Add survey_anonymous_show_answered conf settings - refs BT#15280

Allow show answers in anonymous surveys

main/install/configuration.dist.php

@@ -525,6 +525,8 @@ ALTER TABLE c_survey_question ADD is_required TINYINT(1) DEFAULT 0 NOT NULL;
 // Allow add additional actions (as links) in survey list for teachers.
 // e.g. ['myplugin' => ['MyPlugin', 'urlGeneratorCallback']]
 //$_configuration['survey_additional_teacher_modify_actions'] = [];
+// Allow show answers in anonymous surveys
+//$_configuration['survey_anonymous_show_answered'] = false;
 // ------
 
 // Allow career diagram, requires a DB change:

main/survey/survey.lib.php

@@ -1790,6 +1790,15 @@ class SurveyManager
         } else {
             $sql = "SELECT DISTINCT user FROM $table_survey_answer
 			        WHERE c_id = $course_id AND survey_id= '".$survey_id."'  ";
+
+            if (api_get_configuration_value('survey_anonymous_show_answered')) {
+                $tblInvitation = Database::get_course_table(TABLE_SURVEY_INVITATION);
+                $tblSurvey = Database::get_course_table(TABLE_SURVEY);
+
+                $sql = "SELECT i.user FROM $tblInvitation i
+                    INNER JOIN $tblSurvey s ON i.survey_code = s.code
+                    WHERE i.answered IS TRUE AND s.iid = $survey_id";
+            }
         }
 
         $res = Database::query($sql);

main/survey/survey_invitation.php

@@ -55,7 +55,7 @@ Display::display_header($tool_name);
 
 // Getting all the people who have filled this survey
 $answered_data = SurveyManager::get_people_who_filled_survey($survey_id);
-if ($survey_data['anonymous'] == 1) {
+if ($survey_data['anonymous'] == 1 && !api_get_configuration_value('survey_anonymous_show_answered')) {
     echo Display::return_message(
         get_lang('AnonymousSurveyCannotKnowWhoAnswered').' '.count(
             $answered_data
@@ -122,7 +122,8 @@ while ($row = Database::fetch_assoc($res)) {
         echo '	<td>'.Display::dateToStringAgoAndLongDate($row['invitation_date']).'</td>';
         echo '	<td>';
 
-        if (in_array($row['user'], $answered_data) && !api_get_configuration_value('hide_survey_reporting_button')) {
+        if (in_array($row['user'], $answered_data) && !api_get_configuration_value('hide_survey_reporting_button') &&
+            !api_get_configuration_value('survey_anonymous_show_answered')) {
             echo '<a href="'.
                 api_get_path(WEB_CODE_PATH).
                 'survey/reporting.php?action=userreport&survey_id='.$survey_id.'&user='.$row['user'].'&'.api_get_cidreq().'">'.