[PATCH] introduce new.rename_tags for renamed (moved) messages

[Michael J Gruber <git@grubix.eu>]

IMAP clients (such as webmail) use folders to mark messages as junk
etc., some even to mark messages as trash ("move to trash"). Such a
change is reported by notmuch as a rename; the message is not tagged
with new.tags since it is not new, so that there is no way to act upon a
rename.

Introduce new.rename_tags (default: not set) which are added by `notmuch
new` to renamed messages. This allows to act upon renames, e.g. to keep
the IMAP folder structure in sync with tags with a tool like `afew` or
homecooked scripts simply by filtering for this tag in the same ways as
one would filter for new messages using new.tags.

Signed-off-by: Michael J Gruber <git@grubix.eu>
---
 NEWS                        | 11 +++++++++++
 doc/man1/notmuch-config.rst |  6 ++++++
 notmuch-client.h            |  8 ++++++++
 notmuch-config.c            | 26 ++++++++++++++++++++++++++
 notmuch-new.c               | 23 +++++++++++++++++++++++
 5 files changed, 74 insertions(+)

diff --git a/NEWS b/NEWS
index 240d594b..e3b75e74 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,14 @@
+Notmuch 0.28 (UNRELEASED)
+=========================
+
+New command-line features
+-------------------------
+
+User-configurable tags for renamed messages
+
+  A new "new.rename_tags" option is available in the configuration file to
+  determine which tags are applied to renamed (moved) messages.
+
 Notmuch 0.27 (2018-06-13)
 =========================
 
diff --git a/doc/man1/notmuch-config.rst b/doc/man1/notmuch-config.rst
index 89909808..9e4198a1 100644
--- a/doc/man1/notmuch-config.rst
+++ b/doc/man1/notmuch-config.rst
@@ -77,6 +77,12 @@ The available configuration items are described below.
 
     Default: ``unread;inbox``.
 
+**new.rename_tags**
+    A list of tags that will be added to all messages which
+    **notmuch new** identifies as renamed (moved).
+
+    Default: not set.
+
 **new.ignore**
     A list to specify files and directories that will not be searched
     for messages by **notmuch new**. Each entry in the list is either:
diff --git a/notmuch-client.h b/notmuch-client.h
index 6c84ecc0..5e1e6b66 100644
--- a/notmuch-client.h
+++ b/notmuch-client.h
@@ -316,6 +316,14 @@ notmuch_config_set_new_tags (notmuch_config_t *config,
 			     const char *new_tags[],
 			     size_t length);
 
+const char **
+notmuch_config_get_rename_tags (notmuch_config_t *config,
+			     size_t *length);
+void
+notmuch_config_set_rename_tags (notmuch_config_t *config,
+			     const char *rename_tags[],
+			     size_t length);
+
 const char **
 notmuch_config_get_new_ignore (notmuch_config_t *config,
 			       size_t *length);
diff --git a/notmuch-config.c b/notmuch-config.c
index e1b16609..02f7d247 100644
--- a/notmuch-config.c
+++ b/notmuch-config.c
@@ -132,6 +132,8 @@ struct _notmuch_config {
     size_t user_other_email_length;
     const char **new_tags;
     size_t new_tags_length;
+    const char **rename_tags;
+    size_t rename_tags_length;
     const char **new_ignore;
     size_t new_ignore_length;
     bool maildir_synchronize_flags;
@@ -712,6 +714,14 @@ notmuch_config_get_new_tags (notmuch_config_t *config,   size_t *length)
 			     &(config->new_tags_length), length);
 }
 
+const char **
+notmuch_config_get_rename_tags (notmuch_config_t *config,   size_t *length)
+{
+    return _config_get_list (config, "new", "rename_tags",
+			     &(config->rename_tags),
+			     &(config->rename_tags_length), length);
+}
+
 const char **
 notmuch_config_get_new_ignore (notmuch_config_t *config, size_t *length)
 {
@@ -738,6 +748,15 @@ notmuch_config_set_new_tags (notmuch_config_t *config,
 		     &(config->new_tags));
 }
 
+void
+notmuch_config_set_rename_tags (notmuch_config_t *config,
+				     const char *list[],
+				     size_t length)
+{
+    _config_set_list (config, "new", "rename_tags", list, length,
+		     &(config->rename_tags));
+}
+
 void
 notmuch_config_set_new_ignore (notmuch_config_t *config,
 			       const char *list[],
@@ -867,6 +886,13 @@ notmuch_config_command_get (notmuch_config_t *config, char *item)
 	tags = notmuch_config_get_new_tags (config, &length);
 	for (i = 0; i < length; i++)
 	    printf ("%s\n", tags[i]);
+    } else if (strcmp(item, "new.rename_tags") == 0) {
+	const char **tags;
+	size_t i, length;
+
+	tags = notmuch_config_get_rename_tags (config, &length);
+	for (i = 0; i < length; i++)
+	    printf ("%s\n", tags[i]);
     } else if (STRNCMP_LITERAL (item, BUILT_WITH_PREFIX) == 0) {
 	printf ("%s\n",
 		notmuch_built_with (item + strlen (BUILT_WITH_PREFIX)) ? "true" : "false");
diff --git a/notmuch-new.c b/notmuch-new.c
index 6a54a1a1..e6d3dc82 100644
--- a/notmuch-new.c
+++ b/notmuch-new.c
@@ -50,6 +50,8 @@ typedef struct {
     bool full_scan;
     const char **new_tags;
     size_t new_tags_length;
+    const char **rename_tags;
+    size_t rename_tags_length;
     const char **ignore_verbatim;
     size_t ignore_verbatim_length;
     regex_t *ignore_regex;
@@ -948,9 +950,18 @@ remove_filename (notmuch_database_t *notmuch,
 
     status = notmuch_database_remove_message (notmuch, path);
     if (status == NOTMUCH_STATUS_DUPLICATE_MESSAGE_ID) {
+        const char **tag;
 	add_files_state->renamed_messages++;
+	notmuch_message_freeze (message);
+
+	for (tag = add_files_state->rename_tags; tag != NULL && *tag != NULL; tag++) {
+	    notmuch_message_add_tag (message, *tag);
+	}
+
+
 	if (add_files_state->synchronize_flags == true)
 	    notmuch_message_maildir_flags_to_tags (message);
+	notmuch_message_thaw (message);
 	status = NOTMUCH_STATUS_SUCCESS;
     } else if (status == NOTMUCH_STATUS_SUCCESS) {
 	add_files_state->removed_messages++;
@@ -1095,6 +1106,7 @@ notmuch_new_command (notmuch_config_t *config, int argc, char *argv[])
 	add_files_state.verbosity = VERBOSITY_VERBOSE;
 
     add_files_state.new_tags = notmuch_config_get_new_tags (config, &add_files_state.new_tags_length);
+    add_files_state.rename_tags = notmuch_config_get_rename_tags (config, &add_files_state.rename_tags_length);
     add_files_state.synchronize_flags = notmuch_config_get_maildir_synchronize_flags (config);
     db_path = notmuch_config_get_database_path (config);
     add_files_state.db_path = db_path;
@@ -1113,6 +1125,17 @@ notmuch_new_command (notmuch_config_t *config, int argc, char *argv[])
 	}
     }
 
+    for (i = 0; i < add_files_state.rename_tags_length; i++) {
+	const char *error_msg;
+
+	error_msg = illegal_tag (add_files_state.rename_tags[i], false);
+	if (error_msg) {
+	    fprintf (stderr, "Error: tag '%s' in rename.tags: %s\n",
+		     add_files_state.rename_tags[i], error_msg);
+	    return EXIT_FAILURE;
+	}
+    }
+
     if (hooks) {
 	ret = notmuch_run_hook (db_path, "pre-new");
 	if (ret)
-- 
2.18.0.226.g7b49cad896