<?php

namespace Sabre\Uri;

/**
 * This file contains all the uri handling functions.
 *
 * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
 * @author Evert Pot (http://evertpot.com/)
 * @license http://sabre.io/license/
 */

/**
 * Resolves relative urls, like a browser would.
 *
 * This function takes a basePath, which itself _may_ also be relative, and
 * then applies the relative path on top of it.
 *
 * @param string $basePath
 * @param string $newPath
 * @return string
 */
function resolve($basePath, $newPath) {

    $base = parse($basePath);
    $delta = parse($newPath);

    $pick = function($part) use ($base, $delta) {

        if ($delta[$part]) {
            return $delta[$part];
        } elseif ($base[$part]) {
            return $base[$part];
        }
        return null;

    };

    // If the new path defines a scheme, it's absolute and we can just return
    // that.
    if ($delta['scheme']) {
        return build($delta);
    }

    $newParts = [];

    $newParts['scheme'] = $pick('scheme');
    $newParts['host'] = $pick('host');
    $newParts['port'] = $pick('port');

    $path = '';
    if ($delta['path']) {
        // If the path starts with a slash
        if ($delta['path'][0] === '/') {
            $path = $delta['path'];
        } else {
            // Removing last component from base path.
            $path = $base['path'];
            if (strpos($path, '/') !== false) {
                $path = substr($path, 0, strrpos($path, '/'));
            }
            $path .= '/' . $delta['path'];
        }
    } else {
        $path = $base['path'] ?: '/';
    }
    // Removing .. and .
    $pathParts = explode('/', $path);
    $newPathParts = [];
    foreach ($pathParts as $pathPart) {

        switch ($pathPart) {
            //case '' :
            case '.' :
                break;
            case '..' :
                array_pop($newPathParts);
                break;
            default :
                $newPathParts[] = $pathPart;
                break;
        }
    }

    $path = implode('/', $newPathParts);

    // If the source url ended with a /, we want to preserve that.
    $newParts['path'] = $path;
    if ($delta['query']) {
        $newParts['query'] = $delta['query'];
    } elseif (!empty($base['query']) && empty($delta['host']) && empty($delta['path'])) {
        // Keep the old query if host and path didn't change
        $newParts['query'] = $base['query'];
    }
    if ($delta['fragment']) {
        $newParts['fragment'] = $delta['fragment'];
    }
    return build($newParts);

}

/**
 * Takes a URI or partial URI as its argument, and normalizes it.
 *
 * After normalizing a URI, you can safely compare it to other URIs.
 * This function will for instance convert a %7E into a tilde, according to
 * rfc3986.
 *
 * It will also change a %3a into a %3A.
 *
 * @param string $uri
 * @return string
 */
function normalize($uri) {

    $parts = parse($uri);

    if (!empty($parts['path'])) {
        $pathParts = explode('/', ltrim($parts['path'], '/'));
        $newPathParts = [];
        foreach ($pathParts as $pathPart) {
            switch ($pathPart) {
                case '.':
                    // skip
                    break;
                case '..' :
                    // One level up in the hierarchy
                    array_pop($newPathParts);
                    break;
                default :
                    // Ensuring that everything is correctly percent-encoded.
                    $newPathParts[] = rawurlencode(rawurldecode($pathPart));
                    break;
            }
        }
        $parts['path'] = '/' . implode('/', $newPathParts);
    }

    if ($parts['scheme']) {
        $parts['scheme'] = strtolower($parts['scheme']);
        $defaultPorts = [
            'http'  => '80',
            'https' => '443',
        ];

        if (!empty($parts['port']) && isset($defaultPorts[$parts['scheme']]) && $defaultPorts[$parts['scheme']] == $parts['port']) {
            // Removing default ports.
            unset($parts['port']);
        }
        // A few HTTP specific rules.
        switch ($parts['scheme']) {
            case 'http' :
            case 'https' :
                if (empty($parts['path'])) {
                    // An empty path is equivalent to / in http.
                    $parts['path'] = '/';
                }
                break;
        }
    }

    if ($parts['host']) $parts['host'] = strtolower($parts['host']);

    return build($parts);

}

/**
 * Parses a URI and returns its individual components.
 *
 * This method largely behaves the same as PHP's parse_url, except that it will
 * return an array with all the array keys, including the ones that are not
 * set by parse_url, which makes it a bit easier to work with.
 *
 * Unlike PHP's parse_url, it will also convert any non-ascii characters to
 * percent-encoded strings. PHP's parse_url corrupts these characters on OS X.
 *
 * @param string $uri
 * @return array
 */
function parse($uri) {

    // Normally a URI must be ASCII, however. However, often it's not and
    // parse_url might corrupt these strings.
    //
    // For that reason we take any non-ascii characters from the uri and
    // uriencode them first.
    $uri = preg_replace_callback(
        '/[^[:ascii:]]/u',
        function($matches) {
            return rawurlencode($matches[0]);
        },
        $uri
    );

    $result = parse_url($uri);
    if (!$result) {
        $result = _parse_fallback($uri);
    }

    return
         $result + [
            'scheme'   => null,
            'host'     => null,
            'path'     => null,
            'port'     => null,
            'user'     => null,
            'query'    => null,
            'fragment' => null,
        ];

}

/**
 * This function takes the components returned from PHP's parse_url, and uses
 * it to generate a new uri.
 *
 * @param array $parts
 * @return string
 */
function build(array $parts) {

    $uri = '';

    $authority = '';
    if (!empty($parts['host'])) {
        $authority = $parts['host'];
        if (!empty($parts['user'])) {
            $authority = $parts['user'] . '@' . $authority;
        }
        if (!empty($parts['port'])) {
            $authority = $authority . ':' . $parts['port'];
        }
    }

    if (!empty($parts['scheme'])) {
        // If there's a scheme, there's also a host.
        $uri = $parts['scheme'] . ':';

    }
    if ($authority || (!empty($parts['scheme']) && $parts['scheme'] === 'file')) {
        // No scheme, but there is a host.
        $uri .= '//' . $authority;

    }

    if (!empty($parts['path'])) {
        $uri .= $parts['path'];
    }
    if (!empty($parts['query'])) {
        $uri .= '?' . $parts['query'];
    }
    if (!empty($parts['fragment'])) {
        $uri .= '#' . $parts['fragment'];
    }

    return $uri;

}

/**
 * Returns the 'dirname' and 'basename' for a path.
 *
 * The reason there is a custom function for this purpose, is because
 * basename() is locale aware (behaviour changes if C locale or a UTF-8 locale
 * is used) and we need a method that just operates on UTF-8 characters.
 *
 * In addition basename and dirname are platform aware, and will treat
 * backslash (\) as a directory separator on windows.
 *
 * This method returns the 2 components as an array.
 *
 * If there is no dirname, it will return an empty string. Any / appearing at
 * the end of the string is stripped off.
 *
 * @param string $path
 * @return array
 */
function split($path) {

    $matches = [];
    if (preg_match('/^(?:(?:(.*)(?:\/+))?([^\/]+))(?:\/?)$/u', $path, $matches)) {
        return [$matches[1], $matches[2]];
    }
    return [null,null];

}

/**
 * This function is another implementation of parse_url, except this one is
 * fully written in PHP.
 *
 * The reason is that the PHP bug team is not willing to admit that there are
 * bugs in the parse_url implementation.
 *
 * This function is only called if the main parse method fails. It's pretty
 * crude and probably slow, so the original parse_url is usually preferred.
 *
 * @param string $uri
 * @return array
 */
function _parse_fallback($uri) {

    // Normally a URI must be ASCII, however. However, often it's not and
    // parse_url might corrupt these strings.
    //
    // For that reason we take any non-ascii characters from the uri and
    // uriencode them first.
    $uri = preg_replace_callback(
        '/[^[:ascii:]]/u',
        function($matches) {
            return rawurlencode($matches[0]);
        },
        $uri
    );

    $result = [
        'scheme'   => null,
        'host'     => null,
        'port'     => null,
        'user'     => null,
        'path'     => null,
        'fragment' => null,
        'query'    => null,
    ];

    if (preg_match('% ^([A-Za-z][A-Za-z0-9+-\.]+): %x', $uri, $matches)) {

        $result['scheme'] = $matches[1];
        // Take what's left.
        $uri = substr($uri, strlen($result['scheme']) + 1);

    }

    // Taking off a fragment part
    if (strpos($uri, '#')) {
        list($uri, $result['fragment']) = explode('#', $uri, 2);
    }
    // Taking off the query part
    if (strpos($uri, '?')) {
        list($uri, $result['query']) = explode('?', $uri, 2);
    }

    if (substr($uri, 0, 3) === '///') {
      // The triple slash uris are a bit unusual, but we have special handling
      // for them.
      $result['path'] = substr($uri, 2);
      $result['host'] = '';
    } elseif (substr($uri, 0, 2) === '//') {
        // Uris that have an authority part.
        $regex = '
          %^
            //
            (?: (?<user> [^:@]+) (: (?<pass> [^@]+)) @)?
            (?<host> ( [^:/]* | \[ [^\]]+ \] ))
            (?: : (?<port> [0-9]+))?
            (?<path> / .*)?
          $%x
        ';
        if (!preg_match($regex, $uri, $matches)) {
            throw new InvalidUriException('Invalid, or could not parse URI');
        }
        if ($matches['host']) $result['host'] = $matches['host'];
        if ($matches['port']) $result['port'] = (int)$matches['port'];
        if (isset($matches['path'])) $result['path'] = $matches['path'];
        if ($matches['user']) $result['user'] = $matches['user'];
        if ($matches['pass']) $result['pass'] = $matches['pass'];
    } else {
        $result['path'] = $uri;
    }

    return $result;
}
