;;!emacs
;;
;; FILE:         hsmail.el
;; SUMMARY:      Support for Hyperbole buttons in mail composer: mail and mh-letter.
;; USAGE:        GNU Emacs Lisp Library
;; KEYWORDS:     hypermedia, mail
;;
;; AUTHOR:       Bob Weiner
;; ORG:          Brown U.
;;
;; ORIG-DATE:     9-May-91 at 04:50:20
;; LAST-MOD:      8-Aug-95 at 10:55:17 by Bob Weiner
;;
;; This file is part of Hyperbole.
;; Available for use and distribution under the same terms as GNU Emacs.
;;
;; Copyright (C) 1991-1995, Free Software Foundation, Inc.
;; Developed with support from Motorola Inc.
;;
;; DESCRIPTION:  
;; DESCRIP-END.

;;; ************************************************************************
;;; Other required Elisp libraries
;;; ************************************************************************

(require 'sendmail)

;;; ************************************************************************
;;; Public variables
;;; ************************************************************************


(defvar smail:comment '(format
			"Comments: Hyperbole mail buttons accepted, v%s.\n"
			hyperb:version)
  "Default comment form to evaluate and add to outgoing mail.
Set to the empty string, \"\", for no comment.")

;;; Used by 'mail-send' in Emacs "sendmail.el".
(if (boundp 'send-mail-function)
    (or (if (listp send-mail-function)
	    (if (equal (nth 2 send-mail-function) '(smail:widen))
		nil
	      (error
		"(hsmail): Set 'send-mail-function' to a symbol-name, not a list, before load.")))
	(setq send-mail-function
	      (list 'lambda nil '(smail:widen) (list send-mail-function))))
  (error "(hsmail): Install an Emacs \"sendmail.el\" which includes 'send-mail-function'."))

(if (fboundp 'mail-prefix-region)
    ;;
    ;; For compatibility with rsw-modified sendmail.el.
    (defvar mail-yank-hook
      (function
	(lambda ()
	  ;; Set off original message.
	  (mail-prefix-region (hypb:mark t) (point))))
      "*Hook to run mail yank preface function.
Expects point and mark to be set to the region to preface.")
  ;;
  ;; Else for compatibility with Supercite and Emacs V19.
  ;; If you create your own yank hook, set this variable rather than
  ;; 'mail-yank-hook' from above.
  (defvar mail-citation-hook nil
    "*Hook for modifying a citation just inserted in the mail buffer.
Each hook function can find the citation between (point) and (mark t).
And each hook function should leave point and mark around the citation
text as modified.

If this hook is entirely empty (nil), a default action is taken
instead of no action.")
  (defvar mail-yank-hooks '(mail-indent-citation)
    "*Obsolete hook to run mail yank citation function.  Use mail-citation-hook instead.
Expects point and mark to be set to the region to cite."))

;; For compatibility with Supercite and Emacs V19.
(defvar mail-yank-prefix nil
  "*Prefix insert on lines of yanked message being replied to.
nil means use indentation.")
(defvar mail-indentation-spaces 3
  "*Number of spaces to insert at the beginning of each cited line.")

;;; ************************************************************************
;;; Public functions
;;; ************************************************************************

(defun smail:comment-add (&optional comment-form)
  "Adds a comment to the current outgoing message if Hyperbole has been loaded.
Optional COMMENT-FORM is evaluated to obtain the string to add to the
message.  If not given, 'smail:comment' is evaluated by default."
  (let ((comment (eval (or comment-form smail:comment))))
    (if (and comment (featurep 'hsite))
	(save-excursion
	  (goto-char (point-min))
	  (and (or (search-forward mail-header-separator nil t)
		   (if (eq major-mode 'mh-letter-mode)
		       (search-forward "\n--------" nil t)))
	       (not (search-backward comment nil t))
	       (progn (beginning-of-line) (insert comment)))))))

(defun smail:widen ()
  "Widens outgoing mail buffer to include Hyperbole button data."
  (if (fboundp 'mail+narrow) (mail+narrow) (widen)))

;; Overlay this function from V19 "sendmail.el" to work with V18.
(defun mail-indent-citation ()
  "Modify text just inserted from a message to be cited.
The inserted text should be the region.
When this function returns, the region is again around the modified text.

Normally, indent each nonblank line `mail-indentation-spaces' spaces.
However, if `mail-yank-prefix' is non-nil, insert that prefix on each line."
  (let ((start (point)))
    ;; Don't ever remove headers if user uses Supercite package,
    ;; since he can set an option in that package to do
    ;; the removal.
    (or (hypb:supercite-p)
	(mail-yank-clear-headers start (hypb:mark t)))
    (if (null mail-yank-prefix)
	(indent-rigidly start (hypb:mark t) mail-indentation-spaces)
      (save-excursion
	(goto-char start)
	(while (< (point) (hypb:mark t))
	  (insert mail-yank-prefix)
	  (forward-line 1))))))

;; Overlay this function from "sendmail.el" to include Hyperbole button
;; data when yanking in a message and to highlight buttons if possible.
(defun mail-yank-original (arg)
  "Insert the message being replied to, if any.
Puts point before the text and mark after.
Applies 'mail-citation-hook', 'mail-yank-hook' or 'mail-yank-hooks'
to text (in decreasing order of precedence).
Just \\[universal-argument] as argument means don't apply hooks
and don't delete any header fields.

If supercite is in use, header fields are never deleted.
Use (setq sc-nuke-mail-headers-p t) to have them removed."
  (interactive "P")
  (if mail-reply-buffer
      (let ((start (point)) opoint)
	(delete-windows-on mail-reply-buffer)
	(unwind-protect
	    (progn
	      (save-excursion
		(set-buffer mail-reply-buffer)
		;; Might be called from newsreader before any
		;; Hyperbole mail reader support has been autoloaded.
		(cond ((fboundp 'rmail:msg-widen) (rmail:msg-widen))
		      ((eq major-mode 'news-reply-mode) (widen))))
	      (setq opoint (point))
	      (insert-buffer mail-reply-buffer)
	      (hmail:msg-narrow)
	      (if (fboundp 'hproperty:but-create) (hproperty:but-create))
	      (if (consp arg)
		  nil
		;; Don't ever remove headers if user uses Supercite package,
		;; since he can set an option in that package to do
		;; the removal.
		(or (hypb:supercite-p)
		    (mail-yank-clear-headers
		      start (marker-position (hypb:mark-marker t))))
		(let ((mail-indentation-spaces (if arg (prefix-numeric-value arg)
						 mail-indentation-spaces)))
		  (cond ((and (boundp 'mail-citation-hook) mail-citation-hook)
			 (run-hooks 'mail-citation-hook))
			((and (boundp 'mail-yank-hook) mail-yank-hook)
			 (run-hooks 'mail-yank-hook))
			((and (boundp 'mail-yank-hooks) mail-yank-hooks)
			 (run-hooks 'mail-yank-hooks))
			(t (mail-indent-citation))))
		(goto-char (min (point-max) (hypb:mark t)))
		(set-mark opoint)
		(delete-region (point)	; Remove trailing blank lines.
			       (progn (re-search-backward "[^ \^I\^L\n]")
				      (end-of-line)
				      (point))))
	      (or (eq major-mode 'news-reply-mode)
   	          ;; This is like exchange-point-and-mark, but doesn't activate the mark.
	          ;; It is cleaner to avoid activation, even though the command
	          ;; loop would deactivate the mark because we inserted text.
	          (goto-char (prog1 (hypb:mark t)
		               (set-marker (hypb:mark-marker t)
					   (point) (current-buffer)))))
	      (if (not (eolp)) (insert ?\n))
	      )
	  (save-excursion
	    (set-buffer mail-reply-buffer)
	    (hmail:msg-narrow))))))

;;; ************************************************************************
;;; Private variables
;;; ************************************************************************

;;; Try to setup comment addition as the first element of these hooks.
(if (fboundp 'add-hook)
    (progn
      (add-hook 'mail-setup-hook     'smail:comment-add)
      (add-hook 'mh-letter-mode-hook 'smail:comment-add))
  (var:append 'mail-setup-hook     '(smail:comment-add))
  (var:append 'mh-letter-mode-hook '(smail:comment-add)))

(provide 'hsmail)