<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Tag
 * @subpackage ItemList
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: ItemList.php 10020 2009-08-18 14:34:09Z j.fischer@metaways.de $
 */

/**
 * @see Zend_Tag_Taggable
 */
require_once 'Zend/Tag/Taggable.php';

/**
 * @category   Zend
 * @package    Zend_Tag
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Tag_ItemList implements Countable, SeekableIterator, ArrayAccess
{
    /**
     * Items in this list
     *
     * @var array
     */
    protected $_items = array();
    
    /**
     * Count all items
     *
     * @return integer
     */
    public function count()
    {
        return count($this->_items);
    }
    
    /**
     * Spread values in the items relative to their weight
     *
     * @param  array $values
     * @throws Zend_Tag_Exception When value list is empty
     * @return void
     */
    public function spreadWeightValues(array $values)
    {
        // Don't allow an empty value list
        if (count($values) === 0) {
            require_once 'Zend/Tag/Exception.php';
            throw new Zend_Tag_Exception('Value list may not be empty');
        }
        
        // Re-index the array
        $values = array_values($values);
        
        // If just a single value is supplied simply assign it to to all tags
        if (count($values) === 1) {
            foreach ($this->_items as $item) {
                $item->setParam('weightValue', $values[0]);
            }
        } else {
            // Calculate min- and max-weight
            $minWeight = null;
            $maxWeight = null;
            
            foreach ($this->_items as $item) {
                if ($minWeight === null && $maxWeight === null) {
                    $minWeight = $item->getWeight();
                    $maxWeight = $item->getWeight();
                } else {
                    $minWeight = min($minWeight, $item->getWeight());
                    $maxWeight = max($maxWeight, $item->getWeight());                
                }
            }
            
            // Calculate the thresholds
            $steps      = count($values);
            $delta      = ($maxWeight - $minWeight) / ($steps - 1);
            $thresholds = array();
            
            for ($i = 0; $i < $steps; $i++) {
                $thresholds[$i] = floor(100 * log(($minWeight + $i * $delta) + 2));
            }
    
            // Then assign the weight values 
            foreach ($this->_items as $item) {
                $threshold = floor(100 * log($item->getWeight() + 2));
                 
                for ($i = 0; $i < $steps; $i++) {
                    if ($threshold <= $thresholds[$i]) {
                        $item->setParam('weightValue', $values[$i]);
                        break;
                    }
                }
            }
        }
    }
    
    /**
     * Seek to an absolute positio
     *
     * @param  integer $index
     * @throws OutOfBoundsException When the seek position is invalid
     * @return void
     */
    public function seek($index)
    {
        $this->rewind();
        $position = 0;
        
        while ($position < $index && $this->valid()) {
            $this->next();
            $position++;
        }
        
        if (!$this->valid()) {
            throw new OutOfBoundsException('Invalid seek position');
        }       
    }
    
    /**
     * Return the current element
     *
     * @return mixed
     */
    public function current()
    {
        return current($this->_items);
    }
    
    /**
     * Move forward to next element
     *
     * @return mixed
     */
    public function next()
    {
        return next($this->_items);
    }
    
    /**
     * Return the key of the current element
     *
     * @return mixed
     */
    public function key()
    {
        return key($this->_items);
    }

    /**
     * Check if there is a current element after calls to rewind() or next()
     *
     * @return boolean
     */
    public function valid()
    {
        return ($this->current() !== false);
    }
    
    /**
     * Rewind the Iterator to the first element
     *
     * @return void
     */
    public function rewind()
    {
        reset($this->_items);
    }
    
    /**
     * Check if an offset exists
     *
     * @param  mixed $offset
     * @return boolean
     */
    public function offsetExists($offset) {
        return array_key_exists($offset, $this->_items);
    }
 
    /**
     * Get the value of an offset
     *
     * @param  mixed $offset
     * @return Zend_Tag_Taggable
     */
    public function offsetGet($offset) {
        return $this->_items[$offset];
    }
 
    /**
     * Append a new item
     *
     * @param  mixed          $offset
     * @param  Zend_Tag_Taggable $item
     * @throws OutOfBoundsException When item does not implement Zend_Tag_Taggable
     * @return void
     */
    public function offsetSet($offset, $item) {
        // We need to make that check here, as the method signature must be
        // compatible with ArrayAccess::offsetSet()
        if (!($item instanceof Zend_Tag_Taggable)) {
            require_once 'Zend/Tag/Exception.php';
            throw new Zend_Tag_Exception('Item must implement Zend_Tag_Taggable');
        }
    
        if ($offset === null) {
            $this->_items[] = $item;
        } else {
            $this->_items[$offset] = $item;
        }
    }
 
    /**
     * Unset an item
     *
     * @param  mixed $offset
     * @return void
     */
    public function offsetUnset($offset) {
        unset($this->_items[$offset]);
    }
}
