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<?php

declare(strict_types=1);

namespace GuzzleHttp\Psr7;

use Psr\Http\Message\UriInterface;

/**

 * Provides methods to normalize and compare URIs.

 *

 * @author Tobias Schultze

 *

 * @link https://tools.ietf.org/html/rfc3986#section-6

 */

final class UriNormalizer

{

    /**

     * Default normalizations which only include the ones that preserve semantics.

     */

    public const PRESERVING_NORMALIZATIONS =

        self::CAPITALIZE_PERCENT_ENCODING |

        self::DECODE_UNRESERVED_CHARACTERS |

        self::CONVERT_EMPTY_PATH |

        self::REMOVE_DEFAULT_HOST |

        self::REMOVE_DEFAULT_PORT |

        self::REMOVE_DOT_SEGMENTS;

    /**

     * All letters within a percent-encoding triplet (e.g., "%3A") are case-insensitive, and should be capitalized.

     *

     * Example: http://example.org/a%c2%b1b → http://example.org/a%C2%B1b

     */

    public const CAPITALIZE_PERCENT_ENCODING = 1;

    /**

     * Decodes percent-encoded octets of unreserved characters.

     *

     * For consistency, percent-encoded octets in the ranges of ALPHA (%41–%5A and %61–%7A), DIGIT (%30–%39),

     * hyphen (%2D), period (%2E), underscore (%5F), or tilde (%7E) should not be created by URI producers and,

     * when found in a URI, should be decoded to their corresponding unreserved characters by URI normalizers.

     *

     * Example: http://example.org/%7Eusern%61me/ → http://example.org/~username/

     */

    public const DECODE_UNRESERVED_CHARACTERS = 2;

    /**

     * Converts the empty path to "/" for http and https URIs.

     *

     * Example: http://example.org → http://example.org/

     */

    public const CONVERT_EMPTY_PATH = 4;

    /**

     * Removes the default host of the given URI scheme from the URI.

     *

     * Only the "file" scheme defines the default host "localhost".

     * All of `file:/myfile`, `file:///myfile`, and `file://localhost/myfile`

     * are equivalent according to RFC 3986. The first format is not accepted

     * by PHPs stream functions and thus already normalized implicitly to the

     * second format in the Uri class. See `GuzzleHttp\Psr7\Uri::composeComponents`.

     *

     * Example: file://localhost/myfile → file:///myfile

     */

    public const REMOVE_DEFAULT_HOST = 8;

    /**

     * Removes the default port of the given URI scheme from the URI.

     *

     * Example: http://example.org:80/ → http://example.org/

     */

    public const REMOVE_DEFAULT_PORT = 16;

    /**

     * Removes unnecessary dot-segments.

     *

     * Dot-segments in relative-path references are not removed as it would

     * change the semantics of the URI reference.

     *

     * Example: http://example.org/../a/b/../c/./d.html → http://example.org/a/c/d.html

     */

    public const REMOVE_DOT_SEGMENTS = 32;

    /**

     * Paths which include two or more adjacent slashes are converted to one.

     *

     * Webservers usually ignore duplicate slashes and treat those URIs equivalent.

     * But in theory those URIs do not need to be equivalent. So this normalization

     * may change the semantics. Encoded slashes (%2F) are not removed.

     *

     * Example: http://example.org//foo///bar.html → http://example.org/foo/bar.html

     */

    public const REMOVE_DUPLICATE_SLASHES = 64;

    /**

     * Sort query parameters with their values in alphabetical order.

     *

     * However, the order of parameters in a URI may be significant (this is not defined by the standard).

     * So this normalization is not safe and may change the semantics of the URI.

     *

     * Example: ?lang=en&article=fred → ?article=fred&lang=en

     *

     * Note: The sorting is neither locale nor Unicode aware (the URI query does not get decoded at all) as the

     * purpose is to be able to compare URIs in a reproducible way, not to have the params sorted perfectly.

     */

    public const SORT_QUERY_PARAMETERS = 128;

    /**

     * Returns a normalized URI.

     *

     * The scheme and host component are already normalized to lowercase per PSR-7 UriInterface.

     * This methods adds additional normalizations that can be configured with the $flags parameter.

     *

     * PSR-7 UriInterface cannot distinguish between an empty component and a missing component as

     * getQuery(), getFragment() etc. always return a string. This means the URIs "/?#" and "/" are

     * treated equivalent which is not necessarily true according to RFC 3986. But that difference

     * is highly uncommon in reality. So this potential normalization is implied in PSR-7 as well.

     *

     * @param UriInterface $uri   The URI to normalize

     * @param int          $flags A bitmask of normalizations to apply, see constants

     *

     * @link https://tools.ietf.org/html/rfc3986#section-6.2

     */

    public static function normalize(UriInterface $uri, int $flags = self::PRESERVING_NORMALIZATIONS): UriInterface

    {

        if ($flags & self::CAPITALIZE_PERCENT_ENCODING) {

            $uri = self::capitalizePercentEncoding($uri);

        }

        if ($flags & self::DECODE_UNRESERVED_CHARACTERS) {

            $uri = self::decodeUnreservedCharacters($uri);

        }

        if ($flags & self::CONVERT_EMPTY_PATH && $uri->getPath() === '' &&

            ($uri->getScheme() === 'http' || $uri->getScheme() === 'https')

        ) {

            $uri = $uri->withPath('/');

        }

        if ($flags & self::REMOVE_DEFAULT_HOST && $uri->getScheme() === 'file' && $uri->getHost() === 'localhost') {

            $uri = $uri->withHost('');

        }

        if ($flags & self::REMOVE_DEFAULT_PORT && $uri->getPort() !== null && Uri::isDefaultPort($uri)) {

            $uri = $uri->withPort(null);

        }

        if ($flags & self::REMOVE_DOT_SEGMENTS && !Uri::isRelativePathReference($uri)) {

            $uri = $uri->withPath(UriResolver::removeDotSegments($uri->getPath()));

        }

        if ($flags & self::REMOVE_DUPLICATE_SLASHES) {

            $uri = $uri->withPath(preg_replace('#//++#', '/', $uri->getPath()));

        }

        if ($flags & self::SORT_QUERY_PARAMETERS && $uri->getQuery() !== '') {

            $queryKeyValues = explode('&', $uri->getQuery());

            sort($queryKeyValues);

            $uri = $uri->withQuery(implode('&', $queryKeyValues));

        }

        return $uri;

    }

    /**

     * Whether two URIs can be considered equivalent.

     *

     * Both URIs are normalized automatically before comparison with the given $normalizations bitmask. The method also

     * accepts relative URI references and returns true when they are equivalent. This of course assumes they will be

     * resolved against the same base URI. If this is not the case, determination of equivalence or difference of

     * relative references does not mean anything.

     *

     * @param UriInterface $uri1           An URI to compare

     * @param UriInterface $uri2           An URI to compare

     * @param int          $normalizations A bitmask of normalizations to apply, see constants

     *

     * @link https://tools.ietf.org/html/rfc3986#section-6.1

     */

    public static function isEquivalent(UriInterface $uri1, UriInterface $uri2, int $normalizations = self::PRESERVING_NORMALIZATIONS): bool

    {

        return (string) self::normalize($uri1, $normalizations) === (string) self::normalize($uri2, $normalizations);

    }

    private static function capitalizePercentEncoding(UriInterface $uri): UriInterface

    {

        $regex = '/(?:%[A-Fa-f0-9]{2})++/';

        $callback = function (array $match) {

            return strtoupper($match[0]);

        };

        return

            $uri->withPath(

                preg_replace_callback($regex, $callback, $uri->getPath())

            )->withQuery(

                preg_replace_callback($regex, $callback, $uri->getQuery())

            );

    }

    private static function decodeUnreservedCharacters(UriInterface $uri): UriInterface

    {

        $regex = '/%(?:2D|2E|5F|7E|3[0-9]|[46][1-9A-F]|[57][0-9A])/i';

        $callback = function (array $match) {

            return rawurldecode($match[0]);

        };

        return

            $uri->withPath(

                preg_replace_callback($regex, $callback, $uri->getPath())

            )->withQuery(

                preg_replace_callback($regex, $callback, $uri->getQuery())

            );

    }

    private function __construct()

    {

        // cannot be instantiated

    }

}