/**
* Copyright (c) 2026 Ivan Iraci <ivan.iraci@professioneit.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
import { ENV } from '../constants.js';
export type LogLevel = 'debug' | 'info' | 'warn' | 'error';
const LOG_LEVELS: Record<LogLevel, number> = {
debug: 0,
info: 1,
warn: 2,
error: 3,
};
/**
* Simple logger that writes to stderr (to avoid interfering with stdio transport).
*/
class Logger {
private level: LogLevel = 'info';
constructor() {
// Initialize from environment variable
const envLevel = process.env[ENV.LOG_LEVEL];
if (envLevel && this.isValidLevel(envLevel)) {
this.level = envLevel;
}
}
private isValidLevel(level: string): level is LogLevel {
return level in LOG_LEVELS;
}
setLevel(level: LogLevel): void {
this.level = level;
}
getLevel(): LogLevel {
return this.level;
}
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 prefix = `[${timestamp}] [${level.toUpperCase()}]`;
if (data !== undefined) {
const dataStr = typeof data === 'string' ? data : JSON.stringify(data, null, 2);
return `${prefix} ${message}\n${dataStr}`;
}
return `${prefix} ${message}`;
}
private log(level: LogLevel, message: string, data?: unknown): void {
if (this.shouldLog(level)) {
const formatted = this.formatMessage(level, message, data);
// Write to stderr to avoid interfering with stdio transport
process.stderr.write(formatted + '\n');
}
}
debug(message: string, data?: unknown): void {
this.log('debug', message, data);
}
info(message: string, data?: unknown): void {
this.log('info', message, data);
}
warn(message: string, data?: unknown): void {
this.log('warn', message, data);
}
error(message: string, data?: unknown): void {
this.log('error', message, data);
}
/**
* Log an error with stack trace if available.
*/
exception(message: string, error: unknown): void {
if (error instanceof Error) {
this.error(message, {
name: error.name,
message: error.message,
stack: error.stack,
});
} else {
this.error(message, error);
}
}
}
// Export singleton instance
export const logger = new Logger();
// Export for type usage
export { Logger };
// Convenience function exports
export function log(level: LogLevel, message: string, data?: unknown): void {
switch (level) {
case 'debug': logger.debug(message, data); break;
case 'info': logger.info(message, data); break;
case 'warn': logger.warn(message, data); break;
case 'error': logger.error(message, data); break;
}
}
export function setLogLevel(level: LogLevel): void {
logger.setLevel(level);
}
