Display an error message listing empty feeds (no read/unread items)

index.php

@@ -344,6 +344,11 @@ Router\get_action('refresh-all', function() {
 // Display all feeds
 Router\get_action('feeds', function() {
 
+    $empty_feeds = Model\get_empty_feeds();
+    if (count($empty_feeds) > 0) {
+        $message = t('The following feeds are empty, there may be an error : ') . implode(', ', $empty_feeds);
+        Session\flash_error($message);
+    }
     Response\html(Template\layout('feeds', array(
         'feeds' => Model\get_feeds(),
         'nothing_to_read' => Request\int_param('nothing_to_read'),

locales/fr_FR/translations.php

@@ -1,6 +1,8 @@
 <?php
 
 return array(
+    'The following feeds are empty, there may be an error : ' =>
+    'Les abonnements suivants sont vides, il doit y avoir une erreur :',
     'Items per page' => 'Nombre d\'éléments par page',
     'Previous page' => 'Page précédente',
     'Next page' => 'Page suivante',

model.php

@@ -247,6 +247,30 @@ function get_feed($feed_id)
         ->findOne();
 }
 
+function get_empty_feeds()
+{
+    $feeds = \PicoTools\singleton('db')
+        ->table('feeds')
+        ->gt('last_checked', 0)
+        ->asc('id')
+        ->listing('id', 'title');
+    $ids = array_keys($feeds);
+
+    // fake DISTINCT
+    $not_empty_feeds = \PicoTools\singleton('db')
+        ->table('items')
+        ->asc('feed_id')
+        ->listing('feed_id', 'feed_id');
+    $not_empty_ids = array_keys($not_empty_feeds);
+
+    $diff = array_diff($ids, $not_empty_ids);
+    $return = array();
+    foreach ($diff as $id) {
+        $return[$id] = $feeds[$id];
+    }
+    return $return;
+}
+
 
 function update_feed_last_checked($feed_id)
 {