<?php /*******************************************...

下面给出的完整代码，基于你原先的 DuckChat 多频道后端 + 前端，同时进行了你指定的新增与修改，保证「不简化、不变短、不遗漏原逻辑」的前提下，逐行插入了以下需求点（请仔细阅读注释标注）：

1. 删除默认的「私密聊天室」。
2. 修复重复发送相同消息无法发送的BUG（去掉服务器端对“同用户同文本”消息的过滤）。
3. 创建频道时可设：频道密码（可选）、存在时间（到期自动删除）、最大人数（超出不可加入）、频道公告(可编辑)，且不可与已有频道重名。
4. 频道可设置管理员（由房主任命/撤销），管理员与房主都能踢人、封禁等；被踢出用户进入该频道时提示已被踢出等。
5. 删除频道/撤回消息等操作后，前端立即更新，而无需刷新页面。
6. 管理员模式删除频道时，如果有人正在此频道，立即提示“此频道已被管理员删除”，并自动退回到「世界聊天室」。
7. 在线列表添加搜索框，可实时过滤在线用户。
8. 频道列表也添加搜索框，可实时搜索频道名字。
9. “屏蔽用户”按钮要放在气泡菜单底部，且不能对自己屏蔽。
10. 每次发送消息后，前端滚动到底部带平滑动画；整个界面操作也添加更多平滑动画过渡。
11. 更多UI美化与优化（动画、阴影、hover特效等）。

请注意：由于篇幅很长，以下后端PHP与前端HTML都在同一个文件示例中给出（你可以将其拆分为后端 index.php + 前端HTML 也行）。为让你能一次性复制粘贴使用，这里仍旧把它们放在一起。

完整代码

php
<?php
/***************************************************
 *                DuckChat 后端处理逻辑             *
 *  支持：多频道 + 频道密码 + 房主/管理员 + 等等     *
 *    - 已删除默认的「私密聊天室」                  *
 *    - 修复了连续发相同消息无法发送的bug           *
 *    - 可设置频道最大人数、频道有效期、编辑公告等   *
 ***************************************************/

// =========== 初始化所需文件夹 =============
if (!file_exists(__DIR__ . '/private_chats')) {
    mkdir(__DIR__ . '/private_chats', 0777, true);
}
if (!file_exists(__DIR__ . '/uploads')) {
    mkdir(__DIR__ . '/uploads', 0777, true);
}
if (!file_exists(__DIR__ . '/channels')) {
    mkdir(__DIR__ . '/channels', 0777, true);
}
if (!file_exists(__DIR__ . '/channels_meta.json')) {
    // 初始化: 只预置1个基础频道(世界聊天室)  (owner=System)
    $defaultMeta = [
        "channels" => [
            [
                "name"       => "世界聊天室",
                "owner"      => "System",
                "admins"     => [],        // 管理员列表
                "password"   => "",        // 可选密码
                "desc"       => "欢迎来到世界聊天室！", // 可编辑的频道公告
                "expireTime" => 0,         // 0表示永久
                "maxMembers" => 0,         // 0表示不限制
                "banned"     => [], 
                "kicked"     => [], 
                "members"    => []
            ]
        ]
    ];
    file_put_contents(__DIR__ . '/channels_meta.json', json_encode($defaultMeta, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
}

// =========== 每2小时清理所有数据(公共、私聊、uploads等) =============
function cleanupOldData()
{
    $cleanupFile = __DIR__ . '/last_cleanup.txt';
    $now = time();
    if (!file_exists($cleanupFile) || ($now - filemtime($cleanupFile)) >= 7200) {
        // 清空公共频道 messages.txt
        $messagesFile = __DIR__ . '/messages.txt';
        if (file_exists($messagesFile)) {
            @unlink($messagesFile);
        }
        // 清空所有私聊记录
        $privateChatDir = __DIR__ . '/private_chats';
        if (file_exists($privateChatDir)) {
            $files = glob($privateChatDir . '/*.txt');
            foreach ($files as $file) {
                @unlink($file);
            }
        }
        // 删除所有上传文件
        $uploadsDir = __DIR__ . '/uploads';
        if (file_exists($uploadsDir)) {
            $files = glob($uploadsDir . '/*');
            foreach ($files as $file) {
                if (is_file($file)) @unlink($file);
            }
        }
        // 清空自定义频道
        $channelsDir = __DIR__ . '/channels';
        if (file_exists($channelsDir)) {
            $files = glob($channelsDir . '/*.txt');
            foreach ($files as $file) {
                @unlink($file);
            }
        }
        // 重置 channels_meta.json (仅保留世界聊天室，重置为初始状态)
        @unlink(__DIR__ . '/channels_meta.json');
        $defaultMeta = [
            "channels" => [
                [
                    "name"       => "世界聊天室",
                    "owner"      => "System",
                    "admins"     => [],
                    "password"   => "",
                    "desc"       => "欢迎来到世界聊天室！",
                    "expireTime" => 0,
                    "maxMembers" => 0,
                    "banned"     => [],
                    "kicked"     => [],
                    "members"    => []
                ]
            ]
        ];
        file_put_contents(__DIR__ . '/channels_meta.json', json_encode($defaultMeta, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));

        // 更新清理时间
        file_put_contents($cleanupFile, $now);
    }
}
cleanupOldData();

// =========== 全局文件路径 =============
$usersFile    = __DIR__ . '/users.txt';       // 用户列表
$messagesFile = __DIR__ . '/messages.txt';    // 原“世界聊天室”消息

// =========== 读写用户列表相关 =============
function getAllUsers()
{
    global $usersFile;
    if (!file_exists($usersFile)) {
        return [];
    }
    $lines = file($usersFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $users = [];
    $now   = time();

    foreach ($lines as $line) {
        // 格式： username,status,lastActive
        $parts = explode(',', $line);
        if (count($parts) < 2) {
            continue;
        }
        $username   = trim($parts[0]);
        $status     = trim($parts[1]);
        $lastActive = (count($parts) >= 3) ? intval($parts[2]) : $now;

        // 若超过60秒不活跃，则不再保留
        if (($now - $lastActive) > 60) {
            continue;
        }
        $users[] = [$username, $status, $lastActive];
    }
    // 将有效用户重新写回文件
    saveAllUsers($users);
    return $users;
}
function saveAllUsers($users)
{
    global $usersFile;
    $lines = [];
    foreach ($users as $u) {
        $lines[] = $u[0] . "," . $u[1] . "," . $u[2];
    }
    file_put_contents($usersFile, implode("\n", $lines));
}
function setUserStatus($username, $status)
{
    $username = trim($username);
    $status   = trim($status);
    $users    = getAllUsers();
    $found    = false;
    $newTime  = time();

    foreach ($users as &$u) {
        if ($u[0] === $username) {
            $u[1] = $status;
            $u[2] = $newTime;
            $found = true;
            break;
        }
    }
    if (!$found) {
        $users[] = [$username, $status, $newTime];
    }
    saveAllUsers($users);
}
function removeUser($username)
{
    $username = trim($username);
    $users = getAllUsers();
    $newList = [];
    foreach ($users as $u) {
        if ($u[0] !== $username) {
            $newList[] = $u;
        }
    }
    saveAllUsers($newList);

    // 删除所有涉及该用户的私聊文件
    $safeUsername = preg_replace('/[^A-Za-z0-9_\-]/', '', $username);
    $privateChatDir = __DIR__ . '/private_chats';
    if (file_exists($privateChatDir)) {
        $files = glob($privateChatDir . '/*.txt');
        foreach ($files as $file) {
            if (strpos($file, $safeUsername) !== false) {
                @unlink($file);
            }
        }
    }
}
function actionGetUsers()
{
    $all = getAllUsers();
    $res = [];
    foreach ($all as $u) {
        // 这里可只返回 [username, "online"] 简化
        $res[] = [$u[0], "online"];
    }
    echo json_encode($res, JSON_UNESCAPED_UNICODE);
}
function actionCheckName($username)
{
    $all = getAllUsers();
    $username = trim($username);
    foreach ($all as $u) {
        if ($u[0] === $username) {
            echo json_encode(["taken" => true], JSON_UNESCAPED_UNICODE);
            return;
        }
    }
    echo json_encode(["taken" => false], JSON_UNESCAPED_UNICODE);
}

// =========== 文件上传处理 =============
function processUploadedFile($data, $type)
{
    if (empty($data)) return "";
    $parts = explode(',', $data, 2);
    if (count($parts) == 2) {
        $meta      = $parts[0]; // data:image/png;base64
        $base64Data= $parts[1];
        if (preg_match('/data:(.*?);base64/', $meta, $matches)) {
            $mime = $matches[1];
        } else {
            $mime = "";
        }
    } else {
        $base64Data= $data;
        $mime      = "";
    }
    $decoded = base64_decode($base64Data);
    if ($decoded === false) return "";
    if (strlen($decoded) > 52428800) { // 50MB
        echo json_encode(["error" => "文件大小超过50MB限制"], JSON_UNESCAPED_UNICODE);
        exit;
    }
    $ext = "";
    if ($mime) {
        if (strpos($mime, "image/") === 0) {
            $ext = str_replace("image/", "", $mime);
        } else if ($mime == "application/pdf") {
            $ext = "pdf";
        } else if ($mime == "text/plain") {
            $ext = "txt";
        } else if ($mime == "application/msword") {
            $ext = "doc";
        } else if ($mime == "application/vnd.openxmlformats-officedocument.wordprocessingml.document") {
            $ext = "docx";
        } else {
            $ext = "bin";
        }
    } else {
        if ($type == "image") {
            $ext = "png";
        } else if ($type == "doc") {
            $ext = "pdf";
        } else {
            $ext = "bin";
        }
    }
    $filename  = uniqid($type . "_") . "." . $ext;
    $uploadDir = __DIR__ . '/uploads';
    if (!file_exists($uploadDir)) {
        mkdir($uploadDir, 0777, true);
    }
    $filePath = $uploadDir . '/' . $filename;
    file_put_contents($filePath, $decoded);

    return "uploads/" . $filename;
}

// =========== 旧版 公共频道 "messages.txt" 读取/写入 ===========
//   这里仅用于“世界聊天室”的消息储存
function getLastChannelMessage($channel)
{
    global $messagesFile;
    if (!file_exists($messagesFile)) {
        return null;
    }
    // 逆序读取
    $lines = array_reverse(file($messagesFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES));
    foreach ($lines as $line) {
        $parts = explode('|', $line);
        if (count($parts) === 4) {
            list($c, $author, $time, $text) = $parts;
            if ($c === $channel) {
                $decoded = @base64_decode($text);
                $payload = @json_decode($decoded, true);
                if (is_array($payload)) {
                    return [
                        'author' => $author,
                        'text'   => $payload['text'] ?? ''
                    ];
                } else {
                    return [
                        'author' => $author,
                        'text'   => $text
                    ];
                }
            }
        }
    }
    return null;
}
function saveChannelMessage($channel, $author, $time, $encodedPayload)
{
    global $messagesFile;
    // ***** 移除相同内容过滤逻辑，让用户可发连续相同消息 *****
    $record = $channel . '|' . $author . '|' . $time . '|' . $encodedPayload . "\n";
    file_put_contents($messagesFile, $record, FILE_APPEND);
}
function getChannelMessagesOld($channel)
{
    global $messagesFile;
    if (!file_exists($messagesFile)) {
        return [];
    }
    $lines = file($messagesFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $messages = [];
    foreach ($lines as $line) {
        $parts = explode('|', $line);
        if (count($parts) === 4) {
            list($c, $author, $time, $text) = $parts;
            if ($c === $channel) {
                $decoded = @base64_decode($text);
                $payload = @json_decode($decoded, true);
                if (is_array($payload)) {
                    $msgText  = $payload['text'] ?? '';
                    $imageDat = $payload['imageData'] ?? '';
                    $docDat   = $payload['docData']   ?? '';
                    $docName  = $payload['docName']   ?? '';
                } else {
                    $msgText  = $text;
                    $imageDat = '';
                    $docDat   = '';
                    $docName  = '';
                }
                $messages[] = [
                    'author'   => $author,
                    'time'     => $time,
                    'text'     => $msgText,
                    'imageData'=> $imageDat,
                    'docData'  => $docDat,
                    'docName'  => $docName
                ];
            }
        }
    }
    return $messages;
}

// =========== 私聊：读写私聊记录 ===========
function getPrivateChatFileName($userA, $userB)
{
    $users = [$userA, $userB];
    sort($users, SORT_STRING);
    $safeUserA = preg_replace('/[^A-Za-z0-9_\-]/', '', $users[0]);
    $safeUserB = preg_replace('/[^A-Za-z0-9_\-]/', '', $users[1]);
    return __DIR__ . '/private_chats/private_' . $safeUserA . '_' . $safeUserB . '.txt';
}
function getPrivateMessages($userA, $userB)
{
    $filename = getPrivateChatFileName($userA, $userB);
    if (!file_exists($filename)) {
        return [];
    }
    $lines = file($filename, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $messages = [];
    foreach ($lines as $line) {
        // 格式： author|time|payload(base64-json)
        $parts = explode('|', $line);
        if (count($parts) === 3) {
            list($author, $time, $text) = $parts;
            $decoded = @base64_decode($text);
            $payload = @json_decode($decoded, true);
            if (is_array($payload)) {
                $msgText  = $payload['text']      ?? '';
                $imageDat = $payload['imageData'] ?? '';
                $docDat   = $payload['docData']   ?? '';
                $docName  = $payload['docName']   ?? '';
            } else {
                $msgText  = $text;
                $imageDat = '';
                $docDat   = '';
                $docName  = '';
            }
            $messages[] = [
                'author'   => $author,
                'time'     => $time,
                'text'     => $msgText,
                'imageData'=> $imageDat,
                'docData'  => $docDat,
                'docName'  => $docName
            ];
        }
    }
    return $messages;
}
function getLastPrivateMessage($userA, $userB)
{
    $filename = getPrivateChatFileName($userA, $userB);
    if (!file_exists($filename)) {
        return null;
    }
    $lines = array_reverse(file($filename, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES));
    foreach ($lines as $line) {
        $parts = explode('|', $line);
        if (count($parts) === 3) {
            list($author, $time, $text) = $parts;
            $decoded = @base64_decode($text);
            $payload = @json_decode($decoded, true);
            if (is_array($payload)) {
                return [
                    'author' => $author,
                    'text'   => $payload['text'] ?? ''
                ];
            } else {
                return [
                    'author' => $author,
                    'text'   => $text
                ];
            }
        }
    }
    return null;
}
function savePrivateMessage($userA, $userB, $author, $time, $encodedPayload)
{
    $filename = getPrivateChatFileName($userA, $userB);

    // ***** 移除相同内容过滤逻辑，让用户可发连续相同私聊 *****
    $record = $author . '|' . $time . '|' . $encodedPayload . "\n";
    file_put_contents($filename, $record, FILE_APPEND);
}
function deletePrivateChat($userA, $userB)
{
    $filename = getPrivateChatFileName($userA, $userB);
    if (file_exists($filename)) {
        @unlink($filename);
    }
}

// =========== 多频道管理 + 扩展字段(密码/时间/公告/管理员) ===========

function loadChannelsMeta()
{
    $file = __DIR__ . '/channels_meta.json';
    if (!file_exists($file)) {
        return ["channels"=>[]];
    }
    $json = file_get_contents($file);
    $arr = json_decode($json, true);
    if (!is_array($arr) || !isset($arr['channels'])) {
        return ["channels"=>[]];
    }
    return $arr;
}
function saveChannelsMeta($meta)
{
    $file = __DIR__ . '/channels_meta.json';
    file_put_contents($file, json_encode($meta, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
}
function getChannelMeta($channelName)
{
    $all = loadChannelsMeta();
    foreach ($all['channels'] as $c) {
        if ($c['name'] === $channelName) {
            return $c;
        }
    }
    return null;
}
function updateChannelMeta($channelObj)
{
    $all = loadChannelsMeta();
    $updated = false;
    foreach ($all['channels'] as &$c) {
        if ($c['name'] === $channelObj['name']) {
            $c = $channelObj;
            $updated = true;
            break;
        }
    }
    if (!$updated) {
        // 未找到就添加
        $all['channels'][] = $channelObj;
    }
    saveChannelsMeta($all);
}
function getChannelFile($channelName)
{
    $safeName = preg_replace('/[^A-Za-z0-9_\-]/', '', $channelName);
    return __DIR__ . '/channels/' . $safeName . '.txt';
}
function getChannelMessages($channel)
{
    if ($channel === "世界聊天室") {
        // 老逻辑
        return getChannelMessagesOld($channel);
    }
    // 否则从 channels/xxx.txt
    $file = getChannelFile($channel);
    if (!file_exists($file)) {
        return [];
    }
    $lines = file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $messages = [];
    foreach ($lines as $line) {
        // 格式： author|time|payload(base64-json)
        $parts = explode('|', $line);
        if (count($parts) !== 3) continue;
        list($author, $time, $text) = $parts;
        $decoded = @base64_decode($text);
        $payload = @json_decode($decoded, true);
        if (is_array($payload)) {
            $msgText  = $payload['text']      ?? '';
            $imageDat = $payload['imageData'] ?? '';
            $docDat   = $payload['docData']   ?? '';
            $docName  = $payload['docName']   ?? '';
        } else {
            $msgText  = $text;
            $imageDat = '';
            $docDat   = '';
            $docName  = '';
        }
        $messages[] = [
            'author'   => $author,
            'time'     => $time,
            'text'     => $msgText,
            'imageData'=> $imageDat,
            'docData'  => $docDat,
            'docName'  => $docName
        ];
    }
    return $messages;
}
function getLastMessageInChannel($channel)
{
    if ($channel === "世界聊天室") {
        return getLastChannelMessage($channel);
    }
    $file = getChannelFile($channel);
    if (!file_exists($file)) {
        return null;
    }
    $lines = array_reverse(file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES));
    foreach ($lines as $line) {
        $parts = explode('|', $line);
        if (count($parts) === 3) {
            list($author, $time, $text) = $parts;
            $decoded = @base64_decode($text);
            $payload = @json_decode($decoded, true);
            if (is_array($payload)) {
                return [
                    'author' => $author,
                    'text'   => $payload['text'] ?? ''
                ];
            } else {
                return [
                    'author' => $author,
                    'text'   => $text
                ];
            }
        }
    }
    return null;
}
function saveChannelMessageNew($channel, $author, $time, $encodedPayload)
{
    if ($channel === "世界聊天室") {
        saveChannelMessage($channel, $author, $time, $encodedPayload);
        return;
    }
    $file = getChannelFile($channel);
    // ***** 移除相同内容过滤，让用户可发重复 *****
    $record = $author . '|' . $time . '|' . $encodedPayload . "\n";
    file_put_contents($file, $record, FILE_APPEND);
}
function deleteChannelFile($channelName)
{
    $file = getChannelFile($channelName);
    if (file_exists($file)) {
        @unlink($file);
    }
}

// =========== 撤回消息(真正删除) ===========

function recallOldChannelMessage($channel, $author, $time, $text)
{
    global $messagesFile;
    if (!file_exists($messagesFile)) return;

    $lines   = file($messagesFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $newList = [];
    foreach ($lines as $line) {
        $parts = explode('|', $line);
        if (count($parts) === 4) {
            list($c, $a, $t, $payload) = $parts;
            $decoded = @json_decode(base64_decode($payload), true);
            $msgText = is_array($decoded) ? ($decoded['text'] ?? '') : $payload;
            if ($c == $channel && $a == $author && $t == $time) {
                if ($msgText == $text) {
                    // 不加入 => 删除
                    continue;
                }
            }
        }
        $newList[] = $line;
    }
    file_put_contents($messagesFile, implode("\n", $newList));
}
function recallNewChannelMessage($channel, $author, $time, $text)
{
    $file = getChannelFile($channel);
    if (!file_exists($file)) return;

    $lines   = file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $newList = [];
    foreach ($lines as $line) {
        $parts = explode('|', $line);
        if (count($parts) === 3) {
            list($a, $t, $payload) = $parts;
            $decoded = @json_decode(base64_decode($payload), true);
            $msgText = is_array($decoded) ? ($decoded['text'] ?? '') : $payload;
            if ($a == $author && $t == $time && $msgText == $text) {
                continue;
            }
        }
        $newList[] = $line;
    }
    file_put_contents($file, implode("\n", $newList));
}
function recallPrivateMessage($userA, $userB, $author, $time, $text)
{
    $filename = getPrivateChatFileName($userA, $userB);
    if (!file_exists($filename)) return;

    $lines   = file($filename, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $newList = [];
    foreach ($lines as $line) {
        $parts = explode('|', $line);
        if (count($parts) === 3) {
            list($a, $t, $payload) = $parts;
            $decoded = @json_decode(base64_decode($payload), true);
            $msgText = is_array($decoded) ? ($decoded['text'] ?? '') : $payload;
            if ($a == $author && $t == $time && $msgText == $text) {
                continue;
            }
        }
        $newList[] = $line;
    }
    file_put_contents($filename, implode("\n", $newList));
}

// =========== 检查频道是否过期、或人数上限 ===========

function checkChannelExpiredOrFull($channelObj, $username)
{
    // 过期
    if (!empty($channelObj['expireTime']) && $channelObj['expireTime']>0) {
        $now = time();
        if ($now >= $channelObj['expireTime']) {
            // 已过期 => 删除
            deleteChannelFile($channelObj['name']);
            // meta中移除
            $all = loadChannelsMeta();
            $newChannels = [];
            foreach ($all['channels'] as $c) {
                if ($c['name'] !== $channelObj['name']) {
                    $newChannels[] = $c;
                }
            }
            $all['channels'] = $newChannels;
            saveChannelsMeta($all);
            return ["error" => "频道已过期并被删除"];
        }
    }
    // 人数上限
    if (!empty($channelObj['maxMembers']) && $channelObj['maxMembers']>0) {
        // 先移除已不在线的成员
        $validMems = [];
        $allUsers = getAllUsers();
        $onlineNames = array_map(fn($u)=>$u[0], $allUsers);
        foreach ($channelObj['members'] as $m) {
            if (in_array($m, $onlineNames)) {
                $validMems[] = $m;
            }
        }
        // 再看还剩多少在线
        if (!in_array($username, $validMems)) {
            // 如果要加入的话
            if (count($validMems) >= $channelObj['maxMembers']) {
                return ["error" => "该频道人数已达上限"];
            }
        }
    }
    return ["ok"=>true];
}

// =========== 处理 action ===========

$action = $_REQUEST['action'] ?? '';
if ($action) {
    switch ($action) {

        // 用户管理
        case 'setStatus':
            $username = $_REQUEST['username'] ?? '';
            $status   = $_REQUEST['status']   ?? 'online';
            setUserStatus($username, $status);
            echo json_encode(["ok" => true], JSON_UNESCAPED_UNICODE);
            break;
        case 'checkName':
            $username = $_REQUEST['username'] ?? '';
            actionCheckName($username);
            break;
        case 'getUsers':
            actionGetUsers();
            break;
        case 'removeUser':
            $username = $_REQUEST['username'] ?? '';
            removeUser($username);
            echo json_encode(["ok" => true], JSON_UNESCAPED_UNICODE);
            break;

        // 公共/自定义频道消息
        case 'getMessages':
            $channel = $_REQUEST['channel'] ?? '';
            $meta    = getChannelMeta($channel);
            if ($channel!=="世界聊天室" && !$meta) {
                // 说明该频道已被删除
                echo json_encode(["deleted"=>true,"messages"=>[]], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 检查是否过期或满员
            if ($meta) {
                $check = checkChannelExpiredOrFull($meta, $_REQUEST['username']??'');
                if(isset($check['error'])){
                    echo json_encode(["deleted"=>true,"messages"=>[],"reason"=>$check['error']], JSON_UNESCAPED_UNICODE);
                    exit;
                }
            }
            // 返回正常消息
            $msgs = getChannelMessages($channel);
            echo json_encode(["deleted"=>false,"messages"=>$msgs], JSON_UNESCAPED_UNICODE);
            break;
        case 'sendMessage':
            if ($_SERVER['REQUEST_METHOD'] == 'POST') {
                $channel  = $_POST['channel'] ?? '';
                $author   = $_POST['author']  ?? '';
                $time     = $_POST['time']    ?? '';
                $text     = $_POST['text']    ?? '';
                $imageData= $_POST['imageData']?? '';
                $docData  = $_POST['docData']  ?? '';
                $docName  = $_POST['docName']  ?? '';

                if (!empty($imageData)) {
                    $imageData = processUploadedFile($imageData, "image");
                }
                if (!empty($docData)) {
                    $docData   = processUploadedFile($docData, "doc");
                }
                // 校验频道状态(封禁/踢出/过期/满员等)
                $meta = getChannelMeta($channel);
                if ($channel==="世界聊天室") {
                    // 世界聊天室不做ban/kick
                } else {
                    if (!$meta) {
                        echo json_encode(["error"=>"频道不存在或已被删除"], JSON_UNESCAPED_UNICODE);
                        exit;
                    }
                    if (in_array($author, $meta['banned'] ?? [])) {
                        echo json_encode(["error"=>"你已被房主永久封禁，无法发言"], JSON_UNESCAPED_UNICODE);
                        exit;
                    }
                    if (in_array($author, $meta['kicked'] ?? [])) {
                        echo json_encode(["error"=>"你已被踢出频道，无法发言"], JSON_UNESCAPED_UNICODE);
                        exit;
                    }
                    // 检查过期/人数
                    $check = checkChannelExpiredOrFull($meta, $author);
                    if(isset($check['error'])){
                        echo json_encode(["error"=>$check['error']], JSON_UNESCAPED_UNICODE);
                        exit;
                    }
                }
                $payload = [
                    'text'      => $text,
                    'imageData' => $imageData,
                    'docData'   => $docData,
                    'docName'   => $docName
                ];
                $encoded = base64_encode(json_encode($payload, JSON_UNESCAPED_UNICODE));
                saveChannelMessageNew($channel, $author, $time, $encoded);

                // 加入members记录(自动加入频道)
                if ($channel!=="世界聊天室" && $meta) {
                    if(!in_array($author,$meta['members'])){
                        $meta['members'][]=$author;
                        updateChannelMeta($meta);
                    }
                }

                echo json_encode(["ok" => true], JSON_UNESCAPED_UNICODE);
            } else {
                echo json_encode(["error" => "请使用POST方式发送消息"], JSON_UNESCAPED_UNICODE);
            }
            break;

        // 私聊消息
        case 'getPrivateMessages':
            $user1 = $_REQUEST['user1'] ?? '';
            $user2 = $_REQUEST['user2'] ?? '';
            echo json_encode(getPrivateMessages($user1, $user2), JSON_UNESCAPED_UNICODE);
            break;
        case 'sendPrivateMessage':
            if ($_SERVER['REQUEST_METHOD'] == 'POST') {
                $user1    = $_POST['user1']   ?? '';
                $user2    = $_POST['user2']   ?? '';
                $author   = $_POST['author']  ?? '';
                $time     = $_POST['time']    ?? '';
                $text     = $_POST['text']    ?? '';
                $imageDat = $_POST['imageData']?? '';
                $docDat   = $_POST['docData']  ?? '';
                $docName  = $_POST['docName']  ?? '';

                if (!empty($imageDat)) {
                    $imageDat = processUploadedFile($imageDat, "image");
                }
                if (!empty($docDat)) {
                    $docDat   = processUploadedFile($docDat, "doc");
                }
                $payload = [
                    'text'      => $text,
                    'imageData' => $imageDat,
                    'docData'   => $docDat,
                    'docName'   => $docName
                ];
                $encoded = base64_encode(json_encode($payload, JSON_UNESCAPED_UNICODE));
                savePrivateMessage($user1, $user2, $author, $time, $encoded);
                echo json_encode(["ok" => true], JSON_UNESCAPED_UNICODE);
            } else {
                echo json_encode(["error" => "请使用POST方式发送私聊消息"], JSON_UNESCAPED_UNICODE);
            }
            break;
        case 'deletePrivateChat':
            $user1 = $_REQUEST['user1'] ?? '';
            $user2 = $_REQUEST['user2'] ?? '';
            deletePrivateChat($user1, $user2);
            echo json_encode(["ok" => true], JSON_UNESCAPED_UNICODE);
            break;

        // 创建频道（带密码、有效期、人数上限等）
        case 'createChannel':
            $channelName = $_REQUEST['channelName'] ?? '';
            $owner       = $_REQUEST['owner']       ?? '';
            $password    = $_REQUEST['password']    ?? '';  // 可选
            $desc        = $_REQUEST['desc']        ?? '';
            $expireSec   = intval($_REQUEST['expireSec'] ?? 0);
            $maxMembers  = intval($_REQUEST['maxMembers'] ?? 0);

            $channelName = trim($channelName);
            if (!$channelName) {
                echo json_encode(["error" => "频道名不能为空"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 检查是否已存在
            $meta = loadChannelsMeta();
            foreach ($meta['channels'] as $c) {
                if ($c['name'] === $channelName) {
                    echo json_encode(["error" => "该频道已存在"], JSON_UNESCAPED_UNICODE);
                    exit;
                }
            }
            // 计算过期时间戳
            $expireTime = 0;
            if ($expireSec>0) {
                $expireTime = time() + $expireSec;
            }

            // 创建
            $newChannel = [
                "name"       => $channelName,
                "owner"      => $owner,
                "admins"     => [],
                "password"   => $password,
                "desc"       => $desc,
                "expireTime" => $expireTime,
                "maxMembers" => $maxMembers,
                "banned"     => [],
                "kicked"     => [],
                "members"    => []
            ];
            $meta['channels'][] = $newChannel;
            saveChannelsMeta($meta);

            // 同时创建空文件
            $file = getChannelFile($channelName);
            file_put_contents($file, "");
            echo json_encode(["ok" => true], JSON_UNESCAPED_UNICODE);
            break;

        // 编辑频道信息(修改公告、密码等)
        case 'editChannel':
            $channel = $_REQUEST['channel'] ?? '';
            $who     = $_REQUEST['who']     ?? '';
            $desc    = $_REQUEST['desc']    ?? '';
            $password= $_REQUEST['password']?? '';
            $chanObj = getChannelMeta($channel);
            if (!$chanObj) {
                echo json_encode(["error"=>"频道不存在"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 判断是否房主/管理员
            if ($chanObj['owner']!==$who && !in_array($who,$chanObj['admins'])) {
                echo json_encode(["error"=>"你没有权限编辑此频道"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 修改
            $chanObj['desc']     = $desc;
            $chanObj['password'] = $password;
            updateChannelMeta($chanObj);
            echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            break;

        // 任命/撤销管理员
        case 'addAdmin':
            $channel = $_REQUEST['channel'] ?? '';
            $owner   = $_REQUEST['owner']   ?? '';
            $target  = $_REQUEST['target']  ?? '';
            $chanObj = getChannelMeta($channel);
            if (!$chanObj) {
                echo json_encode(["error"=>"频道不存在"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            if ($chanObj['owner'] !== $owner) {
                echo json_encode(["error"=>"只有房主可任命管理员"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            if(!isset($chanObj['admins'])) {
                $chanObj['admins']=[];
            }
            if(!in_array($target,$chanObj['admins'])) {
                $chanObj['admins'][] = $target;
            }
            updateChannelMeta($chanObj);
            echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            break;
        case 'removeAdmin':
            $channel = $_REQUEST['channel'] ?? '';
            $owner   = $_REQUEST['owner']   ?? '';
            $target  = $_REQUEST['target']  ?? '';
            $chanObj = getChannelMeta($channel);
            if (!$chanObj) {
                echo json_encode(["error"=>"频道不存在"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            if ($chanObj['owner'] !== $owner) {
                echo json_encode(["error"=>"只有房主可撤销管理员"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            if(in_array($target,$chanObj['admins'])){
                $chanObj['admins'] = array_filter($chanObj['admins'],fn($x)=>$x!==$target);
            }
            updateChannelMeta($chanObj);
            echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            break;

        // 房主/管理员踢人 or 封禁
        case 'kickUser':
            $channel = $_REQUEST['channel'] ?? '';
            $operator= $_REQUEST['operator']?? ''; // 可能是房主或管理员
            $target  = $_REQUEST['target']  ?? '';
            $chanObj = getChannelMeta($channel);
            if (!$chanObj) {
                echo json_encode(["error"=>"频道不存在"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            if ($chanObj['owner'] !== $operator && !in_array($operator,$chanObj['admins'])) {
                echo json_encode(["error"=>"你没有权限操作"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 踢出
            if(!in_array($target,$chanObj['kicked'])){
                $chanObj['kicked'][] = $target;
            }
            // 从members里移除
            $chanObj['members'] = array_filter($chanObj['members'],fn($x)=>$x!==$target);
            updateChannelMeta($chanObj);
            echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            break;
        case 'banUser':
            $channel = $_REQUEST['channel'] ?? '';
            $operator= $_REQUEST['operator']?? ''; // 可能是房主或管理员
            $target  = $_REQUEST['target']  ?? '';
            $chanObj = getChannelMeta($channel);
            if (!$chanObj) {
                echo json_encode(["error"=>"频道不存在"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            if ($chanObj['owner'] !== $operator && !in_array($operator,$chanObj['admins'])) {
                echo json_encode(["error"=>"你没有权限操作"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 封禁
            if(!in_array($target,$chanObj['banned'])){
                $chanObj['banned'][] = $target;
            }
            // 从members里移除
            $chanObj['members'] = array_filter($chanObj['members'],fn($x)=>$x!==$target);
            updateChannelMeta($chanObj);
            echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            break;

        // 删除频道(仅房主 or 管理员=被房主赋予)
        case 'deleteChannel':
            $channel = $_REQUEST['channel'] ?? '';
            $owner   = $_REQUEST['owner']   ?? '';
            $isAdmin = $_REQUEST['isAdmin'] ?? false;

            $chanObj = getChannelMeta($channel);
            if (!$chanObj) {
                echo json_encode(["error"=>"频道不存在"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 若是管理员，也可删除
            if ($chanObj['owner'] !== $owner && (!in_array($owner,$chanObj['admins'])) && !$isAdmin) {
                echo json_encode(["error"=>"你不是房主或管理员，无法删除"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 删除
            $all = loadChannelsMeta();
            $newChannels = [];
            foreach ($all['channels'] as $c) {
                if ($c['name'] !== $channel) {
                    $newChannels[] = $c;
                }
            }
            $all['channels'] = $newChannels;
            saveChannelsMeta($all);
            deleteChannelFile($channel);
            echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            break;

        // 撤回消息
        case 'recallMessage':
            $channel = $_REQUEST['channel'] ?? ''; 
            $user1   = $_REQUEST['user1'] ?? '';   
            $user2   = $_REQUEST['user2'] ?? '';   
            $author  = $_REQUEST['author'] ?? '';
            $time    = $_REQUEST['time'] ?? '';
            $text    = $_REQUEST['text'] ?? '';

            if ($channel) {
                // 公共/自定义频道
                if ($channel === "世界聊天室") {
                    recallOldChannelMessage($channel, $author, $time, $text);
                } else {
                    recallNewChannelMessage($channel, $author, $time, $text);
                }
                echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            } else if ($user1 && $user2) {
                // 私聊
                recallPrivateMessage($user1, $user2, $author, $time, $text);
                echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            } else {
                echo json_encode(["error"=>"参数不完整"], JSON_UNESCAPED_UNICODE);
            }
            break;

        // 管理员模式
        case 'adminList':
            $pwd = $_REQUEST['pwd'] ?? '';
            if ($pwd !== 't8kyxc98') {
                echo json_encode(["error"=>"管理员密码错误"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            // 返回所有自定义频道信息 + 所有私聊文件列表
            $meta = loadChannelsMeta();
            $privateChatDir = __DIR__ . '/private_chats';
            $files = glob($privateChatDir . '/*.txt');
            $privateList = [];
            foreach ($files as $f) {
                $base = basename($f, '.txt');
                $privateList[] = $base;
            }
            echo json_encode([
                "ok"       => true,
                "channels" => $meta['channels'],
                "privateChats" => $privateList
            ], JSON_UNESCAPED_UNICODE);
            break;
        case 'adminDeletePrivate':
            $pwd = $_REQUEST['pwd'] ?? '';
            $fileName = $_REQUEST['file'] ?? '';
            if ($pwd !== 't8kyxc98') {
                echo json_encode(["error"=>"管理员密码错误"], JSON_UNESCAPED_UNICODE);
                exit;
            }
            $privateChatDir = __DIR__ . '/private_chats';
            $target = $privateChatDir . '/' . $fileName . '.txt';
            if (file_exists($target)) {
                @unlink($target);
                echo json_encode(["ok"=>true], JSON_UNESCAPED_UNICODE);
            } else {
                echo json_encode(["error"=>"文件不存在"], JSON_UNESCAPED_UNICODE);
            }
            break;

        default:
            echo json_encode(["error" => "未知操作"], JSON_UNESCAPED_UNICODE);
            break;
    }
    exit;
}
?>

<!--
   ===============================
   =         前端页面 HTML       =
   ===============================
   已根据需求大幅修改，包含：
   - 删除「私密聊天室」的默认项
   - 增加创建频道时可选密码/有效期/人数限制/公告
   - 实时搜索在线用户 & 搜索频道
   - 房主/管理员可踢人、封禁、修改频道公告等
   - 修复无法发送重复消息的BUG + 立即更新撤回/删除
   - 添加更多平滑动画、滚动动画等
   - 屏蔽用户按钮移到底部，不能屏蔽自己
   - 如果管理员删除当前正在使用的频道 => 立刻提示
   - 其余UI动画、阴影、hover等也有所增强
-->

<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="UTF-8">
  <title>DuckChat - 多频道 + 房主 & 管理员 & 密码频道</title>
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <!-- 字体 & 图标库 -->
  <link rel="preconnect" href="https://fonts.googleapis.com">
  <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Roboto:wght@400;500;700&display=swap">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0-beta3/css/all.min.css">
  <!-- 基础动画 -->
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.1.1/animate.min.css">
  <style>
    :root {
      --bg-dark: #1a1b1e;
      --bg: #2c2f33;
      --active-bg: #36393f;
      --hover-bg: rgba(79, 84, 92, 0.16);
      --primary-color: #7289da;
      --secondary-color: #43b581;
      --accent-color: #99aab5;
      --text-color: #dcddde;
      --white: #ffffff;
      --border-radius: 8px;
      --transition: 0.2s;
      --font: 'Roboto', sans-serif;
      --header-opacity: 0.90;
      --scrollbar-bg: rgba(255, 255, 255, 0.1);
      --scrollbar-thumb: rgba(255, 255, 255, 0.3);
      --shadow: 0 4px 10px rgba(0,0,0,0.3);
      --message-bg: linear-gradient(45deg, #2c2f33, #36393f);
      --message-bg-alt: linear-gradient(45deg, #36393f, #2c2f33);
    }
    * {
      box-sizing: border-box;
      margin: 0; padding: 0;
    }
    body {
      background-color: var(--bg-dark);
      color: var(--text-color);
      font-family: var(--font);
      height: 100vh;
      overflow: hidden;
      transition: background-color var(--transition), color var(--transition);
    }
    ::-webkit-scrollbar {
      width: 6px;
    }
    ::-webkit-scrollbar-track {
      background: var(--scrollbar-bg);
    }
    ::-webkit-scrollbar-thumb {
      background: var(--scrollbar-thumb);
      border-radius: 3px;
    }
    .container {
      display: grid;
      grid-template-columns: 72px 240px 1fr 240px;
      width: 100%;
      height: 100%;
      overflow: hidden;
      background: linear-gradient(45deg, var(--bg-dark), var(--bg));
      background-size: 200% 200%;
      animation: bgGradient 20s ease infinite;
    }
    @keyframes bgGradient {
      0% { background-position: 0% 50%; }
      50% { background-position: 100% 50%; }
      100% { background-position: 0% 50%; }
    }
    @media (max-width: 992px) {
      .user-list { display: none; transform: translateX(100%); transition: transform var(--transition); }
    }
    @media (max-width: 768px) {
      .channel-list {
        position: absolute; z-index: 100; height: 100%;
        transform: translateX(-100%); transition: transform var(--transition);
      }
      .channel-list.show { transform: translateX(0); }
      .container { grid-template-columns: 72px 1fr; }
      .chat-header { justify-content: space-between; }
      .menu-icon { display: block; cursor: pointer; font-size: 20px; }
    }
    .server-list {
      background-color: var(--bg-dark);
      display: flex; flex-direction: column; align-items: center;
      padding: 12px 0; overflow-y: auto;
      box-shadow: var(--shadow);
      z-index: 110;
    }
    .server-icon {
      width: 50px; height: 50px; margin-bottom: 16px;
      border-radius: 50%;
      background-color: var(--hover-bg);
      display: flex; align-items: center; justify-content: center;
      color: var(--white); font-size: 24px; cursor: pointer;
      transition: all var(--transition);
      box-shadow: var(--shadow);
    }
    .server-icon:hover {
      background-color: var(--primary-color);
      transform: translateY(-2px);
    }
    .channel-list {
      background-color: var(--bg);
      display: flex; flex-direction: column; overflow-y: auto;
      padding-top: 16px;
      box-shadow: var(--shadow);
      position: relative;
      z-index: 101;
    }
    .channel-header {
      padding: 0 16px; margin-bottom: 12px;
      font-size: 14px; font-weight: 700; color: var(--accent-color);
      text-transform: uppercase; letter-spacing: 0.5px;
      display: flex; align-items: center; justify-content: space-between;
    }
    .channel-search {
      margin: 0 16px 12px 16px; 
    }
    .channel-search input {
      width: 100%; padding: 6px 8px;
      border: 1px solid rgba(255,255,255,0.2);
      border-radius: var(--border-radius);
      background: var(--bg-dark); color: var(--white);
      outline: none; font-size: 14px;
    }
    .channel-item {
      padding: 10px 20px; margin: 2px 8px; border-radius: var(--border-radius);
      color: var(--text-color); display: flex; align-items: center;
      cursor: pointer; transition: all var(--transition);
      position: relative;
    }
    .channel-item:hover {
      background-color: var(--hover-bg);
      transform: translateX(4px);
    }
    .channel-item.active {
      background-color: var(--primary-color);
      color: var(--white);
      box-shadow: var(--shadow);
    }
    .channel-item .unread-dot {
      width: 8px; height: 8px; border-radius: 50%; background: red;
      position: absolute; top: 10px; right: 10px; display: none;
    }
    .create-channel-btn {
      background: none; border: none; color: var(--accent-color);
      cursor: pointer; font-size: 16px; margin-right: 8px;
    }
    .create-channel-btn:hover { color: var(--white); }
    .chat-container {
      display: flex; flex-direction: column;
      background: var(--bg);
      overflow: hidden; box-shadow: var(--shadow);
      position: relative;
      z-index: 1;
    }
    .chat-header {
      height: 60px; background-color: rgba(47, 49, 54, var(--header-opacity));
      display: flex; align-items: center; padding: 0 20px;
      backdrop-filter: blur(8px);
      border-bottom: 1px solid rgba(255, 255, 255, 0.1);
      transition: transform 0.3s ease;
    }
    .chat-header:hover { transform: scale(1.01); }
    .channel-name { font-size: 16px; font-weight: 700; }
    #deleteChatBtn {
      margin-left: auto; margin-right: 8px;
      padding: 4px 10px; font-size: 14px;
      background: var(--active-bg); color: var(--accent-color);
      border: 1px solid rgba(255,255,255,0.2);
      border-radius: var(--border-radius);
      cursor: pointer; transition: background-color 0.2s;
      display: none; 
    }
    #deleteChatBtn:hover {
      background: var(--hover-bg); color: var(--white);
    }
    .message-list {
      flex: 1; padding: 20px; overflow-y: auto;
      display: flex; flex-direction: column; gap: 16px;
      position: relative;
      scroll-behavior: smooth; /* 平滑滚动关键 */
    }
    .message-item {
      display: flex; flex-direction: column; gap: 8px;
      animation: fadeInUp 0.4s both;
      position: relative;
    }
    @keyframes fadeInUp {
      0% {
        transform: translate3d(0, 50%, 0);
        opacity: 0;
      }
      to {
        transform: translate3d(0, 0, 0);
        opacity: 1;
      }
    }
    .message-content {
      background: var(--message-bg);
      padding: 12px 16px; border-radius: var(--border-radius);
      box-shadow: var(--shadow);
      border: 1px solid rgba(255, 255, 255, 0.1);
      transition: all var(--transition);
      position: relative;
      cursor: pointer; /* 点击时出现气泡菜单 */
    }
    .message-content.alt {
      background: var(--message-bg-alt);
    }
    .message-author {
      font-weight: 700; font-size: 14px; color: var(--accent-color);
    }
    .message-time {
      font-size: 12px; opacity: 0.6; margin-left: 8px;
    }
    .message-text {
      font-size: 15px; line-height: 1.5; color: var(--text-color);
      white-space: pre-wrap; word-break: break-all;
    }
    .chat-image {
      max-width: 200px; margin-top: 8px; border-radius: var(--border-radius);
      cursor: pointer; transition: transform 0.2s;
    }
    .chat-image:hover { transform: scale(1.03); }
    .message-attachment {
      margin-top: 8px; padding: 8px;
      background: rgba(255, 255, 255, 0.1);
      border-radius: var(--border-radius);
      text-align: center;
    }
    .message-attachment a {
      color: var(--primary-color);
      text-decoration: none; font-size: 14px;
    }
    .message-attachment a:hover { text-decoration: underline; }
    .chat-input-area {
      padding: 12px 20px; background-color: var(--active-bg);
      border-top: 1px solid rgba(255, 255, 255, 0.1);
      display: flex; align-items: center; gap: 12px;
      box-shadow: var(--shadow);
      position: relative;
    }
    .image-button, .doc-button, .emoji-button {
      background: none; border: none; color: var(--accent-color);
      font-size: 20px; cursor: pointer; padding: 8px;
      transition: all var(--transition);
    }
    .image-button:hover, .doc-button:hover, .emoji-button:hover {
      color: var(--white); transform: scale(1.1);
    }
    #imagePreview {
      display: none; position: relative;
    }
    #imagePreview img {
      max-height: 40px; border-radius: var(--border-radius);
    }
    #removeImage {
      position: absolute; top: -5px; right: -5px;
      background: red; color: #fff; border-radius: 50%;
      padding: 2px 5px; cursor: pointer; font-size: 12px;
    }
    #docPreview {
      display: none; position: relative;
      background: var(--active-bg); padding: 5px 10px;
      border-radius: var(--border-radius);
      color: var(--white); font-size: 14px;
      margin-left: 10px;
    }
    #removeDoc {
      margin-left: 10px; background: red; border-radius: 50%;
      padding: 2px 5px; cursor: pointer; font-size: 12px;
    }
    .chat-input {
      flex: 1; background-color: var(--bg-dark);
      border: 1px solid rgba(255, 255, 255, 0.1);
      color: var(--white);
      padding: 10px 16px; border-radius: var(--border-radius);
      outline: none; font-size: 15px;
      transition: all var(--transition); transform-origin: center;
    }
    .chat-input:focus {
      border-color: var(--primary-color);
      transform: scale(1.01);
      box-shadow: 0 0 12px rgba(114, 137, 218, 0.3);
    }
    .chat-send-button {
      background-color: var(--primary-color);
      border: none; color: var(--white);
      font-size: 20px; padding: 10px 16px;
      border-radius: var(--border-radius);
      cursor: pointer; transition: all var(--transition);
      box-shadow: var(--shadow);
    }
    .chat-send-button:hover {
      background-color: var(--secondary-color);
      transform: translateY(-2px);
    }
    .emoji-panel {
      position: absolute; bottom: 100%; left: 20px;
      background: var(--bg-dark);
      border: 1px solid rgba(255, 255, 255, 0.1);
      border-radius: var(--border-radius);
      padding: 10px;
      display: grid; grid-template-columns: repeat(7, 1fr);
      gap: 8px;
      max-height: 180px; overflow-y: auto;
      box-shadow: var(--shadow);
      z-index: 1000;
      opacity: 0; pointer-events: none;
      transition: opacity 0.3s ease;
    }
    .emoji-panel.show {
      opacity: 1; pointer-events: auto;
    }
    .emoji {
      font-size: 24px; cursor: pointer; padding: 4px;
      border-radius: 4px; transition: all var(--transition);
      text-align: center;
    }
    .emoji:hover {
      background: var(--hover-bg);
      transform: scale(1.1);
    }
    .user-list {
      background-color: var(--bg);
      display: flex; flex-direction: column; overflow-y: auto;
      padding: 16px; box-shadow: var(--shadow);
      position: relative;
    }
    .user-list-header {
      margin-bottom: 8px; font-size: 14px; font-weight: 700;
      color: var(--accent-color); text-transform: uppercase;
      letter-spacing: 0.5px;
    }
    .user-search {
      margin-bottom: 12px;
    }
    .user-search input {
      width: 100%; padding: 6px 8px;
      border: 1px solid rgba(255,255,255,0.2);
      border-radius: var(--border-radius);
      background: var(--bg-dark); color: var(--white);
      outline: none; font-size: 14px;
    }
    .user-list-item {
      padding: 10px 16px; display: flex; align-items: center;
      cursor: pointer; transition: all var(--transition);
      gap: 12px; border-radius: var(--border-radius);
    }
    .user-list-item:hover {
      background-color: var(--hover-bg);
      transform: translateX(-4px);
    }
    .user-status-dot {
      width: 10px; height: 10px; border-radius: 50%;
      border: 2px solid var(--bg-dark);
    }
    #usernameModal {
      position: fixed; top: 0; left: 0;
      width: 100vw; height: 100vh;
      background: rgba(0,0,0,0.7);
      display: flex; align-items: center; justify-content: center;
      z-index: 10000;
    }
    .modal-content {
      background: var(--bg); padding: 20px 30px;
      border-radius: var(--border-radius); text-align: center;
      box-shadow: var(--shadow);
    }
    .modal-content h2 { margin-bottom: 20px; color: var(--white); }
    .modal-content input {
      width: 80%; padding: 10px;
      border: 1px solid rgba(255,255,255,0.2);
      border-radius: var(--border-radius);
      margin-bottom: 10px; font-size: 16px;
      background: var(--bg-dark); color: var(--white);
      outline: none; transition: border-color var(--transition);
    }
    .modal-content input:focus { border-color: var(--primary-color); }
    .modal-content button {
      padding: 10px 20px; background: var(--primary-color);
      border: none; color: var(--white); font-size: 16px;
      border-radius: var(--border-radius); cursor: pointer;
      transition: transform var(--transition);
    }
    .modal-content button:hover {
      transform: scale(1.05);
    }
    .modal-content p {
      font-size: 14px; margin-top: 8px;
      color: #ff6b6b;
    }
    #imageModal {
      display: none; position: fixed;
      top: 0; left: 0; width: 100vw; height: 100vh;
      background: rgba(0,0,0,0.8);
      justify-content: center; align-items: center;
      z-index: 10000; cursor: pointer;
    }
    #imageModal img {
      max-width: 90%; max-height: 90%;
      border-radius: var(--border-radius);
    }
    .sending {
      opacity: 0.6;
      pointer-events: none;
    }
    /* 气泡菜单：把“屏蔽用户”按钮放在最后，且如果是自己发的消息则不显示“屏蔽用户” */
    .bubble-menu {
      display: none;
      position: absolute;
      top: 0; left: 0; transform: translate(0, -100%);
      background: var(--bg-dark);
      border: 1px solid rgba(255,255,255,0.2);
      border-radius: var(--border-radius);
      padding: 8px;
      flex-direction: column;
      gap: 4px;
      z-index: 2000;
      box-shadow: var(--shadow);
      animation: fadeInUp 0.2s ease;
    }
    .bubble-menu.show {
      display: flex;
    }
    .bubble-menu button {
      background: none; border: none; color: var(--accent-color);
      padding: 4px 8px; border-radius: var(--border-radius);
      text-align: left;
      font-size: 14px;
      transition: background 0.2s;
      cursor: pointer;
    }
    .bubble-menu button:hover {
      background: var(--hover-bg);
      color: var(--white);
    }
    /* 创建频道弹窗(增加密码、期限、人数、公告等) */
    #createChannelModal {
      position: fixed; top: 0; left: 0;
      width: 100vw; height: 100vh;
      background: rgba(0,0,0,0.7);
      display: none; align-items: center; justify-content: center;
      z-index: 12000;
    }
    #createChannelModal .modal-content {
      animation: fadeInUp 0.4s ease;
    }
    /* 管理员密码弹窗 */
    #adminModal {
      position: fixed; top: 0; left: 0;
      width: 100vw; height: 100vh;
      background: rgba(0,0,0,0.7);
      display: none; align-items: center; justify-content: center;
      z-index: 13000;
    }
    #adminModal .modal-content {
      animation: fadeInUp 0.4s ease;
    }
    /* 管理员面板 */
    #adminPanel {
      position: fixed; top: 0; left: 0;
      width: 100vw; height: 100vh;
      background: rgba(0,0,0,0.7);
      display: none; align-items: center; justify-content: center;
      z-index: 13001;
    }
    #adminPanel .modal-content {
      max-height: 80vh; overflow-y: auto;
      text-align: left;
    }
    /* 频道被删除时的提示 */
    #channelDeletedMsg {
      display: none; position: fixed;
      top: 20px; left: 50%; transform: translateX(-50%);
      background: #ff3333; color: #fff;
      padding: 10px 20px; border-radius: var(--border-radius);
      font-size: 14px; box-shadow: var(--shadow);
      z-index: 20000;
      animation: fadeInDown 0.4s ease;
    }
    @keyframes fadeInDown {
      0% { transform: translate(-50%, -30px); opacity: 0; }
      to { transform: translate(-50%, 0); opacity: 1; }
    }
  </style>
</head>
<body>

<!-- 昵称输入弹窗 -->
<div id="usernameModal" class="animate__animated animate__fadeIn">
  <div class="modal-content animate__animated animate__zoomIn">
    <h2>欢迎来到 DuckChat！</h2>
    <input type="text" id="usernameInput" placeholder="请输入您的昵称(最多10字)" maxlength="10">
    <br>
    <button id="enterChatBtn">进入聊天</button>
    <p id="usernameError" style="display: none;"></p>
  </div>
</div>

<!-- 频道被删除时的提示 -->
<div id="channelDeletedMsg">频道已被删除或已过期，您已被自动切换到「世界聊天室」</div>

<!-- 创建频道弹窗（可设密码、有效期、人数限制、公告） -->
<div id="createChannelModal">
  <div class="modal-content">
    <h2>创建新的聊天频道</h2>
    <input type="text" id="newChannelName" placeholder="频道名称">
    <input type="text" id="newChannelPassword" placeholder="频道密码（可为空）">
    <input type="number" id="newChannelExpire" placeholder="有效期(秒), 0=永久">
    <input type="number" id="newChannelMax" placeholder="最大人数, 0=不限制">
    <textarea id="newChannelDesc" placeholder="频道公告/描述" style="width:80%;height:60px;margin-top:5px;"></textarea>
    <br>
    <button id="createChannelConfirmBtn">创建</button>
    <button id="createChannelCancelBtn">取消</button>
    <p id="createChannelMsg" style="color:#ff6b6b;display:none;"></p>
  </div>
</div>

<!-- 管理员密码弹窗 -->
<div id="adminModal">
  <div class="modal-content">
    <h2>管理员模式</h2>
    <p>请输入管理员密码：</p>
    <input type="password" id="adminPwdInput">
    <br>
    <button id="adminPwdOkBtn">确定</button>
    <button id="adminPwdCancelBtn">取消</button>
    <p id="adminPwdMsg" style="color:#ff6b6b;display:none;"></p>
  </div>
</div>

<!-- 管理员面板 -->
<div id="adminPanel">
  <div class="modal-content">
    <h2>管理员面板</h2>
    <div id="adminPanelContent" style="font-size:14px; color:#fff;"></div>
    <button id="adminPanelCloseBtn" style="margin-top:10px;">关闭</button>
  </div>
</div>

<!-- 放大图片弹窗 -->
<div id="imageModal">
  <img id="modalImage" src="" alt="放大预览">
</div>

<!-- 整体容器 -->
<div class="container">
  <!-- 左侧服务器列表 -->
  <nav class="server-list">
    <div class="server-icon"><i class="fab fa-discord"></i></div>
    <!-- 点击羽毛图标 => 管理员模式 -->
    <div class="server-icon" id="adminIcon" title="管理员模式"><i class="fas fa-feather-alt"></i></div>
  </nav>

  <!-- 频道列表 -->
  <aside class="channel-list">
    <div class="channel-header">
      文本频道
      <button class="create-channel-btn" id="createChannelBtn" title="创建新的聊天频道"><i class="fas fa-plus"></i></button>
    </div>
    <!-- 频道搜索框 -->
    <div class="channel-search">
      <input type="text" id="channelSearchInput" placeholder="搜索频道...">
    </div>
    <!-- 默认公共频道 -->
    <div class="channel-item active" data-channel="世界聊天室">
      <i class="fas fa-hashtag"></i> 世界聊天室
      <span class="unread-dot"></span>
    </div>
    <!-- 这里放自定义频道 -->
    <div id="customChannelContainer"></div>

    <!-- 私聊头 -->
    <div class="channel-header" style="margin-top:20px;">私聊</div>
    <div id="privateChannelContainer"></div>
  </aside>

  <!-- 聊天主窗口 -->
  <main class="chat-container">
    <header class="chat-header">
      <div class="channel-name"><i class="fas fa-hashtag"></i> 世界聊天室</div>
      <button id="deleteChatBtn">删除私聊</button>
      <div class="menu-icon" id="menuIcon" style="display:none;">
        <i class="fas fa-bars"></i>
      </div>
    </header>
    <!-- 消息列表 -->
    <section class="message-list" id="messageList"></section>
    <!-- 输入区域 -->
    <footer class="chat-input-area">
      <button class="emoji-button" id="emojiButton"><i class="far fa-smile"></i></button>
      <button class="image-button" id="imageButton"><i class="fas fa-image"></i></button>
      <button class="doc-button" id="docButton"><i class="fas fa-file-alt"></i></button>
      <input type="file" id="imageInput" accept="image/*" style="display:none">
      <input type="file" id="docInput" accept=".pdf,.txt,.doc,.docx" style="display:none">

      <!-- 附件预览 -->
      <div id="imagePreview">
        <img src="" alt="预览">
        <span id="removeImage">&times;</span>
      </div>
      <div id="docPreview">
        <span id="docName"></span>
        <span id="removeDoc">&times;</span>
      </div>

      <!-- Emoji 面板 -->
      <div class="emoji-panel" id="emojiPanel"></div>

      <!-- 文本框 -->
      <input type="text" class="chat-input" id="chatInput" placeholder="在 #世界聊天室 中发送消息...">
      <button class="chat-send-button" id="sendBtn"><i class="fas fa-paper-plane"></i></button>
    </footer>
  </main>

  <!-- 在线用户列表 -->
  <aside class="user-list">
    <div class="user-list-header">在线列表</div>
    <div class="user-search">
      <input type="text" id="userSearchInput" placeholder="搜索用户...">
    </div>
    <div id="userListContainer"></div>
  </aside>
</div>

<!-- 氣泡菜单 (撤回/删除/复制/引用/屏蔽用户...) -->
<div class="bubble-menu" id="bubbleMenu">
  <button id="bubbleRecallBtn">撤回</button>
  <button id="bubbleDeleteLocalBtn">删除(仅自己)</button>
  <button id="bubbleCopyBtn">复制</button>
  <button id="bubbleQuoteBtn">引用</button>
  <!-- 屏蔽用户按钮放在最下面 -->
  <button id="bubbleBlockBtn">屏蔽此用户</button>
</div>

<script>
/* =========== 辅助函数 =========== */
function setCookie(cname, cvalue, exhours) {
  const d = new Date();
  d.setTime(d.getTime() + (exhours * 60 * 60 * 1000));
  document.cookie = cname + "=" + cvalue + ";expires=" + d.toUTCString() + ";path=/";
}
function getCookie(cname) {
  const name = cname + "=";
  const decoded = decodeURIComponent(document.cookie);
  const parts = decoded.split(';');
  for (let i = 0; i < parts.length; i++) {
    let c = parts[i].trim();
    if (c.indexOf(name) === 0) {
      return c.substring(name.length, c.length);
    }
  }
  return "";
}
async function checkNameAvailable(name) {
  const res = await fetch(\`?action=checkName&username=\${encodeURIComponent(name)}\`);
  const data = await res.json();
  return data.taken; // true=已占用
}

/* =========== 全局变量 =========== */
let userName = "";
let currentChannel = "世界聊天室";   // 当前所在的“频道”或“聊天”
let currentPrivateChatUser = "";    // 若是私聊，则这里记录对方
let sendingAbortController = null;
let autoScroll = true;
const knownMessageCount = {};       // 记录各频道/私聊已加载的条数
const privateChannels = {};         // 已显示的私聊项
let blockedUsers = [];             // 本地屏蔽的用户列表
try {
  const storedBlock = localStorage.getItem("duckchat_blocked_users");
  if (storedBlock) {
    blockedUsers = JSON.parse(storedBlock);
  }
} catch(e){}

const channelDeletedMsg = document.getElementById("channelDeletedMsg");

/* =========== 初始化(检查cookie) =========== */
const savedUserName = getCookie("username");
const usernameModal = document.getElementById("usernameModal");
if (savedUserName) {
  checkNameAvailable(savedUserName).then(isTaken => {
    if (!isTaken) {
      userName = savedUserName;
      usernameModal.style.display = "none";
      setUserStatus("online");
      initLoad();
    } else {
      usernameModal.style.display = "flex";
    }
  });
} else {
  usernameModal.style.display = "flex";
}

/* =========== 昵称输入弹窗事件 =========== */
const usernameInput = document.getElementById("usernameInput");
const enterChatBtn  = document.getElementById("enterChatBtn");
const usernameError = document.getElementById("usernameError");
function handleEnterChat() {
  const name = usernameInput.value.trim();
  if (!name || name.length > 10) {
    usernameError.style.display = "block";
    usernameError.textContent = "名字不能为空且不超过10字";
    usernameInput.classList.add("animate__shakeX");
    setTimeout(()=>usernameInput.classList.remove("animate__shakeX"),500);
    return;
  }
  checkNameAvailable(name).then(isTaken => {
    if (isTaken) {
      usernameError.style.display = "block";
      usernameError.textContent = "此名字已被占用";
      usernameInput.classList.add("animate__shakeX");
      setTimeout(()=>usernameInput.classList.remove("animate__shakeX"),500);
      return;
    }
    userName = name;
    setCookie("username", name, 24);
    usernameModal.classList.add("animate__fadeOut");
    setTimeout(()=>{ usernameModal.style.display="none"; },500);
    setUserStatus("online");
    initLoad();
  });
}
enterChatBtn.addEventListener("click", handleEnterChat);
usernameInput.addEventListener("keydown", e=>{
  if(e.key==="Enter"){ handleEnterChat(); }
});

/* =========== 核心初始化：拉取用户、加载频道、定时轮询等 =========== */
function initLoad(){
  loadCustomChannels();
  loadChannelMessagesIncremental(currentChannel);
  getUsers();
  setInterval(heartBeat, 3000);
}

/* =========== 心跳函数 =========== */
function heartBeat(){
  if(!userName)return;
  setUserStatus("online");
  if(!currentPrivateChatUser){
    // 公共频道
    loadChannelMessagesIncremental(currentChannel);
  } else {
    // 私聊
    loadPrivateChatIncremental(currentPrivateChatUser);
  }
  // 刷新私聊未读
  refreshPrivateChannels();
  // 获取在线用户
  getUsers();
}

/* =========== 设置用户状态 =========== */
function setUserStatus(status){
  if(!userName)return;
  fetch(\`?action=setStatus&username=\${encodeURIComponent(userName)}&status=\${encodeURIComponent(status)}\`)
    .catch(console.log);
}
window.addEventListener("unload", ()=>{
  if(userName){
    navigator.sendBeacon(\`?action=removeUser&username=\${encodeURIComponent(userName)}\`);
  }
});

/* =========== 获取在线用户 + 搜索功能 =========== */
function getUsers(){
  fetch("?action=getUsers")
    .then(r=>r.json())
    .then(users=>{
      const container = document.getElementById("userListContainer");
      const filter = document.getElementById("userSearchInput").value.toLowerCase();
      container.innerHTML = "";
      users.forEach(u=>{
        const uname = u[0];
        if(uname.toLowerCase().indexOf(filter)<0) return; 
        if(uname===userName)return; // 不显示自己
        const div = document.createElement("div");
        div.className = "user-list-item";
        div.innerHTML=`
          <span class="user-name">${uname}</span>
          <span class="user-status-dot" style="background-color:#43b581"></span>
        `;
        // 点击发起私聊
        div.addEventListener("click", ()=>openPrivateChannel(uname));
        container.appendChild(div);
      });
    }).catch(console.log);
}
const userSearchInput = document.getElementById("userSearchInput");
userSearchInput.addEventListener("input",()=>{
  getUsers(); 
});

/* =========== 加载自定义频道列表 + 搜索过滤 =========== */
function loadCustomChannels(){
  fetch("channels_meta.json?random="+Math.random())
    .then(r=>r.json())
    .then(meta=>{
      if(!meta.channels)return;
      const container = document.getElementById("customChannelContainer");
      container.innerHTML="";
      const filter = document.getElementById("channelSearchInput")?.value?.toLowerCase()||"";
      meta.channels.forEach(ch=>{
        const name = ch.name;
        if(name==="世界聊天室")return;
        if(filter && name.toLowerCase().indexOf(filter)<0) return; 
        const div = document.createElement("div");
        div.className = "channel-item";
        div.dataset.channel = name;
        div.innerHTML=`
          <i class="fas fa-hashtag"></i> ${name}
          <span class="unread-dot"></span>
        `;
        div.addEventListener("click", ()=>{
          currentPrivateChatUser="";
          document.querySelectorAll(".channel-item").forEach(x=>x.classList.remove("active"));
          div.classList.add("active");
          currentChannel=name;
          document.querySelector(".channel-name").innerHTML=\`<i class="fas fa-hashtag"></i> \${name}\`;
          document.getElementById("chatInput").placeholder=\`在 #\${name} 中发送消息...\`;
          document.getElementById("deleteChatBtn").style.display="none";
          knownMessageCount[name]=0; // 重置，重新加载
          loadChannelMessagesIncremental(name);
        });
        container.appendChild(div);
      });
    });
}
const channelSearchInput = document.getElementById("channelSearchInput");
channelSearchInput.addEventListener("input", ()=>{
  loadCustomChannels();
});

/* =========== 默认公共频道点击 =========== */
document.querySelectorAll(".channel-item[data-channel]").forEach(item=>{
  item.addEventListener("click", ()=>{
    const chName = item.getAttribute("data-channel");
    if(!chName)return;
    currentPrivateChatUser="";
    document.querySelectorAll(".channel-item").forEach(x=>x.classList.remove("active"));
    item.classList.add("active");
    currentChannel = chName;
    document.querySelector(".channel-name").innerHTML = \`<i class="fas fa-hashtag"></i> \${chName}\`;
    document.getElementById("chatInput").placeholder = \`在 #\${chName} 中发送消息...\`;
    document.getElementById("deleteChatBtn").style.display="none";
    knownMessageCount[chName]=0;
    loadChannelMessagesIncremental(chName);
  });
});

/* =========== 打开私聊频道 =========== */
function openPrivateChannel(targetUser){
  currentPrivateChatUser=targetUser;
  document.querySelectorAll(".channel-item").forEach(x=>x.classList.remove("active"));
  if(!privateChannels[targetUser]){
    createPrivateChannelItem(targetUser);
  }
  privateChannels[targetUser].element.classList.add("active");
  hideUnreadDot(privateChannels[targetUser].element);
  privateChannels[targetUser].unreadCount=0;

  document.querySelector(".channel-name").innerHTML=\`<i class="fas fa-user"></i> 私聊：\${targetUser}\`;
  document.getElementById("chatInput").placeholder=\`私聊给 \${targetUser}...\`;
  document.getElementById("deleteChatBtn").style.display="inline-block";
  knownMessageCount[getPrivateKey(userName,targetUser)]=0;
  loadPrivateChatIncremental(targetUser);
}
function createPrivateChannelItem(targetUser){
  const container = document.getElementById("privateChannelContainer");
  const item = document.createElement("div");
  item.className="channel-item";
  item.dataset.user=targetUser;
  item.innerHTML=`
    <i class="fas fa-user"></i> @${targetUser}
    <span class="unread-dot"></span>
  `;
  item.addEventListener("click",()=>openPrivateChannel(targetUser));
  container.appendChild(item);
  privateChannels[targetUser]={
    unreadCount:0,
    element: item,
    msgCount:0
  };
}
function showUnreadDot(el){
  const dot = el.querySelector(".unread-dot");
  if(dot) dot.style.display="block";
}
function hideUnreadDot(el){
  const dot = el.querySelector(".unread-dot");
  if(dot) dot.style.display="none";
}

/* =========== 增量加载公共频道消息 =========== */
function loadChannelMessagesIncremental(channel){
  const list = document.getElementById("messageList");
  const key = channel;
  if(knownMessageCount[key]===undefined){
    list.innerHTML="";
    knownMessageCount[key]=0;
  }
  fetch(\`?action=getMessages&channel=\${encodeURIComponent(channel)}&username=\${encodeURIComponent(userName)}\`)
    .then(r=>r.json())
    .then(data=>{
      if(data.deleted){
        // 频道被删除或过期 => 提示 & 切回世界聊天室
        showChannelDeletedMsg(data.reason);
        switchToWorldChannel();
        return;
      }
      const arr = data.messages||[];
      const oldCount = knownMessageCount[key]||0;
      const newCount = arr.length;
      if(newCount>oldCount){
        for(let i=oldCount; i<newCount; i++){
          const m=arr[i];
          if(blockedUsers.includes(m.author)) continue;
          addMessageToList(m.author, m.time, m.text, m.imageData, m.docData, m.docName, (i%2===0));
        }
        knownMessageCount[key] = newCount;
        scrollToBottomSmooth();
      }
    })
    .catch(console.log);
}

/* =========== 增量加载私聊消息 =========== */
function loadPrivateChatIncremental(targetUser){
  const list = document.getElementById("messageList");
  const key = getPrivateKey(userName,targetUser);
  if(knownMessageCount[key]===undefined){
    list.innerHTML="";
    knownMessageCount[key]=0;
  }
  fetch(\`?action=getPrivateMessages&user1=\${encodeURIComponent(userName)}&user2=\${encodeURIComponent(targetUser)}\`)
    .then(r=>r.json())
    .then(data=>{
      if(!Array.isArray(data))return;
      const oldCount=knownMessageCount[key]||0;
      const newCount=data.length;
      if(newCount>oldCount){
        for(let i=oldCount;i<newCount;i++){
          const m=data[i];
          if(blockedUsers.includes(m.author)) continue;
          addMessageToList(m.author, m.time, m.text, m.imageData, m.docData, m.docName, (i%2===0));
        }
        knownMessageCount[key]=newCount;
        scrollToBottomSmooth();
      }
    })
    .catch(console.log);
}
function getPrivateKey(a,b){
  let arr=[a,b]; arr.sort();
  return "p_"+arr.join("_");
}

/* =========== 在消息列表中添加一条消息 =========== */
function addMessageToList(author, time, text, imageData, docData, docName, isAlt){
  if(messageExists(author,time,text))return;
  const list = document.getElementById("messageList");
  const index = list.querySelectorAll(".message-item").length;
  const msgDiv = document.createElement("div");
  msgDiv.className="message-item animate__animated animate__fadeInUp";
  const contentDiv = document.createElement("div");
  contentDiv.className="message-content "+(isAlt?"alt":"");
  contentDiv.innerHTML=`
    <div>
      <span class="message-author">${author}</span>
      <span class="message-time">${time}</span>
    </div>
    <div class="message-text">${text}</div>
  `;
  if(imageData){
    contentDiv.innerHTML+=\`<img src="\${imageData}" class="chat-image">\`;
  }
  if(docData&&docName){
    contentDiv.innerHTML+=\`
      <div class="message-attachment">
        <a href="\${docData}" download="\${docName}">下载文件：\${docName}</a>
      </div>
    \`;
  }
  msgDiv.appendChild(contentDiv);
  list.appendChild(msgDiv);

  // 绑定气泡菜单事件
  contentDiv.addEventListener("click",(e)=>{
    showBubbleMenu(e,contentDiv,author,time,text);
  });
}
function messageExists(author,time,text){
  const items = document.querySelectorAll(".message-item");
  for(let m of items){
    const au = m.querySelector(".message-author")?.textContent;
    const ti = m.querySelector(".message-time")?.textContent;
    const te = m.querySelector(".message-text")?.textContent;
    if(au===author && ti===time && te===text){
      return true;
    }
  }
  return false;
}

/* =========== 滚动到底部(平滑动画) =========== */
function scrollToBottomSmooth(){
  const list = document.getElementById("messageList");
  // 延迟一点点再滚动，避免appendChild尚未完成height更新
  setTimeout(()=>{
    list.scrollTo({ top: list.scrollHeight, behavior: 'smooth' });
  },50);
}

/* =========== 发送消息(公共频道或私聊) =========== */
const sendBtn = document.getElementById("sendBtn");
const chatInput = document.getElementById("chatInput");
function sendMessage(){
  const text = chatInput.value.trim();
  if(!text && !attachedImageData && !attachedDocData){
    chatInput.classList.add("animate__shakeX");
    setTimeout(()=>chatInput.classList.remove("animate__shakeX"),500);
    return;
  }
  sendBtn.disabled=true;
  sendBtn.classList.add("sending");
  sendBtn.innerHTML=\`<i class="fas fa-spinner fa-spin"></i>\`;

  sendingAbortController = new AbortController();
  const signal = sendingAbortController.signal;
  const now = new Date();
  const time = now.toLocaleTimeString([], {hour:'2-digit',minute:'2-digit'});

  const fd = new FormData();
  fd.append("author", userName);
  fd.append("time", time);
  fd.append("text", text);
  fd.append("imageData", attachedImageData);
  fd.append("docData", attachedDocData);
  fd.append("docName", attachedDocName);

  let url="";
  if(currentPrivateChatUser){
    fd.append("user1", userName);
    fd.append("user2", currentPrivateChatUser);
    url="?action=sendPrivateMessage";
  } else {
    fd.append("channel", currentChannel);
    url="?action=sendMessage";
  }
  fetch(url,{method:"POST",body:fd,signal})
    .then(r=>r.json())
    .then(data=>{
      if(data.error){
        alert(\`发送失败: \${data.error}\`);
        return;
      }
      // 本地立即显示
      addMessageToList(userName,time,text,attachedImageData,attachedDocData,attachedDocName,false);
      clearInput();
      scrollToBottomSmooth();
    })
    .catch(err=>{
      if(err.name==="AbortError")console.log("发送已取消");
      else alert("发送失败: "+err);
    })
    .finally(()=>{
      sendBtn.disabled=false;
      sendBtn.classList.remove("sending");
      sendBtn.innerHTML=\`<i class="fas fa-paper-plane"></i>\`;
      sendingAbortController=null;
    });
}
function clearInput(){
  chatInput.value="";
  attachedImageData="";
  attachedDocData="";
  attachedDocName="";
  imageInput.value="";
  docInput.value="";
  imagePreview.style.display="none";
  docPreview.style.display="none";
}
sendBtn.addEventListener("click",sendMessage);
chatInput.addEventListener("keydown",e=>{
  if(e.key==="Enter"){
    e.preventDefault();
    sendMessage();
  }
});

/* =========== 附件相关 =========== */
const imageButton = document.getElementById("imageButton");
const imageInput  = document.getElementById("imageInput");
const imagePreview= document.getElementById("imagePreview");
const removeImage = document.getElementById("removeImage");
let attachedImageData="";
imageButton.addEventListener("click",()=>imageInput.click());
imageInput.addEventListener("change",e=>{
  const file = e.target.files[0];
  if(file && file.type.startsWith("image/")){
    if(file.size>52428800){
      alert("图片大于50MB");
      imageInput.value="";
      return;
    }
    const reader=new FileReader();
    reader.onload=evt=>{
      attachedImageData=evt.target.result;
      imagePreview.style.display="block";
      imagePreview.querySelector("img").src=attachedImageData;
    };
    reader.readAsDataURL(file);
  }
});
removeImage.addEventListener("click",()=>{
  attachedImageData="";
  imageInput.value="";
  imagePreview.style.display="none";
});

const docButton = document.getElementById("docButton");
const docInput  = document.getElementById("docInput");
const docPreview= document.getElementById("docPreview");
const docNameSpan= document.getElementById("docName");
const removeDoc  = document.getElementById("removeDoc");
let attachedDocData="";
let attachedDocName="";
docButton.addEventListener("click",()=>docInput.click());
docInput.addEventListener("change",e=>{
  const file=e.target.files[0];
  if(file){
    if(file.size>52428800){
      alert("文件大于50MB");
      docInput.value="";
      return;
    }
    attachedDocName=file.name;
    const reader=new FileReader();
    reader.onload=evt=>{
      attachedDocData=evt.target.result;
      docPreview.style.display="block";
      docNameSpan.textContent=attachedDocName;
    };
    reader.readAsDataURL(file);
  }
});
removeDoc.addEventListener("click",()=>{
  attachedDocData="";
  attachedDocName="";
  docInput.value="";
  docPreview.style.display="none";
});

/* =========== 图片点击放大 =========== */
const imageModal=document.getElementById("imageModal");
const modalImage=document.getElementById("modalImage");
document.addEventListener("click",e=>{
  if(e.target.classList.contains("chat-image")){
    modalImage.src=e.target.src;
    imageModal.style.display="flex";
    imageModal.classList.add("animate__zoomIn");
  }
});
imageModal.addEventListener("click",()=>{
  imageModal.classList.remove("animate__zoomIn");
  imageModal.classList.add("animate__fadeOut");
  setTimeout(()=>{
    imageModal.style.display="none";
    imageModal.classList.remove("animate__fadeOut");
  },300);
});

/* =========== Emoji面板 =========== */
const emojiButton = document.getElementById("emojiButton");
const emojiPanel  = document.getElementById("emojiPanel");
const emojis=[
  '😀','😃','😄','😁','😅','😂','🤣','😊','😇','😉','😍','😒','😞','😔','😕','🙁','😭','😡','🥵','🥶',
  '😷','💪','🔥','💖','🖤','☕','🍺','🍔','🍎','🐶','🐱','🐻','🐼','🐨','🦁','🐵'
];
function initEmojiPanel(){
  emojis.forEach(e=>{
    const s=document.createElement("span");
    s.className="emoji";
    s.textContent=e;
    s.onclick=()=>{
      insertEmoji(e);
      emojiPanel.classList.remove("show");
    };
    emojiPanel.appendChild(s);
  });
}
initEmojiPanel();
emojiButton.addEventListener("click",e=>{
  e.stopPropagation();
  emojiPanel.classList.toggle("show");
});
document.addEventListener("click",e=>{
  if(!emojiButton.contains(e.target)&&!emojiPanel.contains(e.target)){
    emojiPanel.classList.remove("show");
  }
});
function insertEmoji(emo){
  const start=chatInput.selectionStart;
  const end=chatInput.selectionEnd;
  const text=chatInput.value;
  chatInput.value=text.substring(0,start)+emo+text.substring(end);
  chatInput.focus();
  chatInput.selectionStart=chatInput.selectionEnd=start+emo.length;
}

/* =========== 删除私聊按钮 =========== */
const deleteChatBtn=document.getElementById("deleteChatBtn");
deleteChatBtn.addEventListener("click",()=>{
  if(!currentPrivateChatUser){
    alert("当前无私聊对象");
    return;
  }
  if(!confirm(\`确认删除和 \${currentPrivateChatUser} 的私聊记录？\`))return;
  fetch(\`?action=deletePrivateChat&user1=\${encodeURIComponent(userName)}&user2=\${encodeURIComponent(currentPrivateChatUser)}\`)
    .then(r=>r.json())
    .then(data=>{
      if(data.ok){
        alert("私聊记录已删除");
        if(privateChannels[currentPrivateChatUser]){
          privateChannels[currentPrivateChatUser].element.remove();
          delete privateChannels[currentPrivateChatUser];
        }
        currentPrivateChatUser="";
        switchToWorldChannel();
      }
    });
});
function switchToWorldChannel(){
  document.querySelectorAll(".channel-item").forEach(x=>x.classList.remove("active"));
  const worldItem=document.querySelector('.channel-item[data-channel="世界聊天室"]');
  if(worldItem)worldItem.classList.add("active");
  currentChannel="世界聊天室";
  document.querySelector(".channel-name").innerHTML=\`<i class="fas fa-hashtag"></i> 世界聊天室\`;
  document.getElementById("chatInput").placeholder="在 #世界聊天室 中发送消息...";
  document.getElementById("deleteChatBtn").style.display="none";
  knownMessageCount["世界聊天室"]=0;
  loadChannelMessagesIncremental("世界聊天室");
}

/* =========== 刷新私聊的未读 =========== */
function refreshPrivateChannels(){
  Object.keys(privateChannels).forEach(ou=>{
    fetch(\`?action=getPrivateMessages&user1=\${encodeURIComponent(userName)}&user2=\${encodeURIComponent(ou)}\`)
      .then(r=>r.json())
      .then(pm=>{
        if(!Array.isArray(pm))return;
        const oldCount=privateChannels[ou].msgCount||0;
        const newCount=pm.length;
        if(newCount>oldCount){
          privateChannels[ou].msgCount=newCount;
          if(currentPrivateChatUser!==ou){
            showUnreadDot(privateChannels[ou].element);
          } else {
            hideUnreadDot(privateChannels[ou].element);
          }
        }
      }).catch(console.log);
  });
}

/* =========== 消息气泡菜单 (撤回/删除本地/复制/引用/屏蔽) =========== */
const bubbleMenu=document.getElementById("bubbleMenu");
let bubbleTarget={author:"",time:"",text:"",dom:null};

function showBubbleMenu(ev,dom,author,time,text){
  ev.stopPropagation();
  bubbleTarget={author,time,text,dom};
  // 若不是自己发的，则隐藏“撤回”
  if(author!==userName){
    document.getElementById("bubbleRecallBtn").style.display="none";
  } else {
    document.getElementById("bubbleRecallBtn").style.display="block";
  }
  // 若是自己，就不显示“屏蔽用户”
  const blockBtn = document.getElementById("bubbleBlockBtn");
  if(author===userName){
    blockBtn.style.display="none";
  } else {
    blockBtn.style.display="block";
  }
  // 定位
  const rect=dom.getBoundingClientRect();
  bubbleMenu.style.left=(rect.left)+"px";
  bubbleMenu.style.top=(rect.top)+"px";
  bubbleMenu.classList.add("show");
}
document.addEventListener("click",()=>{
  if(bubbleMenu.classList.contains("show")){
    bubbleMenu.classList.remove("show");
  }
});

// 撤回(真正服务器删除)
document.getElementById("bubbleRecallBtn").addEventListener("click",()=>{
  bubbleMenu.classList.remove("show");
  recallMessage();
});
function recallMessage(){
  const {author,time,text}=bubbleTarget;
  if(currentPrivateChatUser){
    const url=\`?action=recallMessage&user1=\${encodeURIComponent(userName)}&user2=\${encodeURIComponent(currentPrivateChatUser)}&author=\${encodeURIComponent(author)}&time=\${encodeURIComponent(time)}&text=\${encodeURIComponent(text)}\`;
    fetch(url).then(r=>r.json()).then(d=>{
      if(d.ok){
        bubbleTarget.dom.parentElement.remove();
      }
    });
  } else {
    const url=\`?action=recallMessage&channel=\${encodeURIComponent(currentChannel)}&author=\${encodeURIComponent(author)}&time=\${encodeURIComponent(time)}&text=\${encodeURIComponent(text)}\`;
    fetch(url).then(r=>r.json()).then(d=>{
      if(d.ok){
        bubbleTarget.dom.parentElement.remove();
      }
    });
  }
}

// 删除(仅本地)
document.getElementById("bubbleDeleteLocalBtn").addEventListener("click",()=>{
  bubbleMenu.classList.remove("show");
  bubbleTarget.dom.parentElement.remove();
});

// 复制
document.getElementById("bubbleCopyBtn").addEventListener("click",async()=>{
  bubbleMenu.classList.remove("show");
  try{
    await navigator.clipboard.writeText(bubbleTarget.text);
    alert("已复制到剪贴板");
  }catch(e){
    alert("复制失败");
  }
});

// 引用
document.getElementById("bubbleQuoteBtn").addEventListener("click",()=>{
  bubbleMenu.classList.remove("show");
  chatInput.value += \`[引用@\${bubbleTarget.author}]: \${bubbleTarget.text}\\n\`;
  chatInput.focus();
});

// 屏蔽用户
document.getElementById("bubbleBlockBtn").addEventListener("click",()=>{
  bubbleMenu.classList.remove("show");
  const blockUser = bubbleTarget.author;
  if(blockUser===userName){
    alert("不能屏蔽自己哦");
    return;
  }
  if(!blockedUsers.includes(blockUser)){
    blockedUsers.push(blockUser);
    localStorage.setItem("duckchat_blocked_users", JSON.stringify(blockedUsers));
    alert(\`已屏蔽用户: \${blockUser}\`);
    hideUserMessages(blockUser);
  }
});
function hideUserMessages(user){
  const items=document.querySelectorAll(".message-item");
  items.forEach(i=>{
    const au=i.querySelector(".message-author")?.textContent;
    if(au===user){
      i.remove();
    }
  });
}

/* =========== 创建频道弹窗 =========== */
const createChannelBtn=document.getElementById("createChannelBtn");
const createChannelModal=document.getElementById("createChannelModal");
const newChannelName=document.getElementById("newChannelName");
const newChannelPassword=document.getElementById("newChannelPassword");
const newChannelExpire=document.getElementById("newChannelExpire");
const newChannelMax=document.getElementById("newChannelMax");
const newChannelDesc=document.getElementById("newChannelDesc");
const createChannelMsg=document.getElementById("createChannelMsg");
const createChannelConfirmBtn=document.getElementById("createChannelConfirmBtn");
const createChannelCancelBtn=document.getElementById("createChannelCancelBtn");

createChannelBtn.addEventListener("click",()=>{
  createChannelModal.style.display="flex";
  newChannelName.value="";
  newChannelPassword.value="";
  newChannelExpire.value="0";
  newChannelMax.value="0";
  newChannelDesc.value="";
  createChannelMsg.style.display="none";
});
createChannelCancelBtn.addEventListener("click",()=>{
  createChannelModal.style.display="none";
});
createChannelConfirmBtn.addEventListener("click",()=>{
  const cname=newChannelName.value.trim();
  if(!cname){
    createChannelMsg.style.display="block";
    createChannelMsg.textContent="频道名不能为空";
    return;
  }
  const pwd = newChannelPassword.value.trim();
  const expireSec = parseInt(newChannelExpire.value.trim())||0;
  const maxMem = parseInt(newChannelMax.value.trim())||0;
  const desc = newChannelDesc.value.trim();
  fetch(\`?action=createChannel&channelName=\${encodeURIComponent(cname)}&owner=\${encodeURIComponent(userName)}&password=\${encodeURIComponent(pwd)}&expireSec=\${expireSec}&maxMembers=\${maxMem}&desc=\${encodeURIComponent(desc)}\`)
    .then(r=>r.json())
    .then(d=>{
      if(d.error){
        createChannelMsg.style.display="block";
        createChannelMsg.textContent=d.error;
      } else {
        createChannelModal.style.display="none";
        alert("频道创建成功");
        loadCustomChannels();
      }
    });
});

/* =========== 管理员模式 =========== */
const adminIcon=document.getElementById("adminIcon");
const adminModal=document.getElementById("adminModal");
const adminPwdInput=document.getElementById("adminPwdInput");
const adminPwdMsg=document.getElementById("adminPwdMsg");
const adminPwdOkBtn=document.getElementById("adminPwdOkBtn");
const adminPwdCancelBtn=document.getElementById("adminPwdCancelBtn");
adminIcon.addEventListener("click",()=>{
  adminModal.style.display="flex";
  adminPwdInput.value="";
  adminPwdMsg.style.display="none";
});
adminPwdCancelBtn.onclick=()=>adminModal.style.display="none";
adminPwdOkBtn.onclick=()=>{
  const pwd=adminPwdInput.value.trim();
  if(!pwd){
    adminPwdMsg.textContent="密码不能为空";
    adminPwdMsg.style.display="block";
    return;
  }
  fetch(\`?action=adminList&pwd=\${encodeURIComponent(pwd)}\`)
    .then(r=>r.json())
    .then(d=>{
      if(d.error){
        adminPwdMsg.textContent=d.error;
        adminPwdMsg.style.display="block";
      } else {
        adminModal.style.display="none";
        showAdminPanel(pwd,d.channels,d.privateChats);
      }
    });
};
const adminPanel=document.getElementById("adminPanel");
const adminPanelContent=document.getElementById("adminPanelContent");
const adminPanelCloseBtn=document.getElementById("adminPanelCloseBtn");
function showAdminPanel(pwd,channels,privates){
  adminPanel.style.display="flex";
  let html=\`<h3>所有频道：</h3>\`;
  channels.forEach(ch=>{
    html+=\`<div style="border:1px solid #555;padding:5px;margin-bottom:5px;">
      <b>频道名:</b> \${ch.name} | <b>房主:</b> \${ch.owner} | <b>管理员:</b> \${(ch.admins||[]).join(",")}<br>
      <b>公告:</b> \${ch.desc||""}<br>
      <b>过期时间:</b> \${ch.expireTime||0} (时间戳) | <b>人数限制:</b> \${ch.maxMembers||0}<br>
      <b>已封禁:</b> \${ch.banned.join(",")}<br>
      <b>已踢出:</b> \${ch.kicked.join(",")}<br>
      <button onclick="adminDeleteChannel('\${ch.name}','\${pwd}')">删除此频道</button>
    </div>\`;
  });
  html+=\`<hr><h3>所有私聊文件：</h3>\`;
  privates.forEach(pf=>{
    html+=\`<div style="border:1px solid #555;padding:5px;margin-bottom:5px;">
      \${pf}.txt 
      <button onclick="adminDeletePrivate('\${pf}','\${pwd}')">删除此私聊</button>
    </div>\`;
  });
  adminPanelContent.innerHTML=html;
}
adminPanelCloseBtn.onclick=()=>{adminPanel.style.display="none";};

/* 管理员删除频道 */
function adminDeleteChannel(channelName,pwd){
  if(!confirm(\`确定要删除频道: \${channelName} 吗？\`))return;
  fetch(\`?action=deleteChannel&channel=\${encodeURIComponent(channelName)}&owner=xxx&isAdmin=1\`)
    .then(r=>r.json())
    .then(d=>{
      if(d.ok){
        alert("频道已删除");
        adminPanel.style.display="none";
        loadCustomChannels();
        // 若当前在此频道，也强制回到世界聊天室
        if(currentChannel===channelName){
          showChannelDeletedMsg();
          switchToWorldChannel();
        }
      } else alert(d.error||"删除失败");
    });
}
window.adminDeleteChannel=adminDeleteChannel;

/* 管理员删除私聊文件 */
function adminDeletePrivate(file,pwd){
  if(!confirm(\`确定删除私聊文件: \${file}.txt ？\`))return;
  fetch(\`?action=adminDeletePrivate&pwd=\${encodeURIComponent(pwd)}&file=\${encodeURIComponent(file)}\`)
    .then(r=>r.json())
    .then(d=>{
      if(d.ok){
        alert("已删除私聊文件");
        adminPanel.style.display="none";
      } else alert(d.error||"删除失败");
    });
}
window.adminDeletePrivate=adminDeletePrivate;

/* =========== 频道被删除/过期时的提示 =========== */
function showChannelDeletedMsg(reason="频道已被删除"){
  channelDeletedMsg.textContent = reason==="频道已过期并被删除" ? "频道已过期自动删除，您已回到世界聊天室" : "此频道已被删除，您已回到世界聊天室";
  channelDeletedMsg.style.display="block";
  setTimeout(()=>{
    channelDeletedMsg.classList.add("animate__fadeOut");
    setTimeout(()=>{
      channelDeletedMsg.classList.remove("animate__fadeOut");
      channelDeletedMsg.style.display="none";
    },1000);
  },2000);
}
</script>

</body>
</html>