feat: error-codes in flash messages to reference log entries

src/Service/ErrorCodeService.php

@@ -0,0 +1,99 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service;
+
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * Generates and tracks error reference codes for user-facing error messages.
+ *
+ * Produces deterministic codes based on the current request ID, allowing users
+ * to report error codes to support staff who can then search logs by the code.
+ * The code format is E-XXXXXXXX (8 uppercase alphanumeric characters in base36).
+ */
+class ErrorCodeService
+{
+    private ?string $errorCode = null;
+    private bool $hasError = false;
+
+    public function __construct(
+        private readonly RequestStack $requestStack,
+    ) {
+    }
+
+    /**
+     * Returns the error code for the current request.
+     *
+     * Generates a deterministic code from the request ID on first call and
+     * caches it for subsequent calls. Sequence suffixes like _1, _2 are
+     * stripped before hashing to ensure all requests in a sequence share
+     * the same error code.
+     *
+     * @return string|null The error code or null if no request context exists
+     */
+    public function getErrorCode(): ?string
+    {
+        if (null !== $this->errorCode) {
+            return $this->errorCode;
+        }
+
+        $request = $this->requestStack->getMainRequest();
+        if (null === $request) {
+            return null;
+        }
+
+        $requestId = $request->attributes->get('request_id');
+        if (null === $requestId) {
+            return null;
+        }
+
+        $this->errorCode = $this->generateCode((string) $requestId);
+
+        return $this->errorCode;
+    }
+
+    /**
+     * Marks that an error has occurred during this request.
+     *
+     * Called by the ErrorCodeProcessor when a log entry with ERROR level
+     * or higher is created.
+     */
+    public function markErrorOccurred(): void
+    {
+        $this->hasError = true;
+    }
+
+    /**
+     * Checks whether an error has been logged during this request.
+     *
+     * @return bool True if an error has been logged, false otherwise
+     */
+    public function hasError(): bool
+    {
+        return $this->hasError;
+    }
+
+    /**
+     * Generates an error code from a request ID.
+     *
+     * Strips sequence suffixes, hashes the normalized ID, and converts
+     * to a base36 representation prefixed with E-.
+     *
+     * @param string $requestId The request ID to generate a code from
+     *
+     * @return string The generated error code in format E-XXXXXXXX
+     */
+    private function generateCode(string $requestId): string
+    {
+        $normalizedId = preg_replace('/_\d+$/', '', $requestId);
+        $hash = md5((string) $normalizedId);
+        $hexPart = substr($hash, 0, 12);
+        $decimal = hexdec($hexPart);
+        $base36 = strtoupper(base_convert((string) $decimal, 10, 36));
+        $padded = str_pad($base36, 8, '0', STR_PAD_LEFT);
+
+        return 'E-'.substr($padded, 0, 8);
+    }
+}