<?php

namespace Qs\Form;

use Exception;

trait DynamicFormTrait 
{
    /**
     * @example
     * $this->_dfRelations = array(
     *     array(
     *         '_element' => 'moreInfoType',
     *         'node'     => '[name="moreInfoType"]:checked',
     *         'group'    => '[name="moreInfoType"]',
     *         'event'    => 'change',
     *         'rules'    => array(
     *             array(
     *                 'value'     => 'none',
     *                 '_elements' => array()
     *             ),
     *             array(
     *                 'value'     => 'url',
     *                 '_elements' => array('moreInfoUrl')
     *             ),
     *             array(
     *                 'value'     => 'page',
     *                 '_elements' => array('moreInfoPage')
     *             ),
     *         )
     *     ),
     * );
     * @var array Node relations that will be converted to format compatible with jQuery.dynamicForm()
     */
    protected $_dfRelations = array();

    /**
     * @var array List on elements names that will be preserved in method $this->_dfClearUnusedValues()
     */
    protected $_dfPreserveFields = array();


    /**
     * Clears values of hidden nodes (values of elements listed in $this->_dfPreserveFields will be preserved)
     * @param array $values
     * @throws \Exception
     */
    public function dfClearUnusedValues(array &$values)
    {
        foreach ($this->_dfRelations as $relation) {
            if (!isset($relation['element'])) {
                continue;
            }
            $name = $relation['element'];
            if (!array_key_exists($name, $values)) {
                continue;
            }
            $value = $values[$name];
            $available = array();
            $unavailable = array();
            foreach ($relation['rules'] as $rule) {
                if (isset($rule['_value'])) {
                    $match = ($rule['_value'] instanceof \Closure)
                        ? $rule['_value']($value)
                        : $rule['_value'] == $value;
                } else {
                    if (!is_string($rule['value']) && !is_numeric($rule['value'])) {
                        throw new Exception('Wrong value type in relations config "' . $rule['value'] . '"');
                    }
                    $match = ($rule['value'] == $value);
                }

                if ($match) {
                    if (!empty($rule['_elements'])) {
                        $available = array_merge($available, $rule['_elements']);
                    }
                } else {
                    if (!empty($rule['_elements'])) {
                        $unavailable = array_merge($unavailable, $rule['_elements']);
                    }
                }

            }
            if ($unavailable) {
                $unavailable = array_diff($unavailable, $available);
                $unavailable = array_diff($unavailable, $this->_dfPreserveFields);
                $values = array_merge($values, array_fill_keys($unavailable, null));
            }
        }
        return;
    }

    /**
     * Converts relations config ready to use with jQuery.dynamicForm plugin
     * @return array
     */
    public function dfConvertRelations()
    {
        $relations = array();
        foreach ($this->_dfRelations as $relation) {
            foreach ($relation['rules'] as &$rule) {
                if (!empty($rule['_elements'])) {
                    foreach ($rule['_elements'] as $name) {
                        if (($id = $this->_dfGetElementLabelId($name))) {
                            $rule['nodes'][] = '#' . $id;
                        }
                        if (($id = $this->_dfGetElementContainerId($name))) {
                            $rule['nodes'][] = '#' . $id;
                        }
                    }
                }
                unset($rule['_elements'], $rule['_value']);
            }
            unset($relation['_element']);
            $relations[] = $relation;
        }
        return $relations;
    }

    /**
     * @param string $name element name
     * @return string element label id  (e.g. foo-label)
     */
    abstract protected function _dfGetElementLabelId($name);

    /**
     * @param string $name element name
     * @return string element container id (e.g. foo-element)
     */
    abstract protected function _dfGetElementContainerId($name);

}