Logic for hashing instead of redacting added + code cleanup

src/HashSensitiveProcessor.php

@@ -16,6 +16,7 @@ class HashSensitiveProcessor implements ProcessorInterface
 {
     private array $sensitiveKeys;
     private ?int $lengthLimit;
+    private string $algorithm;
 
     /**
      * Creates a new HashSensitiveProcessor instance.
@@ -27,87 +28,128 @@ public function __construct(array $sensitiveKeys, string $algorithm = 'sha256',
     {
         $this->sensitiveKeys = $sensitiveKeys;
         $this->lengthLimit = $lengthLimit;
+        $this->algorithm = $algorithm;
     }
 
-
+    /**
+     * Invoke hook into the monolog processor execution.
+     *
+     * @param LogRecord $record Log record before being processed.
+     *
+     * @return LogRecord Log record with redacted values hashed.
+     */
     public function __invoke(LogRecord $record): LogRecord
     {
         $redactedContext = $this->traverseInputArray($record->context, $this->sensitiveKeys);
         return $record->with(context: $redactedContext);
     }
 
+    /**
+     * Function to hash the input value, using the specified hashing algorithm and length limit
+     *
+     * @param string $value The value to hash
+     *
+     * @return string|null The hashed value, or null, if the input string was empty
+     */
     private function hash(string $value): ?string
     {
         if (strlen($value) === 0) {
             return null;
         }
 
-        $hiddenLength = $valueLength - abs($length);
-        $hidden = str_repeat($this->replacement, $hiddenLength);
-        $placeholder = sprintf($this->template, $hidden);
-
-        $result = substr_replace($value, $placeholder, max(0, $length), $hiddenLength);
-
-        return $length > 0
-            ? substr($result, 0, $this->lengthLimit)
-            : substr($result, -$this->lengthLimit);
+        // Cut the input to the length limit specified
+        $cutInput = substr($value, 0, $this->lengthLimit);
+        return hash($this->algorithm, $cutInput);
     }
 
     /**
-     * @param array|object $value
-     * @param array|int $keys
-     * @return array|object
+     * Function to handle traversing arrays and objects
+     *
+     * @param string       $key           The key being processed
+     * @param array|object $value         The value of the key in the input data
+     * @param array        $sensitiveKeys The list of keys to hash
+     *
+     * @throws UnexpectedValueException if $value was not either an array of an object
+     *
+     * @return array|object The processed array or object
      */
-    private function traverse(string $key, $value, $keys)
+    private function traverse(string $key, array|object $value, array $sensitiveKeys): array|object
     {
         if (is_array($value)) {
-            return $this->traverseArr($value, $keys);
+            return $this->traverseInputArray($value, $sensitiveKeys);
         }
 
         if (is_object($value)) {
-            return $this->traverseObj($value, $keys);
+            return $this->traverseObject($value, $sensitiveKeys);
         }
 
         throw new UnexpectedValueException("Don't know how to traverse value at key $key");
     }
 
+    /**
+     * Traverse an array and replace all values to be redacted with a hashed version of the value
+     *
+     * @param array $inputArray    Array to redact values from
+     * @param array $sensitiveKeys Keys to redact
+     *
+     * @return array Input array with redacted values hashed
+     */
     private function traverseInputArray(array $inputArray, array $sensitiveKeys): array
     {
         foreach ($inputArray as $key => $value) {
+            if ($value === null) {
+                // Nothing to hash or process
+                continue;
+            }
+
+            // If the value is not an array or an object, hash it if it is a sensitive key
             if (is_scalar($value)) {
                 if (array_key_exists($key, $sensitiveKeys)) {
                     $inputArray[$key] = $this->hash((string) $value);
                 }
+
                 continue;
+            }
+
+            // The value is either an array or an object, let traverse handle the specifics
+            if (array_key_exists($key, $sensitiveKeys)) {
+                $inputArray[$key] = $this->traverse($key, $value, $sensitiveKeys[$key]);
             } else {
-                if (array_key_exists($key, $sensitiveKeys)) {
-                    $inputArray[$key] = $this->traverse($key, $value, $sensitiveKeys[$key]);
-                } else {
-                    $inputArray[$key] = $this->traverse($key, $value, $sensitiveKeys);
-                }
+                $inputArray[$key] = $this->traverse($key, $value, $sensitiveKeys);
             }
         }
 
         return $inputArray;
     }
 
-    private function traverseObj(object $obj, array $keys): object
+    /**
+     * Traverse an object and replace all values to be redacted with a hashed version of the value
+     *
+     * @param object $object        Object to redact values from
+     * @param array  $sensitiveKeys Keys for which to hash the value
+     *
+     * @return object The object with redacted values hashed
+     */
+    private function traverseObject(object $object, array $sensitiveKeys): object
     {
-        foreach (get_object_vars($obj) as $key => $value) {
+        foreach (get_object_vars($object) as $key => $value) {
+            // If the value is not an array or an object, hash it if it is a sensitive key
             if (is_scalar($value)) {
-                if (array_key_exists($key, $keys)) {
-                    $obj->{$key} = $this->redact((string) $value, $keys[$key]);
+                if (array_key_exists($key, $sensitiveKeys)) {
+                    $object->{$key} = $this->hash((string) $value);
                 }
+
                 continue;
+            }
+
+            // The value is either an array or an object, let traverse handle the specifics
+            if (array_key_exists($key, $sensitiveKeys)) {
+                $object->{$key} = $this->traverse($key, $value, $sensitiveKeys[$key]);
             } else {
-                if (array_key_exists($key, $keys)) {
-                    $obj->{$key} = $this->traverse($key, $value, $keys[$key]);
-                } else {
-                    $obj->{$key} = $this->traverse($key, $value, $keys);
-                }
+                $object->{$key} = $this->traverse($key, $value, $sensitiveKeys);
             }
         }
 
-        return $obj;
+        return $object;
     }
 }