Add Response object

src/Response.php

@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nsq;
+
+use PHPinnacle\Buffer\ByteBuffer;
+
+final class Response
+{
+    private const OK = 'OK';
+    private const HEARTBEAT = '_heartbeat_';
+    private const TYPE_RESPONSE = 0;
+    private const TYPE_ERROR = 1;
+    private const TYPE_MESSAGE = 2;
+
+    private int $type;
+
+    private ByteBuffer $buffer;
+
+    public function __construct(ByteBuffer $buffer)
+    {
+        $this->type = $buffer->consumeUint32();
+        $this->buffer = $buffer;
+    }
+
+    public function okOrFail(): void
+    {
+        if (self::TYPE_ERROR === $this->type) {
+            throw new Exception($this->buffer->bytes());
+        }
+
+        if (self::TYPE_RESPONSE !== $this->type) {
+            throw new Exception(sprintf('"%s" type expected, but "%s" received.', self::TYPE_RESPONSE, $this->type));
+        }
+
+        if (self::OK !== $this->buffer->bytes()) {
+            throw new Exception(sprintf('OK response expected, but "%s" received.', $this->buffer->bytes()));
+        }
+    }
+
+    public function isHeartBeat(): bool
+    {
+        return self::TYPE_RESPONSE === $this->type && self::HEARTBEAT === $this->buffer->bytes();
+    }
+
+    public function toMessage(): Message
+    {
+        if (self::TYPE_MESSAGE !== $this->type) {
+            throw new Exception(sprintf('Expecting "%s" type, but NSQ return: "%s"', self::TYPE_MESSAGE, $this->type));
+        }
+
+        $buffer = new ByteBuffer($this->buffer->bytes());
+
+        $timestamp = $buffer->consumeInt64();
+        $attempts = $buffer->consumeUint16();
+        $id = $buffer->consume(Bytes::BYTES_ID);
+        $body = $buffer->flush();
+
+        return new Message($timestamp, $attempts, $id, $body);
+    }
+}