<?php
/**
 * 路由拓扑 · 多用户版 — 前端控制器
 * PHP >= 7.3;存储使用数据库(SQLite / MySQL),详见 config.php。
 *
 * 目录约定:
 *   web/   前端静态文件(可整体替换)
 *   data/  数据目录(数据库文件,持久保存)
 *
 * 启动:php -S 0.0.0.0:8080 index.php  或 Apache 站点根指向本目录
 */
require_once __DIR__ . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'repo.php';

define('SESSION_COOKIE', 'rt_session');
define('WEB_DIR', __DIR__ . DIRECTORY_SEPARATOR . 'web');

/* ============================================================
 * 输出 / 输入
 * ============================================================ */
function json_out($data, $code = 200)
{
    if (!headers_sent()) {
        http_response_code($code);
        header('Content-Type: application/json; charset=utf-8');
        header('Cache-Control: no-store');
    }
    echo json_encode($data, JSON_UNESCAPED_UNICODE);
    exit;
}

function api_ok($extra = array())
{
    $payload = array('ok' => true);
    if (is_array($extra)) {
        $payload = array_merge($payload, $extra);
    }
    json_out($payload, 200);
}

function api_error($message, $code = 400)
{
    json_out(array('ok' => false, 'error' => $message), $code);
}

function json_input()
{
    $raw = file_get_contents('php://input');
    if ($raw === false || $raw === '') {
        return array();
    }
    $data = json_decode($raw, true);
    return is_array($data) ? $data : array();
}

function cfg($key, $default = null)
{
    $c = app_config();
    return array_key_exists($key, $c) ? $c[$key] : $default;
}

/**
 * 站点设置:config.php 提供默认值,数据库中保存的值优先
 */
function site_settings()
{
    $defaults = array(
        'site_name' => '路由拓扑',
        'site_logo' => '',
        'allow_registration' => cfg('allow_registration', true) ? '1' : '0',
        'session_ttl_days' => (string) max(1, (int) round(((int) cfg('session_ttl', 60 * 60 * 24 * 30)) / 86400)),
    );
    $saved = settings_all();
    foreach ($defaults as $k => $v) {
        if (array_key_exists($k, $saved) && $saved[$k] !== null && $saved[$k] !== '') {
            $defaults[$k] = $saved[$k];
        }
    }
    return $defaults;
}

function session_ttl_seconds()
{
    $days = (int) site_settings()['session_ttl_days'];
    if ($days < 1) {
        $days = 30;
    }
    return $days * 86400;
}

function client_ip()
{
    return isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : '';
}

function user_agent_str()
{
    $ua = isset($_SERVER['HTTP_USER_AGENT']) ? $_SERVER['HTTP_USER_AGENT'] : '';
    return str_cut($ua, 250);
}

function str_len($s)
{
    $s = (string) $s;
    return function_exists('mb_strlen') ? mb_strlen($s, 'UTF-8') : strlen($s);
}

function str_cut($s, $len)
{
    $s = (string) $s;
    return function_exists('mb_substr') ? mb_substr($s, 0, $len, 'UTF-8') : substr($s, 0, $len);
}

function valid_id($id)
{
    return is_string($id) && preg_match('/^[A-Za-z0-9_\-]{1,64}$/', $id) === 1;
}

function page_params()
{
    $page = isset($_GET['page']) ? (int) $_GET['page'] : 1;
    $pageSize = isset($_GET['pageSize']) ? (int) $_GET['pageSize'] : 10;
    if ($page < 1) {
        $page = 1;
    }
    if ($pageSize < 1) {
        $pageSize = 10;
    }
    if ($pageSize > 100) {
        $pageSize = 100;
    }
    return array($page, $pageSize, ($page - 1) * $pageSize);
}

/* ============================================================
 * 会话
 * ============================================================ */
function set_session_cookie($token, $expires)
{
    $secure = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off');
    if (PHP_VERSION_ID >= 70300) {
        setcookie(SESSION_COOKIE, $token, array(
            'expires' => $expires,
            'path' => '/',
            'httponly' => true,
            'samesite' => 'Lax',
            'secure' => $secure,
        ));
    } else {
        setcookie(SESSION_COOKIE, $token, $expires, '/; samesite=Lax', '', $secure, true);
    }
}

function clear_session_cookie()
{
    if (PHP_VERSION_ID >= 70300) {
        setcookie(SESSION_COOKIE, '', array(
            'expires' => time() - 3600,
            'path' => '/',
            'httponly' => true,
            'samesite' => 'Lax',
        ));
    } else {
        setcookie(SESSION_COOKIE, '', time() - 3600, '/');
    }
}

function current_user()
{
    static $cached = null;
    static $done = false;
    if ($done) {
        return $cached;
    }
    $done = true;

    $token = isset($_COOKIE[SESSION_COOKIE]) ? $_COOKIE[SESSION_COOKIE] : '';
    if ($token === '') {
        return null;
    }
    $s = session_find($token);
    if (!$s) {
        return null;
    }
    if ((int) $s['expires_at'] < time()) {
        session_delete($token);
        return null;
    }
    $u = user_find_by_id($s['user_id']);
    if (!$u || !empty($u['disabled'])) {
        return null;
    }
    $cached = $u;
    return $cached;
}

function require_auth()
{
    $u = current_user();
    if (!$u) {
        api_error('未登录或登录已过期', 401);
    }
    return $u;
}

function require_admin()
{
    $u = require_auth();
    if (!isset($u['role']) || $u['role'] !== 'admin') {
        api_error('需要管理员权限', 403);
    }
    return $u;
}

/* ============================================================
 * 转换
 * ============================================================ */
function public_user($u)
{
    if (!$u) {
        return null;
    }
    return array(
        'id' => $u['id'],
        'username' => $u['username'],
        'role' => isset($u['role']) ? $u['role'] : 'user',
        'disabled' => !empty($u['disabled']),
        'protected' => !empty($u['protected']),
        'mustChangePassword' => !empty($u['must_change_password']),
        'createdAt' => isset($u['created_at']) ? $u['created_at'] : '',
        'lastLoginAt' => isset($u['last_login_at']) ? $u['last_login_at'] : '',
        'loginCount' => isset($u['login_count']) ? (int) $u['login_count'] : 0,
    );
}

function log_row_out($r)
{
    return array(
        'id' => isset($r['id']) ? (int) $r['id'] : 0,
        'userId' => $r['user_id'],
        'username' => $r['username'],
        'action' => $r['action'],
        'target' => $r['target'],
        'detail' => $r['detail'],
        'ip' => $r['ip'],
        'createdAt' => $r['created_at'],
    );
}

function can_write_topo($row, $user)
{
    $p = topo_permission_for($row, $user);
    return $p === 'owner' || $p === 'edit';
}

function can_read_topo($row, $user)
{
    return topo_permission_for($row, $user) !== 'none';
}

/* 共享管理(增删共享 / 开关共享模式)仅限创建者本人或管理员 */
function can_manage_shares($row, $user)
{
    if (!$row || !$user) {
        return false;
    }
    if (isset($user['role']) && $user['role'] === 'admin') {
        return true;
    }
    return $row['owner_id'] === $user['id'];
}

/**
 * 受保护账号(默认管理员)不允许被任何用户改动
 */
function assert_not_protected($target, $action)
{
    if (!empty($target['protected'])) {
        api_error('受保护的默认管理员账号不允许' . $action, 403);
    }
}

function topo_summary($row, $user, $names)
{
    $ownerId = $row['owner_id'];
    $perm = topo_permission_for($row, $user);
    return array(
        'id' => $row['id'],
        'name' => $row['name'],
        'ownerId' => $ownerId,
        'ownerName' => isset($names[$ownerId]) ? $names[$ownerId] : '未知',
        'visibility' => ($row['visibility'] === 'public') ? 'public' : 'private',
        'createdAt' => isset($row['created_at']) ? $row['created_at'] : '',
        'updatedAt' => isset($row['updated_at']) ? $row['updated_at'] : '',
        'nodeCount' => (int) $row['node_count'],
        'edgeCount' => (int) $row['edge_count'],
        'canEdit' => ($perm === 'owner' || $perm === 'edit'),
        'permission' => $perm,
        'shareMode' => !empty($row['share_mode']),
        'sharedWithMe' => ($ownerId !== $user['id'] && !empty($row['share_mode']) && ($perm === 'edit' || $perm === 'view')),
        'rev' => isset($row['rev']) ? (int) $row['rev'] : 0,
    );
}

/* ============================================================
 * 认证接口
 * ============================================================ */
function api_login($in)
{
    $username = isset($in['username']) ? trim((string) $in['username']) : '';
    $password = isset($in['password']) ? (string) $in['password'] : '';
    if ($username === '' || $password === '') {
        api_error('请输入用户名和密码');
    }
    $u = user_find_by_name($username);
    if (!$u || !password_verify($password, $u['password_hash'])) {
        api_error('用户名或密码错误', 401);
    }
    if (!empty($u['disabled'])) {
        api_error('该账号已被禁用', 403);
    }

    $ttl = session_ttl_seconds();
    $token = bin2hex(random_bytes(32));
    $expires = time() + $ttl;
    session_purge_expired(time());
    session_create($token, $u['id'], $expires, client_ip(), user_agent_str());
    user_touch_login($u['id']);
    log_add($u['id'], $u['username'], 'login', '', '登录成功', client_ip());
    set_session_cookie($token, $expires);

    api_ok(array('user' => public_user(user_find_by_id($u['id']))));
}

/**
 * 密码强度校验(不满足时返回错误文案,满足返回 null)
 */
function weak_password($pw, $username)
{
    $pw = (string) $pw;
    if (strlen($pw) < 8) {
        return '密码至少 8 位';
    }
    if (!preg_match('/[A-Za-z]/', $pw) || !preg_match('/[0-9]/', $pw)) {
        return '密码必须同时包含字母和数字';
    }
    if ($username !== null && $username !== '' && strcasecmp($pw, (string) $username) === 0) {
        return '密码不能与用户名相同';
    }
    return null;
}

function api_register($in)
{
    if (site_settings()['allow_registration'] !== '1') {
        api_error('当前未开放注册,请联系管理员开通账号', 403);
    }
    $username = isset($in['username']) ? trim((string) $in['username']) : '';
    $password = isset($in['password']) ? (string) $in['password'] : '';
    if ($username === '' || $password === '') {
        api_error('用户名和密码不能为空');
    }
    if (!preg_match('/^[A-Za-z0-9_.\-]{2,32}$/', $username)) {
        api_error('用户名需为 2-32 位字母、数字、_ . -');
    }
    $weak = weak_password($password, $username);
    if ($weak !== null) {
        api_error($weak);
    }
    if (user_find_by_name($username)) {
        api_error('用户名已存在', 409);
    }

    $id = gen_id('u');
    user_insert(array(
        'id' => $id,
        'username' => $username,
        'password_hash' => password_hash($password, PASSWORD_DEFAULT),
        'role' => 'user',
        'disabled' => 0,
        'must_change_password' => 0,
        'created_at' => now_iso(),
    ));

    $ttl = session_ttl_seconds();
    $token = bin2hex(random_bytes(32));
    $expires = time() + $ttl;
    session_create($token, $id, $expires, client_ip(), user_agent_str());
    user_touch_login($id);
    log_add($id, $username, 'register', '', '注册账号', client_ip());
    set_session_cookie($token, $expires);

    api_ok(array('user' => public_user(user_find_by_id($id))));
}

function api_logout()
{
    $u = current_user();
    $token = isset($_COOKIE[SESSION_COOKIE]) ? $_COOKIE[SESSION_COOKIE] : '';
    if ($token !== '') {
        session_delete($token);
    }
    if ($u) {
        log_add($u['id'], $u['username'], 'logout', '', '退出登录', client_ip());
    }
    clear_session_cookie();
    api_ok(array('user' => null));
}

/* 公开:站点基本信息(名称 / Logo / 是否开放注册) */
function api_site()
{
    $s = site_settings();
    api_ok(array(
        'site' => array(
            'name' => $s['site_name'],
            'logo' => $s['site_logo'],
            'allowRegistration' => ($s['allow_registration'] === '1'),
        )
    ));
}

function api_change_password($user, $in)
{
    $old = isset($in['oldPassword']) ? (string) $in['oldPassword'] : '';
    $new = isset($in['newPassword']) ? (string) $in['newPassword'] : '';
    if (!password_verify($old, $user['password_hash'])) {
        api_error('原密码不正确', 403);
    }
    $weak = weak_password($new, $user['username']);
    if ($weak !== null) {
        api_error($weak);
    }
    if (password_verify($new, $user['password_hash'])) {
        api_error('新密码不能与原密码相同');
    }
    user_update($user['id'], array(
        'password_hash' => password_hash($new, PASSWORD_DEFAULT),
        'must_change_password' => 0,
    ));
    log_add($user['id'], $user['username'], 'password_change', '', '修改密码', client_ip());
    api_ok(array('user' => public_user(user_find_by_id($user['id']))));
}

/* ============================================================
 * 用户管理接口(管理员)
 * ============================================================ */
function admin_count()
{
    return (int) db_val("SELECT COUNT(*) FROM users WHERE role = 'admin' AND disabled = 0");
}

function api_users_list()
{
    list($page, $pageSize, $offset) = page_params();
    $q = isset($_GET['q']) ? trim((string) $_GET['q']) : '';
    $total = user_count($q);
    $rows = user_search($q, $pageSize, $offset);
    $list = array();
    foreach ($rows as $u) {
        $list[] = public_user($u);
    }
    api_ok(array('users' => $list, 'total' => $total, 'page' => $page, 'pageSize' => $pageSize));
}

function api_user_create($admin, $in)
{
    $username = isset($in['username']) ? trim((string) $in['username']) : '';
    $password = isset($in['password']) ? (string) $in['password'] : '';
    $role = (isset($in['role']) && $in['role'] === 'admin') ? 'admin' : 'user';

    if ($username === '' || $password === '') {
        api_error('用户名和密码不能为空');
    }
    if (!preg_match('/^[A-Za-z0-9_.\-]{2,32}$/', $username)) {
        api_error('用户名需为 2-32 位字母、数字、_ . -');
    }
    $weak = weak_password($password, $username);
    if ($weak !== null) {
        api_error($weak);
    }
    if (user_find_by_name($username)) {
        api_error('用户名已存在', 409);
    }

    $id = gen_id('u');
    user_insert(array(
        'id' => $id,
        'username' => $username,
        'password_hash' => password_hash($password, PASSWORD_DEFAULT),
        'role' => $role,
        'disabled' => 0,
        'must_change_password' => 1,
        'created_at' => now_iso(),
    ));
    log_add($admin['id'], $admin['username'], 'user_create', $id, '创建用户 ' . $username, client_ip());
    api_ok(array('user' => public_user(user_find_by_id($id))));
}

function api_user_update($admin, $id, $in)
{
    $u = user_find_by_id($id);
    if (!$u) {
        api_error('用户不存在', 404);
    }
    if (!empty($u['protected']) && (isset($in['role']) || isset($in['disabled']))) {
        api_error('受保护的默认管理员账号不允许修改角色或状态', 403);
    }

    $fields = array();
    $changes = array();

    if (isset($in['role'])) {
        $newRole = ($in['role'] === 'admin') ? 'admin' : 'user';
        if ($u['role'] === 'admin' && $newRole !== 'admin' && admin_count() <= 1) {
            api_error('至少保留一名管理员');
        }
        $fields['role'] = $newRole;
        $changes[] = '角色改为' . ($newRole === 'admin' ? '管理员' : '普通用户');
    }

    if (isset($in['disabled'])) {
        $disabled = !empty($in['disabled']) ? 1 : 0;
        if ($disabled) {
            if ($u['id'] === $admin['id']) {
                api_error('不能禁用当前登录账号');
            }
            if ($u['role'] === 'admin' && admin_count() <= 1) {
                api_error('至少保留一名可用管理员');
            }
        }
        $fields['disabled'] = $disabled;
        $changes[] = $disabled ? '禁用账号' : '启用账号';
    }

    if ($fields) {
        user_update($id, $fields);
        log_add($admin['id'], $admin['username'], 'user_update', $id, '更新用户 ' . $u['username'] . ':' . implode('、', $changes), client_ip());
    }
    api_ok(array('user' => public_user(user_find_by_id($id))));
}

/**
 * 重置指定用户的密码:需先验证当前管理员本人的密码
 */
function api_user_reset_password($admin, $id, $in)
{
    $u = user_find_by_id($id);
    if (!$u) {
        api_error('用户不存在', 404);
    }
    assert_not_protected($u, '重置密码');
    $adminPw = isset($in['adminPassword']) ? (string) $in['adminPassword'] : '';
    $newPw = isset($in['newPassword']) ? (string) $in['newPassword'] : '';
    if (!password_verify($adminPw, $admin['password_hash'])) {
        api_error('管理员密码不正确', 403);
    }
    $weak = weak_password($newPw, $u['username']);
    if ($weak !== null) {
        api_error($weak);
    }
    if (password_verify($newPw, $u['password_hash'])) {
        api_error('新密码不能与原密码相同');
    }
    user_update($id, array(
        'password_hash' => password_hash($newPw, PASSWORD_DEFAULT),
        'must_change_password' => 1,
    ));
    log_add($admin['id'], $admin['username'], 'user_reset_password', $id, '重置用户密码 ' . $u['username'], client_ip());
    api_ok(array('user' => public_user(user_find_by_id($id))));
}

function api_user_delete($admin, $id)
{
    $u = user_find_by_id($id);
    if (!$u) {
        api_error('用户不存在', 404);
    }
    assert_not_protected($u, '删除');
    if ($u['id'] === $admin['id']) {
        api_error('不能删除当前登录账号');
    }
    if ($u['role'] === 'admin' && admin_count() <= 1) {
        api_error('至少保留一名管理员');
    }
    user_delete($id);
    log_add($admin['id'], $admin['username'], 'user_delete', $id, '删除用户 ' . $u['username'], client_ip());
    api_ok();
}

/* ============================================================
 * 拓扑接口
 * ============================================================ */
function api_topo_list($user)
{
    $rows = topo_list_for_user($user);
    $names = user_name_map();
    $out = array();
    foreach ($rows as $r) {
        $out[] = topo_summary($r, $user, $names);
    }
    api_ok(array('topologies' => $out));
}

function api_topo_create($user, $in)
{
    $name = isset($in['name']) ? trim((string) $in['name']) : '';
    if ($name === '') {
        $name = '未命名拓扑';
    }
    if (str_len($name) > 60) {
        $name = str_cut($name, 60);
    }
    $nodes = (isset($in['nodes']) && is_array($in['nodes'])) ? $in['nodes'] : array();
    $edges = (isset($in['edges']) && is_array($in['edges'])) ? $in['edges'] : array();

    $id = gen_id('t');
    $now = now_iso();
    topo_insert(array(
        'id' => $id,
        'name' => $name,
        'owner_id' => $user['id'],
        'visibility' => 'private',
        'data' => json_encode(array('nodes' => $nodes, 'edges' => $edges), JSON_UNESCAPED_UNICODE),
        'node_count' => count($nodes),
        'edge_count' => count($edges),
        'created_at' => $now,
        'updated_at' => $now,
    ));
    log_add($user['id'], $user['username'], 'topo_create', $id, '创建拓扑 ' . $name, client_ip());
    api_ok(array('topology' => topo_summary(topo_find($id), $user, user_name_map())));
}

function api_topo_get($user, $id)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_read_topo($row, $user)) {
        api_error('无权访问该拓扑', 403);
    }
    $content = json_decode($row['data'], true);
    if (!is_array($content)) {
        $content = array();
    }
    api_ok(array(
        'topology' => topo_summary($row, $user, user_name_map()),
        'data' => array(
            'nodes' => (isset($content['nodes']) && is_array($content['nodes'])) ? $content['nodes'] : array(),
            'edges' => (isset($content['edges']) && is_array($content['edges'])) ? $content['edges'] : array(),
        ),
    ));
}

function api_topo_save($user, $id, $in)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_write_topo($row, $user)) {
        api_error('无权修改该拓扑', 403);
    }

    // 协同版本冲突检测:客户端携带的 baseRev 与服务端不一致时,返回最新数据供三方合并
    if (isset($in['baseRev'])) {
        $curRev = isset($row['rev']) ? (int) $row['rev'] : 0;
        if ((int) $in['baseRev'] !== $curRev) {
            $content = json_decode($row['data'], true);
            if (!is_array($content)) {
                $content = array();
            }
            json_out(array(
                'ok' => false,
                'error' => '版本冲突:该拓扑已被其他协作者更新',
                'conflict' => true,
                'rev' => $curRev,
                'topology' => topo_summary($row, $user, user_name_map()),
                'data' => array(
                    'nodes' => (isset($content['nodes']) && is_array($content['nodes'])) ? $content['nodes'] : array(),
                    'edges' => (isset($content['edges']) && is_array($content['edges'])) ? $content['edges'] : array(),
                ),
            ), 409);
        }
    }

    $nodes = (isset($in['nodes']) && is_array($in['nodes'])) ? $in['nodes'] : array();
    $edges = (isset($in['edges']) && is_array($in['edges'])) ? $in['edges'] : array();

    $name = null;
    if (isset($in['name']) && trim((string) $in['name']) !== '') {
        $name = str_cut(trim((string) $in['name']), 60);
    }
    topo_update(
        $id,
        json_encode(array('nodes' => $nodes, 'edges' => $edges), JSON_UNESCAPED_UNICODE),
        count($nodes),
        count($edges),
        now_iso(),
        $name
    );

    api_ok(array('topology' => topo_summary(topo_find($id), $user, user_name_map())));
}

function api_topo_delete($user, $id)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_write_topo($row, $user)) {
        api_error('无权删除该拓扑', 403);
    }
    topo_delete($id);
    log_add($user['id'], $user['username'], 'topo_delete', $id, '删除拓扑 ' . $row['name'], client_ip());
    api_ok();
}

function api_topo_permission($user, $id, $in)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_write_topo($row, $user)) {
        api_error('无权修改该拓扑', 403);
    }
    $vis = (isset($in['visibility']) && $in['visibility'] === 'public') ? 'public' : 'private';
    topo_set_visibility($id, $vis, now_iso());
    log_add($user['id'], $user['username'], 'topo_permission', $id, '拓扑可见性设为' . ($vis === 'public' ? '公开' : '私有') . ':' . $row['name'], client_ip());
    api_ok(array('topology' => topo_summary(topo_find($id), $user, user_name_map())));
}

function api_topo_rename($user, $id, $in)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_write_topo($row, $user)) {
        api_error('无权修改该拓扑', 403);
    }
    $name = isset($in['name']) ? trim((string) $in['name']) : '';
    if ($name === '') {
        api_error('拓扑名称不能为空');
    }
    if (str_len($name) > 60) {
        $name = str_cut($name, 60);
    }
    topo_set_name($id, $name, now_iso());
    log_add($user['id'], $user['username'], 'topo_rename', $id, '重命名拓扑 ' . $row['name'] . ' → ' . $name, client_ip());
    api_ok(array('topology' => topo_summary(topo_find($id), $user, user_name_map())));
}

function api_admin_topologies()
{
    list($page, $pageSize, $offset) = page_params();
    $q = isset($_GET['q']) ? trim((string) $_GET['q']) : '';
    $owner = isset($_GET['owner']) ? trim((string) $_GET['owner']) : '';
    $total = topo_admin_count($q, $owner);
    $rows = topo_admin_search($q, $owner, $pageSize, $offset);
    $user = current_user();
    $names = user_name_map();
    $list = array();
    foreach ($rows as $r) {
        $list[] = topo_summary($r, $user, $names);
    }
    api_ok(array('topologies' => $list, 'total' => $total, 'page' => $page, 'pageSize' => $pageSize));
}

/* 导出全部或指定的拓扑(含完整节点/连线数据),仅管理员可用 */
function api_admin_topologies_export()
{
    $idsParam = isset($_GET['ids']) ? trim((string) $_GET['ids']) : '';
    $ids = array();
    if ($idsParam !== '') {
        foreach (explode(',', $idsParam) as $one) {
            $one = trim($one);
            if ($one !== '' && valid_id($one)) {
                $ids[] = $one;
            }
        }
        if (!$ids) {
            api_error('未提供有效的拓扑 ID');
        }
    }

    $rows = topo_export_rows($ids);
    $names = user_name_map();
    $list = array();
    foreach ($rows as $r) {
        $content = json_decode($r['data'], true);
        if (!is_array($content)) {
            $content = array();
        }
        $list[] = array(
            'id' => $r['id'],
            'name' => $r['name'],
            'ownerId' => $r['owner_id'],
            'ownerName' => isset($names[$r['owner_id']]) ? $names[$r['owner_id']] : '未知',
            'visibility' => ($r['visibility'] === 'public') ? 'public' : 'private',
            'createdAt' => isset($r['created_at']) ? $r['created_at'] : '',
            'updatedAt' => isset($r['updated_at']) ? $r['updated_at'] : '',
            'nodeCount' => (int) $r['node_count'],
            'edgeCount' => (int) $r['edge_count'],
            'nodes' => (isset($content['nodes']) && is_array($content['nodes'])) ? $content['nodes'] : array(),
            'edges' => (isset($content['edges']) && is_array($content['edges'])) ? $content['edges'] : array(),
        );
    }
    api_ok(array('topologies' => $list, 'total' => count($list), 'exportedAt' => now_iso()));
}

/* 站点设置:读取(管理员) */
function api_admin_settings_get()
{
    $s = site_settings();
    api_ok(array(
        'settings' => array(
            'site_name' => $s['site_name'],
            'site_logo' => $s['site_logo'],
            'allow_registration' => ($s['allow_registration'] === '1'),
            'session_ttl_days' => (int) $s['session_ttl_days'],
        )
    ));
}

/* 站点设置:保存(管理员) */
function api_admin_settings_update($user, $in)
{
    $changes = array();

    if (isset($in['site_name'])) {
        $name = trim((string) $in['site_name']);
        if ($name === '') {
            api_error('网站名称不能为空');
        }
        if (str_len($name) > 40) {
            $name = str_cut($name, 40);
        }
        setting_set('site_name', $name);
        $changes[] = '名称';
    }

    if (array_key_exists('site_logo', $in)) {
        $logo = (string) $in['site_logo'];
        if ($logo !== '') {
            if (!preg_match('#^data:image/(png|jpe?g|gif|webp|svg\+xml);base64,#i', $logo)) {
                api_error('Logo 格式不支持,请上传 PNG / JPG / GIF / WEBP / SVG 图片');
            }
            if (strlen($logo) > 400000) {
                api_error('Logo 图片过大,请控制在 300KB 以内');
            }
        }
        setting_set('site_logo', $logo);
        $changes[] = 'Logo';
    }

    if (array_key_exists('allow_registration', $in)) {
        setting_set('allow_registration', !empty($in['allow_registration']) ? '1' : '0');
        $changes[] = '注册开关';
    }

    if (isset($in['session_ttl_days'])) {
        $days = (int) $in['session_ttl_days'];
        if ($days < 1) {
            $days = 1;
        }
        if ($days > 365) {
            $days = 365;
        }
        setting_set('session_ttl_days', (string) $days);
        $changes[] = '会话有效期';
    }

    log_add($user['id'], $user['username'], 'site_settings', '', '更新站点设置:' . ($changes ? implode('、', $changes) : '无变更'), client_ip());
    api_admin_settings_get();
}

/* ============================================================
 * 概览 / 日志(管理员)
 * ============================================================ */
function api_dashboard()
{
    $stats = stats_overview();
    $user = current_user();
    $names = user_name_map();

    $recentLogs = array();
    foreach (log_recent(8) as $r) {
        $recentLogs[] = log_row_out($r);
    }
    $recentTopos = array();
    foreach (topo_recent(5) as $r) {
        $recentTopos[] = topo_summary($r, $user, $names);
    }
    api_ok(array('stats' => $stats, 'recentLogs' => $recentLogs, 'recentTopos' => $recentTopos));
}

function api_logs()
{
    list($page, $pageSize, $offset) = page_params();
    $q = isset($_GET['q']) ? trim((string) $_GET['q']) : '';
    $total = log_count($q);
    $rows = log_search($q, $pageSize, $offset);
    $list = array();
    foreach ($rows as $r) {
        $list[] = log_row_out($r);
    }
    api_ok(array('logs' => $list, 'total' => $total, 'page' => $page, 'pageSize' => $pageSize));
}

/* ============================================================
 * 用户分组接口(管理员)
 * ============================================================ */
function group_out($g, $count)
{
    return array(
        'id' => $g['id'],
        'name' => $g['name'],
        'description' => isset($g['description']) ? $g['description'] : '',
        'memberCount' => (int) $count,
        'createdAt' => isset($g['created_at']) ? $g['created_at'] : '',
        'updatedAt' => isset($g['updated_at']) ? $g['updated_at'] : '',
    );
}

function api_groups_list()
{
    $counts = group_member_counts();
    $list = array();
    foreach (group_list() as $g) {
        $list[] = group_out($g, isset($counts[$g['id']]) ? $counts[$g['id']] : 0);
    }
    api_ok(array('groups' => $list));
}

function api_group_create($admin, $in)
{
    $name = isset($in['name']) ? trim((string) $in['name']) : '';
    $desc = isset($in['description']) ? trim((string) $in['description']) : '';
    if ($name === '') {
        api_error('请输入分组名称');
    }
    if (str_len($name) > 40) {
        $name = str_cut($name, 40);
    }
    if (str_len($desc) > 120) {
        $desc = str_cut($desc, 120);
    }
    if (group_find_by_name($name)) {
        api_error('分组名称已存在', 409);
    }
    $id = gen_id('g');
    group_insert(array('id' => $id, 'name' => $name, 'description' => $desc));
    log_add($admin['id'], $admin['username'], 'group_create', $id, '创建分组 ' . $name, client_ip());
    api_ok(array('group' => group_out(group_find($id), 0)));
}

function api_group_update($admin, $id, $in)
{
    $g = group_find($id);
    if (!$g) {
        api_error('分组不存在', 404);
    }
    $fields = array();
    if (isset($in['name'])) {
        $name = trim((string) $in['name']);
        if ($name === '') {
            api_error('分组名称不能为空');
        }
        if (str_len($name) > 40) {
            $name = str_cut($name, 40);
        }
        $dup = group_find_by_name($name);
        if ($dup && $dup['id'] !== $id) {
            api_error('分组名称已存在', 409);
        }
        $fields['name'] = $name;
    }
    if (isset($in['description'])) {
        $desc = trim((string) $in['description']);
        if (str_len($desc) > 120) {
            $desc = str_cut($desc, 120);
        }
        $fields['description'] = $desc;
    }
    if ($fields) {
        group_update($id, $fields);
        log_add($admin['id'], $admin['username'], 'group_update', $id, '更新分组 ' . $g['name'], client_ip());
    }
    $counts = group_member_counts();
    api_ok(array('group' => group_out(group_find($id), isset($counts[$id]) ? $counts[$id] : 0)));
}

function api_group_delete($admin, $id)
{
    $g = group_find($id);
    if (!$g) {
        api_error('分组不存在', 404);
    }
    group_delete($id);
    log_add($admin['id'], $admin['username'], 'group_delete', $id, '删除分组 ' . $g['name'], client_ip());
    api_ok();
}

function api_group_members($id)
{
    if (!group_find($id)) {
        api_error('分组不存在', 404);
    }
    api_ok(array('members' => group_members($id)));
}

function api_group_members_set($admin, $id, $in)
{
    $g = group_find($id);
    if (!$g) {
        api_error('分组不存在', 404);
    }
    $ids = (isset($in['userIds']) && is_array($in['userIds'])) ? $in['userIds'] : array();
    $valid = array();
    foreach ($ids as $uid) {
        $uid = (string) $uid;
        if ($uid !== '' && user_find_by_id($uid) && !in_array($uid, $valid, true)) {
            $valid[] = $uid;
        }
    }
    group_set_members($id, $valid);
    log_add($admin['id'], $admin['username'], 'group_members', $id, '更新分组成员 ' . $g['name'] . ':共 ' . count($valid) . ' 人', client_ip());
    api_ok(array('members' => group_members($id)));
}

function group_name_map()
{
    $map = array();
    foreach (group_list() as $g) {
        $map[$g['id']] = $g['name'];
    }
    return $map;
}

/* ============================================================
 * 拓扑共享接口
 * ============================================================ */
function share_out($s, $userNames, $groupNames)
{
    if ($s['target_type'] === 'user') {
        $name = isset($userNames[$s['target_id']]) ? $userNames[$s['target_id']] : '未知用户';
    } else {
        $name = isset($groupNames[$s['target_id']]) ? $groupNames[$s['target_id']] : '未知分组';
    }
    return array(
        'id' => $s['id'],
        'targetType' => $s['target_type'],
        'targetId' => $s['target_id'],
        'targetName' => $name,
        'permission' => ($s['permission'] === 'edit') ? 'edit' : 'view',
    );
}

function api_topo_shares_get($user, $id)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_manage_shares($row, $user)) {
        api_error('仅创建者可管理该拓扑的共享', 403);
    }
    $userNames = user_name_map();
    $groupNames = group_name_map();
    $shares = array();
    foreach (share_list_by_topo($id) as $s) {
        $shares[] = share_out($s, $userNames, $groupNames);
    }
    api_ok(array(
        'shareMode' => !empty($row['share_mode']),
        'shares' => $shares,
    ));
}

function api_topo_shares_set($user, $id, $in)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_manage_shares($row, $user)) {
        api_error('仅创建者可管理该拓扑的共享', 403);
    }
    $shareMode = !empty($in['shareMode']);
    $rows = array();
    $seen = array();
    if ($shareMode && isset($in['shares']) && is_array($in['shares'])) {
        foreach ($in['shares'] as $s) {
            if (!is_array($s)) {
                continue;
            }
            $tt = (isset($s['targetType']) && $s['targetType'] === 'group') ? 'group' : 'user';
            $tid = isset($s['targetId']) ? (string) $s['targetId'] : '';
            if ($tid === '') {
                continue;
            }
            if ($tt === 'user') {
                if ($tid === $row['owner_id'] || !user_find_by_id($tid)) {
                    continue;
                }
            } else {
                if (!group_find($tid)) {
                    continue;
                }
            }
            $key = $tt . ':' . $tid;
            if (isset($seen[$key])) {
                continue;
            }
            $seen[$key] = true;
            $rows[] = array(
                'target_type' => $tt,
                'target_id' => $tid,
                'permission' => (isset($s['permission']) && $s['permission'] === 'edit') ? 'edit' : 'view',
            );
        }
    }
    share_replace($id, $rows, $user['id']);
    topo_set_share_mode($id, $shareMode, now_iso());
    log_add(
        $user['id'],
        $user['username'],
        'topo_share',
        $id,
        ($shareMode ? '开启共享' : '关闭共享') . '(共 ' . count($rows) . ' 项):' . $row['name'],
        client_ip()
    );
    api_topo_shares_get($user, $id);
}

/* ============================================================
 * 通讯录 / 概览
 * ============================================================ */
function api_directory()
{
    $users = array();
    foreach (db_all('SELECT id, username FROM users WHERE disabled = 0 ORDER BY username ASC') as $u) {
        $users[] = array('id' => $u['id'], 'username' => $u['username']);
    }
    $groups = array();
    foreach (group_list() as $g) {
        $groups[] = array('id' => $g['id'], 'name' => $g['name']);
    }
    api_ok(array('users' => $users, 'groups' => $groups));
}

function api_overview($user)
{
    $own = 0;
    $shared = 0;
    foreach (topo_list_for_user($user) as $r) {
        if ($r['owner_id'] === $user['id']) {
            $own++;
            continue;
        }
        $perm = topo_permission_for($r, $user);
        if (!empty($r['share_mode']) && ($perm === 'edit' || $perm === 'view')) {
            $shared++;
        }
    }
    api_ok(array(
        'overview' => array(
            'myTopo' => $own,
            'sharedToMe' => $shared,
            'myGroups' => count(group_ids_of_user($user['id'])),
            'publicTopo' => (int) db_val("SELECT COUNT(*) FROM topologies WHERE visibility = 'public'"),
        )
    ));
}

/* 当前用户所属分组(普通用户可用) */
function api_my_groups($user)
{
    $out = array();
    foreach (group_ids_of_user($user['id']) as $gid) {
        $g = group_find($gid);
        if (!$g) {
            continue;
        }
        $out[] = array(
            'id' => $g['id'],
            'name' => $g['name'],
            'description' => isset($g['description']) ? $g['description'] : '',
            'memberCount' => count(group_member_ids($gid)),
        );
    }
    api_ok(array('groups' => $out));
}

/* ============================================================
 * 协同:在线状态 / 版本推送
 * ============================================================ */
function presence_online_out($plist, $selfId)
{
    $out = array();
    foreach ($plist as $p) {
        $out[] = array(
            'id' => $p['user_id'],
            'username' => $p['username'],
            'self' => ($p['user_id'] === $selfId),
        );
    }
    return $out;
}

function sse_event($event, $data)
{
    echo 'event: ' . $event . "\n";
    echo 'data: ' . json_encode($data, JSON_UNESCAPED_UNICODE) . "\n\n";
    if (ob_get_level() > 0) {
        @ob_flush();
    }
    @flush();
}

/**
 * SSE 推送:拓扑版本变化 + 在线成员。
 * 有界存活(约 30s)后关闭,由前端 EventSource 自动重连。
 * 注意:php -S 单进程下会占用一个 worker,建议设置 PHP_CLI_SERVER_WORKERS;
 * Apache / PHP-FPM 无此限制。
 */
function api_topo_stream($user, $id, $since)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_read_topo($row, $user)) {
        api_error('无权访问该拓扑', 403);
    }

    @ini_set('zlib.output_compression', '0');
    @ini_set('output_buffering', '0');
    @set_time_limit(0);
    while (ob_get_level() > 0) {
        @ob_end_flush();
    }

    header('Content-Type: text/event-stream; charset=utf-8');
    header('Cache-Control: no-cache, no-store');
    header('X-Accel-Buffering: no');

    $deadline = time() + 30;
    $lastRev = null;
    $lastPresence = null;

    presence_touch($id, $user);
    presence_purge(time() - 120);

    while (time() < $deadline) {
        if (connection_aborted()) {
            return;
        }
        $cur = topo_find($id);
        if (!$cur) {
            sse_event('gone', array('reason' => 'deleted'));
            return;
        }
        $rev = isset($cur['rev']) ? (int) $cur['rev'] : 0;
        if ($rev !== $lastRev) {
            $lastRev = $rev;
            if ($rev !== $since) {
                sse_event('revision', array('rev' => $rev));
            }
        }

        presence_touch($id, $user);
        $plist = presence_online_out(presence_list($id, 15), $user['id']);
        $hash = md5(json_encode($plist));
        if ($hash !== $lastPresence) {
            $lastPresence = $hash;
            sse_event('presence', array('users' => $plist));
        }

        sse_event('ping', array('t' => time()));
        usleep(1500000);
    }
    sse_event('bye', array('t' => time()));
}

function api_topo_poll($user, $id, $since)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_read_topo($row, $user)) {
        api_error('无权访问该拓扑', 403);
    }
    presence_touch($id, $user);
    presence_purge(time() - 120);
    $rev = isset($row['rev']) ? (int) $row['rev'] : 0;
    api_ok(array(
        'rev' => $rev,
        'changed' => ($since >= 0 && (int) $since !== $rev),
        'presence' => presence_online_out(presence_list($id, 15), $user['id']),
    ));
}

function api_topo_presence($user, $id, $in)
{
    if (!valid_id($id)) {
        api_error('非法的拓扑 ID');
    }
    $row = topo_find($id);
    if (!$row) {
        api_error('拓扑不存在', 404);
    }
    if (!can_read_topo($row, $user)) {
        api_error('无权访问该拓扑', 403);
    }
    if (!empty($in['leave'])) {
        presence_remove($id, $user['id']);
    } else {
        presence_touch($id, $user);
    }
    presence_purge(time() - 120);
    api_ok(array('presence' => presence_online_out(presence_list($id, 15), $user['id'])));
}

/* ============================================================
 * 路由
 * ============================================================ */
function handle_api($method, $segments)
{
    $resource = isset($segments[1]) ? $segments[1] : '';
    $id = isset($segments[2]) ? $segments[2] : '';
    $action = isset($segments[3]) ? $segments[3] : '';

    switch ($resource) {

        case 'login':
            if ($method !== 'POST') {
                api_error('方法不允许', 405);
            }
            api_login(json_input());
            break;

        case 'register':
            if ($method !== 'POST') {
                api_error('方法不允许', 405);
            }
            api_register(json_input());
            break;

        case 'logout':
            if ($method !== 'POST') {
                api_error('方法不允许', 405);
            }
            api_logout();
            break;

        case 'me':
            if ($method !== 'GET') {
                api_error('方法不允许', 405);
            }
            $u = current_user();
            api_ok(array('user' => $u ? public_user($u) : null));
            break;

        case 'directory':
            require_auth();
            if ($method !== 'GET') {
                api_error('方法不允许', 405);
            }
            api_directory();
            break;

        case 'overview':
            $u = require_auth();
            if ($method !== 'GET') {
                api_error('方法不允许', 405);
            }
            api_overview($u);
            break;

        case 'mygroups':
            $u = require_auth();
            if ($method !== 'GET') {
                api_error('方法不允许', 405);
            }
            api_my_groups($u);
            break;

        case 'site':
            if ($method !== 'GET') {
                api_error('方法不允许', 405);
            }
            api_site();
            break;

        case 'password':
            if ($method !== 'POST' && $method !== 'PUT') {
                api_error('方法不允许', 405);
            }
            api_change_password(require_auth(), json_input());
            break;

        case 'dashboard':
            require_admin();
            if ($method !== 'GET') {
                api_error('方法不允许', 405);
            }
            api_dashboard();
            break;

        case 'logs':
            require_admin();
            if ($method !== 'GET') {
                api_error('方法不允许', 405);
            }
            api_logs();
            break;

        case 'users':
            $admin = require_admin();
            if ($method === 'GET' && $id === '') {
                api_users_list();
            }
            if ($method === 'POST' && $id === '') {
                api_user_create($admin, json_input());
            }
            if ($id !== '') {
                if ($action === 'password' && $method === 'PUT') {
                    api_user_reset_password($admin, $id, json_input());
                }
                if ($action === '' && $method === 'PUT') {
                    api_user_update($admin, $id, json_input());
                }
                if ($action === '' && $method === 'DELETE') {
                    api_user_delete($admin, $id);
                }
            }
            api_error('接口不存在', 404);
            break;

        case 'groups':
            $admin = require_admin();
            if ($method === 'GET' && $id === '') {
                api_groups_list();
            }
            if ($method === 'POST' && $id === '') {
                api_group_create($admin, json_input());
            }
            if ($id !== '') {
                if ($action === 'members') {
                    if ($method === 'GET') {
                        api_group_members($id);
                    }
                    if ($method === 'PUT') {
                        api_group_members_set($admin, $id, json_input());
                    }
                }
                if ($action === '' && $method === 'PUT') {
                    api_group_update($admin, $id, json_input());
                }
                if ($action === '' && $method === 'DELETE') {
                    api_group_delete($admin, $id);
                }
            }
            api_error('接口不存在', 404);
            break;

        case 'admin':
            $admin = require_admin();
            if ($id === 'topologies' && $action === '' && $method === 'GET') {
                api_admin_topologies();
            }
            if ($id === 'topologies' && $action === 'export' && $method === 'GET') {
                api_admin_topologies_export();
            }
            if ($id === 'settings' && $action === '') {
                if ($method === 'GET') {
                    api_admin_settings_get();
                }
                if ($method === 'PUT') {
                    api_admin_settings_update($admin, json_input());
                }
            }
            api_error('接口不存在', 404);
            break;

        case 'topologies':
            $user = require_auth();
            if ($method === 'GET' && $id === '') {
                api_topo_list($user);
            }
            if ($method === 'POST' && $id === '') {
                api_topo_create($user, json_input());
            }
            if ($id !== '') {
                if ($action === 'permission' && $method === 'PUT') {
                    api_topo_permission($user, $id, json_input());
                }
                if ($action === 'rename' && $method === 'PUT') {
                    api_topo_rename($user, $id, json_input());
                }
                if ($action === 'shares' && $method === 'GET') {
                    api_topo_shares_get($user, $id);
                }
                if ($action === 'shares' && $method === 'PUT') {
                    api_topo_shares_set($user, $id, json_input());
                }
                if ($action === 'stream' && $method === 'GET') {
                    api_topo_stream($user, $id, isset($_GET['since']) ? (int) $_GET['since'] : -1);
                    exit;
                }
                if ($action === 'poll' && $method === 'GET') {
                    api_topo_poll($user, $id, isset($_GET['since']) ? (int) $_GET['since'] : -1);
                }
                if ($action === 'presence' && $method === 'POST') {
                    api_topo_presence($user, $id, json_input());
                }
                if ($action === '') {
                    if ($method === 'GET') {
                        api_topo_get($user, $id);
                    }
                    if ($method === 'PUT') {
                        api_topo_save($user, $id, json_input());
                    }
                    if ($method === 'DELETE') {
                        api_topo_delete($user, $id);
                    }
                }
            }
            api_error('接口不存在', 404);
            break;

        default:
            api_error('接口不存在', 404);
    }
}

/* ============================================================
 * 静态文件
 * ============================================================ */
function mime_type($file)
{
    $ext = strtolower(pathinfo($file, PATHINFO_EXTENSION));
    $map = array(
        'html' => 'text/html; charset=utf-8',
        'htm' => 'text/html; charset=utf-8',
        'js' => 'application/javascript; charset=utf-8',
        'mjs' => 'application/javascript; charset=utf-8',
        'css' => 'text/css; charset=utf-8',
        'json' => 'application/json; charset=utf-8',
        'png' => 'image/png',
        'jpg' => 'image/jpeg',
        'jpeg' => 'image/jpeg',
        'gif' => 'image/gif',
        'svg' => 'image/svg+xml',
        'webp' => 'image/webp',
        'ico' => 'image/x-icon',
        'woff' => 'font/woff',
        'woff2' => 'font/woff2',
        'ttf' => 'font/ttf',
        'map' => 'application/json; charset=utf-8',
        'txt' => 'text/plain; charset=utf-8',
    );
    return isset($map[$ext]) ? $map[$ext] : 'application/octet-stream';
}

function serve_static($path)
{
    $rel = ltrim((string) $path, '/');
    if ($rel === '' || $rel === 'index.php' || $rel === 'web') {
        $rel = 'index.html';
    }
    // 兼容以 web/ 前缀访问(如 Apache 直接请求 /web/style.css)
    if (strpos($rel, 'web/') === 0) {
        $rel = substr($rel, 4);
    }
    // 仅放行前端资源,避免通过静态服务泄露后端文件
    $ext = strtolower(pathinfo($rel, PATHINFO_EXTENSION));
    $allow = array('html', 'htm', 'css', 'js', 'mjs', 'json', 'png', 'jpg', 'jpeg', 'gif', 'svg', 'webp', 'ico', 'woff', 'woff2', 'ttf', 'txt', 'map');
    if (!in_array($ext, $allow, true)) {
        $rel = 'index.html';
    }

    $root = realpath(WEB_DIR);
    $file = realpath(WEB_DIR . DIRECTORY_SEPARATOR . $rel);

    if ($root === false || $file === false || strpos($file, $root . DIRECTORY_SEPARATOR) !== 0 || !is_file($file)) {
        $index = realpath(WEB_DIR . DIRECTORY_SEPARATOR . 'index.html');
        if ($index !== false && is_file($index)) {
            header('Content-Type: text/html; charset=utf-8');
            readfile($index);
            return;
        }
        http_response_code(404);
        header('Content-Type: text/plain; charset=utf-8');
        echo '404 Not Found';
        return;
    }

    header('Content-Type: ' . mime_type($file));
    header('Content-Length: ' . filesize($file));
    readfile($file);
}

/* ============================================================
 * 入口
 * ============================================================ */
ensure_seed();

$method = isset($_SERVER['REQUEST_METHOD']) ? strtoupper($_SERVER['REQUEST_METHOD']) : 'GET';

// 支持三种入口(无需 URL 重写):
//   1) ?r=/api/xxx        查询串,兼容性最好(前端默认使用)
//   2) /index.php/api/xxx  PATH_INFO
//   3) /api/xxx            需重写或内置服务器路由
if (isset($_GET['r']) && $_GET['r'] !== '') {
    $r = (string) $_GET['r'];
    $rq = parse_url($r, PHP_URL_QUERY);
    if ($rq !== null && $rq !== false && $rq !== '') {
        parse_str($rq, $extra);
        if (is_array($extra)) {
            foreach ($extra as $k => $v) {
                if (!isset($_GET[$k])) {
                    $_GET[$k] = $v;
                }
            }
        }
    }
    $parsedPath = parse_url($r, PHP_URL_PATH);
} elseif (!empty($_SERVER['PATH_INFO'])) {
    $parsedPath = $_SERVER['PATH_INFO'];
} else {
    $uri = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '/';
    $parsedPath = parse_url($uri, PHP_URL_PATH);
}
if ($parsedPath === false || $parsedPath === null || $parsedPath === '') {
    $parsedPath = '/';
}

$segments = array_values(array_filter(explode('/', $parsedPath), function ($s) {
    return $s !== '';
}));

if (count($segments) > 0 && $segments[0] === 'index.php') {
    array_shift($segments);
}

if (count($segments) > 0 && $segments[0] === 'api') {
    handle_api($method, $segments);
    exit;
}

serve_static($parsedPath);