[Sfeed] Added new format (#3306)

* [Sfeed] Added new format

* [Sfeed] Spaces instead of tabs

* [Sfeed] Move all global functions to class and fix phpcs warnings

formats/SfeedFormat.php

@@ -0,0 +1,64 @@
+<?PHP
+
+class SfeedFormat extends FormatAbstract
+{
+    const MIME_TYPE = 'text/plain';
+
+    private function escape(string $str)
+    {
+        $str = str_replace('\\', '\\\\', $str);
+        $str = str_replace("\n", "\\n", $str);
+        return str_replace("\t", "\\t", $str);
+    }
+
+    private function getFirstEnclosure(array $enclosures)
+    {
+        if (count($enclosures) >= 1) {
+            return $enclosures[0];
+        }
+        return '';
+    }
+
+    private function getCategories(array $cats)
+    {
+        $toReturn = '';
+        $i = 0;
+        foreach ($cats as $cat) {
+            $toReturn .= $cat;
+            if (count($cats) < $i) {
+                $toReturn .= '|';
+            }
+            $i++;
+        }
+        return $toReturn;
+    }
+
+    public function stringify()
+    {
+        $items = $this->getItems();
+
+        $toReturn = '';
+        foreach ($items as $item) {
+            $toReturn .= sprintf(
+                "%s\t%s\t%s\t%s\thtml\t\t%s\t%s\t%s\n",
+                $item->toArray()['timestamp'],
+                $this->escape($item->toArray()['title']),
+                $item->toArray()['uri'],
+                $this->escape($item->toArray()['content']),
+                $item->toArray()['author'],
+                $this->getFirstEnclosure($item->toArray()['enclosures']),
+                $this->getCategories($item->toArray()['categories'])
+            );
+        }
+
+        // Remove invalid non-UTF8 characters
+        ini_set('mbstring.substitute_character', 'none');
+        $toReturn = mb_convert_encoding(
+            $toReturn,
+            $this->getCharset(),
+            'UTF-8'
+        );
+        return $toReturn;
+    }
+}
+// vi: expandtab