<?php

require_once __DIR__ . '/encoding.php';

/**
 * URL parser to replace parse_url() PHP function which got broken in PHP 4.3.0.
 * Adds some browser specific functionality such as expandomatics.
 * Guesses a bit trying to separate the host from the path and
 * tries to keep a raw, possibly unparsable, request string as long as possible.
 *
 * @todo  Check PHP version compatibility and if possible, leverage native PHP functionality.
 */
class SimpleUrl
{
    public $path;

    private $fragment;
    private $host;
    private $password;
    private $port;
    private $raw = false;
    private $request;
    private $scheme;
    private $target;
    private $username;
    private $x;
    private $y;


    /**
     *    Constructor. Parses URL into sections.
     *
     *    @param string $url        Incoming URL.
     */
    public function __construct($url = '')
    {
        list($x, $y) = $this->chompCoordinates($url);
        $this->setCoordinates($x, $y);
        $this->scheme = $this->chompScheme($url);
        if ($this->scheme === 'file') {
            $url = str_replace('\\', '/', $url ?? '');
        }
        list($this->username, $this->password) = $this->chompLogin($url);
        $this->host                            = $this->chompHost($url);
        $this->port                            = false;
        if (preg_match('/(.*?):(.*)/', $this->host, $host_parts)) {
            if ($this->scheme === 'file' && strlen($this->host) === 2) {
                $url        = '/' . $this->host . $url;
                $this->host = false;
            } else {
                $this->host = $host_parts[1];
                $this->port = (integer) $host_parts[2];
            }
        }
        $this->path     = $this->chompPath($url);
        $this->request  = $this->parseRequest($this->chompRequest($url));
        $this->fragment = (strncmp($url, '#', 1) == 0 ? substr($url, 1) : false);
        $this->target   = false;
    }

    /**
     * Extracts the X, Y coordinate pair from an image map.
     *
     * @param string $url   URL so far. The coordinates will be removed.
     *
     * @return array        X, Y as a pair of integers.
     */
    protected function chompCoordinates(&$url)
    {
        if (preg_match('/(.*)\?(\d+),(\d+)$/', $url, $matches)) {
            $url = $matches[1];

            return array((integer) $matches[2], (integer) $matches[3]);
        }

        return array(false, false);
    }

    /**
     * Extracts the scheme part of an incoming URL.
     *
     * @param string $url   URL so far. The scheme will be removed.
     *
     * @return string       Scheme part or false.
     */
    protected function chompScheme(&$url)
    {
        if (preg_match('#^([^/:]*):(//)(.*)#', $url, $matches)) {
            $url = $matches[2] . $matches[3];

            return $matches[1];
        }

        return false;
    }

    /**
     * Extracts the username and password from the incoming URL. The // prefix will be reattached to
     * the URL after the doublet is extracted.
     *
     * @param string $url    URL so far. The username and password are removed.
     *
     * @return array         Two item list of username and password. Will urldecode() them.
     */
    protected function chompLogin(&$url)
    {
        $prefix = '';
        if (preg_match('#^(//)(.*)#', $url, $matches)) {
            $prefix = $matches[1];
            $url    = $matches[2];
        }
        if (preg_match('#^([^/]*)@(.*)#', $url, $matches)) {
            $url   = $prefix . $matches[2];
            $parts = explode(':', $matches[1]);

            return array(
                    urldecode($parts[0]),
                    isset($parts[1]) ? urldecode($parts[1]) : false);
        }
        $url = $prefix . $url;

        return array(false, false);
    }

    /**
     * Extracts the host part of an incoming URL. Includes the port number part. Will extract the
     * host if it starts with // or it has a top level domain or it has at least two dots.
     *
     * @param string $url    URL so far. The host will be removed.
     *
     * @return string        Host part guess or false.
     */
    protected function chompHost(&$url)
    {
        if (preg_match('!^(//)(.*?)(/.*|\?.*|#.*|$)!', $url, $matches)) {
            $url = $matches[3];

            return $matches[2];
        }
        if (preg_match('!(.*?)(\.\./|\./|/|\?|#|$)(.*)!', $url, $matches)) {
            $tlds = self::getAllTopLevelDomains();
            if (preg_match('/[a-z0-9\-]+\.(' . $tlds . ')/i', $matches[1])) {
                $url = $matches[2] . $matches[3];

                return $matches[1];
            } elseif (preg_match('/[a-z0-9\-]+\.[a-z0-9\-]+\.[a-z0-9\-]+/i', $matches[1])) {
                $url = $matches[2] . $matches[3];

                return $matches[1];
            }
        }

        return false;
    }

    /**
     * Extracts the path information from the incoming URL. Strips this path from the URL.
     *
     * @param string $url     URL so far. The host will be removed.
     *
     * @return string         Path part or '/'.
     */
    protected function chompPath(&$url)
    {
        if (preg_match('/(.*?)(\?|#|$)(.*)/', $url, $matches)) {
            $url = $matches[2] . $matches[3];

            return ($matches[1] ? $matches[1] : '');
        }

        return '';
    }

    /**
     * Strips off the request data.
     *
     * @param string $url  URL so far. The request will be removed.
     *
     * @return string      Raw request part.
     */
    protected function chompRequest(&$url)
    {
        if (preg_match('/\?(.*?)(#|$)(.*)/', $url, $matches)) {
            $url = $matches[2] . $matches[3];

            return $matches[1];
        }

        return '';
    }

    /**
     * Breaks the request down into an object.
     *
     * @param string $raw           Raw request.
     *
     * @return SimpleFormEncoding    Parsed data.
     */
    protected function parseRequest($raw)
    {
        $this->raw = $raw;
        $request   = new SimpleGetEncoding();
        foreach (explode('&', $raw) as $pair) {
            if (preg_match('/(.*?)=(.*)/', $pair, $matches)) {
                $request->add(urldecode($matches[1]), urldecode($matches[2]));
            } elseif ($pair) {
                $request->add(urldecode($pair), '');
            }
        }

        return $request;
    }

    /**
     * Accessor for protocol part.
     *
     * @param string $default    Value to use if not present.
     *
     * @return string            Scheme name, e.g "http".
     */
    public function getScheme($default = false)
    {
        return $this->scheme ? $this->scheme : $default;
    }

    /**
     * Accessor for user name.
     *
     * @return string    Username preceding host.
     */
    public function getUsername()
    {
        return $this->username;
    }

    /**
     * Accessor for password.
     *
     * @return string    Password preceding host.
     */
    public function getPassword()
    {
        return $this->password;
    }

    /**
     * Accessor for hostname and port.
     *
     * @param string $default    Value to use if not present.
     *
     * @return string            Hostname only.
     */
    public function getHost($default = false)
    {
        return $this->host ? $this->host : $default;
    }

    /**
     * Accessor for top level domain.
     *
     * @return string       Last part of host.
     */
    public function getTld()
    {
        $path_parts = pathinfo($this->getHost());

        return (isset($path_parts['extension']) ? $path_parts['extension'] : false);
    }

    /**
     * Accessor for port number.
     *
     * @return int    TCP/IP port number.
     */
    public function getPort()
    {
        return $this->port;
    }

    /**
     * Accessor for path.
     *
     * @return string    Full path including leading slash if implied.
     */
    public function getPath()
    {
        if (! $this->path && $this->host) {
            return '/';
        }

        return $this->path;
    }

    /**
     * Accessor for page if any. This may be a directory name if ambiguious.
     *
     * @return            Page name.
     */
    public function getPage()
    {
        if (! preg_match('/([^\/]*?)$/', $this->getPath(), $matches)) {
            return false;
        }

        return $matches[1];
    }

    /**
     * Gets the path to the page.
     *
     * @return string       Path less the page.
     */
    public function getBasePath()
    {
        if (! preg_match('/(.*\/)[^\/]*?$/', $this->getPath(), $matches)) {
            return false;
        }

        return $matches[1];
    }

    /**
     * Accessor for fragment at end of URL after the "#".
     *
     * @return string    Part after "#".
     */
    public function getFragment()
    {
        return $this->fragment;
    }

    /**
     * Sets image coordinates. Set to false to clear them.
     *
     * @param int $x    Horizontal position.
     * @param int $y    Vertical position.
     */
    public function setCoordinates($x = false, $y = false)
    {
        if (($x === false) || ($y === false)) {
            $this->x = $this->y = false;

            return;
        }
        $this->x = (integer) $x;
        $this->y = (integer) $y;
    }

    /**
     * Accessor for horizontal image coordinate.
     *
     * @return int        X value.
     */
    public function getX()
    {
        return $this->x;
    }

    /**
     * Accessor for vertical image coordinate.
     *
     * @return int        Y value.
     */
    public function getY()
    {
        return $this->y;
    }

    /**
     * Accessor for current request parameters in URL string form.
     * Will return teh original request
     * if at all possible even if it doesn't make much sense.
     *
     * @return string   Form is string "?a=1&b=2", etc.
     */
    public function getEncodedRequest()
    {
        if ($this->raw) {
            $encoded = $this->raw;
        } else {
            $encoded = $this->request->asUrlRequest();
        }
        if ($encoded) {
            return '?' . preg_replace('/^\?/', '', $encoded);
        }

        return '';
    }

    /**
     * Adds an additional parameter to the request.
     *
     * @param string $key            Name of parameter.
     * @param string $value          Value as string.
     */
    public function addRequestParameter($key, $value)
    {
        $this->raw = false;
        $this->request->add($key, $value);
    }

    /**
     * Adds additional parameters to the request.
     *
     * @param hash/SimpleFormEncoding $parameters   Additional parameters.
     */
    public function addRequestParameters($parameters)
    {
        $this->raw = false;
        $this->request->merge($parameters);
    }

    /**
     * Clears down all parameters.
     */
    public function clearRequest()
    {
        $this->raw     = false;
        $this->request = new SimpleGetEncoding();
    }

    /**
     * Gets the frame target if present.
     * Although not strictly part of the URL specification it acts
     * as similarily to the browser.
     *
     * @return boolean/string    Frame name or false if none.
     */
    public function getTarget()
    {
        return $this->target;
    }

    /**
     * Attaches a frame target.
     *
     * @param string $frame        Name of frame.
     */
    public function setTarget($frame)
    {
        $this->raw    = false;
        $this->target = $frame;
    }

    /**
     * Renders the URL back into a string.
     *
     * @return string        URL in canonical form.
     */
    public function asString()
    {
        $path   = $this->path;
        $scheme = $identity = $host = $port = $encoded = $fragment = '';
        if ($this->username && $this->password) {
            $identity = $this->username . ':' . $this->password . '@';
        }
        if ($this->getHost()) {
            $scheme = $this->getScheme() ? $this->getScheme() : 'http';
            $scheme .= '://';
            $host = $this->getHost();
        } elseif ($this->getScheme() === 'file') {
            $scheme = 'file://';
        }
        if ($this->getPort() && $this->getPort() != 80) {
            $port = ':' . $this->getPort();
        }

        if (substr($this->path, 0, 1) == '/') {
            $path = $this->normalisePath($this->path);
        }
        $encoded  = $this->getEncodedRequest();
        $fragment = $this->getFragment() ? '#' . $this->getFragment() : '';
        $coords   = $this->getX() === false ? '' : '?' . $this->getX() . ',' . $this->getY();

        return "$scheme$identity$host$port$path$encoded$fragment$coords";
    }

    /**
     * Replaces unknown sections to turn a relative URL into an absolute one.
     * The base URL can be either a string or a SimpleUrl object.
     *
     * @param string/SimpleUrl $base       Base URL.
     */
    public function makeAbsolute($base)
    {
        if (! is_object($base)) {
            $base = new self($base);
        }
        if ($this->getHost()) {
            $scheme   = $this->getScheme();
            $host     = $this->getHost();
            $port     = $this->getPort() ? ':' . $this->getPort() : '';
            $identity = $this->getIdentity() ? $this->getIdentity() . '@' : '';
            if (! $identity) {
                $identity = $base->getIdentity() ? $base->getIdentity() . '@' : '';
            }
        } else {
            $scheme   = $base->getScheme();
            $host     = $base->getHost();
            $port     = $base->getPort() ? ':' . $base->getPort() : '';
            $identity = $base->getIdentity() ? $base->getIdentity() . '@' : '';
        }
        $path     = $this->normalisePath($this->extractAbsolutePath($base));
        $encoded  = $this->getEncodedRequest();
        $fragment = $this->getFragment() ? '#' . $this->getFragment() : '';
        $coords   = $this->getX() === false ? '' : '?' . $this->getX() . ',' . $this->getY();

        return new self("$scheme://$identity$host$port$path$encoded$fragment$coords");
    }

    /**
     * Replaces unknown sections of the path with base parts to return a complete absolute one.
     *
     * @param string/SimpleUrl $base       Base URL.
     * @param string                       Absolute path.
     */
    protected function extractAbsolutePath($base)
    {
        if ($this->getHost()) {
            return $this->path;
        }
        if (! $this->isRelativePath($this->path)) {
            return $this->path;
        }
        if ($this->path) {
            return $base->getBasePath() . $this->path;
        }

        return $base->getPath();
    }

    /**
     * Simple test to see if a path part is relative.
     *
     * @param string $path        Path to test.
     *
     * @return bool            True if starts with a "/".
     */
    protected function isRelativePath($path)
    {
        return (substr($path, 0, 1) != '/');
    }

    /**
     * Extracts the username and password for use in rendering a URL.
     *
     * @return string/boolean    Form of username:password or false.
     */
    public function getIdentity()
    {
        if ($this->username && $this->password) {
            return $this->username . ':' . $this->password;
        }

        return false;
    }

    /**
     * Replaces . and .. sections of the path.
     *
     * @param string $path    Unoptimised path.
     *
     * @return string         Path with dots removed if possible.
     */
    public function normalisePath($path)
    {
        $path = preg_replace('|/\./|', '/', $path);

        return preg_replace('|/[^/]+/\.\./|', '/', $path);
    }

    /**
     * A pipe seperated list of all TLDs that result in two part domain names.
     *
     * @return string        Pipe separated list.
     */
    public static function getAllTopLevelDomains()
    {
        return 'com|edu|net|org|gov|mil|int|biz|info|name|pro|aero|coop|museum';
    }
}
