[PATCH v2] Use notmuch-extract-patch if available

[leo@relevant-information.com]

From: Leo <sourcehut@relevant-information.com>

notmuch-extract-patch is a command line tool from the elpa-mailscripts
package that extracts patches from a thread.  It's a useful way to
extract the latest patch series from an email thread and filter out the
replies and reviews.
---
I've extracted the functionality into its own function as requested, and 
added clarification on where the copied comment came from.  I'm not sure 
how the copyright notice should be formatted though. 


 piem-notmuch.el | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/piem-notmuch.el b/piem-notmuch.el
index 8b2a353..27a7d7c 100644
--- a/piem-notmuch.el
+++ b/piem-notmuch.el
@@ -1,6 +1,6 @@
 ;;; piem-notmuch.el --- Notmuch integration for piem  -*- lexical-binding: t; -*-
 
-;; Copyright (C) 2020-2021  all contributors <piem@inbox.kyleam.com>
+;; Copyright (C) 2020-2021  all contributors <piem@inbox.kyleam.com> (C) 2019 Sean Whitton <spwhitton@spwhitton.name>
 
 ;; Author: Kyle Meyer <kyle@kyleam.com>
 ;; Keywords: vc, tools
@@ -106,6 +106,40 @@ (defun piem-notmuch-am-ready-mbox ()
                     (insert patch)))
                 "mbox"))))))
 
+(defun piem-notmuch-extract-patch-am-ready-mbox ()
+  "Return a function that inserts an am-ready mbox.
+Use the message itself if it looks like a patch using
+notmuch-extract-patch to get the latest patch series from the
+notmuch thread."
+  (when (derived-mode-p 'notmuch-show-mode)
+    (let* ((handle (piem-notmuch--with-current-message
+                     (mm-dissect-buffer)))
+           (n-attachments (notmuch-count-attachments handle))
+           patches)
+      (when (= n-attachments 0)
+          (when (string-match-p piem-patch-subject-re
+                                (notmuch-show-get-subject))
+            (let ((id (notmuch-show-get-message-id))
+                  (thread-id notmuch-show-thread-id))
+              (lambda ()
+                (if-let ((cmd (executable-find "notmuch-extract-patch"))
+                         (tid
+                          ;; Copied from mailscripts.el
+                          ;;
+                          ;; If `notmuch-show' was called with a notmuch query rather
+                          ;; than a thread ID, as `org-notmuch-follow-link' in
+                          ;; org-notmuch.el does, then `notmuch-show-thread-id' might
+                          ;; be an arbitrary notmuch query instead of a thread ID.  We
+                          ;; need to wrap such a query in thread:{} before passing it
+                          ;; to notmuch-extract-patch(1), or we might not get a whole
+                          ;; thread extracted (e.g. if the query is just id:foo)
+                          (if (string= (substring thread-id 0 7) "thread:")
+                              thread-id
+                            (concat "thread:{" thread-id "}"))))
+                    (call-process cmd nil t nil
+                                  tid)
+                  (user-error "The executable notmuch-extract-patch was not found")))))))))
+
 (defun piem-notmuch-show-get-public-inbox-link (mid)
   "Given the message-id MID, return the public-inbox url.
 This will lookup the url in the inboxes returned by

base-commit: e519aa44d148d5b8f22d7fe8844dc566046b04c2
-- 
2.34.1