/*
    [Discuz!] (C)2001-2007 Comsenz Inc.
    This is NOT a freeware, use is subject to license terms
    $Id: index.php 13764 2008-05-19 03:14:01Z heyond $
*/
define('CURSCRIPT', 'index');//定义当前运行脚本名  
require_once './include/common.inc.php';//引入common文件  
require_once DISCUZ_ROOT.'./include/forum.func.php';//引入版块处理函数forum.func.php  
$discuz_action = 1;//?  
if($cacheindexlife && !$discuz_uid && $showoldetails != 'yes' && (!$_DCACHE['settings']['frameon'] || $_DCACHE['settings']['frameon'] && $_GET['frameon'] != 'yes') && emptyempty($gid)) {  
    //分析：$cacheindexlife-首页缓存有效期，$discuz_uid存在，$showoldetails-显示在线详 情，$_DCACHE['settings']['frameon']-左右分栏模式开关，$gid-版块组id，自己看看吧，大概就是判断是否使用一个 静态htm页面的条件，这个由后台是否开启首页缓存时间来决定的  
    $indexcache = getcacheinfo(0);//得到首页缓存，此函数见include/forum.func.php 157行，主要是处理index.htm  
    //下面一段就是判断是否过期咯，如果过期，就删除index.htm，否则读取文件，并根据系统配置决定是否显示debug信息  
    if($timestamp - $indexcache['filemtime'] > $cacheindexlife) {  
        @unlink($indexcache['filename']);  
        define('CACHE_FILE', $indexcache['filename']);  
        $styleid = $_DCACHE['settings']['styleid'];  
    } elseif($indexcache['filename']) {  
        @readfile($indexcache['filename']);  
        $debug && debuginfo();  
        $debug ? die('<mce:script type="text/javascript"><!--  
document.getElementById("debuginfo").innerHTML = " '.($debug ? 'Updated at '.gmdate("H:i:s", $indexcache['filemtime'] + 3600 * 8).', Processed in '.$debuginfo['time'].' second(s), '.$debuginfo['queries'].' Queries'.($gzipcompress ? ', Gzip enabled' : '') : '').'";  
// --></mce:script>') : die();  
    }  
}  
//$validdays?用户组有效时间？  
$validdays = $discuz_uid && !emptyempty($groupexpiry) && $groupexpiry >= $timestamp ? ceil(($groupexpiry - $timestamp) / 86400) : 0;  
//是否显示在线情况  
if(isset($showoldetails)) {  
    switch($showoldetails) {  
        case 'no': dsetcookie('onlineindex', 0, 86400 * 365); break;  
        case 'yes': dsetcookie('onlineindex', 1, 86400 * 365); break;  
    }  
} else {  
    $showoldetails = false;  
}  
$currenttime = gmdate($timeformat, $timestamp + $timeoffset * 3600);//当前时间  
$lastvisittime = gmdate("$dateformat $timeformat", $lastvisit + $timeoffset * 3600);//上次访问时间  
$memberenc = rawurlencode($lastmember);//最后注册用户-对URL进行了编码  
$newthreads = round(($timestamp - $lastvisit + 600) / 1000) * 1000;//这个变量不知道干啥的？  
$rsshead = $rssstatus ? ('<link rel="alternate" type="application/rss+xml" title="'.$bbname.'" href="'.$boardurl.'rss.php?auth='.$rssauth." mce_href="'.$boardurl.'rss.php?auth='.$rssauth."\" />\n") : '';//rss的链接  
$customtopics = '';  
if($qihoo['maxtopics']) {  
    foreach(explode("\t", isset($_DCOOKIE['customkw']) ? $_DCOOKIE['customkw'] : '') as $topic) {  
        $topic = dhtmlspecialchars(trim(stripslashes($topic)));  
        $customtopics .= '<a href="topic.php?keyword='.rawurlencode($topic).'" mce_href="topic.php?keyword='.rawurlencode($topic).'" target="_blank">'.$topic.'</a> ';  
    }  
}//以上两段，qihoo专题？-后台的扩展-qihoo搜索那里可以设置  
$hottagstatus = $tagstatus && $hottags && $_DCACHE['tags'];//显示热门标签  
$catlist = $forumlist = $sublist = $forumname = $collapseimg = $collapse = array();//初始化区、版块、子版等数组  
$threads = $posts = $todayposts = $fids = $announcepm = 0;//初始化帖子、回复、今日回复、版块id等数组  
$postdata = $historyposts ? explode("\t", $historyposts) : array();//历史发帖？  
foreach(array('forumlinks', 'birthdays') as $key) {//处理友情链接与生日用户的显示  
    if(!isset($_COOKIE['discuz_collapse']) || strpos($_COOKIE['discuz_collapse'], $key) === FALSE) {  
        $collapseimg[$key] = 'collapsed_no.gif';  
        $collapse[$key] = '';  
    } else {  
        $collapseimg[$key] = 'collapsed_yes.gif';  
        $collapse[$key] = 'display: none';  
    }  
}  
$gid = !emptyempty($gid) ? intval($gid) : 0;//区显示方式  
if(!$gid) {//如果不是区显示方式，即默认的显示所有版块的首页  
    $announcements = '';//此句与下面一段是处理论坛公告  
    if($_DCACHE['announcements']) {  
        $readapmids = !emptyempty($_DCOOKIE['readapmid']) ? explode('D', $_DCOOKIE['readapmid']) : array();  
        foreach($_DCACHE['announcements'] as $announcement) {  
            if(emptyempty($announcement['groups']) || in_array($groupid, $announcement['groups'])) {  
                if(emptyempty($announcement['type'])) {  
                    $announcements .= '<li><a href="announcement.php?id='.$announcement['id'].'" mce_href="announcement.php?id='.$announcement['id'].'">'.$announcement['subject'].  
                        '<i>('.gmdate($dateformat, $announcement['starttime'] + $timeoffset * 3600).')</i></a></li>';  
                } elseif($announcement['type'] == 1) {  
                    $announcements .= '<li><a href="'.$announcement['message'].'" mce_href="'.$announcement['message'].'" target="_blank">'.$announcement['subject'].  
                        '<i>('.gmdate($dateformat, $announcement['starttime'] + $timeoffset * 3600).')</i></a></li>';  
                }  
            }  
        }  
    }  
    unset($_DCACHE['announcements']);//得到公告的字符串后，及时清空这个公告数组  
    //选出论坛列表的sql，注意这里判断了是否有访问限制，如果$accessmasks不为空，则根据某用户的特殊访问规则选出了 a.allowview这个字段等  
    $sql = !emptyempty($accessmasks) ?  
                "SELECT f.fid, f.fup, f.type, f.name, f.threads, f.posts, f.todayposts, f.lastpost, f.inheritedmod, f.forumcolumns, f.simple, ff.description, ff.moderators, ff.icon, ff.viewperm, ff.redirect, a.allowview FROM {$tablepre}forums f  
                    LEFT JOIN {$tablepre}forumfields ff ON ff.fid=f.fid  
                    LEFT JOIN {$tablepre}access a ON a.uid='$discuz_uid' AND a.fid=f.fid  
                    WHERE f.status>0 ORDER BY f.type, f.displayorder"  
                : "SELECT f.fid, f.fup, f.type, f.name, f.threads, f.posts, f.todayposts, f.lastpost, f.inheritedmod, f.forumcolumns, f.simple, ff.description, ff.moderators, ff.icon, ff.viewperm, ff.redirect FROM {$tablepre}forums f  
                    LEFT JOIN {$tablepre}forumfields ff USING(fid)  
                    WHERE f.status>0 ORDER BY f.type, f.displayorder";  
    $query = $db->query($sql);  
    while($forum = $db->fetch_array($query)) {//从这里开始得到两个重要数组$catlist $forumlist，保存区信息与版块列表信息  
        $forumname[$forum['fid']] = strip_tags($forum['name']);//去掉html与php标记，并存入$forumname数组，以fid为键  
        if($forum['type'] != 'group') {//如果是普通版块(如type=forum或forum=sub)而不是分区  
            $threads += $forum['threads'];//主题总数  
            $posts += $forum['posts'];//帖子总数(主题与回复)  
            $todayposts += $forum['todayposts'];//今日帖子  
            if($forum['type'] == 'forum') {//非最终子版(即type不等于sub和group)的版块  
                if(forum($forum)) {//forum函数来自include/forum.func.php，处理版块，得到比如版主啊图标啊什么的  
                    $catlist[$forum['fup']]['forums'][] = $forum['fid'];//分区数组$catlist更新  
                    $forum['orderid'] = $catlist[$forum['fup']]['forumscount']++;//得到版块的排序，所在分区的版块总数加1，每得到一个子版，就自增1  
                    $forum['subforums'] = '';//将子版字符串设置为空的，这里不是很明白，forum函数里得到了一个相同名的字符串，这里为何要清空？  
                    $forumlist[$forum['fid']] = $forum;//将$forum数组赋值给$forumlist的一个元素  
                }  
            } elseif(isset($forumlist[$forum['fup']])) {//如果此版块的父版块id在$forumlist中存在(由上面的if中得到)，则  
                $forumlist[$forum['fup']]['threads'] += $forum['threads'];  
                $forumlist[$forum['fup']]['posts'] += $forum['posts'];  
                $forumlist[$forum['fup']]['todayposts'] += $forum['todayposts'];//累加三个值  
                if($subforumsindex && $forumlist[$forum['fup']]['permission'] == 2 && !($forumlist[$forum['fup']]['simple'] & 16) || ($forumlist[$forum['fup']]['simple'] & 8)) {  
                    $forumlist[$forum['fup']]['subforums'] .= '<a href="forumdisplay.php?fid='.$forum['fid'].'" mce_href="forumdisplay.php?fid='.$forum['fid'].'">'.$forum['name'].'</a> ';  
                }//对版块的子版字符串进行处理  
            }  
        } else {//否则，如果是分区  
            if(!isset($_COOKIE['discuz_collapse']) || strpos($_COOKIE['discuz_collapse'], 'category_'.$forum['fid']) === FALSE) {  
                $forum['collapseimg'] = 'collapsed_no.gif';  
                $collapse['category_'.$forum['fid']] = '';  
            } else {  
                $forum['collapseimg'] = 'collapsed_yes.gif';  
                $collapse['category_'.$forum['fid']] = 'display: none';  
            }//上面是对分区开启关闭按钮的处理？  
            if($forum['moderators']) {  
                $forum['moderators'] = moddisplay($forum['moderators'], 'flat');  
            }//区版主  
            $forum['forumscount']   = 0;  
            $catlist[$forum['fid']] = $forum;//更新区版块数组  
        }  
    }  
    foreach($catlist as $catid => $category) {//对分区的显示进行处理，如表格宽度，是否横排版块等等  
        if($catlist[$catid]['forumscount'] && $category['forumcolumns']) {  
            $catlist[$catid]['forumcolwidth'] = floor(100 / $category['forumcolumns']).'%';  
            $catlist[$catid]['endrows'] = '';  
            if($colspan = $category['forumscount'] % $category['forumcolumns']) {  
                while(($category['forumcolumns'] - $colspan) > 0) {  
                    $catlist[$catid]['endrows'] .= '<td> </td>';  
                    $colspan ++;  
                }  
                $catlist[$catid]['endrows'] .= '</tr>';  
            }  
        } elseif(emptyempty($category['forumscount'])) {  
            unset($catlist[$catid]);  
        }  
    }  
    unset($catid, $category);  
    if(isset($catlist[0]) && $catlist[0]['forumscount']) {//0表示比分区更大一级的一个“虚拟分区”(暂时这么理解，因为有时候url中有fid=0这样的出现)  
        $catlist[0]['fid'] = 0;  
        $catlist[0]['type'] = 'group';  
        $catlist[0]['name'] = $bbname;  
        $catlist[0]['collapseimg'] = 'collapsed_no.gif';  
    } else {  
        unset($catlist[0]);  
    }  
    if($whosonlinestatus == 1 || $whosonlinestatus == 3) {//显示在线情况  
        $whosonlinestatus = 1;  
        $onlineinfo = explode("\t", $onlinerecord);//$onlineinfo变量,$onlinerecord来自index.php的extract($_DCACHE)处理  
        if(emptyempty($_DCOOKIE['onlineusernum'])) {  
            $onlinenum = $db->result_first("SELECT COUNT(*) FROM {$tablepre}sessions");//在线人数  
            if($onlinenum > $onlineinfo[0]) {//如果当前数据库中取得的在线人数大于原来在线人数，则更新$onlinerecord  
                $_DCACHE['settings']['onlinerecord'] = $onlinerecord = "$onlinenum\t$timestamp";  
                $db->query("UPDATE {$tablepre}settings SET value='$onlinerecord' WHERE variable='onlinerecord'");//同时更新settings表  
                require_once DISCUZ_ROOT.'./include/cache.func.php';  
                updatesettings();//更新settings缓存  
                $onlineinfo = array($onlinenum, $timestamp);//更新$onlineinfo数组  
            }  
            dsetcookie('onlineusernum', intval($onlinenum), 300);//将在线人数写入cookie  
        } else {  
            $onlinenum = intval($_DCOOKIE['onlineusernum']);//如果cookie中在线人数不为空，直接读出  
        }  
        $onlineinfo[1] = gmdate($dateformat, $onlineinfo[1] + ($timeoffset * 3600));//更新在线情况的时间戳  
        $detailstatus = $showoldetails == 'yes' || (((!isset($_DCOOKIE['onlineindex']) && !$whosonline_contract) || $_DCOOKIE['onlineindex']) && $onlinenum < 500 && !$showoldetails);//判断在线详情变量，这里比较复杂，仔细看一下，主要是$showoldetails == 'yes'与cookie中的首页显示啊 一些条件  
        if($detailstatus) {//以下是处理在线人数列表的  
            @include language('actions');//引用语言文件 /templates/default/actions.lang.php  
            $discuz_uid && updatesession();//更新session  
            $membercount = $invisiblecount = 0;//初始化会员数量及隐身的数量  
            $whosonline = array();//初始化数组  
            $maxonlinelist = $maxonlinelist ? $maxonlinelist : 500;//最大在线人数，如果未设置，初始化为500  
            $query = $db->query("SELECT uid, username, groupid, invisible, action, lastactivity, fid FROM {$tablepre}sessions ".(isset($_DCACHE['onlinelist'][7]) ? '' : 'WHERE uid <> 0')." ORDER BY uid DESC LIMIT ".$maxonlinelist);  
            while($online = $db->fetch_array($query)) {  
                if($online['uid']) {//会员  
                    $membercount ++;//会员总数  
                    if($online['invisible']) {//隐身用户  
                        $invisiblecount++;  
                        continue;  
                    } else {  
                        $online['icon'] = isset($_DCACHE['onlinelist'][$online['groupid']]) ? $_DCACHE['onlinelist'][$online['groupid']] : $_DCACHE['onlinelist'][0];//用户组的图标  
                    }  
                } else {//游客，区别是数据表session里，其uid为0  
                    $online['icon'] = $_DCACHE['onlinelist'][7];  
                    $online['username'] = $_DCACHE['onlinelist']['guest'];  
                }  
                $online['fid'] = $online['fid'] ? $forumname[$online['fid']] : 0;//用户正浏览版块？  
                $online['action'] = $actioncode[$online['action']];//用户正进行的动作  
                $online['lastactivity'] = gmdate($timeformat, $online['lastactivity'] + ($timeoffset * 3600));//用户上次访问？  
                $whosonline[] = $online;//赋值给$whosonline数组  
            }  
            unset($actioncode, $online);//清空两个变量  
            if($onlinenum > $maxonlinelist) {//如果总在线人数大于最大在线人数(系统默认为500)，分别取出已登录用户和隐身用户  
                $membercount = $db->result_first("SELECT COUNT(*) FROM {$tablepre}sessions WHERE uid <> '0'");  
                $invisiblecount = $db->result_first("SELECT COUNT(*) FROM {$tablepre}sessions WHERE invisible = '1'");  
            }  
            if($onlinenum < $membercount) {//如果总在线人数小于在线会员数，则更新cookie中的在线用户人数，注意是onlineusernum而不是onlinenum  
                $onlinenum = $db->result_first("SELECT COUNT(*) FROM {$tablepre}sessions");  
                dsetcookie('onlineusernum', intval($onlinenum), 300);  
            }  
            //总结：这里有些混乱，比如总在线人数，在线会员等等，因为变量类似，很容易看错理解错误，多看几遍吧。。。  
            $guestcount = $onlinenum - $membercount;  
            $db->free_result($query);//释放数据库连接  
            unset($online);//清空，230行不是有么？又清空一次？  
        }  
    } else {  
        $whosonlinestatus = 0;//如果后台设置不显示在线人数，则不显示在线列表  
    }  
} else {//对应第77行，如果是分区显示，如url为：index.php?gid=2，则调用下面这个文件，  
    require_once DISCUZ_ROOT.'./include/category.inc.php';  
}  
include template('discuz');//解析首页的模板文件