<?php

declare(strict_types=1);

namespace GuzzleHttp\Psr7;

use Psr\Http\Message\UriInterface;

/**
 * Resolves a URI reference in the context of a base URI and the opposite way.
 *
 * @author Tobias Schultze
 *
 * @see https://datatracker.ietf.org/doc/html/rfc3986#section-5
 */
final class UriResolver
{
    /**
     * Removes dot segments from a path and returns the new path.
     *
     * @see https://datatracker.ietf.org/doc/html/rfc3986#section-5.2.4
     */
    public static function removeDotSegments(string $path): string
    {
        if ($path === '' || $path === '/') {
            return $path;
        }

        $results = [];
        $segments = explode('/', $path);
        foreach ($segments as $segment) {
            if ($segment === '..') {
                array_pop($results);
            } elseif ($segment !== '.') {
                $results[] = $segment;
            }
        }

        $newPath = implode('/', $results);

        if ($path[0] === '/' && (!isset($newPath[0]) || $newPath[0] !== '/')) {
            // Re-add the leading slash if necessary for cases like "/.."
            $newPath = '/'.$newPath;
        } elseif ($newPath !== '' && ($segment === '.' || $segment === '..')) {
            // Add the trailing slash if necessary
            // If newPath is not empty, then $segment must be set and is the last segment from the foreach
            $newPath .= '/';
        }

        return $newPath;
    }

    /**
     * Converts the relative URI into a new URI that is resolved against the base URI.
     *
     * @see https://datatracker.ietf.org/doc/html/rfc3986#section-5.2
     */
    public static function resolve(UriInterface $base, UriInterface $rel): UriInterface
    {
        if ((string) $rel === '') {
            // we can simply return the same base URI instance for this same-document reference
            return $base;
        }

        if ($rel->getScheme() != '') {
            return $rel->withPath(self::removeDotSegments($rel->getPath()));
        }

        if ($rel->getAuthority() != '') {
            $targetAuthority = $rel->getAuthority();
            $targetPath = self::removeDotSegments($rel->getPath());
            $targetQuery = $rel->getQuery();
        } else {
            $targetAuthority = $base->getAuthority();
            if ($rel->getPath() === '') {
                $targetPath = $base->getPath();
                $targetQuery = $rel->getQuery() != '' ? $rel->getQuery() : $base->getQuery();
            } else {
                if ($rel->getPath()[0] === '/') {
                    $targetPath = $rel->getPath();
                } else {
                    if ($targetAuthority != '' && $base->getPath() === '') {
                        $targetPath = '/'.$rel->getPath();
                    } else {
                        $lastSlashPos = strrpos($base->getPath(), '/');
                        if ($lastSlashPos === false) {
                            $targetPath = $rel->getPath();
                        } else {
                            $targetPath = substr($base->getPath(), 0, $lastSlashPos + 1).$rel->getPath();
                        }
                    }
                }
                $targetPath = self::removeDotSegments($targetPath);
                $targetQuery = $rel->getQuery();
            }
        }

        return new Uri(Uri::composeComponents(
            $base->getScheme(),
            $targetAuthority,
            $targetPath,
            $targetQuery,
            $rel->getFragment()
        ));
    }

    /**
     * Returns the target URI as a relative reference from the base URI.
     *
     * This method is the counterpart to resolve():
     *
     *    (string) $target === (string) UriResolver::resolve($base, UriResolver::relativize($base, $target))
     *
     * One use-case is to use the current request URI as base URI and then generate relative links in your documents
     * to reduce the document size or offer self-contained downloadable document archives.
     *
     *    $base = new Uri('http://example.com/a/b/');
     *    echo UriResolver::relativize($base, new Uri('http://example.com/a/b/c'));  // prints 'c'.
     *    echo UriResolver::relativize($base, new Uri('http://example.com/a/x/y'));  // prints '../x/y'.
     *    echo UriResolver::relativize($base, new Uri('http://example.com/a/b/?q')); // prints '?q'.
     *    echo UriResolver::relativize($base, new Uri('http://example.org/a/b/'));   // prints '//example.org/a/b/'.
     *
     * This method also accepts a target that is already relative and will try to relativize it further. Only a
     * relative-path reference will be returned as-is.
     *
     *    echo UriResolver::relativize($base, new Uri('/a/b/c'));  // prints 'c' as well
     */
    public static function relativize(UriInterface $base, UriInterface $target): UriInterface
    {
        if ($target->getScheme() !== ''
            && ($base->getScheme() !== $target->getScheme() || $target->getAuthority() === '' && $base->getAuthority() !== '')
        ) {
            return $target;
        }

        if (Uri::isRelativePathReference($target)) {
            // As the target is already highly relative we return it as-is. It would be possible to resolve
            // the target with `$target = self::resolve($base, $target);` and then try make it more relative
            // by removing a duplicate query. But let's not do that automatically.
            return $target;
        }

        if ($target->getAuthority() !== '' && $base->getAuthority() !== $target->getAuthority()) {
            return $target->withScheme('');
        }

        // We must remove the path before removing the authority because if the path starts with two slashes, the URI
        // would turn invalid. And we also cannot set a relative path before removing the authority, as that is also
        // invalid.
        $emptyPathUri = $target->withScheme('')->withPath('')->withUserInfo('')->withPort(null)->withHost('');

        if ($base->getPath() !== $target->getPath()) {
            return $emptyPathUri->withPath(self::getRelativePath($base, $target));
        }

        if ($base->getQuery() === $target->getQuery()) {
            // Only the target fragment is left. And it must be returned even if base and target fragment are the same.
            return $emptyPathUri->withQuery('');
        }

        // If the base URI has a query but the target has none, we cannot return an empty path reference as it would
        // inherit the base query component when resolving.
        if ($target->getQuery() === '') {
            $segments = explode('/', $target->getPath());
            /** @var string $lastSegment */
            $lastSegment = end($segments);

            return $emptyPathUri->withPath($lastSegment === '' ? './' : $lastSegment);
        }

        return $emptyPathUri;
    }

    private static function getRelativePath(UriInterface $base, UriInterface $target): string
    {
        $sourceSegments = explode('/', $base->getPath());
        $targetSegments = explode('/', $target->getPath());
        array_pop($sourceSegments);
        $targetLastSegment = array_pop($targetSegments);
        foreach ($sourceSegments as $i => $segment) {
            if (isset($targetSegments[$i]) && $segment === $targetSegments[$i]) {
                unset($sourceSegments[$i], $targetSegments[$i]);
            } else {
                break;
            }
        }
        $targetSegments[] = $targetLastSegment;
        $relativePath = str_repeat('../', count($sourceSegments)).implode('/', $targetSegments);

        // A reference to am empty last segment or an empty first sub-segment must be prefixed with "./".
        // This also applies to a segment with a colon character (e.g., "file:colon") that cannot be used
        // as the first segment of a relative-path reference, as it would be mistaken for a scheme name.
        if ('' === $relativePath || false !== strpos(explode('/', $relativePath, 2)[0], ':')) {
            $relativePath = "./$relativePath";
        } elseif ('/' === $relativePath[0]) {
            if ($base->getAuthority() != '' && $base->getPath() === '') {
                // In this case an extra slash is added by resolve() automatically. So we must not add one here.
                $relativePath = ".$relativePath";
            } else {
                $relativePath = "./$relativePath";
            }
        }

        return $relativePath;
    }

    private function __construct()
    {
        // cannot be instantiated
    }
}

.NET Framework

Project Request

ProjectC

Vehicle Maintenance

Movie Navigator

Customers Exchange

ATM

.NET Core

Mail Daemon

Custom

Buns of code

PHP

Mediabox

Loan Castle

Content Management

Laravel

Phone Check

Frontend

Forex Wall

Business projects

Certification Center

Amerikas Auto

Pet projects

Geolocation Assistant

Web Dynamics

Blackball

Good old times

DOS Clock

BrainOut

Airport Administrator

Atomizer

Mediabox