/**
* Simple logger for Fizzy MCP Server
* Logs to stderr to avoid interfering with stdio transport
*/
export type LogLevel = "debug" | "info" | "warn" | "error";
const LOG_LEVELS: Record<LogLevel, number> = {
debug: 0,
info: 1,
warn: 2,
error: 3,
};
class Logger {
private level: LogLevel;
private prefix: string;
constructor(prefix = "fizzy-mcp") {
this.prefix = prefix;
this.level = (process.env.LOG_LEVEL as LogLevel) || "info";
}
private shouldLog(level: LogLevel): boolean {
return LOG_LEVELS[level] >= LOG_LEVELS[this.level];
}
private formatMessage(level: LogLevel, message: string, data?: unknown): string {
const timestamp = new Date().toISOString();
const dataStr = data ? ` ${JSON.stringify(data)}` : "";
return `[${timestamp}] [${this.prefix}] [${level.toUpperCase()}] ${message}${dataStr}`;
}
debug(message: string, data?: unknown): void {
if (this.shouldLog("debug")) {
console.error(this.formatMessage("debug", message, data));
}
}
info(message: string, data?: unknown): void {
if (this.shouldLog("info")) {
console.error(this.formatMessage("info", message, data));
}
}
warn(message: string, data?: unknown): void {
if (this.shouldLog("warn")) {
console.error(this.formatMessage("warn", message, data));
}
}
error(message: string, error?: unknown): void {
if (this.shouldLog("error")) {
const errorData =
error instanceof Error
? { name: error.name, message: error.message, stack: error.stack }
: error;
console.error(this.formatMessage("error", message, errorData));
}
}
/**
* Create a child logger with a sub-prefix
*/
child(subPrefix: string): Logger {
const child = new Logger(`${this.prefix}:${subPrefix}`);
child.level = this.level;
return child;
}
/**
* Set the log level dynamically
*/
setLevel(level: LogLevel): void {
this.level = level;
}
}
// Export singleton instance
export const logger = new Logger();
// Export class for creating child loggers
export { Logger };
