<?php
/**
 * Converts an array-represented URL to a string
 *
 * Source: http://php.net/manual/en/function.parse-url.php#106731
 *
 * @see http://php.net/manual/en/function.parse-url.php
 *
 * @param array $parsedUrl an array-represented URL
 *
 * @return string the string representation of the URL
 */
function unparse_url($parsedUrl)
{
    $scheme   = isset($parsedUrl['scheme']) ? $parsedUrl['scheme'].'://' : '';
    $host     = isset($parsedUrl['host']) ? $parsedUrl['host'] : '';
    $port     = isset($parsedUrl['port']) ? ':'.$parsedUrl['port'] : '';
    $user     = isset($parsedUrl['user']) ? $parsedUrl['user'] : '';
    $pass     = isset($parsedUrl['pass']) ? ':'.$parsedUrl['pass']  : '';
    $pass     = ($user || $pass) ? "$pass@" : '';
    $path     = isset($parsedUrl['path']) ? $parsedUrl['path'] : '';
    $query    = isset($parsedUrl['query']) ? '?'.$parsedUrl['query'] : '';
    $fragment = isset($parsedUrl['fragment']) ? '#'.$parsedUrl['fragment'] : '';

    return "$scheme$user$pass$host$port$path$query$fragment";
}

/**
 * URL representation and cleanup utilities
 *
 * Form
 *   scheme://[username:password@]host[:port][/path][?query][#fragment]
 *
 * Examples
 *   http://username:password@hostname:9090/path?arg1=value1&arg2=value2#anchor
 *   https://host.name.tld
 *   https://h2.g2/faq/?vendor=hitchhiker&item=guide&dest=galaxy#answer
 *
 * @see http://www.faqs.org/rfcs/rfc3986.html
 */
class Url
{
    private static $annoyingQueryParams = array(
        // Facebook
        'action_object_map=',
        'action_ref_map=',
        'action_type_map=',
        'fb_',
        'fb=',

        // Scoop.it
        '__scoop',

        // Google Analytics & FeedProxy
        'utm_',

        // ATInternet
        'xtor='
    );

    private static $annoyingFragments = array(
        // ATInternet
        'xtor=RSS-',

        // Misc.
        'tk.rss_all'
    );

    /*
     * URL parts represented as an array
     *
     * @see http://php.net/parse_url
     */
    protected $parts;

    /**
     * Parses a string containing a URL
     *
     * @param string $url a string containing a URL
     */
    public function __construct($url)
    {
        $this->parts = parse_url($url);

        if (!empty($url) && empty($this->parts['scheme'])) {
            $this->parts['scheme'] = 'http';
        }
    }

    /**
     * Returns a string representation of this URL
     */
    public function __toString()
    {
        return unparse_url($this->parts);
    }

    /**
     * Removes undesired query parameters
     */
    protected function cleanupQuery()
    {
        if (! isset($this->parts['query'])) {
            return;
        }

        $queryParams = explode('&', $this->parts['query']);

        foreach (self::$annoyingQueryParams as $annoying) {
            foreach ($queryParams as $param) {
                if (startsWith($param, $annoying)) {
                    $queryParams = array_diff($queryParams, array($param));
                    continue;
                }
            }
        }

        if (count($queryParams) == 0) {
            unset($this->parts['query']);
            return;
        }

        $this->parts['query'] = implode('&', $queryParams);
    }    

    /**
     * Removes undesired fragments
     */
    protected function cleanupFragment()
    {
        if (! isset($this->parts['fragment'])) {
            return;
        }

        foreach (self::$annoyingFragments as $annoying) {
            if (startsWith($this->parts['fragment'], $annoying)) {
                unset($this->parts['fragment']);
                break;
            }
        }
    }

    /**
     * Removes undesired query parameters and fragments
     *
     * @return string the string representation of this URL after cleanup
     */
    public function cleanup()
    {
        $this->cleanupQuery();
        $this->cleanupFragment();
        return $this->__toString();
    }

    /**
     * Get URL scheme.
     *
     * @return string the URL scheme or false if none is provided.
     */
    public function getScheme() {
        if (!isset($this->parts['scheme'])) {
            return false;
        }
        return $this->parts['scheme'];
    }
}