<?php declare (strict_types=1);

namespace Sabre\Xml\Deserializer;

use Sabre\Xml\Reader;

/**
 * This class provides a number of 'deserializer' helper functions.
 * These can be used to easily specify custom deserializers for specific
 * XML elements.
 *
 * You can either use these functions from within the $elementMap in the
 * Service or Reader class, or you can call them from within your own
 * deserializer functions.
 */

/**
 * The 'keyValue' deserializer parses all child elements, and outputs them as
 * a "key=>value" array.
 *
 * For example, keyvalue will parse:
 *
 * <?xml version="1.0"?>
 * <s:root xmlns:s="http://sabredav.org/ns">
 *   <s:elem1>value1</s:elem1>
 *   <s:elem2>value2</s:elem2>
 *   <s:elem3 />
 * </s:root>
 *
 * Into:
 *
 * [
 *   "{http://sabredav.org/ns}elem1" => "value1",
 *   "{http://sabredav.org/ns}elem2" => "value2",
 *   "{http://sabredav.org/ns}elem3" => null,
 * ];
 *
 * If you specify the 'namespace' argument, the deserializer will remove
 * the namespaces of the keys that match that namespace.
 *
 * For example, if you call keyValue like this:
 *
 * keyValue($reader, 'http://sabredav.org/ns')
 *
 * it's output will instead be:
 *
 * [
 *   "elem1" => "value1",
 *   "elem2" => "value2",
 *   "elem3" => null,
 * ];
 *
 * Attributes will be removed from the top-level elements. If elements with
 * the same name appear twice in the list, only the last one will be kept.
 */
function keyValue(Reader $reader, string $namespace = null) : array {

    // If there's no children, we don't do anything.
    if ($reader->isEmptyElement) {
        $reader->next();
        return [];
    }

    $values = [];

    $reader->read();
    do {

        if ($reader->nodeType === Reader::ELEMENT) {
            if ($namespace !== null && $reader->namespaceURI === $namespace) {
                $values[$reader->localName] = $reader->parseCurrentElement()['value'];
            } else {
                $clark = $reader->getClark();
                $values[$clark] = $reader->parseCurrentElement()['value'];
            }
        } else {
            $reader->read();
        }
    } while ($reader->nodeType !== Reader::END_ELEMENT);

    $reader->read();

    return $values;

}

/**
 * The 'enum' deserializer parses elements into a simple list
 * without values or attributes.
 *
 * For example, Elements will parse:
 *
 * <?xml version="1.0"? >
 * <s:root xmlns:s="http://sabredav.org/ns">
 *   <s:elem1 />
 *   <s:elem2 />
 *   <s:elem3 />
 *   <s:elem4>content</s:elem4>
 *   <s:elem5 attr="val" />
 * </s:root>
 *
 * Into:
 *
 * [
 *   "{http://sabredav.org/ns}elem1",
 *   "{http://sabredav.org/ns}elem2",
 *   "{http://sabredav.org/ns}elem3",
 *   "{http://sabredav.org/ns}elem4",
 *   "{http://sabredav.org/ns}elem5",
 * ];
 *
 * This is useful for 'enum'-like structures.
 *
 * If the $namespace argument is specified, it will strip the namespace
 * for all elements that match that.
 *
 * For example,
 *
 * enum($reader, 'http://sabredav.org/ns')
 *
 * would return:
 *
 * [
 *   "elem1",
 *   "elem2",
 *   "elem3",
 *   "elem4",
 *   "elem5",
 * ];
 *
 * @return string[]
 */
function enum(Reader $reader, string $namespace = null) : array {

    // If there's no children, we don't do anything.
    if ($reader->isEmptyElement) {
        $reader->next();
        return [];
    }
    $reader->read();
    $currentDepth = $reader->depth;

    $values = [];
    do {

        if ($reader->nodeType !== Reader::ELEMENT) {
            continue;
        }
        if (!is_null($namespace) && $namespace === $reader->namespaceURI) {
            $values[] = $reader->localName;
        } else {
            $values[] = $reader->getClark();
        }

    } while ($reader->depth >= $currentDepth && $reader->next());

    $reader->next();
    return $values;

}

/**
 * The valueObject deserializer turns an xml element into a PHP object of
 * a specific class.
 *
 * This is primarily used by the mapValueObject function from the Service
 * class, but it can also easily be used for more specific situations.
 *
 * @return object
 */
function valueObject(Reader $reader, string $className, string $namespace) {

    $valueObject = new $className();
    if ($reader->isEmptyElement) {
        $reader->next();
        return $valueObject;
    }

    $defaultProperties = get_class_vars($className);

    $reader->read();
    do {

        if ($reader->nodeType === Reader::ELEMENT && $reader->namespaceURI == $namespace) {

            if (property_exists($valueObject, $reader->localName)) {
                if (is_array($defaultProperties[$reader->localName])) {
                    $valueObject->{$reader->localName}[] = $reader->parseCurrentElement()['value'];
                } else {
                    $valueObject->{$reader->localName} = $reader->parseCurrentElement()['value'];
                }
            } else {
                // Ignore property
                $reader->next();
            }
        } else {
            $reader->read();
        }
    } while ($reader->nodeType !== Reader::END_ELEMENT);

    $reader->read();
    return $valueObject;

}

/**
 * This deserializer helps you deserialize xml structures that look like
 * this:
 *
 * <collection>
 *    <item>...</item>
 *    <item>...</item>
 *    <item>...</item>
 * </collection>
 *
 * Many XML documents use patterns like that, and this deserializer
 * allow you to get all the 'items' as an array.
 *
 * In that previous example, you would register the deserializer as such:
 *
 * $reader->elementMap['{}collection'] = function($reader) {
 *     return repeatingElements($reader, '{}item');
 * }
 *
 * The repeatingElements deserializer simply returns everything as an array.
 *
 * $childElementName must either be a a clark-notation element name, or if no
 * namespace is used, the bare element name.
 */
function repeatingElements(Reader $reader, string $childElementName) : array {

    if ($childElementName[0] !== '{') {
        $childElementName = '{}' . $childElementName;
    }
    $result = [];

    foreach ($reader->parseGetElements() as $element) {

        if ($element['name'] === $childElementName) {
            $result[] = $element['value'];
        }

    }

    return $result;

}

/**
 * This deserializer helps you to deserialize structures which contain mixed content like this:
 * 
 * <p>some text <extref>and a inline tag</extref>and even more text</p>
 *
 * The above example will return
 *
 * [
 *     'some text',
 *     [
 *         'name'       => '{}extref',
 *         'value'      => 'and a inline tag',
 *         'attributes' => []
 *     ],
 *     'and even more text'
 * ]
 *
 * In strict XML documents you wont find this kind of markup but in html this is a quite common pattern.
 */
function mixedContent(Reader $reader) : array {

    // If there's no children, we don't do anything.
    if ($reader->isEmptyElement) {
        $reader->next();
        return [];
    }

    $previousDepth = $reader->depth;

    $content = [];
    $reader->read();
    while (true) {
        if ($reader->nodeType == Reader::ELEMENT) {
            $content[] = $reader->parseCurrentElement();
        } elseif ($reader->depth >= $previousDepth && in_array($reader->nodeType, [Reader::TEXT, Reader::CDATA, Reader::WHITESPACE])) {
            $content[] = $reader->value;
            $reader->read();
        } elseif ($reader->nodeType == Reader::END_ELEMENT) {
            // Ensuring we are moving the cursor after the end element.
            $reader->read();
            break;
        } else {
            $reader->read();
        }
    }

    return $content;

}
