"""Custom exceptions for the API."""

from fastapi import HTTPException, status


class APIException(HTTPException):
    """Base API exception with structured error format."""
    
    def __init__(
        self,
        status_code: int,
        message: str,
        field: str = None,
        code: str = None,
        detail: str = None
    ):
        self.message = message
        self.field = field
        self.code = code or self._get_default_code(status_code)
        super().__init__(status_code=status_code, detail=detail or message)
    
    def _get_default_code(self, status_code: int) -> str:
        """Get default error code based on status code."""
        codes = {
            400: "BAD_REQUEST",
            401: "UNAUTHORIZED",
            403: "FORBIDDEN",
            404: "NOT_FOUND",
            409: "CONFLICT",
            422: "VALIDATION_ERROR",
            429: "RATE_LIMIT_EXCEEDED",
            500: "INTERNAL_SERVER_ERROR",
            503: "SERVICE_UNAVAILABLE"
        }
        return codes.get(status_code, "UNKNOWN_ERROR")


class ValidationError(APIException):
    """Validation error exception."""
    
    def __init__(self, message: str, field: str = None):
        super().__init__(
            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
            message=message,
            field=field,
            code="VALIDATION_ERROR"
        )


class NotFoundError(APIException):
    """Resource not found exception."""
    
    def __init__(self, message: str = "Resource not found"):
        super().__init__(
            status_code=status.HTTP_404_NOT_FOUND,
            message=message,
            code="NOT_FOUND"
        )


class RateLimitError(APIException):
    """Rate limit exceeded exception."""
    
    def __init__(self, message: str = "Rate limit exceeded"):
        super().__init__(
            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
            message=message,
            code="RATE_LIMIT_EXCEEDED"
        )