/**
* Logger utility for PayFast MCP Server
*
* CRITICAL: This MCP server uses STDIO transport.
* stdout is reserved for MCP protocol messages.
* ALL logging MUST go to stderr using console.error().
*/
type LogLevel = 'debug' | 'info' | 'warn' | 'error';
const LOG_LEVELS: Record<LogLevel, number> = {
debug: 0,
info: 1,
warn: 2,
error: 3,
};
const SENSITIVE_FIELDS = ['merchantKey', 'passphrase', 'password', 'token', 'signature'];
/**
* Get the configured log level from environment variable
*/
function getLogLevel(): LogLevel {
const level = process.env.LOG_LEVEL?.toLowerCase() as LogLevel;
return LOG_LEVELS[level] !== undefined ? level : 'info';
}
const currentLogLevel = getLogLevel();
/**
* Sanitize an object by redacting sensitive fields
* @param obj - Object to sanitize
* @returns Sanitized copy of the object
*/
export function sanitize(obj: any): any {
if (obj === null || obj === undefined) {
return obj;
}
if (typeof obj !== 'object') {
return obj;
}
if (Array.isArray(obj)) {
return obj.map(item => sanitize(item));
}
const sanitized: any = {};
for (const [key, value] of Object.entries(obj)) {
const lowerKey = key.toLowerCase();
const isSensitive = SENSITIVE_FIELDS.some(field =>
lowerKey.includes(field.toLowerCase())
);
if (isSensitive) {
sanitized[key] = '[REDACTED]';
} else if (typeof value === 'object' && value !== null) {
sanitized[key] = sanitize(value);
} else {
sanitized[key] = value;
}
}
return sanitized;
}
/**
* Format a log message with level and timestamp
*/
function formatMessage(level: string, message: string): string {
const timestamp = new Date().toISOString();
return `[${level.toUpperCase()}] [${timestamp}] ${message}`;
}
/**
* Convert a value to a loggable string
*/
function valueToString(value: any): string {
if (typeof value === 'string') {
return value;
}
if (value instanceof Error) {
const errorObj = {
name: value.name,
message: value.message,
stack: value.stack,
...(value as any), // Include any custom properties
};
return JSON.stringify(sanitize(errorObj));
}
if (typeof value === 'object' && value !== null) {
try {
return JSON.stringify(sanitize(value));
} catch (err) {
return '[Circular or Non-Serializable Object]';
}
}
return String(value);
}
/**
* Check if a message should be logged based on current log level
*/
function shouldLog(level: LogLevel): boolean {
return LOG_LEVELS[level] >= LOG_LEVELS[currentLogLevel];
}
/**
* Write a log message to stderr
*/
function log(level: LogLevel, ...args: any[]): void {
if (!shouldLog(level)) {
return;
}
const message = args.map(valueToString).join(' ');
const formattedMessage = formatMessage(level, message);
// CRITICAL: Write to stderr, never stdout
console.error(formattedMessage);
}
/**
* Logger instance with level-specific methods
*/
export const logger = {
/**
* Log debug information (most verbose)
*/
debug(...args: any[]): void {
log('debug', ...args);
},
/**
* Log informational messages
*/
info(...args: any[]): void {
log('info', ...args);
},
/**
* Log warning messages
*/
warn(...args: any[]): void {
log('warn', ...args);
},
/**
* Log error messages (least verbose, always shown unless silenced)
*/
error(...args: any[]): void {
log('error', ...args);
},
};
export default logger;
