PlainObjectPropertyDiff: diff calculation

library/Director/Db/Branch/PlainObjectPropertyDiff.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Icinga\Module\Director\Db\Branch;
+
+class PlainObjectPropertyDiff
+{
+    public static function calculate(array $old = null, array $new = null)
+    {
+        if ($new === null) {
+            throw new \RuntimeException('Cannot diff for delete');
+        }
+        if ($old === null) {
+            foreach (BranchSettings::ENCODED_DICTIONARIES as $property) {
+                self::flattenProperty($new, $property);
+            }
+
+            return $new;
+        }
+        $unchangedKeys = [];
+        foreach (BranchSettings::ENCODED_DICTIONARIES as $property) {
+            self::flattenProperty($old, $property);
+            self::flattenProperty($new, $property);
+        }
+        foreach ($old as $key => $value) {
+            if (array_key_exists($key, $new)) {
+                if ($value === $new[$key]) {
+                    $unchangedKeys[] = $key;
+                }
+            } else {
+                $new[$key] = null;
+            }
+        }
+        foreach ($unchangedKeys as $key) {
+            unset($new[$key]);
+        }
+
+        return $new;
+    }
+
+    protected static function flattenProperty(array &$properties, $property)
+    {
+        // TODO: dots in varnames -> throw or escape?
+        if (isset($properties[$property])) {
+            foreach ((array) $properties[$property] as $key => $value) {
+                $properties["$property.$key"] = $value;
+            }
+            unset($properties[$property]);
+        }
+    }
+}