[RFC PATCH v2 8/8] WIP: add notmuch-tag-undo

[David Bremner <david@tethera.net>]

---
 emacs/notmuch-tag.el       | 12 ++++++++++++
 test/T315-emacs-tagging.sh | 19 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/emacs/notmuch-tag.el b/emacs/notmuch-tag.el
index 28a2b596..7ed5c1a5 100644
--- a/emacs/notmuch-tag.el
+++ b/emacs/notmuch-tag.el
@@ -506,6 +506,18 @@ notmuch-after-tag-hook will be run."
 		   (query query))
       (run-hooks 'notmuch-after-tag-hook))))
 
+(defun notmuch-tag-undo ()
+  (interactive)
+  (when (null notmuch-tag-history)
+    (error "no further notmuch undo information"))
+  (let* ((action (pop notmuch-tag-history))
+	 (from (plist-get action :from))
+	 (to (plist-get action :to))
+	 (changes (notmuch-tag-change-list (plist-get action :tag-changes) t))
+	 (query (format "lastmod:%d..%d" from to)))
+    (when (<= from to)
+      (notmuch-tag query changes t))))
+
 (defun notmuch-tag-change-list (tags &optional reverse)
   "Convert TAGS into a list of tag changes.
 
diff --git a/test/T315-emacs-tagging.sh b/test/T315-emacs-tagging.sh
index e4540a3a..72d8b5b0 100755
--- a/test/T315-emacs-tagging.sh
+++ b/test/T315-emacs-tagging.sh
@@ -116,4 +116,23 @@ output=$(test_emacs "(let ((notmuch-tag-history nil))
 count=$(notmuch count "$os_x_darwin_thread")
 test_expect_equal "$output" "$count"
 
+test_begin_subtest "undo with empty history is an error"
+test_emacs "(let ((notmuch-tag-history nil))
+  (test-log-error
+   (notmuch-tag-undo)))
+  "
+cat <<EOF > EXPECTED
+(error no further notmuch undo information)
+EOF
+test_expect_equal_file EXPECTED MESSAGES
+
+test_begin_subtest "undo tagging in search mode"
+test_emacs "(let ((notmuch-tag-history nil))
+  (notmuch-search \"$os_x_darwin_thread\")
+  (notmuch-test-wait)
+  (execute-kbd-macro \"+tag-to-be-undone\")
+  (notmuch-tag-undo))"
+count=$(notmuch count "tag:tag-to-be-undone")
+test_expect_equal "$count" "0"
+
 test_done
-- 
2.34.1