amphp (#11)

src/Parser.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nsq;
+
+use Nsq\Exception\NsqException;
+
+class Parser
+{
+    private const SIZE = 4;
+    private const TYPE = 4;
+    private const MESSAGE_HEADER_SIZE =
+        8 +  // timestamp
+        2 +  // attempts
+        16 + // ID
+        4;   // Frame type
+
+    public static function parse(Buffer $buffer): ?Frame
+    {
+        if ($buffer->size() < self::SIZE) {
+            return null;
+        }
+
+        $size = $buffer->readInt32();
+
+        if ($buffer->size() < $size + self::SIZE) {
+            return null;
+        }
+
+        $buffer->discard(self::SIZE);
+
+        $type = $buffer->consumeInt32();
+
+        return match ($type) {
+            Frame::TYPE_RESPONSE => new Frame\Response($buffer->consume($size - self::TYPE)),
+            Frame::TYPE_ERROR => new Frame\Error($buffer->consume($size - self::TYPE)),
+            Frame::TYPE_MESSAGE => new Frame\Message(
+                timestamp: $buffer->consumeTimestamp(),
+                attempts: $buffer->consumeAttempts(),
+                id: $buffer->consumeMessageID(),
+                body: $buffer->consume($size - self::MESSAGE_HEADER_SIZE),
+            ),
+            default => throw new NsqException(sprintf('Unexpected frame type: "%s"', $type)),
+        };
+    }
+}