<?php

/**
 * Syntax based normalization of URI's
 * 
 * This normalises URI's based on the specification RFC 3986 
 * http://www.apps.ietf.org/rfc/rfc3986.html
 * 
 * Example usage:
 * <code>
 * require_once 'URLNormalizer.php';
 * 
 * $url = 'eXAMPLE://a/./b/../b/%63/%7bfoo%7d';
 * $un = new URLNormalizer();
 * $un->setUrl( $url );
 * echo $un->normalize();
 *
 * // result: "example://a/b/c/%7Bfoo%7D"
 * </code>
 *
 * @author Glen Scott <hide@address.com>
 */
class URLNormalizer {
    private $url;
    private $scheme;
    private $host;
    private $port;
    private $user;
    private $pass;
    private $path;
    private $query;
    private $fragment;
    
    public function __construct() {
        $this->scheme   = '';
        $this->host     = '';
        $this->port     = '';
        $this->user     = '';
        $this->pass     = '';
        $this->path     = '';
        $this->query    = '';
        $this->fragment = '';
    }
    
    public function getUrl() {
        return $this->url;
    }
    
    public function setUrl( $url ) { 
        $this->url = $url;

        // parse URL into respective parts
        $url_components = parse_url( $this->url );
        
        if ( ! $url_components ) {
            return false;
        }
        else {
            foreach ( $url_components as $key => $value ) {
                if ( property_exists( $this, $key ) ) {
                    $this->$key = $value;
                }
            }
            
            return true;
        }
    }
    
    public function getScheme() {
        return $this->scheme;
    }
    
    public function normalize() {
        if ( $this->path ) { 
            # case normalization
            $this->path = preg_replace( '/(%([0-9abcdef][0-9abcdef]))/ex', "'%'.strtoupper('\\2')", $this->path );
            
            # percent-encoding normalization
            $this->path = $this->urlDecodeUnreservedChars( $this->path );
            
            # path segment normalization
            $this->path = $this->removeDotSegments( $this->path );
        }

        if ( $this->scheme ) { 
            $this->scheme = strtolower( $this->scheme ) . '://';
        }
        
        if ( $this->host ) {
            $this->host = strtolower( $this->host );
            
        }

        
        return $this->scheme . $this->host . $this->port . $this->user . $this->pass . $this->path . $this->query . $this->fragment;
    }

    /**
     * Decode unreserved characters
     * http://www.apps.ietf.org/rfc/rfc3986.html#sec-2.3
     */
    public function urlDecodeUnreservedChars( $string ) {
        $unreserved = array();
        
        for ( $octet = 65; $octet <= 90; $octet++ ) {
            $unreserved[] = dechex( $octet );
        }
        
        for ( $octet = 97; $octet <= 122; $octet++ ) {
            $unreserved[] = dechex( $octet );
        }
        
        for ( $octet = 48; $octet <= 57; $octet++ ) {
            $unreserved[] = dechex( $octet );
        }
        
        $unreserved[] = dechex( ord( '-' ) );
        $unreserved[] = dechex( ord( '.' ) );
        $unreserved[] = dechex( ord( '_' ) );
        $unreserved[] = dechex( ord( '~' ) );
        
        return preg_replace_callback( array_map( create_function( '$str', 'return "/%" . strtoupper( $str ) . "/x";' ), $unreserved ), create_function( '$matches', 'return chr( hexdec( $matches[0] ));' ), $string );
        //return chr( hexdec( '%63' ) );
    }
        
    /**
     * Path segment normalization
     * http://www.apps.ietf.org/rfc/rfc3986.html#sec-5.2.4
     */
    public function removeDotSegments( $path ) {
        $new_path = '';
        
        $iteration = 0;
        $step      = ' ';
        
        while ( ! empty( $path ) ) {
             //echo ++$iteration . "$step:" . $new_path . "\t\t\t\t"  . $path . "\n";
 
             // A
            $pattern_a   = '!^(\.\./|\./)!x';
            $pattern_b_1 = '!^(/\./)!x';
            $pattern_b_2 = '!^(/\.)$!x';
            $pattern_c   = '!^(/\.\./|/\.\.)!x';
            $pattern_d   = '!^(\.|\.\.)$!x';
            $pattern_e   = '!(/*[^/]*)!x';
            
            if ( preg_match( $pattern_a, $path ) ) {
                $step = 'A';
                // remove prefix from $path
                $path = preg_replace( $pattern_a, '', $path );
            }
            elseif ( preg_match( $pattern_b_1, $path, $matches ) || preg_match( $pattern_b_2, $path, $matches ) ) {
                $step = 'B';
                $path = preg_replace( "!^" . $matches[1] . "!", '/', $path );
            }
            elseif ( preg_match( $pattern_c, $path, $matches ) ) {
                $step = 'C';
                $path = preg_replace( '!^' . preg_quote( $matches[1], '!' ) . '!x', '/', $path );
                
                # remove the last segment and its preceding "/" (if any) from output buffer
                $new_path = preg_replace( '!/([^/]+)$!x', '', $new_path );
            }
            elseif ( preg_match( $pattern_d, $path ) ) {
                $step = 'D';
                $path = preg_replace( $pattern_d, $path );
            }
            else {
                $step = 'E';
                if ( preg_match( $pattern_e, $path, $matches ) ) {
                    $first_path_segment = $matches[1];
                    
                    $path = preg_replace( '/^' . preg_quote( $first_path_segment, '/' ) . '/', '', $path, 1 );
                    
                    $new_path .= $first_path_segment;
                }
            }
        }
        
        return $new_path;
    }
}