Proyectos de Subversion Moodle

<?php

declare(strict_types=1);

namespace OpenSpout\Common\Helper;

use Error;

use OpenSpout\Common\Exception\EncodingConversionException;

/**

 * @internal

 */

final class EncodingHelper

{

    /**

     * Definition of the encodings that can have a BOM.

     */

    public const ENCODING_UTF8 = 'UTF-8';

    public const ENCODING_UTF16_LE = 'UTF-16LE';

    public const ENCODING_UTF16_BE = 'UTF-16BE';

    public const ENCODING_UTF32_LE = 'UTF-32LE';

    public const ENCODING_UTF32_BE = 'UTF-32BE';

    /**

     * Definition of the BOMs for the different encodings.

     */

    public const BOM_UTF8 = "\xEF\xBB\xBF";

    public const BOM_UTF16_LE = "\xFF\xFE";

    public const BOM_UTF16_BE = "\xFE\xFF";

    public const BOM_UTF32_LE = "\xFF\xFE\x00\x00";

    public const BOM_UTF32_BE = "\x00\x00\xFE\xFF";

    /** @var array<string, string> Map representing the encodings supporting BOMs (key) and their associated BOM (value) */

    private array $supportedEncodingsWithBom;

    private readonly bool $canUseIconv;

    private readonly bool $canUseMbString;

    public function __construct(bool $canUseIconv, bool $canUseMbString)

    {

        $this->canUseIconv = $canUseIconv;

        $this->canUseMbString = $canUseMbString;

        $this->supportedEncodingsWithBom = [

            self::ENCODING_UTF8 => self::BOM_UTF8,

            self::ENCODING_UTF16_LE => self::BOM_UTF16_LE,

            self::ENCODING_UTF16_BE => self::BOM_UTF16_BE,

            self::ENCODING_UTF32_LE => self::BOM_UTF32_LE,

            self::ENCODING_UTF32_BE => self::BOM_UTF32_BE,

        ];

    }

    public static function factory(): self

    {

        return new self(

            \function_exists('iconv'),

            \function_exists('mb_convert_encoding'),

        );

    }

    /**

     * Returns the number of bytes to use as offset in order to skip the BOM.

     *

     * @param resource $filePointer Pointer to the file to check

     * @param string   $encoding    Encoding of the file to check

     *

     * @return int Bytes offset to apply to skip the BOM (0 means no BOM)

     */

    public function getBytesOffsetToSkipBOM($filePointer, string $encoding): int

    {

        $byteOffsetToSkipBom = 0;

        if ($this->hasBOM($filePointer, $encoding)) {

            $bomUsed = $this->supportedEncodingsWithBom[$encoding];

            // we skip the N first bytes

            $byteOffsetToSkipBom = \strlen($bomUsed);

        }

        return $byteOffsetToSkipBom;

    }

    /**

     * Attempts to convert a non UTF-8 string into UTF-8.

     *

     * @param string $string         Non UTF-8 string to be converted

     * @param string $sourceEncoding The encoding used to encode the source string

     *

     * @return string The converted, UTF-8 string

     *

     * @throws EncodingConversionException If conversion is not supported or if the conversion failed

     */

    public function attemptConversionToUTF8(?string $string, string $sourceEncoding): ?string

    {

        return $this->attemptConversion($string, $sourceEncoding, self::ENCODING_UTF8);

    }

    /**

     * Attempts to convert a UTF-8 string into the given encoding.

     *

     * @param string $string         UTF-8 string to be converted

     * @param string $targetEncoding The encoding the string should be re-encoded into

     *

     * @return string The converted string, encoded with the given encoding

     *

     * @throws EncodingConversionException If conversion is not supported or if the conversion failed

     */

    public function attemptConversionFromUTF8(?string $string, string $targetEncoding): ?string

    {

        return $this->attemptConversion($string, self::ENCODING_UTF8, $targetEncoding);

    }

    /**

     * Returns whether the file identified by the given pointer has a BOM.

     *

     * @param resource $filePointer Pointer to the file to check

     * @param string   $encoding    Encoding of the file to check

     *

     * @return bool TRUE if the file has a BOM, FALSE otherwise

     */

    private function hasBOM($filePointer, string $encoding): bool

    {

        $hasBOM = false;

        rewind($filePointer);

        if (\array_key_exists($encoding, $this->supportedEncodingsWithBom)) {

            $potentialBom = $this->supportedEncodingsWithBom[$encoding];

            $numBytesInBom = \strlen($potentialBom);

            $hasBOM = (fgets($filePointer, $numBytesInBom + 1) === $potentialBom);

        }

        return $hasBOM;

    }

    /**

     * Attempts to convert the given string to the given encoding.

     * Depending on what is installed on the server, we will try to iconv or mbstring.

     *

     * @param string $string         string to be converted

     * @param string $sourceEncoding The encoding used to encode the source string

     * @param string $targetEncoding The encoding the string should be re-encoded into

     *

     * @return string The converted string, encoded with the given encoding

     *

     * @throws EncodingConversionException If conversion is not supported or if the conversion failed

     */

    private function attemptConversion(?string $string, string $sourceEncoding, string $targetEncoding): ?string

    {

        // if source and target encodings are the same, it's a no-op

        if (null === $string || $sourceEncoding === $targetEncoding) {

            return $string;

        }

        $convertedString = null;

        if ($this->canUseIconv) {

            set_error_handler(static function (): bool {

                return true;

            });

            $convertedString = iconv($sourceEncoding, $targetEncoding, $string);

            restore_error_handler();

        } elseif ($this->canUseMbString) {

            $errorMessage = null;

            set_error_handler(static function ($nr, $message) use (&$errorMessage): bool {

                $errorMessage = $message; // @codeCoverageIgnore

                return true; // @codeCoverageIgnore

            });

            try {

                $convertedString = mb_convert_encoding($string, $targetEncoding, $sourceEncoding);

            } catch (Error $error) {

                $errorMessage = $error->getMessage();

            }

            restore_error_handler();

            if (null !== $errorMessage) {

                $convertedString = false;

            }

        } else {

            throw new EncodingConversionException("The conversion from {$sourceEncoding} to {$targetEncoding} is not supported. Please install \"iconv\" or \"mbstring\".");

        }

        if (false === $convertedString) {

            throw new EncodingConversionException("The conversion from {$sourceEncoding} to {$targetEncoding} failed.");

        }

        return $convertedString;

    }

}