(require 'ring)
(require 'sendmail)
(defgroup mail-hist nil
"Headers and message body history for outgoing mail."
:prefix "mail-hist-"
:group 'mail)
(defun mail-hist-define-keys ()
"Define keys for accessing mail header history. For use in hooks."
(local-set-key "\M-p" 'mail-hist-previous-input)
(local-set-key "\M-n" 'mail-hist-next-input))
(defun mail-hist-enable ()
(add-hook 'mail-mode-hook 'mail-hist-define-keys)
(add-hook 'mail-send-hook 'mail-hist-put-headers-into-history))
(defvar mail-hist-header-ring-alist nil
"Alist of form (header-name . history-ring).
Used for knowing which history list to look in when the user asks for
previous/next input.")
(defcustom mail-hist-history-size (or kill-ring-max 1729)
"*The maximum number of elements in a mail field's history.
Oldest elements are dumped first."
:type 'integer
:group 'mail-hist)
(defcustom mail-hist-keep-history t
"*Non-nil means keep a history for headers and text of outgoing mail."
:type 'boolean
:group 'mail-hist)
(defvar mail-hist-access-count 0)
(defvar mail-hist-last-bounds nil)
(defvar mail-hist-header-regexp "^[^:]*:"
"Regular expression for matching headers in a mail message.")
(defsubst mail-hist-current-header-name ()
"Get name of mail header point is currently in, without the colon.
Returns nil if not in a header, implying that point is in the body of
the message."
(if (>= (point) (mail-text-start))
nil (save-excursion
(let* ((body-start
(mail-text-start))
(name-start
(re-search-backward mail-hist-header-regexp nil t))
(name-end
(prog2 (search-forward ":" body-start t) (1- (point)))))
(and
name-start
name-end
(downcase (buffer-substring-no-properties name-start name-end)))))))
(defsubst mail-hist-forward-header (count)
"Move forward COUNT headers (backward if COUNT is negative).
If last/first header is encountered first, stop there and returns
nil.
Places point on the first non-whitespace on the line following the
colon after the header name, or on the second space following that if
the header is empty."
(let ((boundary (mail-header-end)))
(and
(> boundary 0)
(let ((unstopped t))
(setq boundary (save-excursion
(goto-char boundary)
(beginning-of-line)
(1- (point))))
(if (> count 0)
(while (> count 0)
(setq
unstopped
(re-search-forward mail-hist-header-regexp boundary t))
(setq count (1- count)))
(setq count (1- count))
(while (< count 0)
(setq
unstopped
(re-search-backward mail-hist-header-regexp nil t))
(setq count (1+ count)))
(re-search-forward mail-hist-header-regexp boundary t))
(and (looking-at "\\s-") (forward-char 1))
unstopped))))
(defsubst mail-hist-beginning-of-header ()
"Move to the start of the current header.
The start of the current header is defined as one space after the
colon, or just after the colon if it is not followed by whitespace."
(if (mail-hist-forward-header -1)
(mail-hist-forward-header 1)
(mail-hist-forward-header 1)
(mail-hist-forward-header -1)))
(defsubst mail-hist-current-header-contents ()
"Get the contents of the mail header in which point is located."
(save-excursion
(mail-hist-beginning-of-header)
(let ((start (point)))
(or (mail-hist-forward-header 1)
(goto-char (mail-header-end)))
(beginning-of-line)
(buffer-substring start (1- (point))))))
(defsubst mail-hist-get-header-ring (header)
"Get HEADER's history ring, or nil if none.
HEADER is a string without the colon."
(setq header (downcase header))
(cdr (assoc header mail-hist-header-ring-alist)))
(defcustom mail-hist-text-size-limit nil
"*Don't store any header or body with more than this many characters.
If the value is nil, that means no limit on text size."
:type '(choice (const nil) integer)
:group 'mail-hist)
(defun mail-hist-text-too-long-p (text)
"Return non-nil if TEXT's length exceeds `mail-hist-text-size-limit'."
(if mail-hist-text-size-limit
(> (length text) mail-hist-text-size-limit)))
(defsubst mail-hist-add-header-contents-to-ring (header &optional contents)
"Add the contents of HEADER to the header history ring.
Optional argument CONTENTS is a string which will be the contents
\(instead of whatever's found in the header)."
(setq header (downcase header))
(let ((ctnts (or contents (mail-hist-current-header-contents)))
(ring (cdr (assoc header mail-hist-header-ring-alist))))
(if (mail-hist-text-too-long-p ctnts) (setq ctnts ""))
(or ring
(prog1
(setq ring (make-ring mail-hist-history-size))
(setq mail-hist-header-ring-alist
(cons (cons header ring) mail-hist-header-ring-alist))))
(ring-insert ring ctnts)))
(defun mail-hist-put-headers-into-history ()
"Put headers and contents of this message into mail header history.
Each header has its own independent history, as does the body of the
message.
This function normally would be called when the message is sent."
(and
mail-hist-keep-history
(save-excursion
(goto-char (point-min))
(while (mail-hist-forward-header 1)
(mail-hist-add-header-contents-to-ring
(mail-hist-current-header-name)))
(let ((body-contents
(buffer-substring (mail-text-start) (point-max))))
(mail-hist-add-header-contents-to-ring "body" body-contents)))))
(defun mail-hist-retrieve-and-insert (header access-func)
"Helper for `mail-hist-previous-input' and `mail-hist-next-input'."
(setq header (downcase header))
(let* ((ring (cdr (assoc header mail-hist-header-ring-alist)))
(len (ring-length ring))
(repeat (eq last-command 'mail-hist-input-access)))
(if repeat
(setq mail-hist-access-count
(funcall access-func mail-hist-access-count len))
(setq mail-hist-access-count 0))
(if (null ring)
(progn
(ding)
(message "No history for \"%s\"." header))
(if (ring-empty-p ring)
(error "\"%s\" ring is empty" header)
(and repeat
(delete-region (car mail-hist-last-bounds)
(cdr mail-hist-last-bounds)))
(let ((start (point)))
(insert (ring-ref ring mail-hist-access-count))
(setq mail-hist-last-bounds (cons start (point)))
(setq this-command 'mail-hist-input-access)
(if (string-equal header "body")
(goto-char start)))
))))
(defun mail-hist-previous-input (header)
"Insert the previous contents of this mail header or message body.
Moves back through the history of sent mail messages. Each header has
its own independent history, as does the body of the message.
The history only contains the contents of outgoing messages, not
received mail."
(interactive (list (or (mail-hist-current-header-name) "body")))
(mail-hist-retrieve-and-insert header 'ring-plus1))
(defun mail-hist-next-input (header)
"Insert next contents of this mail header or message body.
Moves back through the history of sent mail messages. Each header has
its own independent history, as does the body of the message.
Although you can do so, it does not make much sense to call this
without having called `mail-hist-previous-header' first
\(\\[mail-hist-previous-header]).
The history only contains the contents of outgoing messages, not
received mail."
(interactive (list (or (mail-hist-current-header-name) "body")))
(mail-hist-retrieve-and-insert header 'ring-minus1))
(provide 'mail-hist)