<?php
  
  namespace Guzzle\Http\Message\Header;
  
  use Guzzle\Common\ToArrayInterface;
  
  /**
   * Provides a case-insensitive collection of headers
   */
  class HeaderCollection implements \IteratorAggregate, \Countable, \ArrayAccess, ToArrayInterface
  {
      /** @var array */
      protected $headers;
  
      public function __construct($headers = array())
      {
          $this->headers = $headers;
      }
  
      public function __clone()
      {
          foreach ($this->headers as &$header) {
              $header = clone $header;
          }
      }
  
      /**
       * Clears the header collection
       */
      public function clear()
      {
          $this->headers = array();
      }
  
      /**
       * Set a header on the collection
       *
       * @param HeaderInterface $header Header to add
       *
       * @return self
       */
      public function add(HeaderInterface $header)
      {
          $this->headers[strtolower($header->getName())] = $header;
  
          return $this;
      }
  
      /**
       * Get an array of header objects
       *
       * @return array
       */
      public function getAll()
      {
          return $this->headers;
      }
  
      /**
       * Alias of offsetGet
       */
      public function get($key)
      {
          return $this->offsetGet($key);
      }
  
      public function count()
      {
          return count($this->headers);
      }
  
      public function offsetExists($offset)
      {
          return isset($this->headers[strtolower($offset)]);
      }
  
      public function offsetGet($offset)
      {
          $l = strtolower($offset);
  
          return isset($this->headers[$l]) ? $this->headers[$l] : null;
      }
  
      public function offsetSet($offset, $value)
      {
          $this->add($value);
      }
  
      public function offsetUnset($offset)
      {
          unset($this->headers[strtolower($offset)]);
      }
  
      public function getIterator()
      {
          return new \ArrayIterator($this->headers);
      }
  
      public function toArray()
      {
          $result = array();
          foreach ($this->headers as $header) {
              $result[$header->getName()] = $header->toArray();
          }
  
          return $result;
      }
  }