<?php
namespace GuzzleHttp\Stream;

/**
* Compose stream implementations based on a hash of functions.
*
* Allows for easy testing and extension of a provided stream without needing
* to create a concrete class for a simple extension point.
*/
class FnStream implements StreamInterface
{
/** @var array */
private $methods;

/** @var array Methods that must be implemented in the given array */
private static $slots = ['__toString', 'close', 'detach', 'attach',
'getSize', 'tell', 'eof', 'isSeekable', 'seek', 'isWritable', 'write',
'isReadable', 'read', 'getContents', 'getMetadata'];

/**
* @param array $methods Hash of method name to a callable.
*/
public function __construct(array $methods)
{
$this->methods = $methods;

// Create the functions on the class
foreach ($methods as $name => $fn) {
$this->{'_fn_' . $name} = $fn;
}
}

/**
* Lazily determine which methods are not implemented.
* @throws \BadMethodCallException
*/
public function __get($name)
{
throw new \BadMethodCallException(str_replace('_fn_', '', $name)
. '() is not implemented in the FnStream');
}

/**
* The close method is called on the underlying stream only if possible.
*/
public function __destruct()
{
if (isset($this->_fn_close)) {
call_user_func($this->_fn_close);
}
}

/**
* Adds custom functionality to an underlying stream by intercepting
* specific method calls.
*
* @param StreamInterface $stream Stream to decorate
* @param array $methods Hash of method name to a closure
*
* @return FnStream
*/
public static function decorate(StreamInterface $stream, array $methods)
{
// If any of the required methods were not provided, then simply
// proxy to the decorated stream.
foreach (array_diff(self::$slots, array_keys($methods)) as $diff) {
$methods[$diff] = [$stream, $diff];
}

return new self($methods);
}

public function __toString()
{
return call_user_func($this->_fn___toString);
}

public function close()
{
return call_user_func($this->_fn_close);
}

public function detach()
{
return call_user_func($this->_fn_detach);
}

public function attach($stream)
{
return call_user_func($this->_fn_attach, $stream);
}

public function getSize()
{
return call_user_func($this->_fn_getSize);
}

public function tell()
{
return call_user_func($this->_fn_tell);
}

public function eof()
{
return call_user_func($this->_fn_eof);
}

public function isSeekable()
{
return call_user_func($this->_fn_isSeekable);
}

public function seek($offset, $whence = SEEK_SET)
{
return call_user_func($this->_fn_seek, $offset, $whence);
}

public function isWritable()
{
return call_user_func($this->_fn_isWritable);
}

public function write($string)
{
return call_user_func($this->_fn_write, $string);
}

public function isReadable()
{
return call_user_func($this->_fn_isReadable);
}

public function read($length)
{
return call_user_func($this->_fn_read, $length);
}

public function getContents()
{
return call_user_func($this->_fn_getContents);
}

public function getMetadata($key = null)
{
return call_user_func($this->_fn_getMetadata, $key);
}
}