Import source: app/backend/src/lib/errors

Import the existing local project snapshot. This commit organizes existing files; it does not represent newly developed functionality.

app/backend/src/lib/errors.ts

@@ -0,0 +1,69 @@
+import type { FastifyReply } from 'fastify';
+
+export class AppError extends Error {
+  constructor(
+    public readonly statusCode: number,
+    public readonly code: string,
+    message?: string,
+  ) {
+    super(message ?? code);
+    this.name = this.constructor.name;
+  }
+
+  send(reply: FastifyReply) {
+    return reply.code(this.statusCode).send({ error: this.code, message: this.message });
+  }
+}
+
+export class NotFoundError extends AppError {
+  constructor(resource: string, identifier?: string) {
+    super(404, 'not_found', identifier ? `${resource} با شناسه ${identifier} یافت نشد` : `${resource} یافت نشد`);
+  }
+}
+
+export class ValidationError extends AppError {
+  constructor(message?: string) {
+    super(400, 'invalid_input', message ?? 'ورودی نامعتبر');
+  }
+}
+
+export class UnauthorizedError extends AppError {
+  constructor() {
+    super(401, 'unauthenticated', 'ابتدا وارد حساب خود شوید');
+  }
+}
+
+export class ForbiddenError extends AppError {
+  constructor(action?: string) {
+    super(403, 'forbidden', action ? `شما اجازه ${action} را ندارید` : 'دسترسی غیرمجاز');
+  }
+}
+
+export class RateLimitedError extends AppError {
+  public readonly retryAfter?: number;
+  constructor(retryAfter?: number) {
+    super(429, 'rate_limited', 'تعداد درخواست‌ها از حد مجاز گذشت');
+    this.retryAfter = retryAfter;
+  }
+
+  send(reply: FastifyReply) {
+    if (this.retryAfter) reply.header('Retry-After', this.retryAfter);
+    return reply.code(this.statusCode).send({ error: this.code, message: this.message, retryAfter: this.retryAfter });
+  }
+}
+
+export class ConflictError extends AppError {
+  constructor(message?: string) {
+    super(409, 'conflict', message ?? 'تداخل داده‌ها');
+  }
+}
+
+export class PublishQualityError extends AppError {
+  constructor(public readonly issues: string[]) {
+    super(409, 'publish_quality', `موارد نیاز به اصلاح: ${issues.join('، ')}`);
+  }
+
+  send(reply: FastifyReply) {
+    return reply.code(this.statusCode).send({ error: this.code, message: this.message, issues: this.issues });
+  }
+}