Add feature flags API

[MAILPOET-2008]

lib/Features/FeatureFlagsController.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace MailPoet\Features;
+
+use MailPoet\Models\FeatureFlag;
+use function MailPoet\Util\array_column;
+
+class FeatureFlagsController {
+  function set($name, $value) {
+    if (!isset(FeaturesController::$defaults[$name])) {
+      throw new \RuntimeException("Feature '$name' does not exist'");
+    }
+
+    $result = FeatureFlag::createOrUpdate([
+      'name' => $name,
+      'value' => $value ,
+    ]);
+
+    if ($result->getErrors()) {
+      throw new \RuntimeException("Error when saving feature '$name''");
+    }
+  }
+
+  function getAll() {
+    $flags = FeatureFlag::findArray();
+    $flagsMap = array_combine(array_column($flags, 'name'), $flags);
+
+    $output = [];
+    foreach (FeaturesController::$defaults as $name => $default) {
+      $output[] = [
+        'name' => $name,
+        'value' => isset($flagsMap[$name]) ? (bool)$flagsMap[$name]['value'] : $default,
+        'default' => $default,
+      ];
+    }
+    return $output;
+  }
+}