emacs/lisp/erc/erc-fill.el

;;; erc-fill.el --- Filling IRC messages in various ways  -*- lexical-binding: t; -*-

;; Copyright (C) 2001-2004, 2006-2023 Free Software Foundation, Inc.

;; Author: Andreas Fuchs <asf@void.at>
;;         Mario Lang <mlang@delysid.org>
;; Maintainer: Amin Bandali <bandali@gnu.org>, F. Jason Park <jp@neverwas.me>
;; URL: https://www.emacswiki.org/emacs/ErcFilling

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;; This package implements filling of messages sent and received.  Use
;; `erc-fill-mode' to switch it on.  Customize `erc-fill-function' to
;; change the style.

;;; Code:

(require 'erc)
(require 'erc-stamp); for the timestamp stuff

(defgroup erc-fill nil
  "Filling means to reformat long lines in different ways."
  :group 'erc)

;;;###autoload(autoload 'erc-fill-mode "erc-fill" nil t)
(define-erc-module fill nil
  "Manage filling in ERC buffers.
ERC fill mode is a global minor mode.  When enabled, messages in
the channel buffers are filled."
  ;; FIXME ensure a consistent ordering relative to hook members from
  ;; other modules.  Ideally, this module's processing should happen
  ;; after "morphological" modifications to a message's text but
  ;; before superficial decorations.
  ((add-hook 'erc-insert-modify-hook #'erc-fill)
   (add-hook 'erc-send-modify-hook #'erc-fill))
  ((remove-hook 'erc-insert-modify-hook #'erc-fill)
   (remove-hook 'erc-send-modify-hook #'erc-fill)))

(defcustom erc-fill-prefix nil
  "Values used as `fill-prefix' for `erc-fill-variable'.
nil means fill with space, a string means fill with this string."
  :type '(choice (const nil) string))

(defcustom erc-fill-function 'erc-fill-variable
  "Function to use for filling messages.

Variable Filling with an `erc-fill-prefix' of nil:

<shortnick> this is a very very very long message with no
	    meaning at all

Variable Filling with an `erc-fill-prefix' of four spaces:

<shortnick> this is a very very very long message with no
    meaning at all

Static Filling with `erc-fill-static-center' of 27:

		<shortnick> foo bar baz
	 <a-very-long-nick> foo bar baz quuuuux
		<shortnick> this is a very very very long message with no
			    meaning at all

These two styles are implemented using `erc-fill-variable' and
`erc-fill-static'.  You can, of course, define your own filling
function.  Narrowing to the region in question is in effect while your
function is called."
  :type '(choice (const :tag "Variable Filling" erc-fill-variable)
                 (const :tag "Static Filling" erc-fill-static)
                 function))

(defcustom erc-fill-static-center 27
  "Column around which all statically filled messages will be centered.
This column denotes the point where the ` ' character between
<nickname> and the entered text will be put, thus aligning nick
names right and text left."
  :type 'integer)

(defcustom erc-fill-variable-maximum-indentation 17
  "Don't indent a line after a long nick more than this many characters.
Set to nil to disable."
  :type 'integer)

(defcustom erc-fill-column 78
  "The column at which a filled paragraph is broken."
  :type 'integer)

;;;###autoload
(defun erc-fill ()
  "Fill a region using the function referenced in `erc-fill-function'.
You can put this on `erc-insert-modify-hook' and/or `erc-send-modify-hook'."
  (unless (erc-string-invisible-p (buffer-substring (point-min) (point-max)))
    (when erc-fill-function
      ;; skip initial empty lines
      (goto-char (point-min))
      (save-match-data
        (while (and (looking-at "[ \t\n]*$")
                    (= (forward-line 1) 0))))
      (unless (eobp)
        (save-restriction
          (narrow-to-region (point) (point-max))
          (funcall erc-fill-function))))))

(defun erc-fill-static ()
  "Fills a text such that messages start at column `erc-fill-static-center'."
  (save-restriction
    (goto-char (point-min))
    (looking-at "^\\(\\S-+\\)")
    (let ((nick (match-string 1)))
        (let ((fill-column (- erc-fill-column (erc-timestamp-offset)))
              (fill-prefix (make-string erc-fill-static-center 32)))
          (insert (make-string (max 0 (- erc-fill-static-center
                                         (length nick) 1))
                               32))
          (erc-fill-regarding-timestamp))
        (erc-restore-text-properties))))

(defun erc-fill-variable ()
  "Fill from `point-min' to `point-max'."
  (let ((fill-prefix erc-fill-prefix)
        (fill-column (or erc-fill-column fill-column)))
    (goto-char (point-min))
    (if fill-prefix
        (let ((first-line-offset (make-string (erc-timestamp-offset) 32)))
          (insert first-line-offset)
          (fill-region (point-min) (point-max) t t)
          (goto-char (point-min))
          (delete-char (length first-line-offset)))
      (save-match-data
        (let* ((nickp (looking-at "^\\(\\S-+\\)"))
               (nick (if nickp
                         (match-string 1)
                       ""))
               (fill-column (- erc-fill-column (erc-timestamp-offset)))
               (fill-prefix (make-string (min (+ 1 (length nick))
                                              (- fill-column 1)
                                              (or erc-fill-variable-maximum-indentation
                                                  fill-column))
                                         32)))
          (erc-fill-regarding-timestamp))))
    (erc-restore-text-properties)))

(defun erc-fill-regarding-timestamp ()
  "Fills a text such that messages start at column `erc-fill-static-center'."
  (fill-region (point-min) (point-max) t t)
  (goto-char (point-min))
  (forward-line)
  (indent-rigidly (point) (point-max) (erc-timestamp-offset)))

(defun erc-timestamp-offset ()
  "Get length of timestamp if inserted left."
  (if (and (boundp 'erc-timestamp-format)
           erc-timestamp-format
           (eq erc-insert-timestamp-function 'erc-insert-timestamp-left)
           (not erc-hide-timestamps))
      (length (format-time-string erc-timestamp-format))
    0))

(provide 'erc-fill)

;;; erc-fill.el ends here
;; Local Variables:
;; generated-autoload-file: "erc-loaddefs.el"
;; End: