/**
 * 阿里云日志服务（SLS）日志模块
 *
 * 功能：
 * - 将 API 请求/响应日志上报到阿里云 SLS
 * - 批量上报，减少 API 调用
 * - 环境变量缺失时静默降级
 */

import ALSClient from 'aliyun-log';

// SLS 配置
const SLS_CONFIG = {
    accessKeyId: process.env.ALIYUN_ACCESS_KEY_ID,
    accessKeySecret: process.env.ALIYUN_ACCESS_KEY_SECRET,
    endpoint: process.env.ALIYUN_SLS_ENDPOINT,
    project: process.env.ALIYUN_SLS_PROJECT,
    logstore: process.env.ALIYUN_SLS_LOGSTORE
};

// 检查配置是否完整
const isConfigured = Object.values(SLS_CONFIG).every(v => v);

let client = null;
let logQueue = [];
const BATCH_SIZE = 10;
const FLUSH_INTERVAL_MS = 5000;

// 初始化 SLS Client
function initClient() {
    if (!isConfigured) {
        console.warn('[SLS] 阿里云日志服务未配置，日志将仅输出到控制台');
        return null;
    }

    try {
        client = new ALSClient({
            accessKeyId: SLS_CONFIG.accessKeyId,
            accessKeySecret: SLS_CONFIG.accessKeySecret,
            endpoint: SLS_CONFIG.endpoint
        });
        console.log('[SLS] 阿里云日志服务客户端初始化成功');
        return client;
    } catch (error) {
        console.error('[SLS] 初始化失败:', error.message);
        return null;
    }
}

// 刷新日志队列
async function flushLogs() {
    if (!client || logQueue.length === 0) return;

    const logsToSend = logQueue.splice(0, BATCH_SIZE);

    try {
        const logs = logsToSend.map(log => ({
            timestamp: Math.floor(Date.now() / 1000),
            content: Object.fromEntries(
                Object.entries(log).map(([key, value]) => [key, String(value ?? '')])
            )
        }));

        await client.postLogStoreLogs(SLS_CONFIG.project, SLS_CONFIG.logstore, { logs });
        console.log(`[SLS] 成功上报 ${logsToSend.length} 条日志`);
    } catch (error) {
        console.error('[SLS] 日志上报失败:', error.message);
        // 失败的日志重新入队（可选：限制重试次数）
        logQueue.unshift(...logsToSend);
    }
}

// 定时刷新
let flushTimer = null;
function startFlushTimer() {
    if (flushTimer || !isConfigured) return;
    flushTimer = setInterval(flushLogs, FLUSH_INTERVAL_MS);
}

/**
 * 记录 API 请求日志
 * @param {Object} logData - 日志数据
 * @param {string} logData.method - HTTP 方法
 * @param {string} logData.endpoint - 请求路径
 * @param {string} logData.model - 模型 ID
 * @param {number} logData.status - 响应状态码
 * @param {number} logData.duration_ms - 请求耗时
 * @param {number} [logData.input_tokens] - 输入 Token 数
 * @param {number} [logData.output_tokens] - 输出 Token 数
 * @param {string} [logData.error] - 错误信息
 */
export function logRequest(logData) {
    const enrichedLog = {
        timestamp: new Date().toISOString(),
        ...logData
    };

    // 始终输出到控制台
    console.log('[SLS]', JSON.stringify(enrichedLog));

    if (!isConfigured) return;

    logQueue.push(enrichedLog);

    // 队列满时立即刷新
    if (logQueue.length >= BATCH_SIZE) {
        flushLogs();
    }
}

/**
 * 优雅关闭，刷新剩余日志
 */
export async function shutdown() {
    if (flushTimer) {
        clearInterval(flushTimer);
        flushTimer = null;
    }
    await flushLogs();
    console.log('[SLS] 已关闭');
}

// 初始化
initClient();
startFlushTimer();

// 进程退出时优雅关闭
process.on('SIGTERM', shutdown);
process.on('SIGINT', shutdown);

export default {
    logRequest,
    shutdown
};