<?php
/**
 * This file contains the DomNodeDataCapable trait.
 * 
 * PHP Version 5.3
 * 
 * @category DOM
 * @package  Dom
 * @author   Gonzalo Chumillas <gonzalo@soloproyectos.com>
 * @license  https://raw.github.com/soloproyectos/core/master/LICENSE BSD 2-Clause License
 * @link     https://github.com/soloproyectos/core
 */
namespace com\soloproyectos\common\dom;
use \StdClass;
use \UnexpectedValueException;

/**
 * DomNodeDataCapable trait.
 * 
 * @category DOM
 * @package  Dom
 * @author   Gonzalo Chumillas <gonzalo@soloproyectos.com>
 * @license  https://raw.github.com/soloproyectos/core/master/LICENSE BSD 2-Clause License
 * @link     https://github.com/soloproyectos/core
 */
trait DomNodeDataCapable
{
    /**
     * Data namespace.
     * @var string
     */
    private static $_namespace = "__phpQueryData__";
    
    /**
     * List of elements.
     * 
     * @return array of DOMElement
     */
    abstract public function elements();
    
    /**
     * Gets or sets arbitrary data.
     * 
     * @param string $name  Data name
     * @param mixed  $value Mixed value (not required)
     * 
     * @return DomNode|mixed
     */
    public function data($name, $value = null)
    {
        if (func_num_args() > 1) {
            return $this->_setData($name, $value);
        }
        
        return $this->_getData($name);
    }
    
    /**
     * Gets data from the node.
     * 
     * @param string $name Data name
     * 
     * @return mixed
     */
    private function _getData($name)
    {
        foreach ($this->elements() as $element) {
            $data = $this->_getDataObject($element);
            
            return property_exists($data, $name)? $data->$name: null;
        }
        
        return null;
    }
    
    /**
     * Sets data into the node.
     * 
     * @param string $name  Data name
     * @param mixed  $value Arbitrary data
     * 
     * @return DomNode
     */
    private function _setData($name, $value)
    {
        foreach ($this->elements() as $element) {
            $data = $this->_getDataObject($element);
            $data->$name = $value;
            $this->_setDataObject($element, $data);
        }
        
        return $this;
    }
    
    /**
     * Gets the data object.
     * 
     * @param DOMElement $element DOM element
     * 
     * @return object
     */
    private function _getDataObject($element)
    {
        $attr = $element->getAttribute(self::$_namespace);
        $data = strlen($attr) > 0? json_decode($attr): new StdClass();
        
        if (!is_object($data)) {
            throw new UnexpectedValueException("The node does not contain valid data");
        }
        
        return $data;
    }
    
    /**
     * Sets te data object.
     * 
     * @param DOMElement $element DOM element
     * @param object     $data    Data
     * 
     * @return void
     */
    private function _setDataObject($element, $data)
    {
        $element->setAttribute(self::$_namespace, json_encode($data));
    }
}