interface UserInfo {
    _id: string;
    openid: string;
    unionid: string | null;
    nickName: string | null;
    avatarUrl: string | null;
    totalDownloads: number;
    createdAt: string;
    lastActiveAt: string;
}

const STORAGE_KEY = 'user_info';
const STORAGE_EXPIRE_KEY = 'user_info_expire';
const EXPIRE_DURATION = 7 * 24 * 60 * 60 * 1000; // 7 天

/** 内存中的用户数据（App 生命周期内有效） */
let currentUser: UserInfo | null = null;

/** 登录进行中的 Promise（防止并发重复调用） */
let loginPromise: Promise<UserInfo> | null = null;

/**
 * 获取当前用户，优先内存 → Storage → 云函数登录
 */
export async function getUser(): Promise<UserInfo> {
    // 1. 内存中有，直接返回
    if (currentUser) return currentUser;

    // 2. 尝试从 Storage 读取
    const cached = loadFromStorage();
    if (cached) {
        currentUser = cached;
        return cached;
    }

    // 3. 静默登录（防止并发）
    if (!loginPromise) {
        loginPromise = silentLogin().finally(() => {
            loginPromise = null;
        });
    }
    return loginPromise;
}

/**
 * 静默登录：调用云函数
 */
async function silentLogin(): Promise<UserInfo> {
    const res = await wx.cloud.callFunction({
        name: 'userLogin',
    });
    const result = (res?.result as any) || {};

    if (result.code !== 0) {
        throw new Error('登录失败');
    }

    const user = result.data as UserInfo;
    currentUser = user;
    saveToStorage(user);
    return user;
}

/**
 * 从 Storage 读取用户数据（检查过期）
 */
function loadFromStorage(): UserInfo | null {
    try {
        const expire = wx.getStorageSync(STORAGE_EXPIRE_KEY);
        if (!expire || Date.now() > expire) {
            wx.removeStorageSync(STORAGE_KEY);
            wx.removeStorageSync(STORAGE_EXPIRE_KEY);
            return null;
        }
        const user = wx.getStorageSync(STORAGE_KEY);
        return user || null;
    } catch {
        return null;
    }
}

/**
 * 写入 Storage
 */
function saveToStorage(user: UserInfo): void {
    try {
        wx.setStorageSync(STORAGE_KEY, user);
        wx.setStorageSync(STORAGE_EXPIRE_KEY, Date.now() + EXPIRE_DURATION);
    } catch {
        // Storage 写入失败不影响主流程
    }
}

/**
 * 清除登录状态
 */
export function clearUser(): void {
    currentUser = null;
    wx.removeStorageSync(STORAGE_KEY);
    wx.removeStorageSync(STORAGE_EXPIRE_KEY);
}

/**
 * 强制刷新用户数据（跳过缓存）
 */
export async function refreshUser(): Promise<UserInfo> {
    clearUser();
    return await silentLogin();
}

export type { UserInfo };