<?php
/**
 * Syntax based normalization of URI's
 *
 * This normalises URI's based on the specification RFC 3986
 * www . apps . ietf . org/rfc/rfc3986.html
 *
 * Example usage:
 * <code>
 * require_once 'PageCacheURLNormalizer.php';
 *
 * $url = 'eXAMPLE://a/./b/../b/%63/%7bfoo%7d';
 * $un = new PageCacheURLNormalizer();
 * $un->setUrl( $url );
 * echo $un->normalize();
 *
 * // result: "example://a/b/c/%7Bfoo%7D"
 * </code>
 *
 *    @author    Glen Scott <glen_scott @ yahoo.co.uk>
 *    @copyright Glen Scott
 *    @license   Open Source
 */

if (!function_exists('pagecacheRawurlencode')) {
    function pagecacheRawurlencode($value) {
        if (is_array($value)) {
            return array_map('rawurldecode', array_values($value));
        } else {
            return rawurldecode($value);
        }
    }
}
if (!class_exists('PageCacheURLNormalizer')) {
    class PageCacheURLNormalizer {
        private $url;
        private $scheme;
        private $host;
        private $port;
        private $user;
        private $pass;
        private $path;
        private $query;
        private $fragment;
        private $default_scheme_ports = array( 'http:' => 80, 'https:' => 443, );
        private $components = array( 'scheme', 'host', 'port', 'user', 'pass', 'path', 'query', 'fragment', );

        public function __construct( $url=null ) {
            if ( $url ) {
                $this->setUrl( $url );
            }
        }

        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 ) {
                // Reset URL
                $this->url = '';

                // Flush properties
                foreach ( $this->components as $key ) {
                    if ( property_exists( $this, $key ) ) {
                        $this->$key = '';
                    }
                }

                return false;
            } else {
                // Update properties
                foreach ( $url_components as $key => $value ) {
                    if ( property_exists( $this, $key ) ) {
                        $this->$key = $value;
                    }
                }

                // Flush missing components
                $missing_components = array_diff (
                        array_values( $this->components ),
                        array_keys( $url_components )
                );

                foreach ( $missing_components as $key ) {
                    if ( property_exists( $this, $key ) ) {
                        $this->$key = '';
                    }
                }

                return true;
            }
        }

        public function normalize() {

            // URI Syntax Components
            // scheme authority path query fragment
            // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3

            // Scheme
            // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.1

            if ( $this->scheme ) {
                // Converting the scheme to lower case
                $this->scheme = Tools::strtolower( $this->scheme ) . ':';
            }

            // Authority
            // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.2

            $authority = '';
            if ( $this->host ) {
                $authority .= '//';

                // User Information
                // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.2.1

                if ( $this->user ) {
                    if ( $this->pass ) {
                        $authority .= $this->user . ':' . $this->pass . '@';
                    } else {
                        $authority .= $this->user . '@';
                    }
                }

                // Host
                // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.2.2

                // Converting the host to lower case
                $authority .= Tools::strtolower( $this->host );

                // Port
                // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.2.3

                // Removing the default port
                if ( isset( $this->default_scheme_ports[$this->scheme] )
                && $this->port == $this->default_scheme_ports[$this->scheme]) {
                    $this->port = '';
                }

                if ( $this->port ) {
                    $authority .= ':' . $this->port;
                }
            }

            // Path
            // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.3

            if ( $this->path ) {
                // Removing dot-segments
                $this->path = $this->removeDotSegments( $this->path );
                $this->path = $this->urlDecodeUnreservedChars( $this->path );
                $this->path = $this->urlDecodeReservedSubDelimChars( $this->path );
            }
            // Add default path only when valid URL is present
            elseif ( $this->url ) {
                // Adding trailing /
                $this->path = '/';
            }

            // Query
            // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.4

            if ( $this->query ) {
                parse_str( $this->query, $query );

                $keys = array_map( 'rawurldecode', array_keys( $query ) );
                $values = array_map( 'pagecacheRawurlencode', array_values( $query ) );
                $query = array_combine( $keys, $values );

                $this->query = '?' . str_replace( '+', '%20', http_build_query( $query, null, '&' ) );

                // Fix http_build_query adding equals sign to empty keys
                $this->query = str_replace( '=&', '&', rtrim( $this->query, '=' ));
            }

            // Fragment
            // @link www.apps.ietf . org/rfc/rfc3986.html#sec-3.5

            if ( $this->fragment ) {
                $this->fragment = rawurldecode( $this->fragment );
                $this->fragment = rawurlencode( $this->fragment );
                $this->fragment = '#' . $this->fragment;
            }

            $this->setUrl( $this->scheme . $authority . $this->path . $this->query . $this->fragment );

            return $this->getUrl();
        }

        /**
         * Path segment normalization
         * www.apps.ietf . org/rfc/rfc3986.html#sec-5.2.4
         */
        public function removeDotSegments( $path ) {
            $new_path = '';

            while ( ! empty( $path ) ) {
                // 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 ) ) {
                    // 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 ) ) {
                    $path = preg_replace( "!^" . $matches[1] . "!", '/', $path );
                }
                elseif ( preg_match( $pattern_c, $path, $matches ) ) {
                    $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 ) ) {
                    $path = preg_replace( $pattern_d, '', $path );
                } else {
                    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;
        }

        public function getScheme() {
            return $this->scheme;
        }

        /**
         * Decode unreserved characters
         *
         * @link www.apps.ietf . org/rfc/rfc3986.html#sec-2.3
         */
        public function urlDecodeUnreservedChars( $string ) {
            $string = rawurldecode( $string );
            $string = rawurlencode( $string );
            $string = str_replace( array( '%2F', '%3A', '%40' ), array( '/', ':', '@' ), $string );

            return $string;
        }

        /**
         * Decode reserved sub-delims
         *
         * @link www.apps.ietf . org/rfc/rfc3986.html#sec-2.2
         */
        public function urlDecodeReservedSubDelimChars( $string ) {
            return str_replace( array( '%21', '%24', '%26', '%27', '%28', '%29', '%2A', '%2B', '%2C', '%3B', '%3D' ),
                    array( '!', '$', '&', "'", '(', ')', '*', '+', ',', ';', '=' ), $string );
        }
    }
}