Chris@0: <?php
Chris@0: namespace GuzzleHttp\Psr7;
Chris@0: 
Chris@0: use Psr\Http\Message\UriInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Resolves a URI reference in the context of a base URI and the opposite way.
Chris@0:  *
Chris@0:  * @author Tobias Schultze
Chris@0:  *
Chris@0:  * @link https://tools.ietf.org/html/rfc3986#section-5
Chris@0:  */
Chris@0: final class UriResolver
Chris@0: {
Chris@0:     /**
Chris@0:      * Removes dot segments from a path and returns the new path.
Chris@0:      *
Chris@0:      * @param string $path
Chris@0:      *
Chris@0:      * @return string
Chris@0:      * @link http://tools.ietf.org/html/rfc3986#section-5.2.4
Chris@0:      */
Chris@0:     public static function removeDotSegments($path)
Chris@0:     {
Chris@0:         if ($path === '' || $path === '/') {
Chris@0:             return $path;
Chris@0:         }
Chris@0: 
Chris@0:         $results = [];
Chris@0:         $segments = explode('/', $path);
Chris@0:         foreach ($segments as $segment) {
Chris@0:             if ($segment === '..') {
Chris@0:                 array_pop($results);
Chris@0:             } elseif ($segment !== '.') {
Chris@0:                 $results[] = $segment;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         $newPath = implode('/', $results);
Chris@0: 
Chris@0:         if ($path[0] === '/' && (!isset($newPath[0]) || $newPath[0] !== '/')) {
Chris@0:             // Re-add the leading slash if necessary for cases like "/.."
Chris@0:             $newPath = '/' . $newPath;
Chris@0:         } elseif ($newPath !== '' && ($segment === '.' || $segment === '..')) {
Chris@0:             // Add the trailing slash if necessary
Chris@0:             // If newPath is not empty, then $segment must be set and is the last segment from the foreach
Chris@0:             $newPath .= '/';
Chris@0:         }
Chris@0: 
Chris@0:         return $newPath;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Converts the relative URI into a new URI that is resolved against the base URI.
Chris@0:      *
Chris@0:      * @param UriInterface $base Base URI
Chris@0:      * @param UriInterface $rel  Relative URI
Chris@0:      *
Chris@0:      * @return UriInterface
Chris@0:      * @link http://tools.ietf.org/html/rfc3986#section-5.2
Chris@0:      */
Chris@0:     public static function resolve(UriInterface $base, UriInterface $rel)
Chris@0:     {
Chris@0:         if ((string) $rel === '') {
Chris@0:             // we can simply return the same base URI instance for this same-document reference
Chris@0:             return $base;
Chris@0:         }
Chris@0: 
Chris@0:         if ($rel->getScheme() != '') {
Chris@0:             return $rel->withPath(self::removeDotSegments($rel->getPath()));
Chris@0:         }
Chris@0: 
Chris@0:         if ($rel->getAuthority() != '') {
Chris@0:             $targetAuthority = $rel->getAuthority();
Chris@0:             $targetPath = self::removeDotSegments($rel->getPath());
Chris@0:             $targetQuery = $rel->getQuery();
Chris@0:         } else {
Chris@0:             $targetAuthority = $base->getAuthority();
Chris@0:             if ($rel->getPath() === '') {
Chris@0:                 $targetPath = $base->getPath();
Chris@0:                 $targetQuery = $rel->getQuery() != '' ? $rel->getQuery() : $base->getQuery();
Chris@0:             } else {
Chris@0:                 if ($rel->getPath()[0] === '/') {
Chris@0:                     $targetPath = $rel->getPath();
Chris@0:                 } else {
Chris@0:                     if ($targetAuthority != '' && $base->getPath() === '') {
Chris@0:                         $targetPath = '/' . $rel->getPath();
Chris@0:                     } else {
Chris@0:                         $lastSlashPos = strrpos($base->getPath(), '/');
Chris@0:                         if ($lastSlashPos === false) {
Chris@0:                             $targetPath = $rel->getPath();
Chris@0:                         } else {
Chris@0:                             $targetPath = substr($base->getPath(), 0, $lastSlashPos + 1) . $rel->getPath();
Chris@0:                         }
Chris@0:                     }
Chris@0:                 }
Chris@0:                 $targetPath = self::removeDotSegments($targetPath);
Chris@0:                 $targetQuery = $rel->getQuery();
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return new Uri(Uri::composeComponents(
Chris@0:             $base->getScheme(),
Chris@0:             $targetAuthority,
Chris@0:             $targetPath,
Chris@0:             $targetQuery,
Chris@0:             $rel->getFragment()
Chris@0:         ));
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Returns the target URI as a relative reference from the base URI.
Chris@0:      *
Chris@0:      * This method is the counterpart to resolve():
Chris@0:      *
Chris@0:      *    (string) $target === (string) UriResolver::resolve($base, UriResolver::relativize($base, $target))
Chris@0:      *
Chris@0:      * One use-case is to use the current request URI as base URI and then generate relative links in your documents
Chris@0:      * to reduce the document size or offer self-contained downloadable document archives.
Chris@0:      *
Chris@0:      *    $base = new Uri('http://example.com/a/b/');
Chris@0:      *    echo UriResolver::relativize($base, new Uri('http://example.com/a/b/c'));  // prints 'c'.
Chris@0:      *    echo UriResolver::relativize($base, new Uri('http://example.com/a/x/y'));  // prints '../x/y'.
Chris@0:      *    echo UriResolver::relativize($base, new Uri('http://example.com/a/b/?q')); // prints '?q'.
Chris@0:      *    echo UriResolver::relativize($base, new Uri('http://example.org/a/b/'));   // prints '//example.org/a/b/'.
Chris@0:      *
Chris@0:      * This method also accepts a target that is already relative and will try to relativize it further. Only a
Chris@0:      * relative-path reference will be returned as-is.
Chris@0:      *
Chris@0:      *    echo UriResolver::relativize($base, new Uri('/a/b/c'));  // prints 'c' as well
Chris@0:      *
Chris@0:      * @param UriInterface $base   Base URI
Chris@0:      * @param UriInterface $target Target URI
Chris@0:      *
Chris@0:      * @return UriInterface The relative URI reference
Chris@0:      */
Chris@0:     public static function relativize(UriInterface $base, UriInterface $target)
Chris@0:     {
Chris@0:         if ($target->getScheme() !== '' &&
Chris@0:             ($base->getScheme() !== $target->getScheme() || $target->getAuthority() === '' && $base->getAuthority() !== '')
Chris@0:         ) {
Chris@0:             return $target;
Chris@0:         }
Chris@0: 
Chris@0:         if (Uri::isRelativePathReference($target)) {
Chris@0:             // As the target is already highly relative we return it as-is. It would be possible to resolve
Chris@0:             // the target with `$target = self::resolve($base, $target);` and then try make it more relative
Chris@0:             // by removing a duplicate query. But let's not do that automatically.
Chris@0:             return $target;
Chris@0:         }
Chris@0: 
Chris@0:         if ($target->getAuthority() !== '' && $base->getAuthority() !== $target->getAuthority()) {
Chris@0:             return $target->withScheme('');
Chris@0:         }
Chris@0: 
Chris@0:         // We must remove the path before removing the authority because if the path starts with two slashes, the URI
Chris@0:         // would turn invalid. And we also cannot set a relative path before removing the authority, as that is also
Chris@0:         // invalid.
Chris@0:         $emptyPathUri = $target->withScheme('')->withPath('')->withUserInfo('')->withPort(null)->withHost('');
Chris@0: 
Chris@0:         if ($base->getPath() !== $target->getPath()) {
Chris@0:             return $emptyPathUri->withPath(self::getRelativePath($base, $target));
Chris@0:         }
Chris@0: 
Chris@0:         if ($base->getQuery() === $target->getQuery()) {
Chris@0:             // Only the target fragment is left. And it must be returned even if base and target fragment are the same.
Chris@0:             return $emptyPathUri->withQuery('');
Chris@0:         }
Chris@0: 
Chris@0:         // If the base URI has a query but the target has none, we cannot return an empty path reference as it would
Chris@0:         // inherit the base query component when resolving.
Chris@0:         if ($target->getQuery() === '') {
Chris@0:             $segments = explode('/', $target->getPath());
Chris@0:             $lastSegment = end($segments);
Chris@0: 
Chris@0:             return $emptyPathUri->withPath($lastSegment === '' ? './' : $lastSegment);
Chris@0:         }
Chris@0: 
Chris@0:         return $emptyPathUri;
Chris@0:     }
Chris@0: 
Chris@0:     private static function getRelativePath(UriInterface $base, UriInterface $target)
Chris@0:     {
Chris@0:         $sourceSegments = explode('/', $base->getPath());
Chris@0:         $targetSegments = explode('/', $target->getPath());
Chris@0:         array_pop($sourceSegments);
Chris@0:         $targetLastSegment = array_pop($targetSegments);
Chris@0:         foreach ($sourceSegments as $i => $segment) {
Chris@0:             if (isset($targetSegments[$i]) && $segment === $targetSegments[$i]) {
Chris@0:                 unset($sourceSegments[$i], $targetSegments[$i]);
Chris@0:             } else {
Chris@0:                 break;
Chris@0:             }
Chris@0:         }
Chris@0:         $targetSegments[] = $targetLastSegment;
Chris@0:         $relativePath = str_repeat('../', count($sourceSegments)) . implode('/', $targetSegments);
Chris@0: 
Chris@0:         // A reference to am empty last segment or an empty first sub-segment must be prefixed with "./".
Chris@0:         // This also applies to a segment with a colon character (e.g., "file:colon") that cannot be used
Chris@0:         // as the first segment of a relative-path reference, as it would be mistaken for a scheme name.
Chris@0:         if ('' === $relativePath || false !== strpos(explode('/', $relativePath, 2)[0], ':')) {
Chris@0:             $relativePath = "./$relativePath";
Chris@0:         } elseif ('/' === $relativePath[0]) {
Chris@0:             if ($base->getAuthority() != '' && $base->getPath() === '') {
Chris@0:                 // In this case an extra slash is added by resolve() automatically. So we must not add one here.
Chris@0:                 $relativePath = ".$relativePath";
Chris@0:             } else {
Chris@0:                 $relativePath = "./$relativePath";
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return $relativePath;
Chris@0:     }
Chris@0: 
Chris@0:     private function __construct()
Chris@0:     {
Chris@0:         // cannot be instantiated
Chris@0:     }
Chris@0: }