fase(7): api server refactor with composition root

src/api/middleware/errorHandler.ts

@@ -0,0 +1,82 @@
+import { Request, Response, NextFunction } from 'express';
+
+export class AppError extends Error {
+  constructor(
+    message: string,
+    public readonly statusCode: number,
+    public readonly code: string,
+    public readonly isOperational = true,
+  ) {
+    super(message);
+    this.name = this.constructor.name;
+    Error.captureStackTrace(this, this.constructor);
+  }
+}
+
+export class ValidationError extends AppError {
+  constructor(message: string, public readonly details?: unknown) {
+    super(message, 400, 'VALIDATION_ERROR');
+  }
+}
+
+export class AuthenticationError extends AppError {
+  constructor(message = 'Unauthorized') {
+    super(message, 401, 'AUTHENTICATION_ERROR');
+  }
+}
+
+export class ForbiddenError extends AppError {
+  constructor(message = 'Forbidden') {
+    super(message, 403, 'FORBIDDEN');
+  }
+}
+
+export class NotFoundError extends AppError {
+  constructor(resource: string) {
+    super(`${resource} not found`, 404, 'NOT_FOUND');
+  }
+}
+
+export class ConflictError extends AppError {
+  constructor(message: string) {
+    super(message, 409, 'CONFLICT');
+  }
+}
+
+export class RateLimitError extends AppError {
+  constructor() {
+    super('Too many requests', 429, 'RATE_LIMIT');
+  }
+}
+
+export function globalErrorHandler(
+  err: Error,
+  req: Request,
+  res: Response,
+  _next: NextFunction,
+): void {
+  const logger = (req as Request & { log?: { warn: Function; error: Function } }).log;
+
+  if (err instanceof AppError && err.isOperational) {
+    if (logger) {
+      logger.warn({ err, statusCode: err.statusCode }, err.message);
+    }
+    const body: Record<string, unknown> = { error: err.message, code: err.code };
+    if (err instanceof ValidationError && err.details !== undefined) {
+      body['details'] = err.details;
+    }
+    res.status(err.statusCode).json(body);
+    return;
+  }
+
+  if (logger) {
+    logger.error({ err }, 'Unhandled error');
+  } else {
+    console.error('Unhandled error', err);
+  }
+
+  res.status(500).json({
+    error: process.env['NODE_ENV'] === 'production' ? 'Internal server error' : err.message,
+    code: 'INTERNAL_ERROR',
+  });
+}