;;; nnkiboze.el --- select virtual news access for Gnus

;; Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
;;   2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.

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

;; This file is part of GNU Emacs.

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

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; The other access methods (nntp, nnspool, etc) are general news
;; access methods.  This module relies on Gnus and can't be used
;; separately.

;;; Code:

(require 'nntp)
(require 'nnheader)
(require 'gnus)
(require 'gnus-score)
(require 'nnoo)
(require 'mm-util)
(eval-when-compile (require 'cl))

(nnoo-declare nnkiboze)
(defvoo nnkiboze-directory (nnheader-concat gnus-directory "kiboze/")
  "nnkiboze will put its files in this directory.")

(defvoo nnkiboze-level 9
  "The maximum level to be searched for articles.")

(defvoo nnkiboze-remove-read-articles t
  "If non-nil, nnkiboze will remove read articles from the kiboze group.")

(defvoo nnkiboze-ephemeral nil
  "If non-nil, don't store any data anywhere.")

(defvoo nnkiboze-scores nil
  "Score rules for generating the nnkiboze group.")

(defvoo nnkiboze-regexp nil
  "Regexp for matching component groups.")

(defvoo nnkiboze-file-coding-system mm-text-coding-system
  "Coding system for nnkiboze files.")



(defconst nnkiboze-version "nnkiboze 1.0")

(defvoo nnkiboze-current-group nil)
(defvoo nnkiboze-status-string "")

(defvoo nnkiboze-headers nil)



;;; Interface functions.

(nnoo-define-basics nnkiboze)

(deffoo nnkiboze-retrieve-headers (articles &optional group server fetch-old)
  (nnkiboze-possibly-change-group group)
  (unless gnus-nov-is-evil
    (if (stringp (car articles))
	'headers
      (let ((nov (nnkiboze-nov-file-name)))
	(when (file-exists-p nov)
	  (save-excursion
	    (set-buffer nntp-server-buffer)
	    (erase-buffer)
	    (let ((nnheader-file-coding-system nnkiboze-file-coding-system))
	      (nnheader-insert-file-contents nov))
	    (nnheader-nov-delete-outside-range
	     (car articles) (car (last articles)))
	    'nov))))))

(deffoo nnkiboze-request-article (article &optional newsgroup server buffer)
  (nnkiboze-possibly-change-group newsgroup)
  (if (not (numberp article))
      ;; This is a real kludge.  It might not work at times, but it
      ;; does no harm I think.  The only alternative is to offer no
      ;; article fetching by message-id at all.
      (nntp-request-article article newsgroup gnus-nntp-server buffer)
    (let* ((header (gnus-summary-article-header article))
	   (xref (mail-header-xref header))
	   num group)
      (unless xref
	(error "nnkiboze: No xref"))
      (unless (string-match " \\([^ ]+\\):\\([0-9]+\\)" xref)
	(error "nnkiboze: Malformed xref"))
      (setq num (string-to-number (match-string 2 xref))
	    group (match-string 1 xref))
      (or (with-current-buffer buffer
	    (or (and gnus-use-cache (gnus-cache-request-article num group))
		(gnus-agent-request-article num group)))
	  (gnus-request-article num group buffer)))))

(deffoo nnkiboze-request-scan (&optional group server)
  (nnkiboze-possibly-change-group group)
  (nnkiboze-generate-group (concat "nnkiboze:" group)))

(deffoo nnkiboze-request-group (group &optional server dont-check)
  "Make GROUP the current newsgroup."
  (nnkiboze-possibly-change-group group)
  (if dont-check
      t
    (let ((nov-file (nnkiboze-nov-file-name))
	  beg end total)
      (save-excursion
	(set-buffer nntp-server-buffer)
	(erase-buffer)
	(unless (file-exists-p nov-file)
	  (nnkiboze-request-scan group))
	(if (not (file-exists-p nov-file))
	    (nnheader-report 'nnkiboze "Can't select group %s" group)
	  (let ((nnheader-file-coding-system nnkiboze-file-coding-system))
	    (nnheader-insert-file-contents nov-file))
	  (if (zerop (buffer-size))
	      (nnheader-insert "211 0 0 0 %s\n" group)
	    (goto-char (point-min))
	    (when (looking-at "[0-9]+")
	      (setq beg (read (current-buffer))))
	    (goto-char (point-max))
	    (when (re-search-backward "^[0-9]" nil t)
	      (setq end (read (current-buffer))))
	    (setq total (count-lines (point-min) (point-max)))
	    (nnheader-insert "211 %d %d %d %s\n" total beg end group)))))))

(deffoo nnkiboze-close-group (group &optional server)
  (nnkiboze-possibly-change-group group)
  ;; Remove NOV lines of articles that are marked as read.
  (when (and (file-exists-p (nnkiboze-nov-file-name))
	     nnkiboze-remove-read-articles)
    (let ((coding-system-for-write nnkiboze-file-coding-system))
      (with-temp-file (nnkiboze-nov-file-name)
	(let ((cur (current-buffer))
	      (nnheader-file-coding-system nnkiboze-file-coding-system))
	  (nnheader-insert-file-contents (nnkiboze-nov-file-name))
	  (goto-char (point-min))
	  (while (not (eobp))
	    (if (not (gnus-article-read-p (read cur)))
		(forward-line 1)
	      (gnus-delete-line))))))
    (setq nnkiboze-current-group nil)))

(deffoo nnkiboze-open-server (server &optional defs)
  (unless (assq 'nnkiboze-regexp defs)
    (push `(nnkiboze-regexp ,server)
	  defs))
  (nnoo-change-server 'nnkiboze server defs))

(deffoo nnkiboze-request-delete-group (group &optional force server)
  (nnkiboze-possibly-change-group group)
  (when force
    (let ((files (nconc
		  (nnkiboze-score-file group)
		  (list (nnkiboze-nov-file-name)
			(nnkiboze-nov-file-name ".newsrc")))))
      (while files
	(and (file-exists-p (car files))
	     (file-writable-p (car files))
	     (delete-file (car files)))
	(setq files (cdr files)))))
  (setq nnkiboze-current-group nil)
  t)

(nnoo-define-skeleton nnkiboze)


;;; Internal functions.

(defun nnkiboze-possibly-change-group (group)
  (setq nnkiboze-current-group group))

(defun nnkiboze-prefixed-name (group)
  (gnus-group-prefixed-name group '(nnkiboze "")))

;;;###autoload
(defun nnkiboze-generate-groups ()
  "\"Usage: emacs -batch -l nnkiboze -f nnkiboze-generate-groups\".
Finds out what articles are to be part of the nnkiboze groups."
  (interactive)
  (let ((mail-sources nil)
	(gnus-use-dribble-file nil)
	(gnus-read-active-file t)
	(gnus-expert-user t))
    (gnus))
  (let* ((gnus-newsrc-alist (gnus-copy-sequence gnus-newsrc-alist))
	 (newsrc (cdr gnus-newsrc-alist))
	 gnus-newsrc-hashtb info)
    (gnus-make-hashtable-from-newsrc-alist)
    ;; We have copied all the newsrc alist info over to local copies
    ;; so that we can mess all we want with these lists.
    (while (setq info (pop newsrc))
      (when (string-match "nnkiboze" (gnus-info-group info))
	;; For each kiboze group, we call this function to generate
	;; it.
	(nnkiboze-generate-group (gnus-info-group info) t))))
  (save-excursion
    (set-buffer gnus-group-buffer)
    (gnus-group-list-groups)))

(defun nnkiboze-score-file (group)
  (list (expand-file-name
	 (concat (file-name-as-directory gnus-kill-files-directory)
		 (nnheader-translate-file-chars
		  (concat (nnkiboze-prefixed-name nnkiboze-current-group)
			  "." gnus-score-file-suffix))))))

(defun nnkiboze-generate-group (group &optional inhibit-list-groups)
  (let* ((info (gnus-get-info group))
	 (newsrc-file (concat nnkiboze-directory
			      (nnheader-translate-file-chars
			       (concat group ".newsrc"))))
	 (nov-file (concat nnkiboze-directory
			   (nnheader-translate-file-chars
			    (concat group ".nov"))))
	 method nnkiboze-newsrc gname newsrc active
	 ginfo lowest glevel orig-info nov-buffer
	 ;; Bind various things to nil to make group entry faster.
	 (gnus-expert-user t)
	 (gnus-large-newsgroup nil)
	 (gnus-score-find-score-files-function 'nnkiboze-score-file)
	 ;; Use only nnkiboze-score-file!
	 (gnus-score-use-all-scores nil)
	 (gnus-use-scoring t)
	 (gnus-verbose (min gnus-verbose 3))
	 gnus-select-group-hook gnus-summary-prepare-hook
	 gnus-thread-sort-functions gnus-show-threads
	 gnus-visual gnus-suppress-duplicates num-unread)
    (unless info
      (error "No such group: %s" group))
    ;; Load the kiboze newsrc file for this group.
    (when (file-exists-p newsrc-file)
      (load newsrc-file))
    (let ((coding-system-for-write nnkiboze-file-coding-system))
      (gnus-make-directory (file-name-directory nov-file))
      (with-temp-file nov-file
        (mm-disable-multibyte)
        (when (file-exists-p nov-file)
          (insert-file-contents nov-file))
        (setq nov-buffer (current-buffer))
        ;; Go through the active hashtb and add new all groups that match the
        ;; kiboze regexp.
        (mapatoms
         (lambda (group)
           (and (string-match nnkiboze-regexp
                              (setq gname (symbol-name group))) ; Match
                (not (assoc gname nnkiboze-newsrc)) ; It isn't registered
                (numberp (car (symbol-value group))) ; It is active
                (or (> nnkiboze-level 7)
                    (and (setq glevel
                               (gnus-info-level (gnus-get-info gname)))
                         (>= nnkiboze-level glevel)))
                (not (string-match "^nnkiboze:" gname)) ; Exclude kibozes
                (push (cons gname (1- (car (symbol-value group))))
                      nnkiboze-newsrc)))
         gnus-active-hashtb)
        ;; `newsrc' is set to the list of groups that possibly are
        ;; component groups to this kiboze group.  This list has elements
        ;; on the form `(GROUP . NUMBER)', where NUMBER is the highest
        ;; number that has been kibozed in GROUP in this kiboze group.
        (setq newsrc nnkiboze-newsrc)
        (while newsrc
          (if (not (setq active (gnus-active (caar newsrc))))
              ;; This group isn't active after all, so we remove it from
              ;; the list of component groups.
              (setq nnkiboze-newsrc (delq (car newsrc) nnkiboze-newsrc))
            (setq lowest (cdar newsrc))
            ;; Ok, we have a valid component group, so we jump to it.
            (switch-to-buffer gnus-group-buffer)
            (gnus-group-jump-to-group (caar newsrc))
            (gnus-message 3 "nnkiboze: Checking %s..." (caar newsrc))
            (setq ginfo (gnus-get-info (gnus-group-group-name))
                  orig-info (gnus-copy-sequence ginfo)
                  num-unread (gnus-group-unread (caar newsrc)))
            (unwind-protect
                (progn
                  ;; We set all list of article marks to nil.  Since we operate
                  ;; on copies of the real lists, we can destroy anything we
                  ;; want here.
                  (when (nth 3 ginfo)
                    (setcar (nthcdr 3 ginfo) nil))
                  ;; We set the list of read articles to be what we expect for
                  ;; this kiboze group -- either nil or `(1 . LOWEST)'.
                  (when ginfo
                    (setcar (nthcdr 2 ginfo)
                            (and (not (= lowest 1)) (cons 1 lowest))))
                  (when (and (or (not ginfo)
                                 (> (length (gnus-list-of-unread-articles
                                             (car ginfo)))
                                    0))
                             (progn
                               (ignore-errors
                                 (gnus-group-select-group nil))
                               (eq major-mode 'gnus-summary-mode)))
                    ;; We are now in the group where we want to be.
                    (setq method (gnus-find-method-for-group
                                  gnus-newsgroup-name))
                    (when (eq method gnus-select-method)
                      (setq method nil))
                    ;; We go through the list of scored articles.
                    (while gnus-newsgroup-scored
                      (when (> (caar gnus-newsgroup-scored) lowest)
                        ;; If it has a good score, then we enter this article
                        ;; into the kiboze group.
                        (nnkiboze-enter-nov
                         nov-buffer
                         (gnus-summary-article-header
                          (caar gnus-newsgroup-scored))
                         gnus-newsgroup-name))
                      (setq gnus-newsgroup-scored (cdr gnus-newsgroup-scored)))
                    ;; That's it.  We exit this group.
                    (when (eq major-mode 'gnus-summary-mode)
                      (kill-buffer (current-buffer)))))
              ;; Restore the proper info.
              (when ginfo
                (setcdr ginfo (cdr orig-info)))
              (setcar (gnus-group-entry (caar newsrc)) num-unread)))
          (setcdr (car newsrc) (cdr active))
          (gnus-message 3 "nnkiboze: Checking %s...done" (caar newsrc))
          (setq newsrc (cdr newsrc)))))
    ;; We save the kiboze newsrc for this group.
    (gnus-make-directory (file-name-directory newsrc-file))
    (with-temp-file newsrc-file
      (mm-disable-multibyte)
      (insert "(setq nnkiboze-newsrc '")
      (gnus-prin1 nnkiboze-newsrc)
      (insert ")\n"))
  (unless inhibit-list-groups
    (save-excursion
      (set-buffer gnus-group-buffer)
      (gnus-group-list-groups)))
  t))

(defun nnkiboze-enter-nov (buffer header group)
  (save-excursion
    (set-buffer buffer)
    (goto-char (point-max))
    (let ((prefix (gnus-group-real-prefix group))
	  (oheader (copy-sequence header))
	  article)
      (if (zerop (forward-line -1))
	  (progn
	    (setq article (1+ (read (current-buffer))))
	    (forward-line 1))
	(setq article 1))
      (mail-header-set-number oheader article)
      (with-temp-buffer
	(insert (or (mail-header-xref oheader) ""))
	(goto-char (point-min))
	(if (re-search-forward " [^ ]+:[0-9]+" nil t)
	    (goto-char (match-beginning 0))
	  (or (eobp) (forward-char 1)))
	;; The first Xref has to be the group this article
	;; really came for - this is the article nnkiboze
	;; will request when it is asked for the article.
	(insert " " group ":"
		(int-to-string (mail-header-number header)) " ")
	(while (re-search-forward " [^ ]+:[0-9]+" nil t)
	  (goto-char (1+ (match-beginning 0)))
	  (insert prefix))
	(mail-header-set-xref oheader (buffer-string)))
      (nnheader-insert-nov oheader))))

(defun nnkiboze-nov-file-name (&optional suffix)
  (concat (file-name-as-directory nnkiboze-directory)
	  (nnheader-translate-file-chars
	   (concat (nnkiboze-prefixed-name nnkiboze-current-group)
		   (or suffix ".nov")))))

(provide 'nnkiboze)

;; arch-tag: 66068271-bdc9-4801-bcde-779702e73a05
;;; nnkiboze.el ends here
