Webservice: List issued certificates

This does not resolve Call list of certificates for a user via API #419 as that specifies getting certificates for a user, not from a date.
Added filter userid and customcertid

Author: michallohnisky

classes/external.php

@@ -244,6 +244,16 @@ public static function list_issues_parameters() {
                     'Timestamp. Returns items created after this date (included).',
                     VALUE_OPTIONAL
                 ),
+                'userid' => new external_value(
+                    PARAM_INT,
+                    'User id. Returns items for this user.',
+                    VALUE_OPTIONAL
+                ),
+                'customcertid' => new external_value(
+                    PARAM_INT,
+                    'Customcert id. Returns items for this customcert.',
+                    VALUE_OPTIONAL
+                ),
             ]
         );
     }
@@ -252,9 +262,11 @@ public static function list_issues_parameters() {
      * Returns array of issued certificates.
      *
      * @param ?int $timecreatedfrom Timestamp. Returns items created after this date (included).
+     * @param ?int $userid User id. Returns items for this user.
+     * @param ?int $customcertid Customcert id. Returns items for this customcert.
      * @return array
      */
-    public static function list_issues($timecreatedfrom = null) {
+    public static function list_issues($timecreatedfrom = null, $userid = null, $customcertid = null) {
         global $DB;
 
         $params = [
@@ -273,10 +285,22 @@ public static function list_issues($timecreatedfrom = null) {
                     ON ci.customcertid = c.id
                   JOIN {customcert_templates} ct
                     ON c.templateid = ct.id";
+        $conditions = [];
         if ($timecreatedfrom) {
-            $sql .= " WHERE ci.timecreated >= :timecreatedfrom";
+            $conditions[] = "ci.timecreated >= :timecreatedfrom";
             $nameparams['timecreatedfrom'] = $timecreatedfrom;
         }
+        if ($userid) {
+            $conditions[] = "ci.userid = :userid";
+            $nameparams['userid'] = $userid;
+        }
+        if ($customcertid) {
+            $conditions[] = "ci.customcertid = :customcertid";
+            $nameparams['customcertid'] = $customcertid;
+        }
+        if ($conditions) {
+            $sql .= " WHERE " . implode(" AND ", $conditions);
+        }
 
         if ($issues = $DB->get_records_sql($sql, $nameparams)) {