Source for file lib_redirects.php

<?php
/*
 * Lokorin.com
 * Copyright 2004-2006
 * Licensed under the GNU LGPL. See COPYING for full terms.
 */
/**
 * A library that contains everything related to the site's url redirect
 * system. The system maps incoming urls to actual files on the server. It
 * allows the site to show one structure to the outside while in reality using
 * a completly different structure on the server.
 * @author Andreas Launila
 * @version $Revision: 1.20 $
 * @package com.lokorin.lokorin.lib
 * @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
 */
 
/**
 * For access to common functions and variables.
 */
require_once('common.php');
 
/**
 * Strips an url of any query string (if one exists).
 * @param string $url The url which's query string should be removed.
 * @return string The url without its query string.
 * @access public
 */
function stripQueryString($url) {
    return preg_replace("/([^?]+)\?.*/", '$1', $url);
}
 
/**
 * Attempts to get a url path to an existing file by starting from a specified
 * url and then translating the related redirects.
 * @param string $url The url, relative to the page root, that the search
 *          should start from.
 * @param boolean $jump Whether or not redirects should be followed. I.e.
 *          whether or not jumps should be executed. True if jumps should be
 *          executed, false otherwise.
 * @return string The url to the file, relative to the page root and with query
 *          string, that the url is resolved to. An empty string is returned if no
 *          file could be found.
 * @access public
 */
function getUrlPath($url, $jump = true) {
    $url = getRealUrl($url);
    $baseUrl = stripQueryString($url);
    $queryString = str_replace($baseUrl, '', $url);
    $filePath = DOC_ROOT.$baseUrl;
    
    //Look for redirects.
    $redirect = getRedirect($baseUrl);
    if(strlen($redirect) != 0) {
        if(!$jump) {
            return $redirect;
        }
        //A redirect was found, apply it.
        doPermanentRedirect($redirect.$queryString);
        exit;
    }
 
    //Look for aliases.
    if(file_exists($filePath)) {
        if(is_dir($filePath)) {
            if((strlen($queryString) == 0) && 
                    (getUrlPath($url.'/', $jump) != '')) {
                if(!$jump) {
                    return $baseUrl.'/';
                }
                doRedirect($baseUrl.'/');
                exit;
            } else {
                return '';
            }
        } else {
            //A match has been found.
            return $url;
        }
    } else if(file_exists($filePath.'.php')) {
        //It's a match.
        return $url;
    } else {
        //Nothing was found.
        return '';
    }
}
 
/**
 * Gets any redirects that apply to a specified url.
 * @param string $requestedUrl The url, relative to the site's root, which
 *          has been requested by the user (no query string).
 * @return string The url that the specified url should be redirected to, or an
 *          empty string if none was found.
 * @access private
 */
function getRedirect($requestedUrl) {
    global $db;
 
    $requestedUrl = str_replace('.php', '', $requestedUrl);
    try {
        $idFields = array(
            'from'    => $requestedUrl
        );
        return $db->querySelectFirst(TABLE_REDIRECTS, 'to', 
                $db->buildSqlSelector($idFields));
    } catch(Exception $e) {
        return '';
    }
}
 
/**
 * Gets the url that a specified url really leads to. For instance a user might
 * request one url while the request is actually transferred to an centralised
 * module behind the scenes.
 * @param string $requestedUrl The url, relative to the site's root, which
 *          has been requested by the user (no query string).
 * @return string The actual url, relative to the site's root, that the call
 *          should be directed to.
 * @access private
 */
function getRealUrl($requestedUrl) {
    global $db;
    
    $idFields = array();
    $idFields[] = '(`from`='.$db->escape($requestedUrl).')';
    if((strlen($requestedUrl) == 0) || 
            ($requestedUrl{strlen($requestedUrl)-1} != '/')) {
         $idFields[] = '(`from`='.$db->escape($requestedUrl.'/').')';
    }
    $rows = $db->querySelect(TABLE_ALIASES, array('to'),
            'WHERE '.implode(' OR ', $idFields));
 
    if(sizeof($rows) > 0) {
        return $rows[0]['to'];
    } else if((strlen($requestedUrl) == 0) || 
            ($requestedUrl{strlen($requestedUrl)-1} === '/')) {
        return getRealUrl($requestedUrl.'index');
    } else {
        return $requestedUrl;
    }
}
 
/**
 * Rebuilds the url aliases master table. It composes all necessary aliases
 * and resets the aliases master table with that info.
 * @access public
 */
function buildUrlAliases() {
    /**
     * The printf pattern that should be used for building the news date from 
     * value.
     * @var string
     * @access private
     */
    define('NEWS_DATE_PATTERN_FROM', 'news/%s/%s/%s');
    /**
     * The printf pattern that should be used for building the news date to 
     * value.
     * @var string
     * @access private
     */
    define('NEWS_DATE_PATTERN_TO', 'news/archive.php?day=%s');
    /**
     * The printf pattern that should be used for building the news comments 
     * from value.
     * @var string
     * @access private
     */
    define('NEWS_COMMENTS_PATTERN_FROM', 'news/comments/entry%s');
    /**
     * The printf pattern that should be used for building the news comments to 
     * value.
     * @var string
     * @access private
     */
    define('NEWS_COMMENTS_PATTERN_TO', 'news/comments.php?news_id=%s');
    /**
     * The printf pattern that should be used for building the news title from
     * value.
     * @vars string
     * @access private
     */
    define('NEWS_TITLE_PATTERN_FROM', 'news/%s_%s');
    /**
     * The printf pattern that should be used for building the news id to 
     * value.
     * @var string
     * @access private
     */
    define('NEWS_TITLE_PATTERN_TO', 'news/archive.php?id=%s');
    /**
     * The printf pattern that should be used for building the project 
     * submenus' to value when it should point to the about module.
     * @var string
     * @access private
     */
    define('PROJECT_ABOUT_TO', '_includes/module_about.php');
    /**
     * The printf pattern that should be used for building the project 
     * submenus' to value when it should point to the progress module.
     * @var string
     * @access private
     */
    define('PROJECT_PROGRESS_TO', '_includes/module_progress.php');
    /**
     * The printf pattern that should be used for building the project 
     * submenus' to value when it should point to the download module.
     * @var string
     * @access private
     */
    define('PROJECT_DOWNLOAD_TO', '_includes/module_download.php');
    /**
     * The printf pattern that should be used for building the project 
     * submenus' to value when it should point to the image module.
     * @var string
     * @access private
     */
    define('PROJECT_IMAGES_TO', '_includes/module_images.php');
    /**
     * The printf pattern that should be used for building the from values for
     * programming language related aliases.
     * @var string
     * @access private
     */
    define('LANG_PATTERN_FROM', 'languages/%s');
    /**
     * The printf pattern that should be used for building the project 
     * submenus' to value when it should point to the download module.
     * @var string
     * @access private
     */
    define('LANG_PATTERN_TO', 'languages.php?id=%s');
    /**
     * The printf pattern that should be used for building the archive month 
     * from value.
     * @var string
     * @access private
     */
    define('ARCHIVE_MONTH_PATTERN_FROM', 'news/%s/%s');
    /**
     * The printf pattern that should be used for building the archive month
     * to value.
     * @var string
     * @access private
     */
    define('ARCHIVE_MONTH_PATTERN_TO', 'news/archive.php?year=%s&month=%s');
    /**
     * The printf pattern that should be used for building the sitemap to 
     * value.
     * @var string
     * @access private
     */
    define('SITEMAP_PATTERN_TO', 'sitemaps/sitemap.php?name=%s');
 
    global $db;    
    $aliases = array();
 
    //Source 1: Custom aliases.
    $fields = array(
        'from',
        'to'
    );
    $rows = $db->querySelect(TABLE_CUSTOM_ALIASES, $fields);
    foreach($rows as $row) {
        $aliases[] = $row;
    }
    
    //Source 2: News
    doInclude('lib_util');
    $fields = array(
        'id',
        'caption',
        'timestamp'
    );
    $rows = $db->querySelect(TABLE_NEWS, $fields);
    $datesFrom = array(); //Stores all redirected dates.
    foreach($rows as $row) {
        //The date alias.
        $dayOfMonth = date('j', $row['timestamp']);
        $month = date('n', $row['timestamp']);
        $year = date('Y', $row['timestamp']);
        $dateFrom = sprintf(NEWS_DATE_PATTERN_FROM, $year, $month, 
                    $dayOfMonth);
        if(!in_array($dateFrom, $datesFrom)) {
            $datesFrom[] = $dateFrom;
            $aliases[] = array(
                'from'    => $dateFrom,
                'to'    => sprintf(NEWS_DATE_PATTERN_TO, 
                        floor($row['timestamp'] / (3600*24)))
            );
        }
        
        //The comments alias.
        $aliases[] = array(
            'from'    => sprintf(NEWS_COMMENTS_PATTERN_FROM, $row['id']),
            'to'    => sprintf(NEWS_COMMENTS_PATTERN_TO, $row['id'])
        );
        
        //The title alias.
        $aliases[] = array(
            'from'    => sprintf(NEWS_TITLE_PATTERN_FROM, 
                    urlEncodeReadable($row['caption']), $row['id']),
            'to'    => sprintf(NEWS_TITLE_PATTERN_TO, $row['id'])
        );
    }
    
    //Source 3: Projects
    $result = $db->query("SELECT proj.relative_path, menu.internal_path " .
        "FROM ".TABLE_PROJECTS." AS proj, ".TABLE_PROJECT_SUBMENUS." AS menu ".
        "WHERE menu.project_id = proj.id");
    while(list($projPath, $menuPath) = mysql_fetch_row($result)) {
        if($menuPath == 'about') {
            //The about module.
            $aliases[] = array(
                'from'    => $projPath.$menuPath,
                'to'    => sprintf(PROJECT_ABOUT_TO)
            );
        } else if($menuPath == 'progress') {
            //The progress module.
            $aliases[] = array(
                'from'    => $projPath.$menuPath,
                'to'    => sprintf(PROJECT_PROGRESS_TO)
            );
        } else if($menuPath == 'download') {
            //The download module.
            $aliases[] = array(
                'from'    => $projPath.$menuPath,
                'to'    => sprintf(PROJECT_DOWNLOAD_TO)
            );
        } else if($menuPath == 'images') {
            //The images module.
            $aliases[] = array(
                'from'    => $projPath.$menuPath,
                'to'    => sprintf(PROJECT_IMAGES_TO)
            );
        }
    }
    
    //Source 4: Programming languages
    $fields = array(
        'id', 
        'name'
    );
    $rows = $db->querySelect(TABLE_PROGRAM_LANGS, $fields);
    foreach($rows as $row) {
        $aliases[] = array(
            'from'    => sprintf(LANG_PATTERN_FROM, strtolower($row['name'])),
            'to'    => sprintf(LANG_PATTERN_TO, $row['id'])
        );
    }
    
    //Source 5: Archive months
    $result = $db->query(
            "SELECT min(timestamp), max(timestamp) FROM ".TABLE_NEWS);
    list($time, $upperBound) = mysql_fetch_row($result);
    do {
        $year = date('Y', $time);
        $month = date('n', $time);
        $aliases[] = array(
            'from'    => sprintf(ARCHIVE_MONTH_PATTERN_FROM, $year, $month),
            'to'    => sprintf(ARCHIVE_MONTH_PATTERN_TO, $year, $month)
        );
        $before = $time;
        $time = mktime(0, 0, 1, $month+1, 1, $year);
    } while($time <= $upperBound);
    
    //Source 6: Sitemaps
    doInclude('lib_sitemap');
    $index = new SitemapIndex();
    $aliases[] = array(
        'from'    => $index->getVirtualLocation(),
        'to'    => sprintf(SITEMAP_PATTERN_TO, '')
    );
    foreach($index->getSitemaps() as $sitemap) {
        $aliases[] = array(
            'from'    => $sitemap->getVirtualLocation(),
            'to'    => sprintf(SITEMAP_PATTERN_TO, $sitemap->getName())
        );
    }
    
    //Reset the master table.
    $db->query("TRUNCATE TABLE ".TABLE_ALIASES);
    foreach($aliases as $alias) {
        $db->queryInsert(TABLE_ALIASES, $alias);    
    }
}
 
/**
 * Rebuilds the url redirects master table. It composes all necessary redirects
 * and resets the redirects master table with that info.
 * @access public
 */
function buildUrlRedirects() {    
    /**
     * The printf pattern that should be used for building the projects' from 
     * values.
     * @var string
     * @access private
     */
    define('PROJECT_FROM', '%sindex');
    /**
     * The printf pattern that should be used for building the projects' to 
     * values.
     * @var string
     * @access private
     */
    define('PROJECT_TO', '%sabout');
    /**
     * The printf pattern that should be used for building the news id from 
     * value.
     * @var string
     * @access private
     */
    define('NEWS_ID_PATTERN_FROM', 'news/entry%s');
    /**
     * The printf pattern that should be used for building the news id to 
     * value.
     * @var string
     * @access private
     */
    define('NEWS_ID_PATTERN_TO', 'news/%s_%s');
    
    global $db;    
    $redirects = array();
 
    //Source 1: Custom redirects.
    $fields = array(
        'from',
        'to'
    );
    $rows = $db->querySelect(TABLE_CUSTOM_REDIRECTS, $fields);
    foreach($rows as $row) {
        $redirects[] = $row;
    }
    
    //Source 2: Projects
    $rows = $db->querySelect(TABLE_PROJECTS, array('relative_path'));
    foreach($rows as $row) {
        $path = $row['relative_path'];
        $redirects[] = array(
            'from'    => sprintf(PROJECT_FROM, $path),
            'to'    => sprintf(PROJECT_TO, $path)
        );
    }
    
    //Source 3: News
    doInclude('lib_util');
    $fields = array(
        'id',
        'caption',
        'timestamp'
    );
    $rows = $db->querySelect(TABLE_NEWS, $fields);
    foreach($rows as $row) {
        //The id redirects.
        $redirects[] = array(
            'from'    => sprintf(NEWS_ID_PATTERN_FROM, $row['id']),
            'to'    => sprintf(NEWS_ID_PATTERN_TO, 
                    urlEncodeReadable($row['caption']), $row['id'])
        );
    }
    
    //Reset the master table.
    $db->query("TRUNCATE TABLE ".TABLE_REDIRECTS);
    foreach($redirects as $redirection) {
        $db->queryInsert(TABLE_REDIRECTS, $redirection);    
    }
}
 
/**
 * Gets all urls that are similar to a specified url. I.e. all urls that exist
 * and are subsets of the specified url.
 * @param string $url The url, relative to the page root, for which all similar
 *          urls should be found. No query string is allowed.
 * @return array An array of string with each string representing a similar url
 *          relative to the page root.
 * @access public
 */
function getSimilarUrls($url) {
    $result = array();
    $parts = array_reverse(explode('/', $url));
    foreach($parts as $key => $part) {
        $baseUrl = getRealUrl(implode('/', array_reverse($parts)), false);
        $filePath = DOC_ROOT.$baseUrl;
    
        if(file_exists($filePath)) {
            if(is_dir($filePath)) {
                if(getUrlPath($baseUrl.'/', false) != '') {
                    $result[] = $baseUrl.'/';
                }
            } else {
                //A match has been found.
                $result[] = $baseUrl;
            }
        }
        unset($parts[$key]);
    }
    
    $result[] = '';
    return $result;
}
 
/**
 * Performs a delayed redirection to the specified url with the speicified
 * delay. The page will be redirected after the specified number of seconds
 * have elapsed.
 * @param string $url The url to the site that the user should be taken to.
 * @param integer $delay The number of seconds that the redirection should be
 *          delayed.
 * @access public
 */
function doDelayedRedirect($url, $delay = 2) {
    Page::getInstance()->addToHead(new HeadData(
        '<meta http-equiv="refresh" content="'.$delay.';url='.$url.'" />'));
}
 
/**
 * Redirects the request to a specified page with a permanent redirect, i.e.
 * with a status code 301. The redirects is performed immedientally without
 * delay and is done via the header sent in response to the request.
 * @param string $destinationUrl The url to which the user should be
 *          redirected. The url should be relative to the page root, relative to
 *          the web root or be absolute, starting with http://.
 */
function doPermanentRedirect($destinationUrl) {
    header("HTTP/1.1 301 Moved Permanently");
    doRedirect($destinationUrl);
}
 
/**
 * Redirects the url to the specified page with a temporary redirect, i.e.
 * a redirect that should not be considered to be permanent by the client.
 * @param string $destinationUrl The url to which the user should be
 *          redirected. The url should be relative to the page root, relative to
 *          the web root or be absolute, starting with http://.
 */
function doRedirect($destinationUrl) {
    if(strpos($destinationUrl, 'http://') !== 0) {
        //Local redirect.
        header("Location: ".ROOT_PATH.stripRootPath($destinationUrl));
    } else {
        //Absolute redirect.
        header("Location: ".$destinationUrl);
    }
}
 
/**
 * Strips the root path from a specified url.
 * @param string $url The url from which the root path should be stripped.
 * @return string The url but without the first occurance of the root path.
 */
function stripRootPath($url) {
    $strpos = strpos($url, ROOT_PATH);
    if($strpos === false || $strpos != 0) {
        //The url does not begin with the root path.
        return $url;
    } else {
        return substr($url, 0, $strpos).substr($url, $strpos.strlen(ROOT_PATH));
    }
}
?>