[PATCH] cli: add support for notmuch search --duplicate=N with --output=messages

[Jani Nikula <jani@nikula.org>]

Print the message IDs of all messages matching the search terms that
have at least N files associated with them.
---
 doc/man1/notmuch-search.rst | 12 ++++++++----
 notmuch-search.c            | 34 ++++++++++++++++++++++++++++++----
 2 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/doc/man1/notmuch-search.rst b/doc/man1/notmuch-search.rst
index 90160f21e23c..aeba4bf604f6 100644
--- a/doc/man1/notmuch-search.rst
+++ b/doc/man1/notmuch-search.rst
@@ -122,10 +122,14 @@ Supported options for **search** include
         rather than the number of matching messages.
 
     ``--duplicate=N``
-        Effective with ``--output=files``, output the Nth filename
-        associated with each message matching the query (N is 1-based).
-        If N is greater than the number of files associated with the
-        message, don't print anything.
+        For ``--output=files``, output the Nth filename associated
+        with each message matching the query (N is 1-based). If N is
+        greater than the number of files associated with the message,
+        don't print anything.
+
+        For ``--output=messages``, only output message IDs of messages
+        matching the search terms that have at least N filenames
+        associated with them.
 
         Note that this option is orthogonal with the **folder:** search
         prefix. The prefix matches messages based on filenames. This
diff --git a/notmuch-search.c b/notmuch-search.c
index bc9be4593ecc..2bf876fd5abf 100644
--- a/notmuch-search.c
+++ b/notmuch-search.c
@@ -215,6 +215,24 @@ do_search_threads (sprinter_t *format,
 }
 
 static int
+_count_filenames (notmuch_message_t *message)
+{
+    notmuch_filenames_t *filenames;
+    int i = 0;
+
+    filenames = notmuch_message_get_filenames (message);
+
+    while (notmuch_filenames_valid (filenames)) {
+	notmuch_filenames_move_to_next (filenames);
+	i++;
+    }
+
+    notmuch_filenames_destroy (filenames);
+
+    return i;
+}
+
+static int
 do_search_messages (sprinter_t *format,
 		    notmuch_query_t *query,
 		    output_t output,
@@ -265,10 +283,13 @@ do_search_messages (sprinter_t *format,
 	    notmuch_filenames_destroy( filenames );
 
 	} else { /* output == OUTPUT_MESSAGES */
-	    format->set_prefix (format, "id");
-	    format->string (format,
-			    notmuch_message_get_message_id (message));
-	    format->separator (format);
+	    /* special case 1 for speed */
+	    if (dupe <= 1 || dupe <= _count_filenames (message)) {
+		format->set_prefix (format, "id");
+		format->string (format,
+				notmuch_message_get_message_id (message));
+		format->separator (format);
+	    }
 	}
 
 	notmuch_message_destroy (message);
@@ -387,6 +408,11 @@ notmuch_search_command (notmuch_config_t *config, int argc, char *argv[])
     if (opt_index < 0)
 	return EXIT_FAILURE;
 
+    if (output != OUTPUT_FILES && output != OUTPUT_MESSAGES && dupe != -1) {
+	fprintf (stderr, "Error: --duplicate=N is only supported with --output=files and --output=messages.\n");
+	return EXIT_FAILURE;
+    }
+
     switch (format_sel) {
     case NOTMUCH_FORMAT_TEXT:
 	format = sprinter_text_create (config, stdout);
-- 
2.1.1