MarcXml.php

<?php

/**
 * MARCXML format support class.
 *
 * PHP version 7
 *
 * Copyright (C) The National Library of Finland 2020-2022.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category VuFind
 * @package  MARC
 * @author   Ere Maijala <ere.maijala@helsinki.fi>
 * @license  http://opensource.org/licenses/gpl-2.0.php GNU General Public License
 * @link     https://vufind.org/wiki/development:plugins:record_drivers Wiki
 */

namespace VuFind\Marc\Serialization;

use function array_slice;
use function count;
use function is_string;
use function strlen;

/**
 * MARCXML format support class.
 *
 * @category VuFind
 * @package  MARC
 * @author   Ere Maijala <ere.maijala@helsinki.fi>
 * @license  http://opensource.org/licenses/gpl-2.0.php GNU General Public License
 * @link     https://vufind.org/wiki/development:plugins:record_drivers Wiki
 */
class MarcXml extends AbstractSerializationFile implements SerializationInterface
{
    /**
     * Current file
     *
     * @var string
     */
    protected $fileName = '';

    /**
     * XML Reader for current file
     *
     * @var \XMLReader
     */
    protected $xml = null;

    /**
     * Current XML element path
     *
     * @var array
     */
    protected $currentXmlPath = [];

    /**
     * Check if this class can parse the given MARC string
     *
     * @param string $marc MARC
     *
     * @return bool
     */
    public static function canParse(string $marc): bool
    {
        // A pretty naïve check, but it's enough to tell the different formats apart
        return strncmp(trim($marc), '<', 1) === 0;
    }

    /**
     * Check if the serialization class can parse the given MARC collection string
     *
     * @param string $marc MARC
     *
     * @return bool
     */
    public static function canParseCollection(string $marc): bool
    {
        // A pretty naïve check, but it's enough to tell the different formats apart
        return strncmp(trim($marc), '<', 1) === 0;
    }

    /**
     * Check if the serialization class can parse the given MARC collection file
     *
     * @param string $file File name
     *
     * @return bool
     */
    public static function canParseCollectionFile(string $file): bool
    {
        if (false === ($f = @fopen($file, 'r'))) {
            throw new \Exception("Cannot open file '$file' for reading");
        }
        do {
            $s = ltrim(fgets($f, 10));
        } while (!$s && !feof($f));
        fclose($f);

        return self::canParseCollection($s);
    }

    /**
     * Parse MARC collection from a string into an array
     *
     * @param string $collection MARC record collection in the format supported by
     * the serialization class
     *
     * @throws \Exception
     * @return array
     */
    public static function collectionFromString(string $collection): array
    {
        $xml = static::loadXML(trim($collection));
        $results = [];
        foreach ($xml->record as $record) {
            $results[] = $record->asXML();
        }
        return $results;
    }

    /**
     * Parse MARCXML string
     *
     * @param string $marc MARCXML
     *
     * @throws \Exception
     * @return array
     */
    public static function fromString(string $marc): array
    {
        $xml = static::loadXML(trim($marc));

        // Move to the record element if we were given a collection
        if ($xml->record) {
            $xml = $xml->record;
        }

        $leader = isset($xml->leader) ? (string)$xml->leader[0] : '';
        $fields = [];

        foreach ($xml->controlfield as $field) {
            $fields[] = [(string)$field['tag'] => (string)$field];
        }

        foreach ($xml->datafield as $field) {
            $newField = [
                'ind1' => str_pad((string)$field['ind1'], 1),
                'ind2' => str_pad((string)$field['ind2'], 1),
                'subfields' => [],
            ];
            foreach ($field->subfield as $subfield) {
                $newField['subfields'][]
                    = [(string)$subfield['code'] => (string)$subfield];
            }
            $fields[] = [(string)$field['tag'] => $newField];
        }

        return compact('leader', 'fields');
    }

    /**
     * Convert record to a MARCXML string
     *
     * @param array $record Record data
     *
     * @throws \Exception
     * @return string
     */
    public static function toString(array $record): string
    {
        $xml = new \XMLWriter();
        $xml->openMemory();
        $xml->setIndent(true);
        $xml->startDocument('1.0', 'UTF-8');
        $xml->startElementNs(null, 'collection', 'http://www.loc.gov/MARC21/slim');
        $xml->writeAttribute(
            'xmlns:xsi',
            'http://www.w3.org/2001/XMLSchema-instance'
        );
        $xml->writeAttribute(
            'xsi:schemaLocation',
            'http://www.loc.gov/MARC21/slim'
            . ' http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd'
        );
        $xml->startElement('record');
        if ($record['leader']) {
            $xml->writeElement('leader', $record['leader']);
        }

        foreach ($record['fields'] as $fieldData) {
            $tag = (string)key($fieldData);
            $field = current($fieldData);
            if (is_string($field)) {
                $xml->startElement('controlfield');
                $xml->writeAttribute('tag', $tag);
                $xml->text($field);
                $xml->endElement();
            } else {
                $xml->startElement('datafield');
                $xml->writeAttribute('tag', $tag);
                $xml->writeAttribute('ind1', $field['ind1']);
                $xml->writeAttribute('ind2', $field['ind2']);
                foreach ($field['subfields'] ?? [] as $subfield) {
                    $subfieldData = current($subfield);
                    $subfieldCode = (string)key($subfield);
                    if ($subfieldData == '') {
                        continue;
                    }
                    $xml->startElement('subfield');
                    $xml->writeAttribute('code', $subfieldCode);
                    $xml->text($subfieldData);
                    $xml->endElement();
                }
                $xml->endElement();
            }
        }
        $xml->endElement();
        $xml->endDocument();

        // Strip illegal characters from XML:
        $xmlString = preg_replace(
            '/[^\x{0009}\x{000a}\x{000d}\x{0020}-\x{D7FF}\x{E000}-\x{FFFD}]+/u',
            '',
            $xml->outputMemory(true)
        );
        if ($xmlString === null) {
            throw new \Exception('Error processing XML');
        }
        return $xmlString;
    }

    /**
     * Load XML into SimpleXMLElement
     *
     * @param string $xml XML
     *
     * @throws \Exception
     * @return \SimpleXMLElement
     */
    protected static function loadXML(string $xml): \SimpleXMLElement
    {
        // Make sure we have an XML prolog with proper encoding:
        $xmlHead = '<?xml version';
        if (strcasecmp(substr($xml, 0, strlen($xmlHead)), $xmlHead) === 0) {
            $decl = substr($xml, 0, strpos($xml, '?>'));
            if (strstr($decl, 'encoding') === false) {
                $xml = $decl . ' encoding="utf-8"' . substr($xml, strlen($decl));
            }
        } else {
            $xml = '<?xml version="1.0" encoding="utf-8"?>' . "\n\n$xml";
        }
        $saveUseErrors = libxml_use_internal_errors(true);
        try {
            libxml_clear_errors();
            $doc = simplexml_load_string(
                $xml,
                \SimpleXMLElement::class,
                LIBXML_COMPACT
            );
            if (false === $doc) {
                $errors = libxml_get_errors();
                $messageParts = [];
                foreach ($errors as $error) {
                    $messageParts[] = '[' . $error->line . ':' . $error->column
                        . '] Error ' . $error->code . ': ' . $error->message;
                }
                throw new \Exception(implode("\n", $messageParts));
            }
            libxml_use_internal_errors($saveUseErrors);
            return $doc;
        } catch (\Exception $e) {
            libxml_use_internal_errors($saveUseErrors);
            throw $e;
        }
    }

    /**
     * Open a collection file
     *
     * @param string $file File name
     *
     * @return void
     *
     * @throws \Exception
     */
    public function openCollectionFile(string $file): void
    {
        $this->fileName = $file;
        $this->xml = new \XMLReader();
        $result = $this->xml->open($file);
        if (false === $result) {
            throw new \Exception("Cannot open file '$file' for reading");
        }
        $this->currentXmlPath = [];
    }

    /**
     * Rewind the collection file
     *
     * @return void
     *
     * @throws \Exception
     */
    public function rewind(): void
    {
        if ('' === $this->fileName) {
            throw new \Exception('Collection file not open');
        }
        $this->openCollectionFile($this->fileName);
    }

    /**
     * Get next record from the file or an empty string on EOF
     *
     * @return string
     *
     * @throws \Exception
     */
    public function getNextRecord(): string
    {
        if (null === $this->xml) {
            throw new \Exception('Collection file not open');
        }
        while ($this->xml->read()) {
            if ($this->xml->nodeType !== \XMLReader::ELEMENT) {
                continue;
            }
            $this->currentXmlPath
                = array_slice($this->currentXmlPath, 0, $this->xml->depth);
            $this->currentXmlPath[] = $this->xml->name;
            $ns = $this->xml->namespaceURI;

            $currentPathString = '/' . implode('/', $this->currentXmlPath);
            $pathOk = '/collection/record' === $currentPathString;
            $namespaceOk = !$ns || 'http://www.loc.gov/MARC21/slim' === $ns;
            if (!$pathOk || !$namespaceOk) {
                if (count($this->currentXmlPath) === 2) {
                    if (!$pathOk) {
                        $this->message(
                            "Unknown element \"$currentPathString\"",
                            E_NOTICE
                        );
                    } elseif (!$namespaceOk) {
                        $this->message(
                            "Unknown namespace \"$ns\" for element \""
                            . $currentPathString . '"',
                            E_NOTICE
                        );
                    }
                }
                continue;
            }
            return $this->xml->readOuterXML();
        }
        return '';
    }
}