Suggest special filters like "All" and "Private messages" in search.

(They will show up for empty queries or queries that are prefixes
of either the operator syntax or the label used in the sidebar.)

(imported from commit 3765896e3bc1fc95caf987194e22d89d649ba5ae)

zephyr/static/js/search.js

@@ -279,6 +279,50 @@ function get_topic_suggestions(query, query_operators) {
     });
 }
 
+function get_special_filter_suggestions(query, operators) {
+    if (operators.length >= 2) {
+        return [];
+    }
+
+    var suggestions = [
+        {
+            search_string: '',
+            description: 'Home'
+        },
+        {
+            search_string: 'in:all',
+            description: 'All messages'
+        },
+        {
+            search_string: 'is:private',
+            description: 'Private messages'
+        },
+        {
+            search_string: 'is:starred',
+            description: 'Starred messages'
+        },
+        {
+            search_string: 'is:mentioned',
+            description: '@-mentions'
+        }
+    ];
+
+    query = query.toLowerCase();
+
+    suggestions = $.grep(suggestions, function (s) {
+        if (s.search_string.toLowerCase() === query) {
+            return false; // redundant
+        }
+        if (query === '') {
+            return true;
+        }
+        return (s.search_string.toLowerCase().indexOf(query) === 0) ||
+               (s.description.toLowerCase().indexOf(query) === 0);
+    });
+
+    return suggestions;
+}
+
 exports.initialize = function () {
     $( "#search_query" ).typeahead({
         source: function (query, process) {
@@ -291,6 +335,9 @@ exports.initialize = function () {
             suggestion = get_suggestion_based_on_query(query, operators);
             result = [suggestion];
 
+            suggestions = get_special_filter_suggestions(query, operators);
+            result = result.concat(suggestions);
+
             suggestions = get_stream_suggestions(query);
             result = result.concat(suggestions);