;;; gnus-picon.el --- displaying pretty icons in Gnus  -*- lexical-binding: t; -*-

;; Copyright (C) 1996-2021 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: news xpm annotation glyph faces

;; 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:

;; There are three picon types relevant to Gnus:
;;
;; Persons: person@subdomain.dom
;;          users/dom/subdomain/person/face.gif
;;          usenix/dom/subdomain/person/face.gif
;;          misc/MISC/person/face.gif
;; Domains: subdomain.dom
;;          domain/dom/subdomain/unknown/face.gif
;; Groups:  comp.lang.lisp
;;          news/comp/lang/lisp/unknown/face.gif
;;
;; Original implementation by Wes Hardaker <hardaker@ece.ucdavis.edu>.
;;
;;; Code:

(require 'gnus)
(require 'gnus-art)

;;; User variables:

(defcustom gnus-picon-news-directories '("news")
  "List of directories to search for newsgroups faces."
  :type '(repeat string)
  :group 'gnus-picon)

(defcustom gnus-picon-user-directories '("users" "usenix" "local" "misc")
  "List of directories to search for user faces."
  :type '(repeat string)
  :group 'gnus-picon)

(defcustom gnus-picon-domain-directories '("domains")
  "List of directories to search for domain faces.
Some people may want to add \"unknown\" to this list."
  :type '(repeat string)
  :group 'gnus-picon)

(defcustom gnus-picon-file-types
  (let ((types (list "xbm")))
    (when (gnus-image-type-available-p 'gif)
      (push "gif" types))
    (when (gnus-image-type-available-p 'xpm)
      (push "xpm" types))
    types)
  "List of suffixes on picon file names to try."
  :type '(repeat string)
  :group 'gnus-picon)

(defcustom gnus-picon-properties '(:color-symbols (("None" . "white")))
  "List of image properties applied to picons."
  :type 'plist
  :version "24.3"
  :group 'gnus-picon)

(defcustom gnus-picon-style 'inline
  "How should picons be displayed.
If `inline', the textual representation is replaced.  If `right', picons are
added right to the textual representation."
  :type '(choice (const inline)
		 (const right))
  :group 'gnus-picon)

(defcustom gnus-picon-inhibit-top-level-domains t
  "If non-nil, don't piconify top-level domains.
These are often not very interesting."
  :version "24.1"
  :type 'boolean
  :group 'gnus-picon)

;;; Internal variables:

(defvar gnus-picon-glyph-alist nil
  "Picon glyphs cache.
List of pairs (KEY . GLYPH) where KEY is either a filename or an URL.")
(defvar gnus-picon-cache nil)

;;; Functions:

(defsubst gnus-picon-split-address (address)
  (setq address (split-string address "@"))
  (if (stringp (cadr address))
      (cons (car address) (split-string (cadr address) "\\."))
    (if (stringp (car address))
	(split-string (car address) "\\."))))

(defun gnus-picon-find-face (address directories &optional exact)
  (let* ((address (gnus-picon-split-address address))
	 (user (pop address))
	 (faddress address)
	 result base) ;; database directory instance
    (catch 'found
      (dolist (database gnus-picon-databases)
	(dolist (directory directories)
	  (setq address faddress
		base (expand-file-name directory database))
	  (while address
	    (when (setq result (gnus-picon-find-image
				(concat base "/" (mapconcat #'downcase
							    (reverse address)
							    "/")
					"/" (downcase user) "/")))
	      (throw 'found result))
	    (if exact
		(setq address nil)
	      (pop address)))
	  ;; Kludge to search MISC as well.  But not in "news".
	  (unless (string= directory "news")
	    (when (setq result (gnus-picon-find-image
				(concat base "/MISC/" user "/")))
	      (throw 'found result))))))))

(defun gnus-picon-find-image (directory)
  (let ((types gnus-picon-file-types)
	found type file)
    (while (and (not found)
		(setq type (pop types)))
      (setq found (file-exists-p (setq file (concat directory "face." type)))))
    (if found
	file
      nil)))

(defun gnus-picon-insert-glyph (glyph category &optional nostring)
  "Insert GLYPH into the buffer.
GLYPH can be either a glyph or a string.  When NOSTRING, no textual
replacement is added."
  ;; Using NOSTRING prevents wrong BBDB entries with `gnus-picon-style' set to
  ;; 'right.
  (if (stringp glyph)
      (insert glyph)
    (gnus-add-wash-type category)
    (gnus-add-image category (car glyph))
    (gnus-put-image (car glyph) (unless nostring (cdr glyph)) category)))

(defun gnus-picon-create-glyph (file)
  (or (cdr (assoc file gnus-picon-glyph-alist))
      (cdar (push (cons file (apply #'gnus-create-image
				    file nil nil
				    gnus-picon-properties))
		  gnus-picon-glyph-alist))))

;;; Functions that does picon transformations:

(declare-function image-size "image.c" (spec &optional pixels frame))

(defun gnus-picon-transform-address (header category)
  (gnus-with-article-headers
   (let ((addresses
	  (mail-header-parse-addresses
	   ;; mail-header-parse-addresses does not work (reliably) on
	   ;; decoded headers.
	   (or
	    (ignore-errors
	     (mail-encode-encoded-word-string
	      (or (mail-fetch-field header) "")))
	    (mail-fetch-field header))))
	 spec file point cache len)
     (dolist (address addresses)
       (setq address (car address))
       (when (and (stringp address)
		  (setq spec (gnus-picon-split-address address)))
	 (if (setq cache (cdr (assoc address gnus-picon-cache)))
	     (setq spec cache)
	   (when (setq file (or (gnus-picon-find-face
				 address gnus-picon-user-directories)
				(gnus-picon-find-face
				 (concat "unknown@"
					 (mapconcat
					  #'identity (cdr spec) "."))
				 gnus-picon-user-directories)))
	     (setcar spec (cons (gnus-picon-create-glyph file)
				(car spec))))

	   (dotimes (i (- (length spec)
			  (if gnus-picon-inhibit-top-level-domains
			      2 1)))
	     (when (setq file (gnus-picon-find-face
			       (concat "unknown@"
				       (mapconcat
					#'identity (nthcdr (1+ i) spec) "."))
			       gnus-picon-domain-directories t))
	       (setcar (nthcdr (1+ i) spec)
		       (cons (gnus-picon-create-glyph file)
			     (nth (1+ i) spec)))))
	   (setq spec (nreverse spec))
	   (push (cons address spec) gnus-picon-cache))

	 (gnus-article-goto-header header)
	 (mail-header-narrow-to-field)
	 (cl-case gnus-picon-style
	       (right
		(when (= (length addresses) 1)
		  (setq len (apply #'+ (mapcar (lambda (x)
						 (condition-case nil
						     (car (image-size (car x)))
						   (error 0)))
					       spec)))
		  (when (> len 0)
		    (goto-char (point-at-eol))
		    (insert (propertize
			     " " 'display
			     (cons 'space
				   (list :align-to (- (window-width) 1 len))))))
		  (goto-char (point-at-eol))
		  (setq point (point-at-eol))
		  (dolist (image spec)
		    (unless (stringp image)
		      (goto-char point)
		      (gnus-picon-insert-glyph image category 'nostring)))))
	       (inline
		 (when (search-forward address nil t)
		   (delete-region (match-beginning 0) (match-end 0))
		   (setq point (point))
		   (while spec
		     (goto-char point)
		     (if (> (length spec) 2)
			 (insert ".")
		       (if (= (length spec) 2)
			   (insert "@")))
		     (gnus-picon-insert-glyph (pop spec) category))))))))))

(defun gnus-picon-transform-newsgroups (header)
  (interactive nil gnus-article-mode gnus-summary-mode)
  (gnus-with-article-headers
   (gnus-article-goto-header header)
   (mail-header-narrow-to-field)
   (let ((groups (message-tokenize-header (mail-fetch-field header)))
	 spec file) ;; point
     (dolist (group groups)
       (unless (setq spec (cdr (assoc group gnus-picon-cache)))
	 (setq spec (nreverse (split-string group "[.]")))
	 (dotimes (i (length spec))
	   (when (setq file (gnus-picon-find-face
			     (concat "unknown@"
				     (mapconcat
				      #'identity (nthcdr i spec) "."))
			     gnus-picon-news-directories t))
	     (setcar (nthcdr i spec)
		     (cons (gnus-picon-create-glyph file)
			   (nth i spec)))))
	 (push (cons group spec) gnus-picon-cache))
       (when (search-forward group nil t)
	 (delete-region (match-beginning 0) (match-end 0))
	 (save-restriction
	   (narrow-to-region (point) (point))
	   (while spec
	     (goto-char (point-min))
	     (if (> (length spec) 1)
		 (insert "."))
	     (gnus-picon-insert-glyph (pop spec) 'newsgroups-picon))
	   (goto-char (point-max))))))))

;;; Commands:

;; #### NOTE: the test for buffer-read-only is the same as in
;; article-display-[x-]face. See the comment up there.

;;;###autoload
(defun gnus-treat-from-picon ()
  "Display picons in the From header.
If picons are already displayed, remove them."
  (interactive nil gnus-article-mode gnus-summary-mode)
  (let ((wash-picon-p buffer-read-only))
    (gnus-with-article-buffer
     (if (and wash-picon-p (memq 'from-picon gnus-article-wash-types))
	 (gnus-delete-images 'from-picon)
       (gnus-picon-transform-address "from" 'from-picon)))))

;;;###autoload
(defun gnus-treat-mail-picon ()
  "Display picons in the Cc and To headers.
If picons are already displayed, remove them."
  (interactive nil gnus-article-mode gnus-summary-mode)
  (let ((wash-picon-p buffer-read-only))
    (gnus-with-article-buffer
     (if (and wash-picon-p (memq 'mail-picon gnus-article-wash-types))
	 (gnus-delete-images 'mail-picon)
       (gnus-picon-transform-address "cc" 'mail-picon)
       (gnus-picon-transform-address "to" 'mail-picon)))))

;;;###autoload
(defun gnus-treat-newsgroups-picon ()
  "Display picons in the Newsgroups and Followup-To headers.
If picons are already displayed, remove them."
  (interactive nil gnus-article-mode gnus-summary-mode)
  (let ((wash-picon-p buffer-read-only))
    (gnus-with-article-buffer
     (if (and wash-picon-p (memq 'newsgroups-picon gnus-article-wash-types))
	 (gnus-delete-images 'newsgroups-picon)
       (gnus-picon-transform-newsgroups "newsgroups")
       (gnus-picon-transform-newsgroups "followup-to")))))

(provide 'gnus-picon)

;;; gnus-picon.el ends here