Display "no data" warning on the page

Previously, the plugin was using an inline javascript to display a
pop-up alert message and then redirect to my view page.

With CSP enabled by default in Mantis 2.x, the inline script was blocked
so this feature was no longer working as expected.

Fixes #21

lang/strings_english.txt

@@ -59,3 +59,4 @@ $s_plugin_GaugeSupport_ASPU_abbr = 'ASPU';
 $s_plugin_GaugeSupport_ASPU_label = 'Average Support per User';
 $s_plugin_GaugeSupport_show_all_pos = '» Show all {project} issues, highest-supported first';
 $s_plugin_GaugeSupport_show_all_neg = '» Show all {project} issues, lowest-supported first';
+$s_plugin_GaugeSupport_no_data = 'There is not enough data to generate a report.';

pages/issue_ranking.php

@@ -48,10 +48,7 @@
  // echo "<p>$dbquery</p>";
  //die();
  $dboutput = db_query($dbquery);
- $noOfRowsWeGot = db_num_rows($dboutput);
- if ($noOfRowsWeGot==0){
- echo "<script>alert('There is not enough data to generate a report');window.location='my_view_page.php';</script>";
- }
+
  $resultset = array();
  // load listable issues into array
  while($row = db_fetch_array($dboutput)) {
@@ -87,6 +84,20 @@
  <div class="widget-body">
  <div class="widget-main no-padding">
 
+<?php
+ if( empty( $resultset ) ) {
+?>
+ <div class="container-fluid">
+ <br>
+ <div class="alert alert-warning center">
+ <?php echo plugin_lang_get( 'no_data' ); ?>
+ </div>
+ &nbsp;
+ </div>
+<?php
+ } else {
+?>
+
  <div class="table-responsive">
  <div class="widget-toolbox padding-8 clearfix">
  <a class="btn btn-primary btn-white btn-round "
@@ -123,7 +134,9 @@
 ?>
  </table>
  </div>
-
+<?php
+ } # if empty result set
+?>
  </div>
  </div>
 </div>