emacs/lisp/gnus/mm-extern.el

;;; mm-extern.el --- showing message/external-body  -*- lexical-binding:t -*-

;; Copyright (C) 2000-2023 Free Software Foundation, Inc.

;; Author: Shenghuo Zhu <zsh@cs.rochester.edu>
;; Keywords: message external-body

;; 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 'mm-util)
(require 'mm-decode)
(require 'mm-url)

(defvar gnus-article-mime-handles)

(defvar mm-extern-function-alist
  `((local-file . ,#'mm-extern-local-file)
    (url . ,#'mm-extern-url)
    (anon-ftp . ,#'mm-extern-anon-ftp)
    (ftp . ,#'mm-extern-ftp)
    ;; (tftp . ,#'mm-extern-tftp)
    (mail-server . ,#'mm-extern-mail-server)
    ;; (afs . ,#'mm-extern-afs))
    ))

(defvar mm-extern-anonymous "anonymous")

(defun mm-extern-local-file (handle)
  (erase-buffer)
  (let ((name (cdr (assq 'name (cdr (mm-handle-type handle)))))
	(coding-system-for-read mm-binary-coding-system))
    (unless name
      (error "The filename is not specified"))
    (mm-disable-multibyte)
    (if (file-exists-p name)
	(mm-insert-file-contents name nil nil nil nil t)
      (error "File %s is gone" name))))

(defun mm-extern-url (handle)
  (erase-buffer)
  (let ((url (cdr (assq 'url (cdr (mm-handle-type handle)))))
	(name buffer-file-name)
	(coding-system-for-read mm-binary-coding-system))
    (unless url
      (error "URL is not specified"))
    (mm-disable-multibyte)
    (mm-url-insert-file-contents url)
    (setq buffer-file-name name)))

(defun mm-extern-anon-ftp (handle)
  (erase-buffer)
  (let* ((params (cdr (mm-handle-type handle)))
	 (name (cdr (assq 'name params)))
	 (site (cdr (assq 'site params)))
	 (directory (cdr (assq 'directory params)))
	 (path (concat "/" (or mm-extern-anonymous
			       (read-string (format "ID for %s: " site)))
		       "@" site ":" directory "/" name))
	 (coding-system-for-read mm-binary-coding-system))
    (unless name
      (error "The filename is not specified"))
    (mm-disable-multibyte)
    (mm-insert-file-contents path nil nil nil nil t)))

(defun mm-extern-ftp (handle)
  (let (mm-extern-anonymous)
    (mm-extern-anon-ftp handle)))

(declare-function message-goto-body "message" (&optional interactive))

(defun mm-extern-mail-server (handle)
  (require 'message)
  (let* ((params (cdr (mm-handle-type handle)))
	 (server (cdr (assq 'server params)))
	 (subject (or (cdr (assq 'subject params)) "none"))
	 (buf (current-buffer))
	 info)
    (if (y-or-n-p (format "Send a request message to %s? " server))
	(save-window-excursion
	  (message-mail server subject)
	  (message-goto-body)
	  (delete-region (point) (point-max))
	  (insert-buffer-substring buf)
	  (message "Requesting external body...")
	  (message-send-and-exit)
	  (setq info "Request is sent.")
	  (message info))
      (setq info "Request is not sent."))
    (goto-char (point-min))
    (insert "[" info "]\n\n")))

;;;###autoload
(defun mm-extern-cache-contents (handle)
  "Put the external-body part of HANDLE into its cache."
  (let* ((access-type (cdr (assq 'access-type
				 (cdr (mm-handle-type handle)))))
	 (func (cdr (assq (intern
			   (downcase
			    (or access-type
				(error "Couldn't find access type"))))
			  mm-extern-function-alist)))
	 handles)
    (unless func
      (error "Access type (%s) is not supported" access-type))
    (mm-with-part handle
      (goto-char (point-max))
      (insert "\n\n")
      ;; It should be just a single MIME handle.
      (setq handles (mm-dissect-buffer t)))
    (unless (bufferp (car handles))
      (mm-destroy-parts handles)
      (error "Multipart external body is not supported"))
    (with-current-buffer (mm-handle-buffer handles)
      (let (good)
	(unwind-protect
	    (progn
	      (funcall func handle)
	      (setq good t))
	  (unless good
	    (mm-destroy-parts handles))))
      (mm-handle-set-cache handle handles))
    (setq gnus-article-mime-handles
	  (mm-merge-handles gnus-article-mime-handles handles))))

;;;###autoload
(defun mm-inline-external-body (handle &optional no-display)
  "Show the external-body part of HANDLE.
This function replaces the buffer of HANDLE with a buffer contains
the entire message.
If NO-DISPLAY is nil, display it.  Otherwise, do nothing after replacing."
  (unless (mm-handle-cache handle)
    (mm-extern-cache-contents handle))
  (unless no-display
    (save-excursion
      (save-restriction
	(narrow-to-region (point) (point))
	(mm-display-part (mm-handle-cache handle))))
    ;; Move undisplayer added to the cached handle to the parent.
    (mm-handle-set-undisplayer
     handle (mm-handle-undisplayer (mm-handle-cache handle)))
    (mm-handle-set-undisplayer (mm-handle-cache handle) nil)))

(provide 'mm-extern)

;;; mm-extern.el ends here