<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * 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@magentocommerce.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category    Mage
 * @package     Mage_Adminhtml
 * @copyright   Copyright (c) 2010 Magento Inc. (http://www.magentocommerce.com)
 * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/**
 * Form element dependencies mapper
 * Assumes that one element may depend on other element values.
 * Will toggle as "enabled" only if all elements it depends from toggle as true.
 */
class Mage_Adminhtml_Block_Widget_Form_Element_Dependence extends Mage_Adminhtml_Block_Abstract
{
    /**
     * name => id mapper
     * @var array
     */
    protected $_fields = array();

    /**
     * Dependencies mapper (by names)
     * array(
     *     'dependent_name' => array(
     *         'depends_from_1_name' => 'mixed value',
     *         'depends_from_2_name' => 'some another value',
     *         ...
     *     )
     * )
     * @var array
     */
    protected $_depends = array();

    /**
     * Additional configuration options for the dependencies javascript controller
     *
     * @var array
     */
    protected $_configOptions = array();

    /**
     * Add name => id mapping
     *
     * @param string $fieldId - element ID in DOM
     * @param string $fieldName - element name in their fieldset/form namespace
     * @return Mage_Adminhtml_Block_Widget_Form_Element_Dependence
     */
    public function addFieldMap($fieldId, $fieldName)
    {
        $this->_fields[$fieldName] = $fieldId;
        return $this;
    }

    /**
     * Register field name dependence one from each other by specified values
     *
     * @TODO: multiple values per dependency is not implemented. The values OR comparison is anticipated
     *
     * @param string $fieldName
     * @param string $fieldNameFrom
     * @param string|array $refValues
     * @return Mage_Adminhtml_Block_Widget_Form_Element_Dependence
     */
    public function addFieldDependence($fieldName, $fieldNameFrom, $refValues)
    {
        if (is_array($refValues)) {
            Mage::throwException('Dependency from multiple values is not implemented yet. Please fix to your widget.xml');
        }
        $this->_depends[$fieldName][$fieldNameFrom] = $refValues;
        return $this;
    }

    /**
     * Add misc configuration options to the javascript dependencies controller
     *
     * @param array $options
     * @return Mage_Adminhtml_Block_Widget_Form_Element_Dependence
     */
    public function addConfigOptions(array $options)
    {
        $this->_configOptions = array_merge($this->_configOptions, $options);
        return $this;
    }

    /**
     * HTML output getter
     * @return string
     */
    protected function _toHtml()
    {
        if (!$this->_depends) {
            return '';
        }
        return '<script type="text/javascript"> new FormElementDependenceController('
            . $this->_getDependsJson()
            . ($this->_configOptions ? ', ' . Mage::helper('core')->jsonEncode($this->_configOptions) : '')
            . '); </script>';
    }

    /**
     * Field dependences JSON map generator
     * @return string
     */
    protected function _getDependsJson()
    {
        $result = array();
        foreach ($this->_depends as $to => $row) {
            foreach ($row as $from => $value) {
                $result[$this->_fields[$to]][$this->_fields[$from]] = $value;
            }
        }
        return Mage::helper('core')->jsonEncode($result);
    }
}