add changes

backend/utils/AppError.js

@@ -0,0 +1,108 @@
+/**
+ * Custom Application Error class for consistent error handling
+ * Extends the built-in Error class with additional properties
+ */
+class AppError extends Error {
+  /**
+   * Create an application error
+   * @param {string} message - Error message
+   * @param {number} statusCode - HTTP status code
+   * @param {boolean} isOperational - Whether the error is operational (expected) or programming error
+   */
+  constructor(message, statusCode = 500, isOperational = true) {
+    super(message);
+    
+    this.statusCode = statusCode;
+    this.status = `${statusCode}`.startsWith('4') ? 'fail' : 'error';
+    this.isOperational = isOperational;
+    
+    // Capture stack trace
+    Error.captureStackTrace(this, this.constructor);
+  }
+}
+
+/**
+ * Create a Bad Request error (400)
+ */
+class BadRequestError extends AppError {
+  constructor(message = 'Bad Request') {
+    super(message, 400);
+  }
+}
+
+/**
+ * Create an Unauthorized error (401)
+ */
+class UnauthorizedError extends AppError {
+  constructor(message = 'Unauthorized') {
+    super(message, 401);
+  }
+}
+
+/**
+ * Create a Forbidden error (403)
+ */
+class ForbiddenError extends AppError {
+  constructor(message = 'Forbidden') {
+    super(message, 403);
+  }
+}
+
+/**
+ * Create a Not Found error (404)
+ */
+class NotFoundError extends AppError {
+  constructor(message = 'Resource not found') {
+    super(message, 404);
+  }
+}
+
+/**
+ * Create a Conflict error (409)
+ */
+class ConflictError extends AppError {
+  constructor(message = 'Resource conflict') {
+    super(message, 409);
+  }
+}
+
+/**
+ * Create an Unprocessable Entity error (422)
+ */
+class ValidationError extends AppError {
+  constructor(message = 'Validation failed', errors = null) {
+    super(message, 422);
+    this.errors = errors;
+  }
+}
+
+/**
+ * Create an Internal Server Error (500)
+ */
+class InternalServerError extends AppError {
+  constructor(message = 'Internal server error') {
+    super(message, 500, false);
+  }
+}
+
+/**
+ * Create a Database Error
+ */
+class DatabaseError extends AppError {
+  constructor(message = 'Database error', originalError = null) {
+    super(message, 500, false);
+    this.originalError = originalError;
+  }
+}
+
+module.exports = {
+  AppError,
+  BadRequestError,
+  UnauthorizedError,
+  ForbiddenError,
+  NotFoundError,
+  ConflictError,
+  ValidationError,
+  InternalServerError,
+  DatabaseError
+};