Shipments: Handle API rate limit message (#14)

* Shipments: Handle API rate limit message

* Update logic to throw exception

* Update logic to apply to all requests

* Use function to check rate limit

* Config: Add request limit option

* Update rate limit handling

* Revert removing retryAfter exception variable

config/shipengine.php

@@ -26,6 +26,7 @@
         'version'  => env('SHIP_ENGINE_API_VERSION', 'v1'),
         'base'     => env('SHIP_ENGINE_ENDPOINT', 'https://api.shipengine.com/'),
     ],
+    'request_limit_per_minute' => env('SHIP_ENGINE_REQUEST_LIMIT_PER_MINUTE', 200),
     'retries'  => env('SHIP_ENGINE_RETRIES', 1),
     'response' => [
         'as_object' => env('SHIP_ENGINE_RESPONSE_AS_OBJECT', false),

src/ShipEngineClient.php

@@ -5,11 +5,13 @@
 use BluefynInternational\ShipEngine\Message\RateLimitExceededException;
 use BluefynInternational\ShipEngine\Message\ShipEngineException;
 use BluefynInternational\ShipEngine\Models\RequestLog;
+use DateInterval;
 use Exception;
 use GuzzleHttp\Client;
 use GuzzleHttp\Exception\GuzzleException;
 use GuzzleHttp\Psr7\Request;
 use Illuminate\Http\Response;
+use Illuminate\Support\Facades\Cache;
 use Throwable;
 
 class ShipEngineClient
@@ -184,10 +186,18 @@ private static function sendRequest(
         }
 
         try {
+            self::incrementRequestCount($config);
+
             $response = $client->send(
                 $request,
                 ['timeout' => $config->timeout->s, 'http_errors' => false]
             );
+
+            $requestLogResponse = json_decode((string)$response->getBody(), true);
+
+            if (self::responseIsRateLimit($requestLogResponse)) {
+                throw new RateLimitExceededException(retryAfter: new DateInterval('PT1S'));
+            }
         } catch (Exception|Throwable  $err) {
             if (config('shipengine.track_requests')) {
                 $requestLog->exception = substr($err->getMessage(), 0, config('shipengine.request_log_table_exception_length'));
@@ -205,7 +215,7 @@ private static function sendRequest(
         }
 
         $requestLog->response_code = $response->getStatusCode();
-        $requestLog->response = json_decode((string)$response->getBody(), true);
+        $requestLog->response = $requestLogResponse;
 
         if (config('shipengine.track_requests')) {
             $requestLog->save();
@@ -269,4 +279,27 @@ private static function deriveUserAgent(): string
 
         return $sdk_version . ' ' . $os_kernel . ' ' . $php_version;
     }
+
+    private static function responseIsRateLimit(array $response) : bool
+    {
+        return 'API rate limit exceeded' === ($response['message'] ?? null);
+    }
+
+    private static function incrementRequestCount(ShipEngineConfig $config) : void
+    {
+        $lock = tap(Cache::lock('shipengine.api-request.lock', 10))->block(10);
+
+        try {
+            $count = Cache::get('shipengine.api-request.count', 0);
+            $nextExpire = now()->seconds(0)->addMinute();
+
+            if ($count > $config->requestLimitPerMinute) {
+                throw new RateLimitExceededException(retryAfter: new DateInterval('PT1S'));
+            }
+
+            Cache::put('shipengine.api-request.count', $count + 1, $nextExpire);
+        } finally {
+            $lock->release();
+        }
+    }
 }

src/ShipEngineConfig.php

@@ -17,6 +17,8 @@ final class ShipEngineConfig implements \JsonSerializable, Arrayable
 
     public int $retries;
 
+    public int $requestLimitPerMinute;
+
     public bool $asObject = false;
 
     public DateInterval $timeout;
@@ -39,6 +41,11 @@ public function __construct(array $config = [])
         $assert->isRetriesValid($retries);
         $this->retries = $retries;
 
+        $requestLimitPerMinute = $config['request_limit_per_minute']
+            ?? config('shipengine.request_limit_per_minute', 200);
+        $assert->isRequestLimitPerMinuteValid($requestLimitPerMinute);
+        $this->requestLimitPerMinute = $requestLimitPerMinute;
+
         $timeout_value = $config['timeout'] ?? new DateInterval(config('shipengine.timeout', 'PT10S'));
         if (is_string($timeout_value)) {
             $timeout_value = new DateInterval($timeout_value);

src/Traits/Shipments.php

@@ -58,7 +58,10 @@ public function createShipment(
             $params,
         );
 
-        if (! $response['has_errors'] && $config->asObject) {
+        if (
+            ! ($response['has_errors'] ?? null)
+            && $config->asObject
+        ) {
             $response['shipments'] = $this->listToObjects($response['shipments'], Shipment::class);
         }
 

src/Util/Assert.php

@@ -60,4 +60,17 @@ public function isRetriesValid(int $retries) : void
             );
         }
     }
+
+    public function isRequestLimitPerMinuteValid(int $requestsPerMinute) : void
+    {
+        if ($requestsPerMinute < 0) {
+            throw new ValidationException(
+                'Requests limit per minute must be zero or greater.',
+                null,
+                'shipengine',
+                'validation',
+                'invalid_field_value'
+            );
+        }
+    }
 }