;;; rmailkwd.el --- part of the "RMAIL" mail reader for Emacs  -*- lexical-binding: t; -*-

;; Copyright (C) 1985, 1988, 1994, 2001-2024 Free Software Foundation,
;; Inc.

;; Maintainer: emacs-devel@gnu.org
;; Keywords: mail
;; Package: rmail

;; 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:

;;; Code:

(require 'rmail)

;; Global to all RMAIL buffers.  It exists for the sake of completion.
;; It is better to use strings with the label functions and let them
;; worry about making the label.
(defvar rmail-label-obarray (make-vector 47 0)
  "Obarray of labels used by Rmail.
`rmail-read-label' uses this to offer completion.")

;; Initialize with the standard labels.
(mapc (lambda (s) (intern (cadr s) rmail-label-obarray))
      rmail-attr-array)

(defun rmail-make-label (s)
  "Intern string S as a downcased symbol in `rmail-label-obarray'."
  (intern (downcase s) rmail-label-obarray))

;;;###autoload
(defun rmail-add-label (label)
  "Add LABEL to labels associated with current RMAIL message.
Completes (see `rmail-read-label') over known labels when reading.
LABEL may be a symbol or string.  Only one label is allowed."
  (interactive (list (rmail-read-label "Add label")))
  (rmail-set-label label t))

;;;###autoload
(defun rmail-kill-label (label)
  "Remove LABEL from labels associated with current RMAIL message.
Completes (see `rmail-read-label') over known labels when reading.
LABEL may be a symbol or string.  Only one label is allowed."
  (interactive (list (rmail-read-label "Remove label")))
  (rmail-set-label label nil))

;;;###autoload
(defun rmail-read-label (prompt)
  "Read a label with completion, prompting with PROMPT.
Completions are chosen from `rmail-label-obarray'.  The default
is `rmail-last-label', if that is non-nil.  Updates `rmail-last-label'
according to the choice made, and returns a symbol."
  (let* ((old nil)
	 (result
	  (progn
	    ;; If the summary exists, we've already read all the
	    ;; existing labels.  If not, read the ones in this message.
	    (or (eq major-mode 'rmail-summary-mode)
		(rmail-summary-exists)
		(and (setq old (rmail-get-keywords))
		     (mapc #'rmail-make-label (split-string old ", "))))
            (completing-read (format-prompt prompt
                                            (and rmail-last-label
                                                 (symbol-name rmail-last-label)))
			     rmail-label-obarray
			     nil
			     nil))))
    (if (string= result "")
	rmail-last-label
      (setq rmail-last-label (rmail-make-label result)))))

(declare-function rmail-summary-update-line "rmailsum" (n))

(defun rmail-set-label (label state &optional msg)
  "Set LABEL as present or absent according to STATE in message MSG.
LABEL may be a symbol or string."
  (or (stringp label) (setq label (symbol-name label)))
  (if (string-search "," label)
      (error "More than one label specified"))
  (with-current-buffer rmail-buffer
    (rmail-maybe-set-message-counters)
    (if (zerop (or msg (setq msg rmail-current-message)))
	(error "No message"))
    ;; Force recalculation of summary for this message.
    (aset rmail-summary-vector (1- msg) nil)
    (let (attr-index)
      ;; Is this label an attribute?
      (dotimes (i (length rmail-attr-array))
	(if (string= (cadr (aref rmail-attr-array i)) label)
	    (setq attr-index i)))
      (if attr-index
	  ;; If so, set it as an attribute.
	  (rmail-set-attribute attr-index state msg)
	;; Is this keyword already present in msg's keyword list?
	(let* ((header (rmail-get-keywords msg))
	       (regexp (concat ", " (regexp-quote label) ","))
	       (present (not (null
			      (string-match regexp (concat ", " header ","))))))
	  ;; If current state is not correct,
	  (unless (eq present state)
	    ;; either add it or delete it.
	    (rmail-set-header
	     rmail-keyword-header msg
	     (if state
		 ;; Add this keyword at the end.
		 (if (and header (not (string= header "")))
		     (concat header ", " label)
		   label)
	       ;; Delete this keyword.
	       (let ((before (substring header 0
					(max 0 (- (match-beginning 0) 2))))
		     (after (substring header
				       (min (length header)
					    (- (match-end 0) 1)))))
		 (cond ((string= before "")
			;; If before and after both empty, delete the header.
			(unless (string= after "")
			  after))
		       ((string= after "")
			before)
		       (t (concat before ", " after))))))))))
    (if (rmail-summary-exists)
	(rmail-select-summary (rmail-summary-update-line msg)))
    (if (= msg rmail-current-message)
	(rmail-display-labels))))

;; Motion on messages with keywords.

;;;###autoload
(defun rmail-previous-labeled-message (n labels)
  "Show previous message with one of the labels LABELS.
LABELS should be a comma-separated list of label names.
If LABELS is empty, the last set of labels specified is used.
With prefix argument N moves backward N messages with these labels."
  (interactive "p\nsMove to previous msg with labels: ")
  (rmail-next-labeled-message (- n) labels))

(declare-function mail-comma-list-regexp "mail-utils" (labels))

;;;###autoload
(defun rmail-next-labeled-message (n labels)
  "Show next message with one of the labels LABELS.
LABELS should be a comma-separated list of label names.
If LABELS is empty, the last set of labels specified is used.
With prefix argument N moves forward N messages with these labels."
  ;; FIXME show the default in the prompt.
  (interactive "p\nsMove to next msg with labels: ")
  (if (string= labels "")
      (setq labels rmail-last-multi-labels))
  (or labels
      (error "No labels to find have been specified previously"))
  (set-buffer rmail-buffer)
  (setq rmail-last-multi-labels labels)
  (rmail-maybe-set-message-counters)
  (let ((lastwin rmail-current-message)
	(current rmail-current-message)
	(regexp (concat " \\("
			(mail-comma-list-regexp labels)
			"\\)\\(,\\|\\'\\)")))
    (while (and (> n 0) (< current rmail-total-messages))
      (setq current (1+ current))
      (if (string-match regexp (rmail-get-labels current))
	  (setq lastwin current n (1- n))))
    (while (and (< n 0) (> current 1))
      (setq current (1- current))
      (if (string-match regexp (rmail-get-labels current))
	  (setq lastwin current n (1+ n))))
    (if (< n 0)
	(error "No previous message with labels %s" labels)
      (if (> n 0)
	  (error "No following message with labels %s" labels)
	(rmail-show-message-1 lastwin)))))

(provide 'rmailkwd)

;;; rmailkwd.el ends here
