Issue #6

Author: fenric

README.md

@@ -543,6 +543,20 @@ $header = new HeaderSetCookie('qwerty', '219ffwef9w0f', new \DateTime('+1 day'),
 $message = $header->addToMessage($message);
 ```
 
+#### Sunset
+
+> Useful link: https://tools.ietf.org/id/draft-wilde-sunset-header-03.html
+
+```php
+use Sunrise\Http\Header\HeaderSunset;
+use Sunrise\Http\Message\ResponseFactory;
+
+$message = (new ResponseFactory)->createResponse();
+
+$header = new HeaderSunset(new \DateTime('2038-01-19 03:14:07'));
+$message = $header->setToMessage($message);
+```
+
 #### Trailer
 
 > Useful link: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Trailer

src/HeaderSunset.php

@@ -0,0 +1,81 @@
+<?php declare(strict_types=1);
+
+/**
+ * It's free open-source software released under the MIT License.
+ *
+ * @author Anatoly Fenric <anatoly@fenric.ru>
+ * @copyright Copyright (c) 2018, Anatoly Fenric
+ * @license https://github.com/sunrise-php/http-header-kit/blob/master/LICENSE
+ * @link https://github.com/sunrise-php/http-header-kit
+ */
+
+namespace Sunrise\Http\Header;
+
+/**
+ * HeaderSunset
+ *
+ * @link https://tools.ietf.org/id/draft-wilde-sunset-header-03.html
+ * @link https://github.com/sunrise-php/http-header-kit/issues/1#issuecomment-457043527
+ */
+class HeaderSunset extends AbstractHeader implements HeaderInterface
+{
+
+	/**
+	 * Timestamp for the header field-value
+	 *
+	 * @var \DateTimeInterface
+	 */
+	protected $timestamp;
+
+	/**
+	 * Constructor of the class
+	 *
+	 * @param \DateTimeInterface $timestamp
+	 */
+	public function __construct(\DateTimeInterface $timestamp)
+	{
+		$this->setTimestamp($timestamp);
+	}
+
+	/**
+	 * Sets timestamp for the header field-value
+	 *
+	 * @param \DateTimeInterface $timestamp
+	 *
+	 * @return self
+	 */
+	public function setTimestamp(\DateTimeInterface $timestamp) : self
+	{
+		$this->timestamp = $timestamp;
+
+		return $this;
+	}
+
+	/**
+	 * Gets timestamp for the header field-value
+	 *
+	 * @return \DateTimeInterface
+	 */
+	public function getTimestamp() : \DateTimeInterface
+	{
+		return $this->timestamp;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getFieldName() : string
+	{
+		return 'Sunset';
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getFieldValue() : string
+	{
+		$this->getTimestamp()->setTimezone(new \DateTimeZone('GMT'));
+
+		return $this->getTimestamp()->format(\DateTime::RFC822);
+	}
+}

tests/HeaderSunsetTest.php

@@ -0,0 +1,96 @@
+<?php
+
+namespace Sunrise\Http\Header\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Sunrise\Http\Header\HeaderSunset;
+use Sunrise\Http\Header\HeaderInterface;
+
+class HeaderSunsetTest extends TestCase
+{
+	public function testConstructor()
+	{
+		$now = new \DateTime('now');
+
+		$header = new HeaderSunset($now);
+
+		$this->assertInstanceOf(HeaderInterface::class, $header);
+	}
+
+	public function testSetTimestamp()
+	{
+		$now = new \DateTime('now');
+
+		$header = new HeaderSunset($now);
+
+		$tomorrow = new \DateTime('+1 day');
+
+		$this->assertInstanceOf(HeaderInterface::class, $header->setTimestamp($tomorrow));
+
+		$this->assertEquals($tomorrow, $header->getTimestamp());
+	}
+
+	public function testGetTimestamp()
+	{
+		$now = new \DateTime('now');
+
+		$header = new HeaderSunset($now);
+
+		$this->assertEquals($now, $header->getTimestamp());
+	}
+
+	public function testGetFieldName()
+	{
+		$now = new \DateTime('now');
+
+		$header = new HeaderSunset($now);
+
+		$this->assertEquals('Sunset', $header->getFieldName());
+	}
+
+	public function testGetFieldValue()
+	{
+		$now = new \DateTime('now', new \DateTimeZone('Europe/Moscow'));
+
+		$header = new HeaderSunset($now);
+
+		$expected = new \DateTime('now', new \DateTimeZone('UTC'));
+
+		$this->assertEquals($expected->format(\DateTime::RFC822), $header->getFieldValue());
+	}
+
+	public function testToString()
+	{
+		$now = new \DateTime('now', new \DateTimeZone('UTC'));
+
+		$header = new HeaderSunset($now);
+
+		$this->assertEquals(\sprintf('Sunset: %s', $now->format(\DateTime::RFC822)), (string) $header);
+	}
+
+	public function testSetToMessage()
+	{
+		$now = new \DateTime('now');
+		$header = new HeaderSunset($now);
+
+		$message = (new \Sunrise\Http\Message\ResponseFactory)->createResponse();
+		$message = $message->withHeader($header->getFieldName(), 'foo bar baz');
+
+		$message = $header->setToMessage($message);
+
+		$this->assertEquals([$header->getFieldValue()], $message->getHeader($header->getFieldName()));
+	}
+
+	public function testAddToMessage()
+	{
+		$now = new \DateTime('now');
+		$header = new HeaderSunset($now);
+
+		$message = (new \Sunrise\Http\Message\ResponseFactory)->createResponse();
+		$message = $message->withHeader($header->getFieldName(), 'foo bar baz');
+
+		$message = $header->addToMessage($message);
+
+		$this->assertEquals(['foo bar baz', $header->getFieldValue()], $message->getHeader($header->getFieldName()));
+	}
+}