Matomo plugin: Add conditions for sending search analytics data

The Matomo plugin only sends data under the following conditions:

* The modal UI is opened
* The query string has length greater than 0
* The query term wasn't used before

Increase debounce limit to 500 ms.

Author: ngulden

packages/docsearch-react/src/MatomoPlugin.tsx

@@ -6,19 +6,22 @@ declare global {
     }
 }
 
+var query_cache = "";
+
 function _matomoSiteSearch(query: string, hits: string) {
+        query_cache = query;
         var _paq = window._paq = window._paq || [];
-        if (query.length > 0) {
-            _paq.push(['trackSiteSearch', query, false, hits]);
-        }
+        _paq.push(['trackSiteSearch', query, false, hits]);
 }
 
-var matomoSiteSearch_debounced = debounce(_matomoSiteSearch, 400);
+var matomoSiteSearch_debounced = debounce(_matomoSiteSearch, 500);
 
 export function createMatomoPlugin() {
     return {
         onStateChange({ state }) {
-            matomoSiteSearch_debounced(state.query, state.context.nbHits);
-        }
+            if ( state.isOpen && state.query.length > 0 && query_cache !== state.query ) {
+                matomoSiteSearch_debounced(state.query, state.context.nbHits);
+            }
+        },
     };
 };