Add Snapshot and Seek support to Cloud Pub/Sub (#428)

* Add Snapshot and Seek support to Cloud Pub/Sub

* Add rest support for snapshot and seek

* Add unit test coverage

* Add snippet tests

* Update pubsub table of contents

* Add snapshot system test

* Address code review

GrpcTrait.php

@@ -178,4 +178,22 @@ private function formatValueForApi($value)
                 return ['list_value' => $this->formatListForApi($value)];
         }
     }
+
+    /**
+     * Format a timestamp for the API with nanosecond precision.
+     *
+     * @param string $value
+     * @return array
+     */
+    private function formatTimestampForApi($value)
+    {
+        preg_match('/\.(\d{1,9})Z/', $value, $matches);
+        $value = preg_replace('/\.(\d{1,9})Z/', '.000000Z', $value);
+        $dt = \DateTimeImmutable::createFromFormat('Y-m-d\TH:i:s.u\Z', $value);
+        $nanos = (isset($matches[1])) ? $matches[1] : 0;
+        return [
+            'seconds' => (int)$dt->format('U'),
+            'nanos' => (int)$nanos
+        ];
+    }
 }

PhpArray.php

@@ -32,13 +32,21 @@ class PhpArray extends Protobuf\Codec\PhpArray
      */
     private $customFilters;
 
+    /**
+     * @var bool
+     */
+    private $useCamelCase;
+
     /**
      * @param array $customFilters A set of callbacks to apply to properties in
      *        a gRPC response.
+     * @param bool $useCamelCase Whether to convert key casing to camelCase.
+     * }
      */
-    public function __construct(array $customFilters = [])
+    public function __construct(array $customFilters = [], $useCamelCase = true)
     {
         $this->customFilters = $customFilters;
+        $this->useCamelCase = $useCamelCase;
     }
 
     /**
@@ -96,7 +104,7 @@ protected function encodeMessage(Protobuf\Message $message)
                 $v = $this->filterValue($v, $field);
             }
 
-            $key = $this->toCamelCase($key);
+            $key = ($this->useCamelCase) ? $this->toCamelCase($key) : $key;
 
             if (isset($this->customFilters[$key])) {
                 $v = call_user_func($this->customFilters[$key], $v);