Add service for fixing newsletter API data

[MAILPOET-3430]

lib/Newsletter/ApiDataSanitizer.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace MailPoet\Newsletter;
+
+class ApiDataSanitizer {
+  /** @var NewsletterHtmlSanitizer */
+  private $htmlSanitizer;
+
+  public function __construct(NewsletterHtmlSanitizer $htmlSanitizer) {
+    $this->htmlSanitizer = $htmlSanitizer;
+  }
+
+  public function sanitizeBody(array $body): array {
+    foreach ($body as $blockName => $block) {
+      $sanitizedBlock = is_array($block) ? $this->sanitizeBlock($block) : $this->htmlSanitizer->sanitize($block);
+      $body[$blockName] = $sanitizedBlock;
+    }
+
+    return $body;
+  }
+
+  private function sanitizeBlock(array $block): array {
+    foreach ($block as $name => $value) {
+      if (is_array($value)) {
+        $block[$name] = $this->sanitizeBlock($value);
+      } else {
+        $block[$name] = $value ? $this->htmlSanitizer->sanitize($value) : $value;
+      }
+    }
+    return $block;
+  }
+}