<?php

/**

 * @category   Zend

 * @package    Zend_Cloud

 * @subpackage Infrastructure

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

require_once 'Zend/Cloud/Infrastructure/Instance.php';

/**

 * List of instances

 *

 * @package    Zend_Cloud

 * @subpackage Infrastructure

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Cloud_Infrastructure_InstanceList implements Countable, Iterator, ArrayAccess

{

    /**

     * @var array Array of Zend_Cloud_Infrastructure_Instance

     */

    protected $instances = array();

    /**

     * @var int Iterator key

     */

    protected $iteratorKey = 0;

    /**

     * @var Zend_Cloud_Infrastructure_Adapter

     */

    protected $adapter;

    /**

     * Constructor

     *

     * @param  Adapter $adapter

     * @param  array $instances

     * @return void

     */

    public function __construct($adapter, array $instances = null)

    {

        if (!($adapter instanceof Zend_Cloud_Infrastructure_Adapter)) {

            require_once 'Zend/Cloud/Infrastructure/Exception.php';

            throw new Zend_Cloud_Infrastructure_Exception('You must pass a Zend_Cloud_Infrastructure_Adapter');

        }

        if (empty($instances)) {

            require_once 'Zend/Cloud/Infrastructure/Exception.php';

            throw new Zend_Cloud_Infrastructure_Exception('You must pass an array of Instances');

        }

        $this->adapter = $adapter;

        $this->constructFromArray($instances);

    }

    /**

     * Transforms the Array to array of Instances

     *

     * @param  array $list

     * @return void

     */

    protected function constructFromArray(array $list)

    {

        foreach ($list as $instance) {

            $this->addInstance(new Zend_Cloud_Infrastructure_Instance($this->adapter,$instance));

        }

    }

    /**

     * Add an instance

     *

     * @param  Instance

     * @return InstanceList

     */

    protected function addInstance(Zend_Cloud_Infrastructure_Instance $instance)

    {

        $this->instances[] = $instance;

        return $this;

    }

    /**

     * Return number of instances

     *

     * Implement Countable::count()

     *

     * @return int

     */

    public function count()

    {

        return count($this->instances);

    }

    /**

     * Return the current element

     *

     * Implement Iterator::current()

     *

     * @return Instance

     */

    public function current()

    {

        return $this->instances[$this->iteratorKey];

    }

    /**

     * Return the key of the current element

     *

     * Implement Iterator::key()

     *

     * @return int

     */

    public function key()

    {

        return $this->iteratorKey;

    }

    /**

     * Move forward to next element

     *

     * Implement Iterator::next()

     *

     * @return void

     */

    public function next()

    {

        $this->iteratorKey++;

    }

    /**

     * Rewind the Iterator to the first element

     *

     * Implement Iterator::rewind()

     *

     * @return void

     */

    public function rewind()

    {

        $this->iteratorKey = 0;

    }

    /**

     * Check if there is a current element after calls to rewind() or next()

     *

     * Implement Iterator::valid()

     *

     * @return bool

     */

    public function valid()

    {

        $numItems = $this->count();

        if ($numItems > 0 && $this->iteratorKey < $numItems) {

            return true;

        }

        return false;

    }

    /**

     * Whether the offset exists

     *

     * Implement ArrayAccess::offsetExists()

     *

     * @param  int $offset

     * @return bool

     */

    public function offsetExists($offset)

    {

        return ($offset < $this->count());

    }

    /**

     * Return value at given offset

     *

     * Implement ArrayAccess::offsetGet()

     *

     * @param  int $offset

     * @return Instance

     * @throws Zend_Cloud_Infrastructure_Exception

     */

    public function offsetGet($offset)

    {

        if (!$this->offsetExists($offset)) {

            require_once 'Zend/Cloud/Infrastructure/Exception.php';

            throw new Zend_Cloud_Infrastructure_Exception('Illegal index');

        }

        return $this->instances[$offset];

    }

    /**

     * Throws exception because all values are read-only

     *

     * Implement ArrayAccess::offsetSet()

     *

     * @param   int     $offset

     * @param   string  $value

     * @throws  Zend_Cloud_Infrastructure_Exception

     */

    public function offsetSet($offset, $value)

    {

        require_once 'Zend/Cloud/Infrastructure/Exception.php';

        throw new Zend_Cloud_Infrastructure_Exception('You are trying to set read-only property');

    }

    /**

     * Throws exception because all values are read-only

     *

     * Implement ArrayAccess::offsetUnset()

     *

     * @param   int     $offset

     * @throws  Zend_Cloud_Infrastructure_Exception

     */

    public function offsetUnset($offset)

    {

        require_once 'Zend/Cloud/Infrastructure/Exception.php';

        throw new Zend_Cloud_Infrastructure_Exception('You are trying to unset read-only property');

    }

}