list tail-undownloaded h)
                   (gnus-agent-append-to-list tail-unfetched    h)
                   (setq headers (cdr headers)))
                  ((cdar alist)
                   (setq alist (cdr alist))
                   (setq headers (cdr headers))
                   nil                  ; ignore already downloaded
                   )
                  (t
                   (setq alist (cdr alist))
                   (setq headers (cdr headers))

                   ;; This article isn't in the agent.  Check to see
                   ;; if it is in the cache.  If it is, it's been
                   ;; downloaded.
                   (while (and cached (< (car cached) a))
                     (setq cached (cdr cached)))
                   (unless (equal a (car cached))
                     (gnus-agent-append-to-list tail-undownloaded a))))))

        (while headers
          (let ((num (pop headers)))
            (gnus-agent-append-to-list tail-undownloaded num)
            (gnus-agent-append-to-list tail-unfetched    num)))

        (setq gnus-newsgroup-undownloaded (cdr undownloaded)
              gnus-newsgroup-unfetched    (cdr unfetched))))))

(defun gnus-agent-catchup ()
  "Mark as read all unhandled articles.
An article is unhandled if it is neither cached, nor downloaded, nor
downloadable."
  (interactive)
  (save-excursion
    (let ((articles gnus-newsgroup-undownloaded))
      (when (or gnus-newsgroup-downloadable
                gnus-newsgroup-cached)
        (setq articles (gnus-sorted-ndifference
                        (gnus-sorted-ndifference
                         (gnus-copy-sequence articles)
                         gnus-newsgroup-downloadable)
                        gnus-newsgroup-cached)))

      (while articles
        (gnus-summary-mark-article
         (pop articles) gnus-catchup-mark)))
    (gnus-summary-position-point)))

(defun gnus-agent-summary-fetch-series ()
  (interactive)
  (when gnus-newsgroup-processable
    (setq gnus-newsgroup-downloadable
          (let* ((dl gnus-newsgroup-downloadable)
                 (processable (sort (gnus-copy-sequence gnus-newsgroup-processable) '<))
                 (gnus-newsgroup-downloadable processable))
            (gnus-agent-summary-fetch-group)

            ;; For each article that I processed that is no longer
            ;; undownloaded, remove its processable mark.

            (mapc #'gnus-summary-remove-process-mark
                  (gnus-sorted-ndifference gnus-newsgroup-processable gnus-newsgroup-undownloaded))

            ;; The preceeding call to (gnus-agent-summary-fetch-group)
            ;; updated the temporary gnus-newsgroup-downloadable to
            ;; remove each article successfully fetched.  Now, I
            ;; update the real gnus-newsgroup-downloadable to only
            ;; include undownloaded articles.
            (gnus-sorted-ndifference dl (gnus-sorted-ndifference processable gnus-newsgroup-undownloaded))))))

(defun gnus-agent-summary-fetch-group (&optional all)
  "Fetch the downloadable articles in the group.
Optional arg ALL, if non-nil, means to fetch all articles."
  (interactive "P")
  (let ((articles
         (if all gnus-newsgroup-articles
           gnus-newsgroup-downloadable))
        (gnus-command-method (gnus-find-method-for-group gnus-newsgroup-name))
        fetched-articles)
    (gnus-agent-while-plugged
      (unless articles
        (error "No articles to download"))
      (gnus-agent-with-fetch
        (setq gnus-newsgroup-undownloaded
              (gnus-sorted-ndifference
               gnus-newsgroup-undownloaded
               (setq fetched-articles
                     (gnus-agent-fetch-articles
                      gnus-newsgroup-name articles)))))
      (save-excursion
        (dolist (article articles)
          (let ((was-marked-downloadable
                 (memq article gnus-newsgroup-downloadable)))
            (cond (gnus-agent-mark-unread-after-downloaded
                   (setq gnus-newsgroup-downloadable
                         (delq article gnus-newsgroup-downloadable))

                   (gnus-summary-mark-article article gnus-unread-mark))
                  (was-marked-downloadable
                   (gnus-summary-set-agent-mark article t)))
            (when (gnus-summary-goto-subject article nil t)
              (gnus-summary-update-download-mark article))))))
    fetched-articles))

(defun gnus-agent-fetch-selected-article ()
  "Fetch the current article as it is selected.
This can be added to `gnus-select-article-hook' or
`gnus-mark-article-hook'."
  (let ((gnus-command-method gnus-current-select-method))
    (when (and gnus-plugged (gnus-agent-method-p gnus-command-method))
      (when (gnus-agent-fetch-articles
             gnus-newsgroup-name
             (list gnus-current-article))
        (setq gnus-newsgroup-undownloaded
              (delq gnus-current-article gnus-newsgroup-undownloaded))
        (gnus-summary-update-download-mark gnus-current-article)))))

;;;
;;; Internal functions
;;;

(defun gnus-agent-synchronize-group-flags (group actions server)
"Update a plugged group by performing the indicated actions."
  (let* ((gnus-command-method (gnus-server-to-method server))
         (info
          ;; This initializer is required as gnus-request-set-mark
          ;; calls gnus-group-real-name to strip off the host name
          ;; before calling the backend.  Now that the backend is
          ;; trying to call gnus-request-set-mark, I have to
          ;; reconstruct the original group name.
          (or (gnus-get-info group)
              (gnus-get-info
               (setq group (gnus-group-full-name
                            group gnus-command-method))))))
    (gnus-request-set-mark group actions)

    (when info
      (dolist (action actions)
        (let ((range (nth 0 action))
              (what  (nth 1 action))
              (marks (nth 2 action)))
          (dolist (mark marks)
            (cond ((eq mark 'read)
                   (gnus-info-set-read
                    info
                    (funcall (if (eq what 'add)
                                 'gnus-range-add
                               'gnus-remove-from-range)
                             (gnus-info-read info)
                             range))
                   (gnus-get-unread-articles-in-group
                    info
                    (gnus-active (gnus-info-group info))))
                  ((memq mark '(tick))
                   (let ((info-marks (assoc mark (gnus-info-marks info))))
                     (unless info-marks
                       (gnus-info-set-marks info (cons (setq info-marks (list mark)) (gnus-info-marks info))))
                     (setcdr info-marks (funcall (if (eq what 'add)
                                  'gnus-range-add
                                'gnus-remove-from-range)
                              (cdr info-marks)
                              range))))))))

      ;;Marks can be synchronized at any time by simply toggling from
      ;;unplugged to plugged.  If that is what is happening right now, make
      ;;sure that the group buffer is up to date.
          (when (gnus-buffer-live-p gnus-group-buffer)
            (gnus-group-update-group group t)))
    nil))

(defun gnus-agent-save-active (method)
  (when (gnus-agent-method-p method)
    (let* ((gnus-command-method method)
           (new (gnus-make-hashtable (count-lines (point-min) (point-max))))
           (file (gnus-agent-lib-file "active")))
      (gnus-active-to-gnus-format nil new)
      (gnus-agent-write-active file new)
      (erase-buffer)
      (let ((nnheader-file-coding-system gnus-agent-file-coding-system))
        (nnheader-insert-file-contents file)))))

(defun gnus-agent-write-active (file new)
    (gnus-make-directory (file-name-directory file))
    (let ((nnmail-active-file-coding-system gnus-agent-file-coding-system))
      ;; The hashtable contains real names of groups.  However, do NOT
      ;; add the foreign server prefix as gnus-active-to-gnus-format
      ;; will add it while reading the file.
      (gnus-write-active-file file new nil)))

;;;###autoload
(defun gnus-agent-possibly-alter-active (group active &optional info)
  "Possibly expand a group's active range to include articles
downloaded into the agent."
  (let* ((gnus-command-method (or gnus-command-method
                                  (gnus-find-method-for-group group))))
    (when (gnus-agent-method-p gnus-command-method)
      (let* ((local (gnus-agent-get-local group))
             (active-min (or (car active) 0))
             (active-max (or (cdr active) 0))
             (agent-min (or (car local) active-min))
             (agent-max (or (cdr local) active-max)))

        (when (< agent-min active-min)
          (setcar active agent-min))

        (when (> agent-max active-max)
          (setcdr active agent-max))

        (when (and info (< agent-max (- active-min 100)))
          ;; I'm expanding the active range by such a large amount
          ;; that there is a gap of more than 100 articles between the
          ;; last article known to the agent and the first article
          ;; currently available on the server.  This gap contains
          ;; articles that have been lost, mark them as read so that
          ;; gnus doesn't waste resources trying to fetch them.

          ;; NOTE: I don't do this for smaller gaps (< 100) as I don't
          ;; want to modify the local file everytime someone restarts
          ;; gnus.  The small gap will cause a tiny performance hit
          ;; when gnus tries, and fails, to retrieve the articles.
          ;; Still that should be smaller than opening a buffer,
          ;; printing this list to the buffer, and then writing it to a
          ;; file.

          (let ((read (gnus-info-read info)))
            (gnus-info-set-read
             info
             (gnus-range-add
              read
              (list (cons (1+ agent-max)
                          (1- active-min))))))

          ;; Lie about the agent's local range for this group to
          ;; disable the set read each time this server is opened.
          ;; NOTE: Opening this group will restore the valid local
          ;; range but it will also expand the local range to
          ;; incompass the new active range.
          (gnus-agent-set-local group agent-min (1- active-min)))))))

(defun gnus-agent-save-group-info (method group active)
  "Update a single group's active range in the agent's copy of the server's active file."
  (when (gnus-agent-method-p method)
    (let* ((gnus-command-method (or method gnus-command-method))
           (coding-system-for-write nnheader-file-coding-system)
           (file-name-coding-system nnmail-pathname-coding-system)
           (file (gnus-agent-lib-file "active"))
           oactive-min oactive-max)
      (gnus-make-directory (file-name-directory file))
      (with-temp-file file
        ;; Emacs got problem to match non-ASCII group in multibyte buffer.
        (mm-disable-multibyte)
        (when (file-exists-p file)
          (nnheader-insert-file-contents file)

          (goto-char (point-min))
          (when (re-search-forward
                 (concat "^" (regexp-quote group) " ") nil t)
            (save-excursion
              (setq oactive-max (read (current-buffer)) ;; max
                    oactive-min (read (current-buffer)))) ;; min
            (gnus-delete-line)))
        (when active
          (insert (format "%S %d %d y\n" (intern group)
                          (max (or oactive-max (cdr active)) (cdr active))
                          (min (or oactive-min (car active)) (car active))))
          (goto-char (point-max))
          (while (search-backward "\\." nil t)
            (delete-char 1)))))))

(defun gnus-agent-get-group-info (method group)
  "Get a single group's active range in the agent's copy of the server's active file."
  (when (gnus-agent-method-p method)
    (let* ((gnus-command-method (or method gnus-command-method))
           (coding-system-for-write nnheader-file-coding-system)
           (file-name-coding-system nnmail-pathname-coding-system)
           (file (gnus-agent-lib-file "active"))
           oactive-min oactive-max)
      (gnus-make-directory (file-name-directory file))
      (with-temp-buffer
        ;; Emacs got problem to match non-ASCII group in multibyte buffer.
        (mm-disable-multibyte)
        (when (file-exists-p file)
          (nnheader-insert-file-contents file)

          (goto-char (point-min))
          (when (re-search-forward
                 (concat "^" (regexp-quote group) " ") nil t)
            (save-excursion
              (setq oactive-max (read (current-buffer)) ;; max
                    oactive-min (read (current-buffer))) ;; min
              (cons oactive-min oactive-max))))))))

(defvar gnus-agent-decoded-group-names nil
  "Alist of non-ASCII group names and decoded ones.")

(defun gnus-agent-decoded-group-name (group)
  "Return a decoded group name of GROUP."
  (or (cdr (assoc group gnus-agent-decoded-group-names))
      (if (string-match "[^\000-\177]" group)
          (let ((decoded (gnus-group-decoded-name group)))
            (push (cons group decoded) gnus-agent-decoded-group-names)
            decoded)
        group)))

(defun gnus-agent-group-path (group)
  "Translate GROUP into a file name."

  ;; NOTE: This is what nnmail-group-pathname does as of Apr 2003.
  ;; The two methods must be kept synchronized, which is why
  ;; gnus-agent-group-pathname was added.

  (setq group
        (nnheader-translate-file-chars
         (nnheader-replace-duplicate-chars-in-string
          (nnheader-replace-chars-in-string
           (gnus-group-real-name (gnus-agent-decoded-group-name group))
           ?/ ?_)
          ?. ?_)))
  (if (or nnmail-use-long-file-names
          (file-directory-p (expand-file-name group (gnus-agent-directory))))
      group
    (nnheader-replace-chars-in-string group ?. ?/)))

(defun gnus-agent-group-pathname (group)
  "Translate GROUP into a file name."
  ;; nnagent uses nnmail-group-pathname to read articles while
  ;; unplugged.  The agent must, therefore, use the same directory
  ;; while plugged.
  (nnmail-group-pathname
   (gnus-group-real-name (gnus-agent-decoded-group-name group))
   (if gnus-command-method
       (gnus-agent-directory)
     (let ((gnus-command-method (gnus-find-method-for-group group)))
       (gnus-agent-directory)))))

(defun gnus-agent-get-function (method)
  (if (gnus-online method)
      (car method)
    (require 'nnagent)
    'nnagent))

(defun gnus-agent-covered-methods ()
  "Return the subset of methods that are covered by the agent."
  (delq nil (mapcar #'gnus-server-to-method gnus-agent-covered-methods)))

;;; History functions

(defun gnus-agent-history-buffer ()
  (cdr (assoc (gnus-agent-method) gnus-agent-history-buffers)))

(defun gnus-agent-open-history ()
  (save-excursion
    (push (cons (gnus-agent-method)
                (set-buffer (gnus-get-buffer-create
                             (format " *Gnus agent %s history*"
                                     (gnus-agent-method)))))
          gnus-agent-history-buffers)
    (mm-disable-multibyte) ;; everything is binary
    (erase-buffer)
    (insert "\n")
    (let ((file (gnus-agent-lib-file "history")))
      (when (file-exists-p file)
        (nnheader-insert-file-contents file))
      (set (make-local-variable 'gnus-agent-file-name) file))))

(defun gnus-agent-close-history ()
  (when (gnus-buffer-live-p gnus-agent-current-history)
    (kill-buffer gnus-agent-current-history)
    (setq gnus-agent-history-buffers
          (delq (assoc (gnus-agent-method) gnus-agent-history-buffers)
                gnus-agent-history-buffers))))

;;;
;;; Fetching
;;;

(defun gnus-agent-fetch-articles (group articles)
  "Fetch ARTICLES from GROUP and put them into the Agent."
  (when articles
    (gnus-agent-load-alist group)
    (let* ((alist gnus-agent-article-alist)
           (headers (if (< (length articles) 2) nil gnus-newsgroup-headers))
           (selected-sets (list nil))
           (current-set-size 0)
           article
           header-number)
      ;; Check each article
      (while (setq article (pop articles))
        ;; Skip alist entries preceeding this article
        (while (> article (or (caar alist) (1+ article)))
          (setq alist (cdr alist)))

        ;; Prune off articles that we have already fetched.
        (unless (and (eq article (caar alist))
                     (cdar alist))
          ;; Skip headers preceeding this article
          (while (> article
                    (setq header-number
                          (let* ((header (car headers)))
                            (if header
                                (mail-header-number header)
                              (1+ article)))))
            (setq headers (cdr headers)))

          ;; Add this article to the current set
          (setcar selected-sets (cons article (car selected-sets)))

          ;; Update the set size, when the set is too large start a
          ;; new one.  I do this after adding the article as I want at
          ;; least one article in each set.
          (when (< gnus-agent-max-fetch-size
                   (setq current-set-size
                         (+ current-set-size
                            (if (= header-number article)
                                (let ((char-size (mail-header-chars
                                                  (car headers))))
                                  (if (<= char-size 0)
                                      ;; The char size was missing/invalid,
                                      ;; assume a worst-case situation of
                                      ;; 65 char/line.  If the line count
                                      ;; is missing, arbitrarily assume a
                                      ;; size of 1000 characters.
                                      (max (* 65 (mail-header-lines
                                                  (car headers)))
                                           1000)
                                    char-size))
                              0))))
            (setcar selected-sets (nreverse (car selected-sets)))
            (setq selected-sets (cons nil selected-sets)
                  current-set-size 0))))

      (when (or (cdr selected-sets) (car selected-sets))
        (let* ((fetched-articles (list nil))
               (tail-fetched-articles fetched-articles)
               (dir (gnus-agent-group-pathname group))
               (date (time-to-days (current-time)))
               (case-fold-search t)
               pos crosses id
               (file-name-coding-system nnmail-pathname-coding-system))

          (setcar selected-sets (nreverse (car selected-sets)))
          (setq selected-sets (nreverse selected-sets))

          (gnus-make-directory dir)
          (gnus-message 7 "Fetching articles for %s..."
                        (gnus-agent-decoded-group-name group))

          (unwind-protect
              (while (setq articles (pop selected-sets))
                ;; Fetch the articles from the backend.
                (if (gnus-check-backend-function 'retrieve-articles group)
                    (setq pos (gnus-retrieve-articles articles group))
                  (with-temp-buffer
                    (let (article)
                      (while (setq article (pop articles))
                        (gnus-message 10 "Fetching article %s for %s..."
                                      article
                                      (gnus-agent-decoded-group-name group))
                        (when (or
                               (gnus-backlog-request-article group article
                                                             nntp-server-buffer)
                               (gnus-request-article article group))
                          (goto-char (point-max))
                          (push (cons article (point)) pos)
                          (insert-buffer-substring nntp-server-buffer)))
                      (copy-to-buffer
                       nntp-server-buffer (point-min) (point-max))
                      (setq pos (nreverse pos)))))
                ;; Then save these articles into the Agent.
                (with-current-buffer nntp-server-buffer
                  (while pos
                    (narrow-to-region (cdar pos) (or (cdadr pos) (point-max)))
                    (goto-char (point-min))
                    (unless (eobp) ;; Don't save empty articles.
                      (when (search-forward "\n\n" nil t)
                        (when (search-backward "\nXrefs: " nil t)
                          ;; Handle cross posting.
                          (goto-char (match-end 0)) ; move to end of header name
                          (skip-chars-forward "^ ") ; skip server name
                          (skip-chars-forward " ")
                          (setq crosses nil)
                          (while (looking-at "\\([^: \n]+\\):\\([0-9]+\\) *")
                            (push (cons (buffer-substring (match-beginning 1)
                                                          (match-end 1))
                                        (string-to-number
                                         (buffer-substring (match-beginning 2)
                                                           (match-end 2))))
                                  crosses)
                            (goto-char (match-end 0)))
                          (gnus-agent-crosspost crosses (caar pos) date)))
                      (goto-char (point-min))
                      (if (not (re-search-forward
                                "^Message-ID: *<\\([^>\n]+\\)>" nil t))
                          (setq id "No-Message-ID-in-article")
                        (setq id (buffer-substring
                                  (match-beginning 1) (match-end 1))))
                      (let ((coding-system-for-write
                             gnus-agent-file-coding-system))
                        (write-region (point-min) (point-max)
                                      (concat dir (number-to-string (caar pos)))
                                      nil 'silent))

                      (gnus-agent-append-to-list
                       tail-fetched-articles (caar pos)))
                    (widen)
                    (setq pos (cdr pos)))))

            (gnus-agent-save-alist group (cdr fetched-articles) date)
            (gnus-agent-update-files-total-fetched-for group (cdr fetched-articles))

            (gnus-message 7 ""))
          (cdr fetched-articles))))))

(defun gnus-agent-unfetch-articles (group articles)
  "Delete ARTICLES that were fetched from GROUP into the agent."
  (when articles
    (gnus-agent-with-refreshed-group
     group
     (gnus-agent-load-alist group)
     (let* ((alist (cons nil gnus-agent-article-alist))
            (articles (sort articles #'<))
            (next-possibility alist)
            (delete-this (pop articles)))
       (while (and (cdr next-possibility) delete-this)
         (let ((have-this (caar (cdr next-possibility))))
           (cond
            ((< delete-this have-this)
             (setq delete-this (pop articles)))
            ((= delete-this have-this)
             (let ((timestamp (cdar (cdr next-possibility))))
               (when timestamp
                 (let* ((file-name (concat (gnus-agent-group-pathname group)
                                           (number-to-string have-this)))
                        (size-file
                         (float (or (and gnus-agent-total-fetched-hashtb
                                         (nth 7 (file-attributes file-name)))
                                    0)))
                        (file-name-coding-system
                         nnmail-pathname-coding-system))
                   (delete-file file-name)
                   (gnus-agent-update-files-total-fetched-for
                    group (- size-file)))))

             (setcdr next-possibility (cddr next-possibility)))
            (t
             (setq next-possibility (cdr next-possibility))))))
       (setq gnus-agent-article-alist (cdr alist))
       (gnus-agent-save-alist group)))))

(defun gnus-agent-crosspost (crosses article &optional date)
  (setq date (or date t))

  (let (gnus-agent-article-alist group alist beg end)
    (with-current-buffer gnus-agent-overview-buffer
      (when (nnheader-find-nov-line article)
        (forward-word 1)
        (setq beg (point))
        (setq end (progn (forward-line 1) (point)))))
    (while crosses
      (setq group (caar crosses))
      (unless (setq alist (assoc group gnus-agent-group-alist))
        (push (setq alist (list group (gnus-agent-load-alist (caar crosses))))
              gnus-agent-group-alist))
      (setcdr alist (cons (cons (cdar crosses) date) (cdr alist)))
      (with-current-buffer (gnus-get-buffer-create
                            (format " *Gnus agent overview %s*"group))
        (when (= (point-max) (point-min))
          (push (cons group (current-buffer)) gnus-agent-buffer-alist)
          (ignore-errors
           (let ((file-name-coding-system nnmail-pathname-coding-system))
             (nnheader-insert-file-contents
              (gnus-agent-article-name ".overview" group)))))
        (nnheader-find-nov-line (string-to-number (cdar crosses)))
        (insert (string-to-number (cdar crosses)))
        (insert-buffer-substring gnus-agent-overview-buffer beg end)
        (gnus-agent-check-overview-buffer))
      (setq crosses (cdr crosses)))))

(defun gnus-agent-backup-overview-buffer ()
  (when gnus-newsgroup-name
    (let ((root (gnus-agent-article-name ".overview" gnus-newsgroup-name))
          (cnt 0)
          name
          (file-name-coding-system nnmail-pathname-coding-system))
      (while (file-exists-p
              (setq name (concat root "~"
                                 (int-to-string (setq cnt (1+ cnt))) "~"))))
      (write-region (point-min) (point-max) name nil 'no-msg)
      (gnus-message 1 "Created backup copy of overview in %s." name)))
  t)

(defun gnus-agent-check-overview-buffer (&optional buffer)
  "Check the overview file given for sanity.
In particular, checks that the file is sorted by article number
and that there are no duplicates."
  (let ((prev-num -1)
        (backed-up nil))
    (save-excursion
      (when buffer
        (set-buffer buffer))
      (save-restriction
        (widen)
        (goto-char (point-min))

        (while (< (point) (point-max))
          (let ((p (point))
                (cur (condition-case nil
                         (read (current-buffer))
                       (error nil))))
            (cond
             ((or (not (integerp cur))
                  (not (eq (char-after) ?\t)))
              (or backed-up
                  (setq backed-up (gnus-agent-backup-overview-buffer)))
              (gnus-message 1
                            "Overview buffer contains garbage '%s'."
                            (buffer-substring
                             p (point-at-eol))))
             ((= cur prev-num)
              (or backed-up
                  (setq backed-up (gnus-agent-backup-overview-buffer)))
              (gnus-message 1
                            "Duplicate overview line for %d" cur)
              (delete-region p (progn (forward-line 1) (point))))
             ((< cur prev-num)
              (or backed-up
                  (setq backed-up (gnus-agent-backup-overview-buffer)))
              (gnus-message 1 "Overview buffer not sorted!")
              (sort-numeric-fields 1 (point-min) (point-max))
              (goto-char (point-min))
              (setq prev-num -1))
             (t
              (setq prev-num cur)))
            (forward-line 1)))))))

(defun gnus-agent-flush-server (&optional server-or-method)
  "Flush all agent index files for every subscribed group within
  the given SERVER-OR-METHOD.  When called with nil, the current
  value of gnus-command-method identifies the server."
  (let* ((gnus-command-method (if server-or-method
                                  (gnus-server-to-method server-or-method)
                                gnus-command-method))
         (alist gnus-newsrc-alist))
    (while alist
      (let ((entry (pop alist)))
        (when (gnus-methods-equal-p gnus-command-method (gnus-info-method entry))
          (gnus-agent-flush-group (gnus-info-group entry)))))))

(defun gnus-agent-flush-group (group)
  "Flush the agent's index files such that the GROUP no longer
appears to have any local content.  The actual content, the
article files, may then be deleted using gnus-agent-expire-group.
If flushing was a mistake, the gnus-agent-regenerate-group method
provides an undo mechanism by reconstructing the index files from
the article files."
  (interactive (list (gnus-agent-read-group)))

  (let* ((gnus-command-method (or gnus-command-method
                                  (gnus-find-method-for-group group)))
         (overview (gnus-agent-article-name ".overview" group))
         (agentview (gnus-agent-article-name ".agentview" group))
         (file-name-coding-system nnmail-pathname-coding-system))

    (if (file-exists-p overview)
        (delete-file overview))
    (if (file-exists-p agentview)
        (delete-file agentview))

    (gnus-agent-update-view-total-fetched-for group nil gnus-command-method)
    (gnus-agent-update-view-total-fetched-for group t   gnus-command-method)

    ;(gnus-agent-set-local group nil nil)
    ;(gnus-agent-save-local t)
    (gnus-agent-save-group-info nil group nil)))

(defun gnus-agent-flush-cache ()
  "Flush the agent's index files such that the group no longer
appears to have any local content.  The actual content, the
article files, is then deleted using gnus-agent-expire-group. The
gnus-agent-regenerate-group method provides an undo mechanism by
reconstructing the index files from the article files."
  (interactive)
  (save-excursion
    (let ((file-name-coding-system nnmail-pathname-coding-system))
      (while gnus-agent-buffer-alist
        (set-buffer (cdar gnus-agent-buffer-alist))
        (let ((coding-system-for-write gnus-agent-file-coding-system))
          (write-region (point-min) (point-max)
                        (gnus-agent-article-name ".overview"
                                                 (caar gnus-agent-buffer-alist))
                        nil 'silent))
        (setq gnus-agent-buffer-alist (cdr gnus-agent-buffer-alist)))
      (while gnus-agent-group-alist
        (with-temp-file (gnus-agent-article-name
                         ".agentview" (caar gnus-agent-group-alist))
          (princ (cdar gnus-agent-group-alist))
          (insert "\n")
          (princ 1 (current-buffer))
          (insert "\n"))
        (setq gnus-agent-group-alist (cdr gnus-agent-group-alist))))))

;;;###autoload
(defun gnus-agent-find-parameter (group symbol)
  "Search for GROUPs SYMBOL in the group's parameters, the group's
topic parameters, the group's category, or the customizable
variables.  Returns the first non-nil value found."
  (or (gnus-group-find-parameter group symbol t)
      (gnus-group-parameter-value (cdr (gnus-group-category group)) symbol t)
      (symbol-value
       (cdr
        (assq symbol
              '((agent-short-article . gnus-agent-short-article)
                (agent-long-article . gnus-agent-long-article)
                (agent-low-score . gnus-agent-low-score)
                (agent-high-score . gnus-agent-high-score)
                (agent-days-until-old . gnus-agent-expire-days)
                (agent-enable-expiration
                 . gnus-agent-enable-expiration)
                (agent-predicate . gnus-agent-predicate)))))))

(defun gnus-agent-fetch-headers (group &optional force)
  "Fetch interesting headers into the agent.  The group's overview
file will be updated to include the headers while a list of available
article numbers will be returned."
  (let* ((fetch-all (and gnus-agent-consider-all-articles
                         ;; Do not fetch all headers if the predicate
                         ;; implies that we only consider unread articles.
                         (not (gnus-predicate-implies-unread
                               (gnus-agent-find-parameter group
                                                          'agent-predicate)))))
         (articles (if fetch-all
                       (if gnus-newsgroup-maximum-articles
                           (let ((active (gnus-active group)))
                             (gnus-uncompress-range
                              (cons (max (car active)
                                         (- (cdr active)
                                            gnus-newsgroup-maximum-articles
                                            -1))
                                    (cdr active))))
                         (gnus-uncompress-range (gnus-active group)))
                     (gnus-list-of-unread-articles group)))
         (gnus-decode-encoded-word-function 'identity)
         (gnus-decode-encoded-address-function 'identity)
         (file (gnus-agent-article-name ".overview" group))
         (file-name-coding-system nnmail-pathname-coding-system))

    (unless fetch-all
      ;; Add articles with marks to the list of article headers we want to
      ;; fetch.  Don't fetch articles solely on the basis of a recent or seen
      ;; mark, but do fetch recent or seen articles if they have other, more
      ;; interesting marks.  (We have to fetch articles with boring marks
      ;; because otherwise the agent will remove their marks.)
      (dolist (arts (gnus-info-marks (gnus-get-info group)))
        (unless (memq (car arts) '(seen recent killed cache))
          (setq articles (gnus-range-add articles (cdr arts)))))
      (setq articles (sort (gnus-uncompress-sequence articles) '<)))

    ;; At this point, I have the list of articles to consider for
    ;; fetching.  This is the list that I'll return to my caller. Some
    ;; of these articles may have already been fetched.  That's OK as
    ;; the fetch article code will filter those out.  Internally, I'll
    ;; filter this list to just those articles whose headers need to
    ;; be fetched.
    (let ((articles articles))
      ;; Remove known articles.
      (when (and (or gnus-agent-cache
                     (not gnus-plugged))
                 (gnus-agent-load-alist group))
        ;; Remove articles marked as downloaded.
        (if fetch-all
            ;; I want to fetch all headers in the active range.
            ;; Therefore, exclude only those headers that are in the
            ;; article alist.
            ;; NOTE: This is probably NOT what I want to do after
            ;; agent expiration in this group.
            (setq articles (gnus-agent-uncached-articles articles group))

          ;; I want to only fetch those headers that have never been
          ;; fetched.  Therefore, exclude all headers that are, or
          ;; WERE, in the article alist.
          (let ((low (1+ (caar (last gnus-agent-article-alist))))
                (high (cdr (gnus-active group))))
            ;; Low can be greater than High when the same group is
            ;; fetched twice in the same session {The first fetch will
            ;; fill the article alist such that (last
            ;; gnus-agent-article-alist) equals (cdr (gnus-active
            ;; group))}.  The addition of one(the 1+ above) then
            ;; forces Low to be greater than High.  When this happens,
            ;; gnus-list-range-intersection returns nil which
            ;; indicates that no headers need to be fetched. -- Kevin
            (setq articles (gnus-list-range-intersection
                            articles (list (cons low high)))))))

      (gnus-message
       10 "gnus-agent-fetch-headers: undownloaded articles are '%s'"
       (gnus-compress-sequence articles t))

      (with-current-buffer nntp-server-buffer
        (if articles
            (progn
              (gnus-message 7 "Fetching headers for %s..."
                            (gnus-agent-decoded-group-name group))

              ;; Fetch them.
              (gnus-make-directory (nnheader-translate-file-chars
                                    (file-name-directory file) t))

              (unless (eq 'nov (gnus-retrieve-headers articles group))
                (nnvirtual-convert-headers))
              (gnus-agent-check-overview-buffer)
              ;; Move these headers to the overview buffer so that
              ;; gnus-agent-braid-nov can merge them with the contents
              ;; of FILE.
              (copy-to-buffer
               gnus-agent-overview-buffer (point-min) (point-max))
              ;; NOTE: Call g-a-brand-nov even when the file does not
              ;; exist.  As a minimum, it will validate the article
              ;; numbers already in the buffer.
              (gnus-agent-braid-nov group articles file)
              (let ((coding-system-for-write
                     gnus-agent-file-coding-system))
                (gnus-agent-check-overview-buffer)
                (write-region (point-min) (point-max) file nil 'silent))
              (gnus-agent-update-view-total-fetched-for group t)
              (gnus-agent-save-alist group articles nil)
              articles)
          (ignore-errors
            (erase-buffer)
            (nnheader-insert-file-contents file)))))
    articles))

(defsubst gnus-agent-read-article-number ()
  "Reads the article number at point.  Returns nil when a valid article number can not be read."

  ;; It is unfortunate but the read function quietly overflows
  ;; integer.  As a result, I have to use string operations to test
  ;; for overflow BEFORE calling read.
  (when (looking-at "[0-9]+\t")
    (let ((len (- (match-end 0) (match-beginning 0))))
      (cond ((< len 9)
             (read (current-buffer)))
            ((= len 9)
             ;; Many 9 digit base-10 numbers can be represented in a 27-bit int
             ;; Back convert from int to string to ensure that this is one of them.
             (let* ((str1 (buffer-substring (match-beginning 0) (1- (match-end 0))))
                    (num (read (current-buffer)))
                    (str2 (int-to-string num)))
               (when (equal str1 str2)
                 num)))))))

(defsubst gnus-agent-copy-nov-line (article)
  "Copy the indicated ARTICLE from the overview buffer to the nntp server buffer."
  (let (art b e)
    (set-buffer gnus-agent-overview-buffer)
    (while (and (not (eobp))
                (or (not (setq art (gnus-agent-read-article-number)))
                    (< art article)))
      (forward-line 1))
    (beginning-of-line)
    (if (or (eobp)
            (not (eq article art)))
        (set-buffer nntp-server-buffer)
      (setq b (point))
      (setq e (progn (forward-line 1) (point)))
      (set-buffer nntp-server-buffer)
      (insert-buffer-substring gnus-agent-overview-buffer b e))))

(defun gnus-agent-braid-nov (group articles file)
  "Merge agent overview data with given file.
Takes unvalidated headers for ARTICLES from
`gnus-agent-overview-buffer' and validated headers from the given
FILE and places the combined valid headers into
`nntp-server-buffer'.  This function can be used, when file
doesn't exist, to valid the overview buffer."
  (let (start last)
    (set-buffer gnus-agent-overview-buffer)
    (goto-char (point-min))
    (set-buffer nntp-server-buffer)
    (erase-buffer)
    (when (file-exists-p file)
      (nnheader-insert-file-contents file))
    (goto-char (point-max))
    (forward-line -1)

    (unless (or (= (point-min) (point-max))
                (< (setq last (read (current-buffer))) (car articles)))
      ;; Old and new overlap -- We do it the hard way.
      (when (nnheader-find-nov-line (car articles))
        ;; Replacing existing NOV entry
        (delete-region (point) (progn (forward-line 1) (point))))
      (gnus-agent-copy-nov-line (pop articles))

      (ignore-errors
        (while articles
          (while (let ((art (read (current-buffer))))
                   (cond ((< art (car articles))
                          (forward-line 1)
                          t)
                         ((= art (car articles))
                          (beginning-of-line)
                          (delete-region
                           (point) (progn (forward-line 1) (point)))
                          nil)
                         (t
                          (beginning-of-line)
                          nil))))

          (gnus-agent-copy-nov-line (pop articles)))))

    (goto-char (point-max))

    ;; Append the remaining lines
    (when articles
      (when last
        (set-buffer gnus-agent-overview-buffer)
        (setq start (point))
        (set-buffer nntp-server-buffer))

      (let ((p (point)))
        (insert-buffer-substring gnus-agent-overview-buffer start)
        (goto-char p))

      (setq last (or last -134217728))
      (while (catch 'problems
               (let (sort art)
                 (while (not (eobp))
                   (setq art (gnus-agent-read-article-number))
                   (cond ((not art)
                          ;; Bad art num - delete this line
                          (beginning-of-line)
                          (delete-region (point) (progn (forward-line 1) (point))))
                         ((< art last)
                          ;; Art num out of order - enable sort
                          (setq sort t)
                          (forward-line 1))
                         ((= art last)
                          ;; Bad repeat of art number - delete this line
                          (beginning-of-line)
                          (delete-region (point) (progn (forward-line 1) (point))))
                         (t
                          ;; Good art num
                          (setq last art)
                          (forward-line 1))))
                 (when sort
                   ;; something is seriously wrong as we simply shouldn't see out-of-order data.
                   ;; First, we'll fix the sort.
                   (sort-numeric-fields 1 (point-min) (point-max))

                   ;; but now we have to consider that we may have duplicate rows...
                   ;; so reset to beginning of file
                   (goto-char (point-min))
                   (setq last -134217728)

                   ;; and throw a code that restarts this scan
                   (throw 'problems t))
                 nil))))))

;; Keeps the compiler from warning about the free variable in
;; gnus-agent-read-agentview.
(defvar gnus-agent-read-agentview)

(defun gnus-agent-load-alist (group)
  "Load the article-state alist for GROUP."
  ;; Bind free variable that's used in `gnus-agent-read-agentview'.
  (let* ((gnus-agent-read-agentview group)
         (file-name-coding-system nnmail-pathname-coding-system)
         (agentview (gnus-agent-article-name ".agentview" group)))
    (setq gnus-agent-article-alist
          (and (file-exists-p agentview)
               (gnus-cache-file-contents
                agentview
                'gnus-agent-file-loading-cache
                'gnus-agent-read-agentview)))))

(defun gnus-agent-read-agentview (file)
  "Load FILE and do a `read' there."
  (with-temp-buffer
    (condition-case nil
        (progn
          (nnheader-insert-file-contents file)
          (goto-char (point-min))
          (let ((alist (read (current-buffer)))
                (version (condition-case nil (read (current-buffer))
                           (end-of-file 0)))
                changed-version)

            (cond
             ((= version 0)
              (let ((inhibit-quit t)
                    entry)
                (gnus-agent-open-history)
                (set-buffer (gnus-agent-history-buffer))
                (goto-char (point-min))
                (while (not (eobp))
                  (if (and (looking-at
                            "[^\t\n]+\t\\([0-9]+\\)\t\\([^ \n]+\\) \\([0-9]+\\)")
                           (string= (match-string 2)
                                    gnus-agent-read-agentview)
                           (setq entry (assoc (string-to-number (match-string 3)) alist)))
                      (setcdr entry (string-to-number (match-string 1))))
                  (forward-line 1))
                (gnus-agent-close-history)
                (setq changed-version t)))
             ((= version 1)
              (setq changed-version (not (= 1 gnus-agent-article-alist-save-format))))
             ((= version 2)
              (let (state sequence uncomp)
                (while alist
                  (setq state (caar alist)
                        sequence (inline (gnus-uncompress-range (cdar alist)))
                        alist (cdr alist))
                  (while sequence
                    (push (cons (pop sequence) state) uncomp)))
                (setq alist (sort uncomp 'car-less-than-car)))
              (setq changed-version (not (= 2 gnus-agent-article-alist-save-format)))))
            (when changed-version
              (let ((gnus-agent-article-alist alist))
                (gnus-agent-save-alist gnus-agent-read-agentview)))
            alist))
      ((end-of-file file-error)
       ;; The agentview file is missing.
       (condition-case nil
           ;; If the agent directory exists, attempt to perform a brute-force
           ;; reconstruction of its contents.
           (let* (alist
                  (file-name-coding-system nnmail-pathname-coding-system)
                  (file-attributes (directory-files-and-attributes
                                    (gnus-agent-article-name ""
                                                             gnus-agent-read-agentview) nil "^[0-9]+$" t)))
             (while file-attributes
               (let ((fa (pop file-attributes)))
                 (unless (nth 1 fa)
                   (push (cons (string-to-number (nth 0 fa)) (time-to-days (nth 5 fa))) alist))))
             alist)
         (file-error nil))))))

(defun gnus-agent-save-alist (group &optional articles state)
  "Save the article-state alist for GROUP."
  (let* ((file-name-coding-system nnmail-pathname-coding-system)
         (prev (cons nil gnus-agent-article-alist))
         (all prev)
         print-level print-length item article)
    (while (setq article (pop articles))
      (while (and (cdr prev)
                  (< (caadr prev) article))
        (setq prev (cdr prev)))
      (cond
       ((not (cdr prev))
        (setcdr prev (list (cons article state))))
       ((> (caadr prev) article)
        (setcdr prev (cons (cons article state) (cdr prev))))
       ((= (caadr prev) article)
        (setcdr (cadr prev) state)))
      (setq prev (cdr prev)))
    (setq gnus-agent-article-alist (cdr all))

    (gnus-agent-set-local group
                          (caar gnus-agent-article-alist)
                          (caar (last gnus-agent-article-alist)))

    (gnus-make-directory (gnus-agent-article-name "" group))
    (with-temp-file (gnus-agent-article-name ".agentview" group)
      (cond ((eq gnus-agent-article-alist-save-format 1)
             (princ gnus-agent-article-alist (current-buffer)))
            ((eq gnus-agent-article-alist-save-format 2)
             (let ((alist gnus-agent-article-alist)
                   article-id day-of-download comp-list compressed)
               (while alist
                 (setq article-id (caar alist)
                       day-of-download (cdar alist)
                       comp-list (assq day-of-download compressed)
                       alist (cdr alist))
                 (if comp-list
                     (setcdr comp-list (cons article-id (cdr comp-list)))
                   (push (list day-of-download article-id) compressed)))
               (setq alist compressed)
               (while alist
                 (setq comp-list (pop alist))
                 (setcdr comp-list
                         (gnus-compress-sequence (nreverse (cdr comp-list)))))
               (princ compressed (current-buffer)))))
      (insert "\n")
      (princ gnus-agent-article-alist-save-format (current-buffer))
      (insert "\n"))

    (gnus-agent-update-view-total-fetched-for group nil)))

(defvar gnus-agent-article-local nil)
(defvar gnus-agent-article-local-times nil)
(defvar gnus-agent-file-loading-local nil)

(defun gnus-agent-load-local (&optional method)
  "Load the METHOD'S local file.  The local file contains min/max
article counts for each of the method's subscribed groups."
  (let ((gnus-command-method (or method gnus-command-method)))
    (when (or (null gnus-agent-article-local-times)
              (zerop gnus-agent-article-local-times))
      (setq gnus-agent-article-local
            (gnus-cache-file-contents
             (gnus-agent-lib-file "local")
             'gnus-agent-file-loading-local
             'gnus-agent-read-and-cache-local))
      (when gnus-agent-article-local-times
        (incf gnus-agent-article-local-times)))
    gnus-agent-article-local))

(defun gnus-agent-read-and-cache-local (file)
  "Load and read FILE then bind its contents to
gnus-agent-article-local.  If that variable had `dirty' (also known as
modified) original contents, they are first saved to their own file."
  (if (and gnus-agent-article-local
           (symbol-value (intern "+dirty" gnus-agent-article-local)))
      (gnus-agent-save-local))
  (gnus-agent-read-local file))

(defun gnus-agent-read-local (file)
  "Load FILE and do a `read' there."
  (let ((my-obarray (gnus-make-hashtable (count-lines (point-min)
                                                      (point-max))))
        (line 1))
    (with-temp-buffer
      (condition-case nil
          (let ((nnheader-file-coding-system gnus-agent-file-coding-system))
            (nnheader-insert-file-contents file))
        (file-error))

      (goto-char (point-min))
      ;; Skip any comments at the beginning of the file (the only place where they may appear)
      (while (= (following-char) ?\;)
        (forward-line 1)
        (setq line (1+ line)))

      (while (not (eobp))
        (condition-case err
            (let (group
                  min
                  max
                  (cur (current-buffer))
                  (obarray my-obarray))
              (setq group (read cur)
                    min (read cur)
                    max (read cur))

              (when (stringp group)
                (setq group (intern group my-obarray)))

              ;; NOTE: The '+ 0' ensure that min and max are both numerics.
              (set group (cons (+ 0 min) (+ 0 max))))
          (error
           (gnus-message 3 "Warning - invalid agent local: %s on line %d: %s"
                         file line (error-message-string err))))
        (forward-line 1)
        (setq line (1+ line))))

    (set (intern "+dirty" my-obarray) nil)
    (set (intern "+method" my-obarray) gnus-command-method)
    my-obarray))

(defun gnus-agent-save-local (&optional force)
  "Save gnus-agent-article-local under it method's agent.lib directory."
  (let ((my-obarray gnus-agent-article-local))
    (when (and my-obarray
               (or force (symbol-value (intern "+dirty" my-obarray))))
      (let* ((gnus-command-method (symbol-value (intern "+method" my-obarray)))
             ;; NOTE: gnus-command-method is used within gnus-agent-lib-file.
             (dest (gnus-agent-lib-file "local")))
        (gnus-make-directory (gnus-agent-lib-file ""))

        (let ((coding-system-for-write gnus-agent-file-coding-system)
              (file-name-coding-system nnmail-pathname-coding-system))
          (with-temp-file dest
            (let ((gnus-command-method (symbol-value (intern "+method" my-obarray)))
                  print-level print-length item article
                  (standard-output (current-buffer)))
              (mapatoms (lambda (symbol)
                          (cond ((not (boundp symbol))
                                 nil)
                                ((member (symbol-name symbol) '("+dirty" "+method"))
                                 nil)
                                (t
                                 (let ((range (symbol-value symbol)))
                                   (when range
                                     (prin1 symbol)
                                     (princ " ")
                                     (princ (car range))
                                     (princ " ")
                                     (princ (cdr range))
                                     (princ "\n"))))))
                        my-obarray))))))))

(defun gnus-agent-get-local (group &optional gmane method)
  (let* ((gmane (or gmane (gnus-group-real-name group)))
         (gnus-command-method (or method (gnus-find-method-for-group group)))
         (local (gnus-agent-load-local))
         (symb (intern gmane local))
         (minmax (and (boundp symb) (symbol-value symb))))
    (unless minmax
      ;; Bind these so that gnus-agent-load-alist doesn't change the
      ;; current alist (i.e. gnus-agent-article-alist)
      (let* ((gnus-agent-article-alist gnus-agent-article-alist)
             (gnus-agent-file-loading-cache gnus-agent-file-loading-cache)
             (alist (gnus-agent-load-alist group)))
        (when alist
          (setq minmax
                (cons (caar alist)
                      (caar (last alist))))
          (gnus-agent-set-local group (car minmax) (cdr minmax)
                                gmane gnus-command-method local))))
    minmax))

(defun gnus-agent-set-local (group min max &optional gmane method local)
  (let* ((gmane (or gmane (gnus-group-real-name group)))
         (gnus-command-method (or method (gnus-find-method-for-group group)))
         (local (or local (gnus-agent-load-local)))
         (symb (intern gmane local))
         (minmax (and (boundp symb) (symbol-value symb))))
    (if (cond ((and minmax
                    (or (not (eq min (car minmax)))
                        (not (eq max (cdr minmax))))
                    min
                    max)
               (setcar minmax min)
               (setcdr minmax max)
               t)
              (minmax
               nil)
              ((and min max)
               (set symb (cons min max))
               t)
              (t
               (unintern symb local)))
        (set (intern "+dirty" local) t))))

(defun gnus-agent-article-name (article group)
  (expand-file-name article
                    (file-name-as-directory
                     (gnus-agent-group-pathname group))))

(defun gnus-agent-batch-confirmation (msg)
  "Show error message and return t."
  (gnus-message 1 "%s" msg)
  t)

;;;###autoload
(defun gnus-agent-batch-fetch ()
  "Start Gnus and fetch session."
  (interactive)
  (gnus)
  (let ((gnus-agent-confirmation-function 'gnus-agent-batch-confirmation))
    (gnus-agent-fetch-session))
  (gnus-group-exit))

(defun gnus-agent-fetch-session ()
  "Fetch all articles and headers that are eligible for fetching."
  (interactive)
  (unless gnus-agent-covered-methods
    (error "No servers are covered by the Gnus agent"))
  (unless gnus-plugged
    (error "Can't fetch articles while Gnus is unplugged"))
  (let ((methods (gnus-agent-covered-methods))
        groups group gnus-command-method)
    (save-excursion
      (while methods
        (setq gnus-command-method (car methods))
        (when (and (or (gnus-server-opened gnus-command-method)
                       (gnus-open-server gnus-command-method))
                   (gnus-online gnus-command-method))
          (setq groups (gnus-groups-from-server (car methods)))
          (gnus-agent-with-fetch
            (while (setq group (pop groups))
              (when (<= (gnus-group-level group)
                        gnus-agent-handle-level)
                (if (or debug-on-error debug-on-quit)
                    (gnus-agent-fetch-group-1
                     group gnus-command-method)
                  (condition-case err
                      (gnus-agent-fetch-group-1
                       group gnus-command-method)
                    (error
                     (unless (funcall gnus-agent-confirmation-function
                                      (format "Error %s while fetching session.  Should gnus continue? "
                                              (error-message-string err)))
                       (error "Cannot fetch articles into the Gnus agent")))
                    (quit
                     (gnus-agent-regenerate-group group)
                     (unless (funcall gnus-agent-confirmation-function
                                      (format
                                       "%s while fetching session.  Should gnus continue? "
                                       (error-message-string err)))
                       (signal 'quit
                               "Cannot fetch articles into the Gnus agent")))))))))
        (setq methods (cdr methods)))
      (gnus-run-hooks 'gnus-agent-fetched-hook)
      (gnus-message 6 "Finished fetching articles into the Gnus agent"))))

(defun gnus-agent-fetch-group-1 (group method)
  "Fetch GROUP."
  (let ((gnus-command-method method)
        (gnus-newsgroup-name group)
        (gnus-newsgroup-dependencies gnus-newsgroup-dependencies)
        (gnus-newsgroup-headers gnus-newsgroup-headers)
        (gnus-newsgroup-scored gnus-newsgroup-scored)
        (gnus-use-cache gnus-use-cache)
        (gnus-summary-expunge-below gnus-summary-expunge-below)
        (gnus-summary-mark-below gnus-summary-mark-below)
        (gnus-orphan-score gnus-orphan-score)
        ;; Maybe some other gnus-summary local variables should also
        ;; be put here.

        gnus-headers
        gnus-score
        articles arts
        category predicate info marks score-param
        )
    (unless (gnus-check-group group)
      (error "Can't open server for %s" group))

    ;; Fetch headers.
    (when (or gnus-newsgroup-active
              (gnus-active group)
              (gnus-activate-group group))
      (let ((marked-articles gnus-newsgroup-downloadable))
        ;; Identify the articles marked for download
        (unless gnus-newsgroup-active
          ;; The variable gnus-newsgroup-active was selected as I need
          ;; a gnus-summary local variable that is NOT bound to any
          ;; value (its global value should default to nil).
          (dolist (mark gnus-agent-download-marks)
            (let ((arts (cdr (assq mark (gnus-info-marks
                                         (setq info (gnus-get-info group)))))))
              (when arts
                (setq marked-articles (nconc (gnus-uncompress-range arts)
                                             marked-articles))
                ))))
        (setq marked-articles (sort marked-articles '<))