gnus, notmuch: Absorb now-shared bits into patch attachment helper

With the previous commit, -notmuch more closely follows -gnus in its
handling of attachments (e.g., getting the content with
mm-display-inline).  Replace piem-am-patch-attachment-p with a helper
that has this shared logic.

Message-Id: <20210104015435.18397-4-kyle@kyleam.com>

3 files changed, 17 insertions, 28 deletions

diff --git a/piem-gnus.el b/piem-gnus.el
index c6b9d0c..5f10be8 100644
--- a/piem-gnus.el
+++ b/piem-gnus.el
@@ -66,18 +66,8 @@ message itself if it looks like a patch."
   (when (derived-mode-p 'gnus-article-mode 'gnus-summary-mode)
     (cond
      (gnus-article-mime-handles
-      (when-let ((patches
-                  (delq nil
-                        (mapcar (lambda (handle)
-                                  (and (listp handle)
-                                       (piem-am-patch-attachment-p
-                                        (mm-handle-media-type handle)
-                                        (mm-handle-filename handle))
-                                       (with-temp-buffer
-                                         (mm-display-inline handle)
-                                         (buffer-substring-no-properties
-                                          (point-min) (point-max)))))
-                                gnus-article-mime-handles))))
+      (when-let ((patches (delq nil (mapcar #'piem-am-extract-attached-patch
+                                            gnus-article-mime-handles))))
         (cons (lambda ()
                 (dolist (patch patches)
                   (insert patch)))
diff --git a/piem-notmuch.el b/piem-notmuch.el
index 915675e..37e695b 100644
--- a/piem-notmuch.el
+++ b/piem-notmuch.el
@@ -92,14 +92,8 @@ message itself if it looks like a patch."
                               "show" "--format=mbox" id))))
         (notmuch-foreach-mime-part
          (lambda (p)
-           (and (piem-am-patch-attachment-p
-                 (mm-handle-media-type p)
-                 (mm-handle-filename p))
-                (with-temp-buffer
-                  (mm-display-inline p)
-                  (push (buffer-substring-no-properties
-                         (point-min) (point-max))
-                        patches))))
+           (when-let ((patch (piem-am-extract-attached-patch p)))
+             (push patch patches)))
          handle)
         (when patches
           (setq patches (nreverse patches))
diff --git a/piem.el b/piem.el
index bf79813..8c23e7b 100644
--- a/piem.el
+++ b/piem.el
@@ -40,6 +40,7 @@
 (require 'cl-lib)
 (require 'mail-extr)
 (require 'message)
+(require 'mm-decode)
 (require 'piem-maildir)
 (require 'rfc2047)
 (require 'subr-x)
@@ -573,14 +574,18 @@ This function depends on :url being configured for entries in
 
 ;;;; Patch handling
 
-(defun piem-am-patch-attachment-p (type filename)
-  "Return non-nil if an attachment should be treated as a patch.
-TYPE is a media type such as \"text/x-patch\".  FILENAME is the
-attachment file name, if any."
-  (or (member type '("text/x-diff" "text/x-patch"))
-      (and filename
-           (equal type "text/plain")
-           (string-match-p "\\.patch\\'" filename))))
+(defun piem-am-extract-attached-patch (handle)
+  "Return content for HANDLE if it looks like a patch."
+  (and (listp handle)
+       (let ((type (mm-handle-media-type handle))
+             (filename (mm-handle-filename handle)))
+         (or (member type '("text/x-diff" "text/x-patch"))
+             (and filename
+                  (equal type "text/plain")
+                  (string-match-p "\\.patch\\'" filename))))
+       (with-temp-buffer
+         (mm-display-inline handle)
+         (buffer-substring-no-properties (point-min) (point-max)))))
 
 (defun piem-extract-mbox-info (&optional buffer)
   "Collect information from message in BUFFER.