import { fetchApi } from './server-api-util';

// 全局缓存对象
const cache: Record<string, { data: any; timestamp: number }> = {};
const CACHE_DURATION = 5 * 60 * 1000; // 5分钟缓存时间

/**
 * 预取数据并缓存
 * @param url API地址
 * @param forceRefresh 是否强制刷新缓存
 * @returns 返回Promise，解析为获取到的数据
 */
export const prefetchData = async <T>(url: string, forceRefresh = false): Promise<T> => {
    const now = Date.now();

    // 检查缓存是否存在且未过期
    if (!forceRefresh && cache[url] && (now - cache[url].timestamp < CACHE_DURATION)) {
        return cache[url].data as T;
    }

    try {
        const data = await fetchApi<T>(url);
        // 缓存数据
        cache[url] = {
            data,
            timestamp: now,
        };
        return data;
    } catch (error) {
        console.error(`Prefetch failed for ${url}:`, error);
        // 如果缓存中有旧数据，返回旧数据
        if (cache[url]) {
            return cache[url].data as T;
        }
        throw error;
    }
};

/**
 * 预取聊天列表
 */
export const prefetchChats = async () => {
    return prefetchData<Array<{ session_id: string; title: string; latest_message?: any }>>('/chats');
};

/**
 * 预取单个聊天详情
 */
export const prefetchChatDetail = async (sessionId: string) => {
    return prefetchData(`/chats/${sessionId}/message-history`);
};

/**
 * 清除指定URL的缓存
 */
export const clearCache = (url?: string) => {
    if (url) {
        delete cache[url];
    } else {
        // 清除所有缓存
        Object.keys(cache).forEach(key => {
            delete cache[key];
        });
    }
};

/**
 * 获取缓存数据
 */
export const getCachedData = <T>(url: string): T | null => {
    const cached = cache[url];
    if (cached && (Date.now() - cached.timestamp < CACHE_DURATION)) {
        return cached.data as T;
    }
    return null;
};