;;; mailalias.el --- expand and complete mailing address aliases

;; Copyright (C) 1985, 1987, 1995, 1996 Free Software Foundation, Inc.

;; Maintainer: FSF
;; Keywords: mail

;; 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 2, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; Basic functions for defining and expanding mail aliases.
;; These seal off the interface to the alias-definition parts of a
;; .mailrc file formatted for BSD's Mail or USL's mailx.

;;; Code:

(require 'sendmail)

(defvar mail-names t
  "Alist of local users, aliases and directory entries as available.
When t this still needs to be initialized.
This is the basis for `mail-complete'.")

(defvar mail-local-names t
  "Alist of local users.
When t this still needs to be initialized.")

(defvar mail-directory-names t
  "Alist of mail address directory entries.
When t this still needs to be initialized.")

(defvar mail-address-field-regexp
  "^\\(Resent-\\)?\\(To\\|From\\|CC\\|BCC\\|Reply-to\\):")

(defvar mail-complete-alist
  `((,mail-address-field-regexp mail-get-names pattern)
    ("Newsgroups:" . (if (boundp 'gnus-active-hashtb)
			 gnus-active-hashtb
		       (if (boundp news-group-article-assoc)
			   news-group-article-assoc)))
    ("Followup-To:" . (mail-sentto-newsgroups))
    ;;("Distribution:" ???)
    )
  "Alist of header field and expression to return alist for completion.
Expression may reference variable `pattern' which is the string being completed.
If not on matching header, `mail-complete-function' gets called instead.")

(defvar mail-complete-function 'ispell-complete-word
  "Function to call when completing outside `mail-complete-alist'-header.")


(defvar mail-directory-function nil
  "Function to get completions from directory service or `nil' for none.
See `mail-directory-requery'.")


;; This is for when the directory is huge, or changes frequently.
(defvar mail-directory-requery nil
  "When non-`nil' call `mail-directory-function' for each completion.
In that case, one argument gets passed to the function, the partial string
entered so far.")


(defvar mail-directory-process nil
  "Unix command when `mail-directory-function' is `mail-directory-process'.
This is a list of the form (COMMAND ARG ...), where each of the list elements
is evaluated.  When `mail-directory-requery' is non-`nil', during
evaluation the variable `pattern' contains the partial input being completed.
This might look like

  '(remote-shell-program \"HOST\" \"-nl\" \"USER\" \"COMMAND\")

or

  '(remote-shell-program \"HOST\" \"-n\" \"COMMAND '^\" pattern \"'\")")

(defvar mail-directory-stream ()
  "List of (HOST SERVICE) for stream connection to mail directory.")

(defvar mail-directory-parser nil
  "How to interpret the output of `mail-directory-function'.
Three types of values are possible:

  - nil means to gather each line as one name
  - regexp means first \\(grouping\\) in successive matches is name
  - function called at beginning of buffer that returns an alist of names")


;; Called from sendmail-send-it, or similar functions,
;; only if some mail aliases are defined.
(defun expand-mail-aliases (beg end &optional exclude)
  "Expand all mail aliases in suitable header fields found between BEG and END.
Suitable header fields are `To', `From', `CC' and `BCC', `Reply-to', and
their `Resent-' variants.

Optional second arg EXCLUDE may be a regular expression defining text to be
removed from alias expansions."
  (sendmail-sync-aliases)
  (if (eq mail-aliases t)
      (progn (setq mail-aliases nil) (build-mail-aliases)))
  (goto-char beg)
  (setq end (set-marker (make-marker) end))
  (let ((case-fold-search nil))
    (while (let ((case-fold-search t))
	     (re-search-forward mail-address-field-regexp end t))
      (skip-chars-forward " \t")
      (let ((beg1 (point))
	    end1 pos epos seplen
	    ;; DISABLED-ALIASES records aliases temporarily disabled
	    ;; while we scan text that resulted from expanding those aliases.
	    ;; Each element is (ALIAS . TILL-WHEN), where TILL-WHEN
	    ;; is where to reenable the alias (expressed as number of chars
	    ;; counting from END1).
	    (disabled-aliases nil))
	(re-search-forward "^[^ \t]" end 'move)
	(beginning-of-line)
	(skip-chars-backward " \t\n")
	(setq end1 (point-marker))
	(goto-char beg1)
	(while (< (point) end1)
	  (setq pos (point))
	  ;; Reenable any aliases which were disabled for ranges
	  ;; that we have passed out of.
	  (while (and disabled-aliases (> pos (- end1 (cdr (car disabled-aliases)))))
	    (setq disabled-aliases (cdr disabled-aliases)))
	  ;; EPOS gets position of end of next name;
	  ;; SEPLEN gets length of whitespace&separator that follows it.
	  (if (re-search-forward "[ \t]*[\n,][ \t]*" end1 t)
	      (setq epos (match-beginning 0)
		    seplen (- (point) epos))
	    (setq epos (marker-position end1) seplen 0))
	  (let (translation
		(string (buffer-substring-no-properties pos epos)))
	    (if (and (not (assoc string disabled-aliases))
		     (setq translation
			   (cdr (assoc string mail-aliases))))
		(progn
		  ;; This name is an alias.  Disable it.
		  (setq disabled-aliases (cons (cons string (- end1 epos))
					       disabled-aliases))
		  ;; Replace the alias with its expansion
		  ;; then rescan the expansion for more aliases.
		  (goto-char pos)
		  (insert translation)
		  (if exclude
 		      (let ((regexp
			     (concat "\\b\\(" exclude "\\)\\b"))
			    (end (point-marker)))
			(goto-char pos)
			(while (re-search-forward regexp end t)
			  (replace-match ""))
			(goto-char end)))
		  (delete-region (point) (+ (point) (- epos pos)))
		  (goto-char pos))
	      ;; Name is not an alias.  Skip to start of next name.
	      (goto-char epos)
	      (forward-char seplen))))
	(set-marker end1 nil)))
    (set-marker end nil)))

;; Called by mail-setup, or similar functions, only if the file specified
;; by mail-personal-alias-file (usually `~/.mailrc') exists.
(defun build-mail-aliases (&optional file)
  "Read mail aliases from personal aliases file and set `mail-aliases'.
By default, this is the file specified by `mail-personal-alias-file'."
  (setq file (expand-file-name (or file mail-personal-alias-file)))
  (let ((buffer nil)
	(obuf (current-buffer)))
    (unwind-protect
	(progn
	  (setq buffer (generate-new-buffer " mailrc"))
	  (set-buffer buffer)
	  (while file
	    (cond ((get-file-buffer file)
		   (insert (save-excursion
			     (set-buffer (get-file-buffer file))
			     (buffer-substring-no-properties
			      (point-min) (point-max)))))
		  ((file-exists-p file) (insert-file-contents file))
		  ((file-exists-p (setq file (concat "~/" file)))
		   (insert-file-contents file))
		  (t (setq file nil)))
	    ;; Don't lose if no final newline.
	    (goto-char (point-max))
	    (or (eq (preceding-char) ?\n) (newline))
	    (goto-char (point-min))
	    ;; handle "\\\n" continuation lines
	    (while (not (eobp))
	      (end-of-line)
	      (if (= (preceding-char) ?\\)
		  (progn (delete-char -1) (delete-char 1) (insert ?\ ))
	        (forward-char 1)))
	    (goto-char (point-min))
	    ;; handle `source' directives -- Eddy/1994/May/25
	    (cond ((re-search-forward "^source[ \t]+" nil t)
		   (re-search-forward "\\S-+")
		   (setq file (buffer-substring-no-properties
			       (match-beginning 0) (match-end 0)))
		   (beginning-of-line)
		   (insert "# ") ; to ensure we don't re-process this file
		   (beginning-of-line))
		  (t (setq file nil))))
	  (goto-char (point-min))
	  (while (re-search-forward
		  "^\\(a\\|alias\\|g\\|group\\)[ \t]+\\([^ \t]+\\)" nil t)
	    (let* ((name (match-string 2))
		   (start (progn (skip-chars-forward " \t") (point))))
	      (end-of-line)
	      (define-mail-alias
		name
		(buffer-substring-no-properties start (point))
		t)))
	  mail-aliases)
      (if buffer (kill-buffer buffer))
      (set-buffer obuf))))

;; Always autoloadable in case the user wants to define aliases
;; interactively or in .emacs.
;;;###autoload
(defun define-mail-alias (name definition &optional from-mailrc-file)
  "Define NAME as a mail alias that translates to DEFINITION.
This means that sending a message to NAME will actually send to DEFINITION.

Normally, the addresses in DEFINITION must be separated by commas.
If FROM-MAILRC-FILE is non-nil, then addresses in DEFINITION 
can be separated by spaces; an address can contain spaces
if it is quoted with double-quotes."

  (interactive "sDefine mail alias: \nsDefine %s as mail alias for: ")
  ;; Read the defaults first, if we have not done so.
  (sendmail-sync-aliases)
  (if (eq mail-aliases t)
      (progn
	(setq mail-aliases nil)
	(if (file-exists-p mail-personal-alias-file)
	    (build-mail-aliases))))
  ;; strip garbage from front and end
  (if (string-match "\\`[ \t\n,]+" definition)
      (setq definition (substring definition (match-end 0))))
  (if (string-match "[ \t\n,]+\\'" definition)
      (setq definition (substring definition 0 (match-beginning 0))))
  (let ((result '())
	;; If DEFINITION is null string, avoid looping even once.
	(start (and (not (equal definition "")) 0))
	(L (length definition))
	end tem)
    (while start
      ;; If we're reading from the mailrc file, then addresses are delimited
      ;; by spaces, and addresses with embedded spaces must be surrounded by
      ;; double-quotes.  Otherwise, addresses are separated by commas.
      (if from-mailrc-file
	  (if (eq ?\" (aref definition start))
	      (setq start (1+ start)
		    end (string-match "\"[ \t,]*" definition start))
	    (setq end (string-match "[ \t,]+" definition start)))
	(setq end (string-match "[ \t\n,]*,[ \t\n,]*" definition start)))
      (setq result (cons (substring definition start end) result))
      (setq start (and end
		       (/= (match-end 0) L)
		       (match-end 0))))
    (setq definition (mapconcat (function identity)
				(nreverse result)
				", "))
    (setq tem (assoc name mail-aliases))
    (if tem
	(rplacd tem definition)
      (setq mail-aliases (cons (cons name definition) mail-aliases)
	    mail-names t))))

;;;###autoload
(defun mail-complete (arg)
  "Perform completion on header field or word preceding point.
Completable headers are according to `mail-complete-alist'.  If none matches
current header, calls `mail-complete-function' and passes prefix arg if any."
  (interactive "P")
  ;; Read the defaults first, if we have not done so.
  (sendmail-sync-aliases)
  (if (eq mail-aliases t)
      (progn
	(setq mail-aliases nil)
	(if (file-exists-p mail-personal-alias-file)
	    (build-mail-aliases))))
  (let ((list mail-complete-alist))
    (if (and (save-excursion (search-forward
			      (concat "\n" mail-header-separator "\n")
			      nil t))
	     (save-excursion
	       (if (re-search-backward "^[^\t]" nil t)
		   (while list
		     (if (looking-at (car (car list)))
			 (setq arg (cdr (car list))
			       list ())
		       (setq list (cdr list)))))
	       arg))
	(let* ((end (point))
	       (beg (save-excursion
		      (skip-chars-backward "^ \t<,:")
		      (point)))
	       (pattern (buffer-substring beg end))
	       completion)
	  (setq list (eval arg)
		completion (try-completion pattern list))
	  (cond ((eq completion t))
		((null completion)
		 (message "Can't find completion for \"%s\"" pattern)
		 (ding))
		((not (string= pattern completion))
		 (delete-region beg end)
		 (insert completion))
		(t
		 (message "Making completion list...")
		 (with-output-to-temp-buffer "*Completions*"
		   (display-completion-list
		    (all-completions pattern list)))
		 (message "Making completion list...%s" "done"))))
      (funcall mail-complete-function arg))))

(defun mail-get-names (pattern)
  "Fetch local users and global mail adresses for completion.
Consults `/etc/passwd' and a directory service if one is set up via
`mail-directory-function'."
  (if (eq mail-local-names t)
      (save-excursion
	(set-buffer (generate-new-buffer " passwd"))
	(insert-file-contents "/etc/passwd" nil nil nil t)
	(setq mail-local-names)
	(while (not (eobp))
	  ;;Recognize lines like
	  ;;  nobody:*:65534:65534::/:
	  ;;  +demo::::::/bin/csh
	  ;;  +ethanb
	  ;;while skipping
	  ;;  +@SOFTWARE
	  (if (looking-at "\\+?\\([^:@\n+]+\\)")
	      (add-to-list 'mail-local-names (list (match-string 1))))
	  (beginning-of-line 2))
	(kill-buffer (current-buffer))))
  (if (or (eq mail-names t)
		(eq mail-directory-names t))
      (let (directory)
	(and mail-directory-function
	     (eq mail-directory-names t)
	     (setq directory
		   (mail-directory (if mail-directory-requery pattern))))
	(if (or directory
		(eq mail-names t))
	    (setq mail-names
		  (sort (append (if (consp mail-aliases) mail-aliases)
				(if (consp mail-local-names)
				    mail-local-names)
				directory)
			(lambda (a b)
			  ;; should cache downcased strings
			  (string< (downcase (car a))
				   (downcase (car b)))))))
	(or mail-directory-requery
	    (setq mail-directory-names directory))))
  mail-names)


(defun mail-directory (pattern)
  "Call directory to get names matching PATTERN or all if `nil'.
Calls `mail-directory-function' and applies `mail-directory-parser' to output."
  (save-excursion
    (message "Querying directory...")
    (set-buffer (generate-new-buffer " *mail-directory*"))
    (funcall mail-directory-function pattern)
    (goto-char 1)
    (let (directory)
      (if (stringp mail-directory-parser)
	  (while (re-search-forward mail-directory-parser nil t)
	    (setq directory
		  `((,(match-string 1))
		    ,@directory)))
	(if mail-directory-parser
	    (setq directory (funcall mail-directory-parser))
	  (while (not (eobp))
	    (setq directory
		  `((,(buffer-substring (point)
					(progn
					  (forward-line)
					  (if (bolp)
					    (1- (point))
					    (point)))))
		    ,@directory)))))
      (kill-buffer (current-buffer))
      (message "Querying directory...done")
      directory)))


(defun mail-directory-process (pattern)
  "Call a Unix process to output names in directory.
See `mail-directory-process'."
  (apply 'call-process (eval (car mail-directory-process)) nil t nil
	 (mapcar 'eval (cdr mail-directory-process))))

;; This should handle a dialog.  Currently expects port to spit out names.
(defun mail-directory-stream (pattern)
  "Open a stream to retrieve names in directory.
See `mail-directory-stream'."
  (let (mailalias-done)
    (set-process-sentinel
     (apply 'open-network-stream "mailalias" (current-buffer)
	    mail-directory-stream)
     (lambda (x x)
       (setq mailalias-done t)))
    (while (not mailalias-done)
      (sit-for .1))))

(defun mail-sentto-newsgroups ()
  "Return all entries from Newsgroups: header as completion alist."
  (save-excursion
    (if (mail-position-on-field "newsgroups" t)
	(let ((point (point))
	      list)
	  (while (< (skip-chars-backward "^:, \t\n") 0)
	    (setq list `((,(buffer-substring (point) point))
			 ,@list))
	    (skip-chars-backward ", \t\n")
	    (setq point (point)))
	  list))))

(provide 'mailalias)

;;; mailalias.el ends here