import { LogLevel, LogMessage } from '../types/logger.types.js';
/**
* 日志服务接口
*/
export interface ILoggerService {
debug(message: string, ...args: any[]): void;
info(message: string, ...args: any[]): void;
warn(message: string, ...args: any[]): void;
error(message: string, ...args: any[]): void;
setLogLevel(level: LogLevel): void;
getLogLevel(): LogLevel;
demonstrateStreams(): void;
}
/**
* 日志消息格式
*/
interface McpLogMessage {
jsonrpc: "2.0";
method: "log";
params: {
level: "debug" | "info" | "warn" | "error";
message: string;
args?: any[];
timestamp: string;
};
}
/**
* 日志级别权重映射
*/
const LOG_LEVEL_WEIGHTS: Record<LogLevel, number> = {
[LogLevel.DEBUG]: 0,
[LogLevel.INFO]: 1,
[LogLevel.WARN]: 2,
[LogLevel.ERROR]: 3
};
/**
* 日志服务实现类
*/
class LoggerImpl implements ILoggerService {
private static instance: LoggerImpl;
private static instanceCount: number = 0;
private currentLogLevel: LogLevel;
private readonly instanceId: string;
private constructor() {
LoggerImpl.instanceCount++;
this.instanceId = Math.random().toString(36).substring(2, 8);
// 从环境变量读取日志级别，默认为INFO
const envLogLevel = process.env.LOG_LEVEL?.toUpperCase();
this.currentLogLevel = this.parseLogLevel(envLogLevel) || LogLevel.INFO;
// 如果是开发环境或设置了DEBUG环境变量，则启用DEBUG级别
if (process.env.NODE_ENV === 'development' || process.env.DEBUG) {
this.currentLogLevel = LogLevel.DEBUG;
}
// 输出初始化信息，不受级别限制
this.outputLog("info", `Logger[${this.instanceId}] initialized with level: ${this.currentLogLevel} (total instances: ${LoggerImpl.instanceCount})`);
}
public static getInstance(): LoggerImpl {
if (!LoggerImpl.instance) {
LoggerImpl.instance = new LoggerImpl();
} else {
// 输出重复调用信息
process.stderr.write(`{"jsonrpc":"2.0","method":"log","params":{"level":"debug","message":"[SINGLETON] Logger.getInstance() called, returning existing instance [${LoggerImpl.instance.instanceId}]","timestamp":"${new Date().toISOString()}"}}\n`);
}
return LoggerImpl.instance;
}
/**
* 解析日志级别字符串
*/
private parseLogLevel(level?: string): LogLevel | null {
if (!level) return null;
switch (level) {
case 'DEBUG': return LogLevel.DEBUG;
case 'INFO': return LogLevel.INFO;
case 'WARN': return LogLevel.WARN;
case 'ERROR': return LogLevel.ERROR;
default: return null;
}
}
/**
* 检查是否应该输出指定级别的日志
*/
private shouldLog(level: LogLevel): boolean {
return LOG_LEVEL_WEIGHTS[level] >= LOG_LEVEL_WEIGHTS[this.currentLogLevel];
}
/**
* 设置日志级别
*/
public setLogLevel(level: LogLevel): void {
this.currentLogLevel = level;
this.outputLog("info", `Logger[${this.instanceId}] level changed to: ${level}`);
}
/**
* 获取当前日志级别
*/
public getLogLevel(): LogLevel {
return this.currentLogLevel;
}
/**
* 创建日志消息
*/
private createLogMessage(level: "debug" | "info" | "warn" | "error", message: string, args: any[] = []): string {
const logMessage: McpLogMessage = {
jsonrpc: "2.0",
method: "log",
params: {
level,
message: `[${this.instanceId}] ${message}`,
args: args.length > 0 ? args : undefined,
timestamp: new Date().toISOString()
}
};
return JSON.stringify(logMessage);
}
/**
* 统一输出日志到stderr和console，确保MCP客户端能够捕获且方便开发调试
*/
private outputLog(level: "debug" | "info" | "warn" | "error", message: string, args: any[] = []): void {
const logString = this.createLogMessage(level, message, args);
// 输出到stderr，供MCP客户端捕获
process.stderr.write(logString + '\n');
// 同时输出到console，保持JSON格式便于调试
switch (level) {
case "debug":
console.debug(logString);
break;
case "info":
console.info(logString);
break;
case "warn":
console.warn(logString);
break;
case "error":
console.error(logString);
break;
}
}
public debug(message: string, ...args: any[]): void {
if (this.shouldLog(LogLevel.DEBUG)) {
this.outputLog("debug", message, args);
}
}
public info(message: string, ...args: any[]): void {
if (this.shouldLog(LogLevel.INFO)) {
this.outputLog("info", message, args);
}
}
public warn(message: string, ...args: any[]): void {
if (this.shouldLog(LogLevel.WARN)) {
this.outputLog("warn", message, args);
}
}
public error(message: string, ...args: any[]): void {
if (this.shouldLog(LogLevel.ERROR)) {
this.outputLog("error", message, args);
}
}
/**
* 演示stdout和stderr的区别
*/
public demonstrateStreams(): void {
// 输出到stdout（会污染MCP协议，不推荐）
process.stdout.write("This goes to STDOUT - may interfere with MCP protocol\n");
// 输出到stderr（MCP Logs会显示这个）
process.stderr.write("This goes to STDERR - will appear in MCP Logs\n");
// Console方法的默认行为
console.log("console.log → stdout"); // 输出到stdout
console.error("console.error → stderr"); // 输出到stderr
console.info("console.info → stdout"); // 输出到stdout
console.debug("console.debug → stderr"); // 输出到stderr
}
}
// 导出单例实例
export const Logger = LoggerImpl;
