<?php

namespace Readability;

/**
 * JavaScript-like HTML DOM Element.
 *
 * This class extends PHP's DOMElement to allow
 * users to get and set the innerHTML property of
 * HTML elements in the same way it's done in
 * JavaScript.
 *
 * Example usage:
 *     require_once 'JSLikeHTMLElement.php';
 *     header('Content-Type: text/plain');
 *     $doc = new DOMDocument();
 *     $doc->registerNodeClass('DOMElement', 'JSLikeHTMLElement');
 *     $doc->loadHTML('<div><p>Para 1</p><p>Para 2</p></div>');
 *     $elem = $doc->getElementsByTagName('div')->item(0);
 *
 *     // print innerHTML
 *     echo $elem->innerHTML; // prints '<p>Para 1</p><p>Para 2</p>'
 *     echo "\n\n";
 *
 *     // set innerHTML
 *     $elem->innerHTML = '<a href="http://fivefilters.org">FiveFilters.org</a>';
 *     echo $elem->innerHTML; // prints '<a href="http://fivefilters.org">FiveFilters.org</a>'
 *     echo "\n\n";
 *
 *     // print document (with our changes)
 *     echo $doc->saveXML();
 *
 * @author Keyvan Minoukadeh - http://www.keyvan.net - keyvan@keyvan.net
 *
 * @see http://fivefilters.org (the project this was written for)
 */
class JSLikeHTMLElement extends \DOMElement
{
    /**
     * Used for setting innerHTML like it's done in JavaScript:.
     *
     * @code
     * $div->innerHTML = '<h2>Chapter 2</h2><p>The story begins...</p>';
     * @endcode
     */
    public function __set($name, $value)
    {
        if ($name !== 'innerHTML') {
            $trace = debug_backtrace();
            trigger_error('Undefined property via __set(): ' . $name . ' in ' . $trace[0]['file'] . ' on line ' . $trace[0]['line'], E_USER_NOTICE);

            return;
        }

        // first, empty the element
        for ($x = $this->childNodes->length - 1; $x >= 0; --$x) {
            $this->removeChild($this->childNodes->item($x));
        }

        // $value holds our new inner HTML
        $value = trim($value);
        if (empty($value)) {
            return;
        }

        // ensure bad entity won't generate warning
        $previousError = libxml_use_internal_errors(true);

        $f = $this->ownerDocument->createDocumentFragment();

        // appendXML() expects well-formed markup (XHTML)
        $result = $f->appendXML($value);
        if ($result) {
            if ($f->hasChildNodes()) {
                $this->appendChild($f);
            }
        } else {
            // $value is probably ill-formed
            $f = new \DOMDocument();
            $value = mb_convert_encoding($value, 'HTML-ENTITIES', 'UTF-8');

            // Using <htmlfragment> will generate a warning, but so will bad HTML
            // (and by this point, bad HTML is what we've got).
            // We use it (and suppress the warning) because an HTML fragment will
            // be wrapped around <html><body> tags which we don't really want to keep.
            // Note: despite the warning, if loadHTML succeeds it will return true.
            $result = $f->loadHTML('<htmlfragment>' . $value . '</htmlfragment>');

            if ($result) {
                $import = $f->getElementsByTagName('htmlfragment')->item(0);

                foreach ($import->childNodes as $child) {
                    $importedNode = $this->ownerDocument->importNode($child, true);
                    $this->appendChild($importedNode);
                }
            }
        }

        libxml_clear_errors();
        libxml_use_internal_errors($previousError);
    }

    /**
     * Used for getting innerHTML like it's done in JavaScript:.
     *
     * @code
     * $string = $div->innerHTML;
     * @endcode
     */
    public function __get($name)
    {
        if ($name === 'innerHTML') {
            $inner = '';

            foreach ($this->childNodes as $child) {
                $inner .= $this->ownerDocument->saveXML($child);
            }

            return $inner;
        }

        $trace = debug_backtrace();
        trigger_error('Undefined property via __get(): ' . $name . ' in ' . $trace[0]['file'] . ' on line ' . $trace[0]['line'], E_USER_NOTICE);

        return;
    }

    public function __toString()
    {
        return '[' . $this->tagName . ']';
    }
}
