InjectStack middleware for ChunkedEncoding

gistfile1.aw

<?php
/*
 * Created by Martin Wernståhl on 2011-04-25.
 * Copyright (c) 2011 Martin Wernståhl.
 * All rights reserved.
 */

namespace Inject\Stack\Middleware;

use \Inject\Stack\MiddlewareInterface;

/**
 * Applies chunked Transfer-Encoding to "streamed" responses (ie. callbacks),
 * interface for using "streamed" responses is still the same.
 */
class ChunkedEncoding implements MiddlewareInterface
{
	/**
	 * The callback for the next middleware or the endpoint in this middleware
	 * stack.
	 * 
	 * @var \Inject\Stack\MiddlewareInterface|Closure|ObjectImplementing__invoke
	 */
	protected $next;
	
	// ------------------------------------------------------------------------
	
	/**
	 * Tells this middleware which middleware or endpoint it should call if it
	 * wants the call-chain to proceed.
	 * 
	 * @param  \Inject\Stack\MiddlewareInterface|Closure|ObjectImplementing__invoke
	 */
	public function setNext($next)
	{
		$this->next = $next;
	}
	
	public function __invoke($env)
	{
		// Just pass the request through
		$callback = $this->next;
		$ret      = $callback($env);
		
		// If we have a callback, we apply chunked encoding
		if( ! empty($ret[2]) && is_callable($ret[2]))
		{
			$content = $ret[2];
			
			// Wrap the callback in another callback
			$ret[2] = function($writer) use($content)
			{
				// Apply chunked transformations to all the chunks coming through
				$chunked_writer = function($string) use($writer)
				{
					$writer(sprintf('%X', strlen($string))."\r\n".$string."\r\n");
				};
				
				$content($chunked_writer);
				
				// Terminate chunked response
				$writer("0\r\n\r\n");
			};
			
			if(empty($ret[1]['Transfer-Encoding']))
			{
				$ret[1]['Transfer-Encoding'] = 'chunked';
			}
			else
			{
				// Multiple Transfer-Encodings are listed in the order they were applied:
				$ret[1]['Transfer-Encoding'] .= "\nchunked";
			}
		}
		
		return $ret;
	}
}