nanodrop/src/middleware/logging.ts

import { appendFile } from 'fs/promises';

interface AuthLogParams {
  ip: string;
  userAgent: string;
  username: string;
}

interface FileNotFoundParams {
  ip: string;
  userAgent: string;
  fileId: string;
}

interface AuthLockoutTriggeredParams extends AuthLogParams {
  durationSeconds: number;
}

interface AuthLockedAttemptParams extends AuthLogParams {
  retryAfterSeconds: number;
}

interface AuthRateLimitedParams {
  ip: string;
  userAgent: string;
  route: string;
}

export interface Logger {
  authSuccess(params: AuthLogParams): Promise<void>;
  authFailure(params: AuthLogParams): Promise<void>;
  authLockoutTriggered(params: AuthLockoutTriggeredParams): Promise<void>;
  authLockedAttempt(params: AuthLockedAttemptParams): Promise<void>;
  authRateLimited(params: AuthRateLimitedParams): Promise<void>;
  fileNotFound(params: FileNotFoundParams): Promise<void>;
}

export function createLogger(logFile: string): Logger {
  function timestamp(): string {
    return new Date().toISOString();
  }

  async function write(line: string): Promise<void> {
    await appendFile(logFile, line + '\n');
  }

  function authLine(event: string, { ip, userAgent, username }: AuthLogParams): string {
    return `[${timestamp()}] ${event} ip=${ip} user-agent="${userAgent}" username="${username}"`;
  }

  return {
    authSuccess: (params) => write(authLine('AUTH_SUCCESS', params)),
    authFailure: (params) => write(authLine('AUTH_FAILURE', params)),
    authLockoutTriggered: ({ durationSeconds, ...auth }) =>
      write(`${authLine('AUTH_LOCKOUT_TRIGGERED', auth)} duration_seconds=${durationSeconds}`),
    authLockedAttempt: ({ retryAfterSeconds, ...auth }) =>
      write(`${authLine('AUTH_LOCKED_ATTEMPT', auth)} retry_after_seconds=${retryAfterSeconds}`),
    authRateLimited: ({ ip, userAgent, route }) =>
      write(`[${timestamp()}] AUTH_RATE_LIMITED ip=${ip} user-agent="${userAgent}" route="${route}"`),
    fileNotFound: ({ ip, userAgent, fileId }) =>
      write(`[${timestamp()}] FILE_NOT_FOUND ip=${ip} user-agent="${userAgent}" file_id="${fileId}"`),
  };
}