added json, xml and txt invoice renderer (#1576)

src/Twig/Extensions.php

@@ -71,6 +71,7 @@ class Extensions extends AbstractExtension
             new TwigFilter('language', [$this, 'language']),
             new TwigFilter('amount', [$this, 'amount']),
             new TwigFilter('docu_link', [$this, 'documentationLink']),
+            new TwigFilter('multiline_indent', [$this, 'multilineIndent']),
         ];
     }
 
@@ -98,6 +99,24 @@ class Extensions extends AbstractExtension
         return get_class($object);
     }
 
+    public function multilineIndent(?string $string, string $indent): string
+    {
+        if (null === $string || '' === $string) {
+            return '';
+        }
+
+        $parts = explode("\r\n", $string);
+        if (count($parts) === 1) {
+            $parts = explode("\n", $string);
+        }
+
+        $parts = array_map(function ($part) use ($indent) {
+            return $indent . $part;
+        }, $parts);
+
+        return implode("\n", $parts);
+    }
+
     /**
      * Transforms seconds into a duration string.
      *