+(defun notmuch-show-toggle-part-invisibility (&optional button)
+ (interactive)
+ (let* ((button (or button (button-at (point))))
+ (overlay (button-get button 'overlay))
+ (lazy-part (button-get button :notmuch-lazy-part)))
+ ;; We have a part to toggle if there is an overlay or if there is a lazy part.
+ ;; If neither is present we cannot toggle the part so we just return nil.
+ (when (or overlay lazy-part)
+ (let* ((show (button-get button :notmuch-part-hidden))
+ (new-start (button-start button))
+ (button-label (button-get button :base-label))
+ (old-point (point))
+ (properties (text-properties-at (button-start button)))
+ (inhibit-read-only t))
+ ;; Toggle the button itself.
+ (button-put button :notmuch-part-hidden (not show))
+ (goto-char new-start)
+ (insert "[ " button-label (if show " ]" " (hidden) ]"))
+ (set-text-properties new-start (point) properties)
+ (let ((old-end (button-end button)))
+ (move-overlay button new-start (point))
+ (delete-region (point) old-end))
+ (goto-char (min old-point (1- (button-end button))))
+ ;; Return nil if there is a lazy-part, it is empty, and we are
+ ;; trying to show it. In all other cases return t.
+ (if lazy-part
+ (when show
+ (button-put button :notmuch-lazy-part nil)
+ (notmuch-show-lazy-part lazy-part button))
+ ;; else there must be an overlay.
+ (overlay-put overlay 'invisible (not show))
+ t)))))
+
+;; Part content ID handling
+
+(defvar notmuch-show--cids nil
+ "Alist from raw content ID to (MSG PART).")
+(make-variable-buffer-local 'notmuch-show--cids)
+
+(defun notmuch-show--register-cids (msg part)
+ "Register content-IDs in PART and all of PART's sub-parts."
+ (let ((content-id (plist-get part :content-id)))
+ (when content-id
+ ;; Note that content-IDs are globally unique, except when they
+ ;; aren't: RFC 2046 section 5.1.4 permits children of a
+ ;; multipart/alternative to have the same content-ID, in which
+ ;; case the MUA is supposed to pick the best one it can render.
+ ;; We simply add the content-ID to the beginning of our alist;
+ ;; so if this happens, we'll take the last (and "best")
+ ;; alternative (even if we can't render it).
+ (push (list content-id msg part) notmuch-show--cids)))
+ ;; Recurse on sub-parts
+ (let ((ctype (notmuch-split-content-type
+ (downcase (plist-get part :content-type)))))
+ (cond ((equal (first ctype) "multipart")
+ (mapc (apply-partially #'notmuch-show--register-cids msg)
+ (plist-get part :content)))
+ ((equal ctype '("message" "rfc822"))
+ (notmuch-show--register-cids
+ msg
+ (first (plist-get (first (plist-get part :content)) :body)))))))
+
+(defun notmuch-show--get-cid-content (cid)
+ "Return a list (CID-content content-type) or nil.
+
+This will only find parts from messages that have been inserted
+into the current buffer. CID must be a raw content ID, without
+enclosing angle brackets, a cid: prefix, or URL encoding. This
+will return nil if the CID is unknown or cannot be retrieved."
+ (let ((descriptor (cdr (assoc cid notmuch-show--cids))))
+ (when descriptor
+ (let* ((msg (first descriptor))
+ (part (second descriptor))
+ ;; Request caching for this content, as some messages
+ ;; reference the same cid: part many times (hundreds!).
+ (content (notmuch-get-bodypart-binary
+ msg part notmuch-show-process-crypto 'cache))
+ (content-type (plist-get part :content-type)))
+ (list content content-type)))))
+
+(defun notmuch-show-setup-w3m ()
+ "Instruct w3m how to retrieve content from a \"related\" part of a message."
+ (interactive)
+ (if (boundp 'w3m-cid-retrieve-function-alist)
+ (unless (assq 'notmuch-show-mode w3m-cid-retrieve-function-alist)
+ (push (cons 'notmuch-show-mode #'notmuch-show--cid-w3m-retrieve)
+ w3m-cid-retrieve-function-alist)))
+ (setq mm-inline-text-html-with-images t))
+
+(defvar w3m-current-buffer) ;; From `w3m.el'.
+(defun notmuch-show--cid-w3m-retrieve (url &rest args)
+ ;; url includes the cid: prefix and is URL encoded (see RFC 2392).
+ (let* ((cid (url-unhex-string (substring url 4)))
+ (content-and-type
+ (with-current-buffer w3m-current-buffer
+ (notmuch-show--get-cid-content cid))))
+ (when content-and-type
+ (insert (first content-and-type))
+ (second content-and-type))))
+
+;; MIME part renderers
+
+(defun notmuch-show-multipart/*-to-list (part)
+ (mapcar (lambda (inner-part) (plist-get inner-part :content-type))
+ (plist-get part :content)))
+
+(defun notmuch-show-insert-part-multipart/alternative (msg part content-type nth depth button)
+ (let ((chosen-type (car (notmuch-multipart/alternative-choose (notmuch-show-multipart/*-to-list part))))
+ (inner-parts (plist-get part :content))
+ (start (point)))
+ ;; This inserts all parts of the chosen type rather than just one,
+ ;; but it's not clear that this is the wrong thing to do - which
+ ;; should be chosen if there are more than one that match?
+ (mapc (lambda (inner-part)
+ (let* ((inner-type (plist-get inner-part :content-type))
+ (hide (not (or notmuch-show-all-multipart/alternative-parts
+ (string= chosen-type inner-type)))))
+ (notmuch-show-insert-bodypart msg inner-part depth hide)))
+ inner-parts)
+
+ (when notmuch-show-indent-multipart
+ (indent-rigidly start (point) 1)))
+ t)
+
+(defun notmuch-show-insert-part-multipart/related (msg part content-type nth depth button)
+ (let ((inner-parts (plist-get part :content))
+ (start (point)))
+
+ ;; Render the primary part. FIXME: Support RFC 2387 Start header.
+ (notmuch-show-insert-bodypart msg (car inner-parts) depth)
+ ;; Add hidden buttons for the rest
+ (mapc (lambda (inner-part)
+ (notmuch-show-insert-bodypart msg inner-part depth t))
+ (cdr inner-parts))
+
+ (when notmuch-show-indent-multipart
+ (indent-rigidly start (point) 1)))
+ t)
+
+(defun notmuch-show-insert-part-multipart/signed (msg part content-type nth depth button)
+ (button-put button 'face 'notmuch-crypto-part-header)
+ ;; add signature status button if sigstatus provided
+ (if (plist-member part :sigstatus)
+ (let* ((from (notmuch-show-get-header :From msg))
+ (sigstatus (car (plist-get part :sigstatus))))
+ (notmuch-crypto-insert-sigstatus-button sigstatus from))
+ ;; if we're not adding sigstatus, tell the user how they can get it
+ (button-put button 'help-echo "Set notmuch-crypto-process-mime to process cryptographic MIME parts."))
+
+ (let ((inner-parts (plist-get part :content))
+ (start (point)))
+ ;; Show all of the parts.
+ (mapc (lambda (inner-part)
+ (notmuch-show-insert-bodypart msg inner-part depth))
+ inner-parts)
+
+ (when notmuch-show-indent-multipart
+ (indent-rigidly start (point) 1)))
+ t)
+
+(defun notmuch-show-insert-part-multipart/encrypted (msg part content-type nth depth button)
+ (button-put button 'face 'notmuch-crypto-part-header)
+ ;; add encryption status button if encstatus specified
+ (if (plist-member part :encstatus)
+ (let ((encstatus (car (plist-get part :encstatus))))
+ (notmuch-crypto-insert-encstatus-button encstatus)
+ ;; add signature status button if sigstatus specified
+ (if (plist-member part :sigstatus)
+ (let* ((from (notmuch-show-get-header :From msg))
+ (sigstatus (car (plist-get part :sigstatus))))
+ (notmuch-crypto-insert-sigstatus-button sigstatus from))))
+ ;; if we're not adding encstatus, tell the user how they can get it
+ (button-put button 'help-echo "Set notmuch-crypto-process-mime to process cryptographic MIME parts."))
+
+ (let ((inner-parts (plist-get part :content))
+ (start (point)))
+ ;; Show all of the parts.
+ (mapc (lambda (inner-part)
+ (notmuch-show-insert-bodypart msg inner-part depth))
+ inner-parts)
+
+ (when notmuch-show-indent-multipart
+ (indent-rigidly start (point) 1)))
+ t)
+
+(defun notmuch-show-insert-part-multipart/* (msg part content-type nth depth button)
+ (let ((inner-parts (plist-get part :content))
+ (start (point)))
+ ;; Show all of the parts.
+ (mapc (lambda (inner-part)
+ (notmuch-show-insert-bodypart msg inner-part depth))
+ inner-parts)
+
+ (when notmuch-show-indent-multipart
+ (indent-rigidly start (point) 1)))
+ t)
+
+(defun notmuch-show-insert-part-message/rfc822 (msg part content-type nth depth button)
+ (let* ((message (car (plist-get part :content)))
+ (body (car (plist-get message :body)))
+ (start (point)))
+
+ ;; Override `notmuch-message-headers' to force `From' to be
+ ;; displayed.
+ (let ((notmuch-message-headers '("From" "Subject" "To" "Cc" "Date")))
+ (notmuch-show-insert-headers (plist-get message :headers)))
+
+ ;; Blank line after headers to be compatible with the normal
+ ;; message display.
+ (insert "\n")
+
+ ;; Show the body
+ (notmuch-show-insert-bodypart msg body depth)
+
+ (when notmuch-show-indent-multipart
+ (indent-rigidly start (point) 1)))
+ t)
+
+(defun notmuch-show-insert-part-text/plain (msg part content-type nth depth button)
+ ;; For backward compatibility we want to apply the text/plain hook
+ ;; to the whole of the part including the part button if there is
+ ;; one.
+ (let ((start (if button
+ (button-start button)
+ (point))))
+ (insert (notmuch-get-bodypart-text msg part notmuch-show-process-crypto))