;;; nndoc.el --- single file access for Gnus

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

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;;	Masanobu UMEDA <umerin@flab.flab.fujitsu.junet>
;; 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:

;; For Outlook mail boxes format, see http://mbx2mbox.sourceforge.net/

;;; Code:

(require 'nnheader)
(require 'message)
(require 'nnmail)
(require 'nnoo)
(require 'gnus-util)
(require 'mm-util)
(eval-when-compile (require 'cl))

(nnoo-declare nndoc)

(defvoo nndoc-article-type 'guess
  "*Type of the file.
One of `mbox', `babyl', `digest', `news', `rnews', `mmdf', `forward',
`rfc934', `rfc822-forward', `mime-parts', `standard-digest',
`slack-digest', `clari-briefs', `nsmail', `outlook', `oe-dbx',
`mailman', `exim-bounce', or `guess'.")

(defvoo nndoc-post-type 'mail
  "*Whether the nndoc group is `mail' or `post'.")

(defvoo nndoc-open-document-hook 'nnheader-ms-strip-cr
  "Hook run after opening a document.
The default function removes all trailing carriage returns
from the document.")

(defvar nndoc-type-alist
  `((mmdf
     (article-begin .  "^\^A\^A\^A\^A\n")
     (body-end .  "^\^A\^A\^A\^A\n"))
    (debbugs-db
     (file-begin    . "^\005")
     (article-begin . "^[\005\007]\n")
     (body-end      . "^\003"))
    (mime-digest
     (article-begin . "")
     (head-begin . "^ ?\n")
     (head-end . "^ ?$")
     (body-end . "")
     (file-end . "")
     (subtype digest guess))
    (nsmail
     (article-begin .  "^From - "))
    (news
     (article-begin . "^Path:"))
    (rnews
     (article-begin . "^#! *rnews +\\([0-9]+\\) *\n")
     (body-end-function . nndoc-rnews-body-end))
    (mbox
     (article-begin-function . nndoc-mbox-article-begin)
     (body-end-function . nndoc-mbox-body-end))
    (babyl
     (article-begin . "\^_\^L *\n")
     (body-end . "\^_")
     (body-begin-function . nndoc-babyl-body-begin)
     (head-begin-function . nndoc-babyl-head-begin))
    (mime-parts
     (generate-head-function . nndoc-generate-mime-parts-head)
     (article-transform-function . nndoc-transform-mime-parts))
    (exim-bounce
     (article-begin . "^------ This is a copy of the message, including all the headers. ------\n\n")
     (body-end-function . nndoc-exim-bounce-body-end-function))
    (rfc934
     (article-begin . "^--.*\n+")
     (body-end . "^--.*$")
     (prepare-body-function . nndoc-unquote-dashes))
    (mailman
     (article-begin . "^--__--__--\n\nMessage:")
     (body-end . "^--__--__--$")
     (prepare-body-function . nndoc-unquote-dashes))
    (clari-briefs
     (article-begin . "^ \\*")
     (body-end . "^\t------*[ \t]^*\n^ \\*")
     (body-begin . "^\t")
     (head-end . "^\t")
     (generate-head-function . nndoc-generate-clari-briefs-head)
     (article-transform-function . nndoc-transform-clari-briefs))

    (standard-digest
     (first-article . ,(concat "^" (make-string 70 ?-) "\n *\n+"))
     (article-begin . ,(concat "^\n" (make-string 30 ?-) "\n *\n+"))
     (prepare-body-function . nndoc-unquote-dashes)
     (body-end-function . nndoc-digest-body-end)
     (head-end . "^ *$")
     (body-begin . "^ *\n")
     (file-end . "^End of .*digest.*[0-9].*\n\\*\\*\\|^End of.*Digest *$")
     (subtype digest guess))
    (slack-digest
     (article-begin . "^------------------------------*[\n \t]+")
     (head-end . "^ ?$")
     (body-end-function . nndoc-digest-body-end)
     (body-begin . "^ ?$")
     (file-end . "^End of")
     (prepare-body-function . nndoc-unquote-dashes)
     (subtype digest guess))
    (google
     (pre-dissection-function . nndoc-decode-content-transfer-encoding)
     (article-begin . "^== [0-9]+ of [0-9]+ ==$")
     (head-begin . "^Date:")
     (head-end . "^$")
     (body-end-function . nndoc-digest-body-end)
     (body-begin . "^$")
     (file-end . "^==============================================================================$")
     (prepare-body-function . nndoc-unquote-dashes)
     (subtype digest guess))
    (lanl-gov-announce
     (article-begin . "^\\\\\\\\\n")
     (head-begin . "^\\(Paper.*:\\|arXiv:\\)")
     (head-end   . "\\(^\\\\\\\\.*\n\\|-----------------\\)")
     (body-begin . "")
     (body-end   . "\\(-------------------------------------------------\\|%-%-%-%-%-%-%-%-%-%-%-%-%-%-\\|%%--%%--%%--%%--%%--%%--%%--%%--\\|%%%---%%%---%%%---%%%---\\)")
     (file-end   . "\\(^Title: Recent Seminal\\|%%%---%%%---%%%---%%%---\\)")
     (generate-head-function . nndoc-generate-lanl-gov-head)
     (article-transform-function . nndoc-transform-lanl-gov-announce)
     (subtype preprints guess))
    (git
     (file-begin . "\n- Log ---.*")
     (article-begin . "^commit ")
     (head-begin . "^Author: ")
     (body-begin . "^$")
     (file-end . "\n-----------------------------------------------------------------------")
     (article-transform-function . nndoc-transform-git-article)
     (header-transform-function . nndoc-transform-git-headers))
    (rfc822-forward
     (article-begin . "^\n+")
     (body-end-function . nndoc-rfc822-forward-body-end-function)
     (generate-head-function . nndoc-rfc822-forward-generate-head)
     (generate-article-function . nndoc-rfc822-forward-generate-article))
    (outlook
     (article-begin-function . nndoc-outlook-article-begin)
     (body-end .  "\0"))
    (oe-dbx  ;; Outlook Express DBX format
     (dissection-function . nndoc-oe-dbx-dissection)
     (generate-head-function . nndoc-oe-dbx-generate-head)
     (generate-article-function . nndoc-oe-dbx-generate-article))
    (forward
     (article-begin . "^-+ \\(Start of \\)?forwarded message.*\n+")
     (body-end . "^-+ End \\(of \\)?forwarded message.*$")
     (prepare-body-function . nndoc-unquote-dashes))
    (mail-in-mail ;; Wild guess on mailer daemon's messages or others
     (article-begin-function . nndoc-mail-in-mail-article-begin))
    (guess
     (guess . t)
     (subtype nil))
    (digest
     (guess . t)
     (subtype nil))
    (preprints
     (guess . t)
     (subtype nil))))

(defvar nndoc-binary-file-names ".[Dd][Bb][Xx]$"
  "Regexp for binary nndoc file names.")


(defvoo nndoc-file-begin nil)
(defvoo nndoc-first-article nil)
(defvoo nndoc-article-begin nil)
(defvoo nndoc-head-begin nil)
(defvoo nndoc-head-end nil)
(defvoo nndoc-file-end nil)
(defvoo nndoc-body-begin nil)
(defvoo nndoc-body-end-function nil)
(defvoo nndoc-body-begin-function nil)
(defvoo nndoc-head-begin-function nil)
(defvoo nndoc-body-end nil)
;; nndoc-dissection-alist is a list of sublists.  Each sublist holds the
;; following items.  ARTICLE acts as the association key and is an ordinal
;; starting at 1.  HEAD-BEGIN [0], HEAD-END [1], BODY-BEGIN [2] and BODY-END
;; [3] are positions in the `nndoc' buffer.  LINE-COUNT [4] is a count of
;; lines in the body.  For MIME dissections only, ARTICLE-INSERT [5] and
;; SUMMARY-INSERT [6] give headers to insert for full article or summary line
;; generation, respectively.  Other headers usually follow directly from the
;; buffer.  Value nil means no insert.
(defvoo nndoc-dissection-alist nil)
(defvoo nndoc-prepare-body-function nil)
(defvoo nndoc-generate-head-function nil)
(defvoo nndoc-article-transform-function nil)
(defvoo nndoc-header-transform-function nil)
(defvoo nndoc-article-begin-function nil)
(defvoo nndoc-generate-article-function nil)
(defvoo nndoc-dissection-function nil)
(defvoo nndoc-pre-dissection-function nil)

(defvoo nndoc-status-string "")
(defvoo nndoc-group-alist nil)
(defvoo nndoc-current-buffer nil
  "Current nndoc news buffer.")
(defvoo nndoc-address nil)

(defconst nndoc-version "nndoc 1.0"
  "nndoc version.")



;;; Interface functions

(nnoo-define-basics nndoc)

(deffoo nndoc-retrieve-headers (articles &optional newsgroup server fetch-old)
  (when (nndoc-possibly-change-buffer newsgroup server)
    (with-current-buffer nntp-server-buffer
      (erase-buffer)
      (let (article entry)
	(if (stringp (car articles))
	    'headers
	  (while articles
	    (when (setq entry (cdr (assq (setq article (pop articles))
					 nndoc-dissection-alist)))
	      (let ((start (point)))
		(insert (format "221 %d Article retrieved.\n" article))
		(if nndoc-generate-head-function
		    (funcall nndoc-generate-head-function article)
		  (insert-buffer-substring
		   nndoc-current-buffer (car entry) (nth 1 entry)))
		(goto-char (point-max))
		(unless (eq (char-after (1- (point))) ?\n)
		  (insert "\n"))
		(insert (format "Lines: %d\n" (nth 4 entry)))
		(insert ".\n")
		(when nndoc-header-transform-function
		  (save-excursion
		    (save-restriction
		      (narrow-to-region start (point))
		      (funcall nndoc-header-transform-function entry)))))))
	  (nnheader-fold-continuation-lines)
	  'headers)))))

(deffoo nndoc-request-article (article &optional newsgroup server buffer)
  (nndoc-possibly-change-buffer newsgroup server)
  (save-excursion
    (let ((buffer (or buffer nntp-server-buffer))
	  (entry (cdr (assq article nndoc-dissection-alist)))
	  beg)
      (set-buffer buffer)
      (erase-buffer)
      (when entry
	(cond
	 ((stringp article) nil)
	 (nndoc-generate-article-function
	  (funcall nndoc-generate-article-function article))
	 (t
	  (insert-buffer-substring
	   nndoc-current-buffer (car entry) (nth 1 entry))
	  (insert "\n")
	  (setq beg (point))
	  (insert-buffer-substring
	   nndoc-current-buffer (nth 2 entry) (nth 3 entry))
	  (goto-char beg)
	  (when nndoc-prepare-body-function
	    (funcall nndoc-prepare-body-function))
	  (when nndoc-article-transform-function
	    (funcall nndoc-article-transform-function article))
	  t))))))

(deffoo nndoc-request-group (group &optional server dont-check info)
  "Select news GROUP."
  (let (number)
    (cond
     ((not (nndoc-possibly-change-buffer group server))
      (nnheader-report 'nndoc "No such file or buffer: %s"
		       nndoc-address))
     (dont-check
      (nnheader-report 'nndoc "Selected group %s" group)
      t)
     ((zerop (setq number (length nndoc-dissection-alist)))
      (nndoc-close-group group)
      (nnheader-report 'nndoc "No articles in group %s" group))
     (t
      (nnheader-insert "211 %d %d %d %s\n" number 1 number group)))))

(deffoo nndoc-retrieve-groups (groups &optional server)
  (dolist (group groups)
    (nndoc-request-group group server))
  t)

(deffoo nndoc-request-type (group &optional article)
  (cond ((not article) 'unknown)
	(nndoc-post-type nndoc-post-type)
	(t 'unknown)))

(deffoo nndoc-close-group (group &optional server)
  (nndoc-possibly-change-buffer group server)
  (and nndoc-current-buffer
       (buffer-name nndoc-current-buffer)
       (kill-buffer nndoc-current-buffer))
  (setq nndoc-group-alist (delq (assoc group nndoc-group-alist)
				nndoc-group-alist))
  (setq nndoc-current-buffer nil)
  (nnoo-close-server 'nndoc server)
  (setq nndoc-dissection-alist nil)
  t)

(deffoo nndoc-request-list (&optional server)
  t)

(deffoo nndoc-request-newgroups (date &optional server)
  nil)

(deffoo nndoc-request-list-newsgroups (&optional server)
  nil)


;;; Internal functions.

(defun nndoc-possibly-change-buffer (group source)
  (let (buf)
    (cond
     ;; The current buffer is this group's buffer.
     ((and nndoc-current-buffer
	   (buffer-name nndoc-current-buffer)
	   (eq nndoc-current-buffer
	       (setq buf (cdr (assoc group nndoc-group-alist))))))
     ;; We change buffers by taking an old from the group alist.
     ;; `source' is either a string (a file name) or a buffer object.
     (buf
      (setq nndoc-current-buffer buf))
     ;; It's a totally new group.
     ((or (and (bufferp nndoc-address)
	       (buffer-name nndoc-address))
	  (and (stringp nndoc-address)
	       (file-exists-p nndoc-address)
	       (not (file-directory-p nndoc-address))))
      (push (cons group (setq nndoc-current-buffer
			      (get-buffer-create
			       (concat " *nndoc " group "*"))))
	    nndoc-group-alist)
      (setq nndoc-dissection-alist nil)
      (with-current-buffer nndoc-current-buffer
	(erase-buffer)
	(if (and (stringp nndoc-address)
		 (string-match nndoc-binary-file-names nndoc-address))
	    (let ((coding-system-for-read 'binary))
	      (mm-insert-file-contents nndoc-address))
	  (if (stringp nndoc-address)
	      (nnheader-insert-file-contents nndoc-address)
	    (insert-buffer-substring nndoc-address))
	  (run-hooks 'nndoc-open-document-hook)))))
    ;; Initialize the nndoc structures according to this new document.
    (when (and nndoc-current-buffer
	       (not nndoc-dissection-alist))
      (with-current-buffer nndoc-current-buffer
	(nndoc-set-delims)
	(if (eq nndoc-article-type 'mime-parts)
	    (nndoc-dissect-mime-parts)
	  (nndoc-dissect-buffer))))
    (unless nndoc-current-buffer
      (nndoc-close-server))
    ;; Return whether we managed to select a file.
    nndoc-current-buffer))

;;;
;;; Deciding what document type we have
;;;

(defun nndoc-set-delims ()
  "Set the nndoc delimiter variables according to the type of the document."
  (let ((vars '(nndoc-file-begin
		nndoc-first-article
		nndoc-article-begin-function
		nndoc-head-begin nndoc-head-end
		nndoc-file-end nndoc-article-begin
		nndoc-body-begin nndoc-body-end-function nndoc-body-end
		nndoc-prepare-body-function nndoc-article-transform-function
		nndoc-header-transform-function
		nndoc-generate-head-function nndoc-body-begin-function
		nndoc-head-begin-function
		nndoc-generate-article-function
		nndoc-dissection-function
		nndoc-pre-dissection-function)))
    (while vars
      (set (pop vars) nil)))
  (let (defs)
    ;; Guess away until we find the real file type.
    (while (assq 'guess (setq defs (cdr (assq nndoc-article-type
					      nndoc-type-alist))))
      (setq nndoc-article-type (nndoc-guess-type nndoc-article-type)))
    ;; Set the nndoc variables.
    (while defs
      (set (intern (format "nndoc-%s" (caar defs)))
	   (cdr (pop defs))))))

(defun nndoc-guess-type (subtype)
  (let ((alist nndoc-type-alist)
	results result entry)
    (while (and (not result)
		(setq entry (pop alist)))
      (when (memq subtype (or (cdr (assq 'subtype entry)) '(guess)))
	(goto-char (point-min))
	;; Remove blank lines.
	(while (eq (following-char) ?\n)
	  (delete-char 1))
	(when (numberp (setq result (funcall (intern
					      (format "nndoc-%s-type-p"
						      (car entry))))))
	  (push (cons result entry) results)
	  (setq result nil))))
    (unless (or result results)
      (error "Document is not of any recognized type"))
    (if result
	(car entry)
      (cadar (last (sort results 'car-less-than-car))))))

;;;
;;; Built-in type predicates and functions
;;;

(defun nndoc-mbox-type-p ()
  (when (looking-at message-unix-mail-delimiter)
    t))

(defun nndoc-mbox-article-begin ()
  (when (re-search-forward (concat "^" message-unix-mail-delimiter) nil t)
    (goto-char (match-beginning 0))))

(defun nndoc-mbox-body-end ()
  (let ((beg (point))
	len end)
    (when
	(save-excursion
	  (and (re-search-backward
		(concat "^" message-unix-mail-delimiter) nil t)
	       (setq end (point))
	       (search-forward "\n\n" beg t)
	       (re-search-backward
		"^Content-Length:[ \t]*\\([0-9]+\\) *$" end t)
	       (setq len (string-to-number (match-string 1)))
	       (search-forward "\n\n" beg t)
	       (unless (= (setq len (+ (point) len)) (point-max))
		 (and (< len (point-max))
		      (goto-char len)
		      (looking-at message-unix-mail-delimiter)))))
      (goto-char len))))

(defun nndoc-mmdf-type-p ()
  (when (looking-at "\^A\^A\^A\^A$")
    t))

(defun nndoc-debbugs-db-type-p ()
  (when (looking-at "\006$")
    t))

(defun nndoc-news-type-p ()
  (when (looking-at "^Path:.*\n")
    t))

(defun nndoc-rnews-type-p ()
  (when (looking-at "#! *rnews")
    t))

(defun nndoc-rnews-body-end ()
  (and (re-search-backward nndoc-article-begin nil t)
       (forward-line 1)
       (goto-char (+ (point) (string-to-number (match-string 1))))))

(defun nndoc-google-type-p ()
  (when (re-search-forward "^=3D=3D 1 of [0-9]+ =3D=3D$" nil t)
    t))

(defun nndoc-decode-content-transfer-encoding ()
  (let ((encoding
	 (save-restriction
	   (message-narrow-to-head)
	   (message-fetch-field "content-transfer-encoding"))))
    (when (and encoding
	       (search-forward "\n\n" nil t))
      (save-restriction
	(narrow-to-region (point) (point-max))
	(mm-decode-content-transfer-encoding
	 (intern (downcase (mail-header-strip encoding))))))))

(defun nndoc-babyl-type-p ()
  (when (re-search-forward "\^_\^L *\n" nil t)
    t))

(defun nndoc-babyl-body-begin ()
  (re-search-forward "^\n" nil t)
  (when (looking-at "\\*\\*\\* EOOH \\*\\*\\*")
    (let ((next (or (save-excursion
		      (re-search-forward nndoc-article-begin nil t))
		    (point-max))))
      (unless (re-search-forward "^\n" next t)
	(goto-char next)
	(forward-line -1)
	(insert "\n")
	(forward-line -1)))))

(defun nndoc-babyl-head-begin ()
  (when (re-search-forward "^[0-9].*\n" nil t)
    (when (looking-at "\\*\\*\\* EOOH \\*\\*\\*")
      (forward-line 1))
    t))

(defun nndoc-forward-type-p ()
  (when (and (re-search-forward "^-+ \\(Start of \\)?forwarded message.*\n+"
				nil t)
	     (looking-at "[\r\n]*[a-zA-Z][a-zA-Z0-9-]*:\\|^>?From "))
    t))

(defun nndoc-rfc934-type-p ()
  (when (and (re-search-forward "^-+ Start of forwarded.*\n+" nil t)
	     (not (re-search-forward "^Subject:.*digest" nil t))
	     (not (re-search-backward "^From:" nil t 2))
	     (not (re-search-forward "^From:" nil t 2)))
    t))

(defun nndoc-mailman-type-p ()
  (when (re-search-forward "^--__--__--\n+" nil t)
    t))

(defun nndoc-rfc822-forward-type-p ()
  (save-restriction
    (message-narrow-to-head)
    (when (re-search-forward "^Content-Type: *message/rfc822" nil t)
      t)))

(defun nndoc-rfc822-forward-body-end-function ()
  (goto-char (point-max)))

(defun nndoc-rfc822-forward-generate-article (article &optional head)
  (let ((entry (cdr (assq article nndoc-dissection-alist)))
	(begin (point))
	encoding)
    (with-current-buffer nndoc-current-buffer
      (save-restriction
	(message-narrow-to-head)
	(setq encoding (message-fetch-field "content-transfer-encoding"))))
    (insert-buffer-substring nndoc-current-buffer (car entry) (nth 3 entry))
    (when encoding
      (save-restriction
	(narrow-to-region begin (point-max))
	(mm-decode-content-transfer-encoding
	 (intern (downcase (mail-header-strip encoding))))))
    (when head
      (goto-char begin)
      (when (search-forward "\n\n" nil t)
	(delete-region (1- (point)) (point-max)))))
  t)

(defun nndoc-rfc822-forward-generate-head (article)
  (nndoc-rfc822-forward-generate-article article 'head))

(defun nndoc-mime-parts-type-p ()
  (let ((case-fold-search t)
	(limit (search-forward "\n\n" nil t)))
    (goto-char (point-min))
    (when (and limit
	       (re-search-forward
		(concat "\
^Content-Type:[ \t]*multipart/[a-z]+ *; *\\(\\(\n[ \t]\\)?.*;\\)*"
			"\\(\n[ \t]\\)?[ \t]*boundary=\"?[^\"\n]*[^\" \t\n]")
		limit t))
      t)))

(defun nndoc-transform-mime-parts (article)
  (let* ((entry (cdr (assq article nndoc-dissection-alist)))
	 (headers (nth 5 entry)))
    (when headers
      (goto-char (point-min))
      (insert headers))))

(defun nndoc-generate-mime-parts-head (article)
  (let* ((entry (cdr (assq article nndoc-dissection-alist)))
	 (headers (nth 6 entry)))
    (save-restriction
      (narrow-to-region (point) (point))
      (insert-buffer-substring
       nndoc-current-buffer (car entry) (nth 1 entry))
      (goto-char (point-max)))
    (when headers
      (insert headers))))

(defun nndoc-clari-briefs-type-p ()
  (when (let ((case-fold-search nil))
	  (re-search-forward "^\t[^a-z]+ ([^a-z]+) --" nil t))
    t))

(defun nndoc-transform-clari-briefs (article)
  (goto-char (point-min))
  (when (looking-at " *\\*\\(.*\\)\n")
    (replace-match "" t t))
  (nndoc-generate-clari-briefs-head article))

(defun nndoc-generate-clari-briefs-head (article)
  (let ((entry (cdr (assq article nndoc-dissection-alist)))
	subject from)
    (with-current-buffer nndoc-current-buffer
      (save-restriction
	(narrow-to-region (car entry) (nth 3 entry))
	(goto-char (point-min))
	(when (looking-at " *\\*\\(.*\\)$")
	  (setq subject (match-string 1))
	  (when (string-match "[ \t]+$" subject)
	    (setq subject (substring subject 0 (match-beginning 0)))))
	(when
	    (let ((case-fold-search nil))
	      (re-search-forward
	       "^\t\\([^a-z]+\\(,[^(]+\\)? ([^a-z]+)\\) --" nil t))
	  (setq from (match-string 1)))))
    (insert "From: " "clari@clari.net (" (or from "unknown") ")"
	    "\nSubject: " (or subject "(no subject)") "\n")))

(defun nndoc-exim-bounce-type-p ()
  (and (re-search-forward "^------ This is a copy of the message, including all the headers. ------" nil t)
       t))

(defun nndoc-exim-bounce-body-end-function ()
  (goto-char (point-max)))


(defun nndoc-mime-digest-type-p ()
  (let ((case-fold-search t)
	boundary-id b-delimiter entry)
    (when (and
	   (re-search-forward
	    (concat "^Content-Type: *multipart/digest;[ \t\n]*[ \t]"
		    "boundary=\"?\\([^\"\n]*[^\" \t\n]\\)")
	    nil t)
	   (match-beginning 1))
      (setq boundary-id (match-string 1)
	    b-delimiter (concat "\n--" boundary-id "[ \t]*$"))
      (setq entry (assq 'mime-digest nndoc-type-alist))
      (setcdr entry
	      (list
	       (cons 'head-begin "^ ?\n")
	       (cons 'head-end "^ ?$")
	       (cons 'body-begin "^ ?\n")
	       (cons 'article-begin b-delimiter)
	       (cons 'body-end-function 'nndoc-digest-body-end)
	       (cons 'file-end (concat "^--" boundary-id "--[ \t]*$"))))
      t)))

(defun nndoc-standard-digest-type-p ()
  (when (and (re-search-forward (concat "^" (make-string 70 ?-) "\n\n") nil t)
	     (re-search-forward
	      (concat "\n\n" (make-string 30 ?-) "\n\n") nil t))
    t))

(defun nndoc-digest-body-end ()
  (and (re-search-forward nndoc-article-begin nil t)
       (goto-char (match-beginning 0))))

(defun nndoc-slack-digest-type-p ()
  0)

(defun nndoc-git-type-p ()
  (and (search-forward "\n- Log ---" nil t)
       (search-forward "\ncommit " nil t)
       (search-forward "\nAuthor: " nil t)))

(defun nndoc-transform-git-article (article)
  (goto-char (point-min))
  (when (re-search-forward "^Author: " nil t)
    (replace-match "From: " t t)))

(defun nndoc-transform-git-headers (entry)
  (goto-char (point-min))
  (when (re-search-forward "^Author: " nil t)
    (replace-match "From: " t t))
  (let (subject)
    (with-current-buffer nndoc-current-buffer
      (goto-char (car entry))
      (when (search-forward "\n\n" nil t)
	(setq subject (buffer-substring (point) (line-end-position)))))
    (when subject
      (goto-char (point-min))
      (forward-line 1)
      (insert (format "Subject: %s\n" subject)))))

(defun nndoc-lanl-gov-announce-type-p ()
  (when (let ((case-fold-search nil))
	  (re-search-forward "^\\\\\\\\\n\\(Paper\\( (\\*cross-listing\\*)\\)?: [a-zA-Z-\\.]+/[0-9]+\\|arXiv:\\)" nil t))
    t))

(defun nndoc-transform-lanl-gov-announce (article)
  (let ((case-fold-search nil))
    (goto-char (point-max))
    (when (re-search-backward "^\\\\\\\\ +( *\\([^ ]*\\) , *\\([^ ]*\\))" nil t)
      (replace-match "\n\nGet it at \\1 (\\2)" t nil))
    (goto-char (point-min))
    (while (re-search-forward "^\\\\\\\\$" nil t)
      (replace-match "" t nil))
    (goto-char (point-min))
    (when (re-search-forward "^replaced with revised version +\\(.*[^ ]\\) +" nil t)
      (replace-match "Date: \\1 (revised) " t nil))
    (goto-char (point-min))
    (unless (re-search-forward "^From" nil t)
      (goto-char (point-min))
      (when (re-search-forward "^Authors?: \\(.*\\)" nil t)
	(goto-char (point-min))
	(insert "From: " (match-string 1) "\n")))
    (when (re-search-forward "^arXiv:" nil t)
      (replace-match "Paper: arXiv:" t nil))))

(defun nndoc-generate-lanl-gov-head (article)
  (let ((entry (cdr (assq article nndoc-dissection-alist)))
	(from "<no address given>")
	subject date)
    (with-current-buffer nndoc-current-buffer
      (save-restriction
	(narrow-to-region (car entry) (nth 1 entry))
	(goto-char (point-min))
	(when (looking-at "^\\(Paper.*: \\|arXiv:\\)\\([0-9a-zA-Z-\\./]+\\)")
	  (setq subject (concat " (" (match-string 2) ")"))
	  (when (re-search-forward "^From: \\(.*\\)" nil t)
	    (setq from (concat "<"
			       (cadr (funcall gnus-extract-address-components
					      (match-string 1))) ">")))
	  (if (re-search-forward "^Date: +\\([^(]*\\)" nil t)
	      (setq date (match-string 1))
	    (when (re-search-forward "^replaced with revised version +\\([^(]*\\)" nil t)
	      (setq date (match-string 1))))
	  (when (re-search-forward "^Title: \\([^\f]*\\)\nAuthors?: \\(.*\\)"
				   nil t)
	    (setq subject (concat (match-string 1) subject))
	    (setq from (concat (match-string 2) " " from))))))
    (while (and from (string-match "([^)]*)" from))
      (setq from (replace-match "" t t from)))
    (insert "From: "  (or from "unknown")
	    "\nSubject: " (or subject "(no subject)") "\n")
    (if date (insert "Date: " date))))

(defun nndoc-nsmail-type-p ()
  (when (looking-at "From - ")
    t))

(defun nndoc-outlook-article-begin ()
  (prog1 (re-search-forward "From:\\|Received:" nil t)
    (goto-char (match-beginning 0))))

(defun nndoc-outlook-type-p ()
  ;; FIXME: Is JMF the magic of outlook mailbox? -- ShengHuo.
  (looking-at "JMF"))

(defun nndoc-oe-dbx-type-p ()
  (looking-at (mm-string-to-multibyte "\317\255\022\376")))

(defun nndoc-read-little-endian ()
  (+ (prog1 (char-after) (forward-char 1))
     (lsh (prog1 (char-after) (forward-char 1)) 8)
     (lsh (prog1 (char-after) (forward-char 1)) 16)
     (lsh (prog1 (char-after) (forward-char 1)) 24)))

(defun nndoc-oe-dbx-decode-block ()
  (list
   (nndoc-read-little-endian)   ;; this address
   (nndoc-read-little-endian)   ;; next address offset
   (nndoc-read-little-endian)   ;; blocksize
   (nndoc-read-little-endian))) ;; next address

(defun nndoc-oe-dbx-dissection ()
  (let ((i 0) blk p tp)
    (goto-char 60117) ;; 0x0000EAD4+1
    (setq p (point))
    (unless (eobp)
      (setq blk (nndoc-oe-dbx-decode-block)))
    (while (and blk (> (car blk) 0) (or (zerop (nth 3 blk))
					(> (nth 3 blk) p)))
      (push (list (incf i) p nil nil nil 0) nndoc-dissection-alist)
      (while (and (> (car blk) 0) (> (nth 3 blk) p))
	(goto-char (1+ (nth 3 blk)))
	(setq blk (nndoc-oe-dbx-decode-block)))
      (if (or (<= (car blk) p)
	      (<= (nth 1 blk) 0)
	      (not (zerop (nth 3 blk))))
	  (setq blk nil)
	(setq tp (+ (car blk) (nth 1 blk) 17))
	(if (or (<= tp p) (>= tp (point-max)))
	    (setq blk nil)
	  (goto-char tp)
	  (setq p tp
		blk (nndoc-oe-dbx-decode-block)))))))

(defun nndoc-oe-dbx-generate-article (article &optional head)
  (let ((entry (cdr (assq article nndoc-dissection-alist)))
	(cur (current-buffer))
	(begin (point))
	blk p)
    (with-current-buffer nndoc-current-buffer
      (setq p (car entry))
      (while (> p (point-min))
	(goto-char p)
	(setq blk (nndoc-oe-dbx-decode-block))
	(setq p (point))
	(with-current-buffer cur
	  (insert-buffer-substring nndoc-current-buffer p (+ p (nth 2 blk))))
	(setq p (1+ (nth 3 blk)))))
    (goto-char begin)
    (while (re-search-forward "\r$" nil t)
      (delete-char -1))
    (when head
      (goto-char begin)
      (when (search-forward "\n\n" nil t)
	(setcar (cddddr entry) (count-lines (point) (point-max)))
	(delete-region (1- (point)) (point-max))))
    t))

(defun nndoc-oe-dbx-generate-head (article)
  (nndoc-oe-dbx-generate-article article 'head))

(defun nndoc-mail-in-mail-type-p ()
  (let (found)
    (save-excursion
      (catch 'done
	(while (re-search-forward "\n\n[-A-Za-z0-9]+:" nil t)
	  (setq found 0)
	  (forward-line)
	  (while (looking-at "[ \t]\\|[-A-Za-z0-9]+:")
	    (if (looking-at "[-A-Za-z0-9]+:")
		(setq found (1+ found)))
	    (forward-line))
	  (if (and (> found 0) (looking-at "\n"))
	      (throw 'done 9999)))
	nil))))

(defun nndoc-mail-in-mail-article-begin ()
  (let (point found)
    (if (catch 'done
	  (while (re-search-forward "\n\n\\([-A-Za-z0-9]+:\\)" nil t)
	    (setq found 0)
	    (setq point (match-beginning 1))
	    (forward-line)
	    (while (looking-at "[ \t]\\|[-A-Za-z0-9]+:")
	      (if (looking-at "[-A-Za-z0-9]+:")
		  (setq found (1+ found)))
	      (forward-line))
	    (if (and (> found 0) (looking-at "\n"))
		(throw 'done t)))
	  nil)
	(goto-char point))))

(deffoo nndoc-request-accept-article (group &optional server last)
  nil)

;;;
;;; Functions for dissecting the documents
;;;

(defun nndoc-search (regexp)
  (prog1
      (re-search-forward regexp nil t)
    (beginning-of-line)))

(defun nndoc-dissect-buffer ()
  "Go through the document and partition it into heads/bodies/articles."
  (let ((i 0)
	(first t)
	art-begin head-begin head-end body-begin body-end)
    (setq nndoc-dissection-alist nil)
    (with-current-buffer nndoc-current-buffer
      (goto-char (point-min))
      ;; Remove blank lines.
      (while (eq (following-char) ?\n)
	(delete-char 1))
      (when nndoc-pre-dissection-function
	(save-excursion
	  (funcall nndoc-pre-dissection-function)))
      (if nndoc-dissection-function
	  (funcall nndoc-dissection-function)
	;; Find the beginning of the file.
	(when nndoc-file-begin
	  (nndoc-search nndoc-file-begin))
	;; Go through the file.
	(while (if (and first nndoc-first-article)
		   (nndoc-search nndoc-first-article)
		 (if art-begin
		     (goto-char art-begin)
		   (nndoc-article-begin)))
	  (setq first nil
		art-begin nil)
	  (cond (nndoc-head-begin-function
		 (funcall nndoc-head-begin-function))
		(nndoc-head-begin
		 (nndoc-search nndoc-head-begin)))
	  (if (or (eobp)
		  (and nndoc-file-end
		       (looking-at nndoc-file-end)))
	      (goto-char (point-max))
	    (setq head-begin (point))
	    (nndoc-search (or nndoc-head-end "^$"))
	    (setq head-end (point))
	    (if nndoc-body-begin-function
		(funcall nndoc-body-begin-function)
	      (nndoc-search (or nndoc-body-begin "^\n")))
	    (setq body-begin (point))
	    (or (and nndoc-body-end-function
		     (funcall nndoc-body-end-function))
		(and nndoc-body-end
		     (nndoc-search nndoc-body-end))
		(and (nndoc-article-begin)
		     (setq art-begin (point)))
		(progn
		  (goto-char (point-max))
		  (when nndoc-file-end
		    (and (re-search-backward nndoc-file-end nil t)
			 (beginning-of-line)))))
	    (setq body-end (point))
	    (push (list (incf i) head-begin head-end body-begin body-end
			(count-lines body-begin body-end))
		  nndoc-dissection-alist)))))
    (setq nndoc-dissection-alist (nreverse nndoc-dissection-alist))))

(defun nndoc-article-begin ()
  (if nndoc-article-begin-function
      (funcall nndoc-article-begin-function)
    (ignore-errors
      (nndoc-search nndoc-article-begin))))

(defun nndoc-unquote-dashes ()
  "Unquote quoted non-separators in digests."
  (while (re-search-forward "^- -"nil t)
    (replace-match "-" t t)))

;; Against compiler warnings.
(defvar nndoc-mime-split-ordinal)

(defun nndoc-dissect-mime-parts ()
  "Go through a MIME composite article and partition it into sub-articles.
When a MIME entity contains sub-entities, dissection produces one article for
the header of this entity, and one article per sub-entity."
  (setq nndoc-dissection-alist nil
	nndoc-mime-split-ordinal 0)
  (with-current-buffer nndoc-current-buffer
    (nndoc-dissect-mime-parts-sub (point-min) (point-max) nil nil nil)))

(defun nndoc-dissect-mime-parts-sub (head-begin body-end article-insert
						position parent)
  "Dissect an entity, within a composite MIME message.
The complete message or MIME entity extends from HEAD-BEGIN to BODY-END.
ARTICLE-INSERT should be added at beginning for generating a full article.
The string POSITION holds a dotted decimal representation of the article
position in the hierarchical structure, it is nil for the outer entity.
PARENT is the message-ID of the parent summary line, or nil for none."
  (let ((case-fold-search t)
	(message-id (nnmail-message-id))
	head-end body-begin summary-insert message-rfc822 multipart-any
	subject content-type type subtype boundary-regexp)
    ;; Gracefully handle a missing body.
    (goto-char head-begin)
    (if (or (and (eq (char-after) ?\n) (or (forward-char 1) t))
	    (search-forward "\n\n" body-end t))
	(setq head-end (1- (point))
	      body-begin (point))
      (setq head-end body-end
	    body-begin body-end))
    (narrow-to-region head-begin head-end)
    ;; Save MIME attributes.
    (goto-char head-begin)
    (setq content-type (message-fetch-field "Content-Type"))
    (when content-type
      (when (string-match
	     "^ *\\([^ \t\n/;]+\\)/\\([^ \t\n/;]+\\)" content-type)
	(setq type (downcase (match-string 1 content-type))
	      subtype (downcase (match-string 2 content-type))
	      message-rfc822 (and (string= type "message")
				  (string= subtype "rfc822"))
	      multipart-any (string= type "multipart")))
      (when (string-match ";[ \t\n]*name=\\([^ \t\n;]+\\)" content-type)
	(setq subject (match-string 1 content-type)))
      (when (string-match "boundary=\"?\\([^\"\n]*[^\" \t\n]\\)" content-type)
	(setq boundary-regexp (concat "^--"
				      (regexp-quote
				       (match-string 1 content-type))
				      "\\(--\\)?[ \t]*\n"))))
    (unless subject
      (when (or multipart-any (not article-insert))
	(setq subject (message-fetch-field "Subject"))))
    (unless type
      (setq type "text"
	    subtype "plain"))
    ;; Prepare the article and summary inserts.
    (unless article-insert
      (setq article-insert (buffer-string)
	    head-end head-begin))
    ;; Fix MIME-Version
    (unless (string-match "MIME-Version:" article-insert)
      (setq article-insert
	    (concat article-insert "MIME-Version: 1.0\n")))
    (setq summary-insert article-insert)
    ;; - summary Subject.
    (setq summary-insert
	  (let ((line (concat "Subject: <" position
			      (and position multipart-any ".")
			      (and multipart-any "*")
			      (and (or position multipart-any) " ")
			      (cond ((string= subtype "plain") type)
				    ((string= subtype "basic") type)
				    (t subtype))
			      ">"
			      (and subject " ")
			      subject
			      "\n")))
	    (if (string-match "Subject:.*\n\\([ \t].*\n\\)*" summary-insert)
		(replace-match line t t summary-insert)
	      (concat summary-insert line))))
    ;; - summary Message-ID.
    (setq summary-insert
	  (let ((line (concat "Message-ID: " message-id "\n")))
	    (if (string-match "Message-ID:.*\n\\([ \t].*\n\\)*" summary-insert)
		(replace-match line t t summary-insert)
	      (concat summary-insert line))))
    ;; - summary References.
    (when parent
      (setq summary-insert
	    (let ((line (concat "References: " parent "\n")))
	      (if (string-match "References:.*\n\\([ \t].*\n\\)*"
				summary-insert)
		  (replace-match line t t summary-insert)
		(concat summary-insert line)))))
    ;; Generate dissection information for this entity.
    (push (list (incf nndoc-mime-split-ordinal)
		head-begin head-end body-begin body-end
		(count-lines body-begin body-end)
		article-insert summary-insert)
	  nndoc-dissection-alist)
    ;; Recurse for all sub-entities, if any.
    (widen)
    (cond
     (message-rfc822
      (save-excursion
	(nndoc-dissect-mime-parts-sub body-begin body-end nil
				      position message-id)))
     ((and multipart-any boundary-regexp)
      (let ((part-counter 0)
	    part-begin part-end eof-flag)
	(while (string-match "\
^\\(Lines\\|Content-\\(Type\\|Transfer-Encoding\\|Disposition\\)\\):.*\n\\([ \t].*\n\\)*"
			     article-insert)
	  (setq article-insert (replace-match "" t t article-insert)))
	(let ((case-fold-search nil))
	  (goto-char body-begin)
	  (setq eof-flag (not (re-search-forward boundary-regexp body-end t)))
	  (while (not eof-flag)
	    (setq part-begin (point))
	    (cond ((re-search-forward boundary-regexp body-end t)
		   (or (not (match-string 1))
		       (string= (match-string 1) "")
		       (setq eof-flag t))
		   (forward-line -1)
		   (setq part-end (point))
		   (forward-line 1))
		  (t (setq part-end body-end
			   eof-flag t)))
	    (save-excursion
	      (nndoc-dissect-mime-parts-sub
	       part-begin part-end article-insert
	       (concat position
		       (and position ".")
		       (format "%d" (incf part-counter)))
	       message-id)))))))))

;;;###autoload
(defun nndoc-add-type (definition &optional position)
  "Add document DEFINITION to the list of nndoc document definitions.
If POSITION is nil or `last', the definition will be added
as the last checked definition, if t or `first', add as the
first definition, and if any other symbol, add after that
symbol in the alist."
  ;; First remove any old instances.
  (gnus-alist-pull (car definition) nndoc-type-alist)
  ;; Then enter the new definition in the proper place.
  (cond
   ((or (null position) (eq position 'last))
    (setq nndoc-type-alist (nconc nndoc-type-alist (list definition))))
   ((or (eq position t) (eq position 'first))
    (push definition nndoc-type-alist))
   (t
    (let ((list (memq (assq position nndoc-type-alist)
		      nndoc-type-alist)))
      (unless list
	(error "No such position: %s" position))
      (setcdr list (cons definition (cdr list)))))))

(provide 'nndoc)

;;; nndoc.el ends here