[PATCH 2/3] emacs/show: optionally insert bodies lazily

[David Bremner <david@tethera.net>]

Intially control lazy insertion by a depth limit.
---
 emacs/notmuch-show.el | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index 203ca7f0..55c4e274 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -111,6 +111,12 @@ displayed."
 		 (function :tag "Function"))
   :group 'notmuch-show)
 
+(defcustom notmuch-show-depth-limit nil
+  "Depth beyond which message bodies are inserted lazily"
+    :type '(choice (const :tag "No limit" nil)
+                   (number :tag "Limit" 10))
+    :group 'notmuch-show)
+
 (defcustom notmuch-show-relative-dates t
   "Display relative dates in the message summary line."
   :type 'boolean
@@ -1065,13 +1071,35 @@ is t, hide the part initially and show the button."
 	(notmuch-show-toggle-part-invisibility button)))
     (notmuch-show-record-part-information part beg (point))))
 
+(defun notmuch-show--insert-body-internal (msg body depth)
+  (mapc (lambda (part) (notmuch-show-insert-bodypart msg part depth)) body))
+
+(defun notmuch-show--insert-body-button (msg body depth)
+  (insert-button
+   "[body]"
+   :type 'notmuch-button-type
+   'action (lambda (button)
+	     (save-excursion
+	       (let* ((inhibit-read-only t)
+		     (start (button-start button))
+		     (end (button-end button))
+		     (marker (copy-marker (1+ end))))
+		 (delete-region start end)
+		 (notmuch-show--insert-body-internal msg body depth)
+		 (when notmuch-show-indent-content
+		   (indent-rigidly start marker
+				   (* notmuch-show-indent-messages-width depth))))))))
+
 (defun notmuch-show-insert-body (msg body depth)
   "Insert the body BODY at depth DEPTH in the current thread."
   ;; Register all content IDs for this message.  According to RFC
   ;; 2392, content IDs are *global*, but it's okay if an MUA treats
   ;; them as only global within a message.
   (notmuch-show--register-cids msg (car body))
-  (mapc (lambda (part) (notmuch-show-insert-bodypart msg part depth)) body))
+  (if (and notmuch-show-depth-limit
+	   (> depth notmuch-show-depth-limit))
+      (notmuch-show--insert-body-button msg body depth)
+    (notmuch-show--insert-body-internal msg body depth)))
 
 (defun notmuch-show-make-symbol (type)
   (make-symbol (concat "notmuch-show-" type)))
-- 
2.35.2