Introduce printf-like template for hidden characters (#6)

README.md

@@ -91,6 +91,45 @@ $logger->info('Completely hidden', ['you_know_nothing' => 'John Snow']);
 Example.INFO: Completely hidden {"you_know_nothing":"*********"} []
 ```
 
+### Custom format
+
+Feel free to customize a replacement character `*` and/or provide your own template.
+
+```php
+use Monolog\Handler\StreamHandler;
+use RedactSensitive\RedactSensitiveProcessor;
+
+$sensitive_keys = ['secret' => 2];
+
+$processor = new RedactSensitiveProcessor($sensitive_keys, template: '%s(redacted)');
+
+$logger = new \Monolog\Logger('Example', [new StreamHandler(STDOUT)]);
+$logger->pushProcessor($processor);
+
+$logger->info('Sensitive', ['secret' => 'my_secret_value']);
+```
+```text
+Example.INFO: Sensitive {"secret":"my*************(redacted)"} []
+```
+
+Custom template allows to discard the masked characters altogether:
+```php
+use Monolog\Handler\StreamHandler;
+use RedactSensitive\RedactSensitiveProcessor;
+
+$sensitive_keys = ['secret' => 2];
+
+$processor = new RedactSensitiveProcessor($sensitive_keys, template: '...');
+
+$logger = new \Monolog\Logger('Example', [new StreamHandler(STDOUT)]);
+$logger->pushProcessor($processor);
+
+$logger->info('Sensitive', ['secret' => 'my_secret_value']);
+```
+```text
+Example.INFO: Sensitive {"secret":"my..."} []
+```
+
 ### Length limit
 
 Use `lengthLimit` to truncate redacted sensitive information, such as lengthy tokens.

src/RedactSensitiveProcessor.php

@@ -21,19 +21,22 @@ class RedactSensitiveProcessor implements ProcessorInterface
 
     private array $sensitiveKeys;
     private string $replacement;
+    private string $template;
     private ?int $lengthLimit;
 
     /**
      * Creates a new RedactSensitiveProcessor instance.
      *
      * @param array $sensitiveKeys Keys that should trigger the redaction.
      * @param string $replacement The replacement character.
+     * @param string $template Template for replacement characters.
      * @param int|null $lengthLimit Max length after redaction.
      */
-    public function __construct(array $sensitiveKeys, string $replacement = self::DEFAULT_REPLACEMENT, ?int $lengthLimit = null)
+    public function __construct(array $sensitiveKeys, string $replacement = self::DEFAULT_REPLACEMENT, string $template = '%s', ?int $lengthLimit = null)
     {
         $this->sensitiveKeys = $sensitiveKeys;
         $this->replacement = $replacement;
+        $this->template = $template;
         $this->lengthLimit = $lengthLimit;
     }
 
@@ -48,8 +51,9 @@ private function redact(string $value, int $length): string
     {
         $hidden_length = strlen($value) - abs($length);
         $hidden = str_repeat($this->replacement, $hidden_length);
+        $placeholder = sprintf($this->template, $hidden);
 
-        $result = substr_replace($value, $hidden, max(0, $length), $hidden_length);
+        $result = substr_replace($value, $placeholder, max(0, $length), $hidden_length);
 
         $result = $length > 0
             ? substr($result, 0, $this->lengthLimit)

tests/RedactSensitiveTest.php

@@ -14,6 +14,22 @@
     expect($processor($record)->context)->toBe(['test' => 'foo***']);
 });
 
+it('redacts using template', function (): void {
+    $sensitive_keys = ['test' => 2];
+    $processor = new RedactSensitiveProcessor($sensitive_keys, template: '%s(redacted)');
+
+    $record = $this->getRecord(context: ['test' => 'foobar']);
+    expect($processor($record)->context)->toBe(['test' => 'fo****(redacted)']);
+});
+
+it('redacts discarding masked', function (): void {
+    $sensitive_keys = ['test' => 1];
+    $processor = new RedactSensitiveProcessor($sensitive_keys, template: '...');
+
+    $record = $this->getRecord(context: ['test' => 'foobar123']);
+    expect($processor($record)->context)->toBe(['test' => 'f...']);
+});
+
 it('truncates masked characters', function (): void {
     $sensitive_keys = ['test' => 3];
     $processor = new RedactSensitiveProcessor($sensitive_keys, lengthLimit: 5);