Fix: Rename directory to remove & character causing shell issues

Renamed ebook_backend&admin_panel to ebook_backend_admin_panel
  The & character was being interpreted by shell as background
  process operator, causing 'Dockerfile not found' errors in Coolify.

ebook_backend_admin_panel/admin-backend/utils/exceptions.py

@@ -0,0 +1,211 @@
+"""
+Custom exceptions for the Ebook Coupon Management System
+Provides structured error handling with proper error codes and messages.
+"""
+from typing import Dict, Any, Optional
+from fastapi import HTTPException
+
+
+class APIException(HTTPException):
+    """Base API exception with structured error information"""
+    
+    def __init__(
+        self,
+        status_code: int,
+        detail: str,
+        error_code: str,
+        extra_data: Optional[Dict[str, Any]] = None
+    ):
+        super().__init__(status_code=status_code, detail=detail)
+        self.error_code = error_code
+        self.extra_data = extra_data or {}
+
+
+class AuthenticationError(APIException):
+    """Authentication related errors"""
+    
+    def __init__(self, detail: str = "Authentication failed"):
+        super().__init__(
+            status_code=401,
+            detail=detail,
+            error_code="AUTHENTICATION_ERROR"
+        )
+
+
+class AuthorizationError(APIException):
+    """Authorization related errors"""
+    
+    def __init__(self, detail: str = "Access denied"):
+        super().__init__(
+            status_code=403,
+            detail=detail,
+            error_code="AUTHORIZATION_ERROR"
+        )
+
+
+class NotFoundError(APIException):
+    """Resource not found errors"""
+    
+    def __init__(self, resource: str, detail: Optional[str] = None):
+        if detail is None:
+            detail = f"{resource} not found"
+        super().__init__(
+            status_code=404,
+            detail=detail,
+            error_code="NOT_FOUND_ERROR"
+        )
+
+
+class ValidationError(APIException):
+    """Validation related errors"""
+    
+    def __init__(self, detail: str, field: Optional[str] = None):
+        if field:
+            detail = f"Validation error in field '{field}': {detail}"
+        super().__init__(
+            status_code=422,
+            detail=detail,
+            error_code="VALIDATION_ERROR"
+        )
+
+
+class ConflictError(APIException):
+    """Resource conflict errors"""
+    
+    def __init__(self, detail: str):
+        super().__init__(
+            status_code=409,
+            detail=detail,
+            error_code="CONFLICT_ERROR"
+        )
+
+
+class RateLimitError(APIException):
+    """Rate limiting errors"""
+    
+    def __init__(self, detail: str = "Rate limit exceeded"):
+        super().__init__(
+            status_code=429,
+            detail=detail,
+            error_code="RATE_LIMIT_ERROR"
+        )
+
+
+class DatabaseError(APIException):
+    """Database related errors"""
+    
+    def __init__(self, detail: str = "Database operation failed"):
+        super().__init__(
+            status_code=500,
+            detail=detail,
+            error_code="DATABASE_ERROR"
+        )
+
+
+class FileUploadError(APIException):
+    """File upload related errors"""
+    
+    def __init__(self, detail: str):
+        super().__init__(
+            status_code=400,
+            detail=detail,
+            error_code="FILE_UPLOAD_ERROR"
+        )
+
+
+class CouponError(APIException):
+    """Coupon related errors"""
+    
+    def __init__(self, detail: str, error_code: str = "COUPON_ERROR"):
+        super().__init__(
+            status_code=400,
+            detail=detail,
+            error_code=error_code
+        )
+
+
+def handle_api_exception(exc: APIException, path: str) -> Dict[str, Any]:
+    """
+    Handle API exception and return structured error response
+    
+    Args:
+        exc: API exception instance
+        path: Request path
+        
+    Returns:
+        Structured error response
+    """
+    return {
+        "success": False,
+        "error": exc.detail,
+        "error_code": exc.error_code,
+        "timestamp": None,  # Will be set by exception handler
+        "path": path,
+        **exc.extra_data
+    }
+
+
+# Coupon specific exceptions
+class CouponNotFoundError(NotFoundError):
+    """Coupon not found error"""
+    
+    def __init__(self, code: str):
+        super().__init__("coupon", f"Coupon code '{code}' not found")
+
+
+class CouponAlreadyUsedError(CouponError):
+    """Coupon already used error"""
+    
+    def __init__(self, code: str):
+        super().__init__(
+            f"Coupon code '{code}' has already been used",
+            "COUPON_ALREADY_USED"
+        )
+
+
+class CouponBlockedError(CouponError):
+    """Coupon blocked error"""
+    
+    def __init__(self, code: str, remaining_minutes: int):
+        super().__init__(
+            f"Coupon code '{code}' is blocked. Try again in {remaining_minutes} minutes",
+            "COUPON_BLOCKED"
+        )
+
+
+class CouponLimitExceededError(CouponError):
+    """Coupon usage limit exceeded error"""
+    
+    def __init__(self, code: str, limit: int):
+        super().__init__(
+            f"Coupon code '{code}' usage limit ({limit}) exceeded",
+            "COUPON_LIMIT_EXCEEDED"
+        )
+
+
+# File upload specific exceptions
+class FileTypeError(FileUploadError):
+    """Invalid file type error"""
+    
+    def __init__(self, allowed_types: list):
+        super().__init__(
+            f"Invalid file type. Allowed types: {', '.join(allowed_types)}"
+        )
+
+
+class FileSizeError(FileUploadError):
+    """File too large error"""
+    
+    def __init__(self, max_size_mb: int):
+        super().__init__(
+            f"File too large. Maximum size: {max_size_mb}MB"
+        )
+
+
+class FileExistsError(FileUploadError):
+    """File already exists error"""
+    
+    def __init__(self, filename: str):
+        super().__init__(
+            f"File '{filename}' already exists. Please delete it first."
+        )