orion/app/exceptions/handler.py

# app/exceptions/handler.py
"""
Exception handler for FastAPI application.

Provides consistent error responses and logging for all custom exceptions.
This module provides classes and functions for:
- Unified exception handling for all application exceptions
- Consistent error response formatting
- Comprehensive logging with structured data
"""

import logging
from typing import Union

from fastapi import Request, HTTPException
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse

from .base import LetzShopException

logger = logging.getLogger(__name__)


def setup_exception_handlers(app):
    """Setup exception handlers for the FastAPI app."""

    @app.exception_handler(LetzShopException)
    async def custom_exception_handler(request: Request, exc: LetzShopException):
        """Handle custom LetzShop exceptions."""

        logger.error(
            f"Custom exception in {request.method} {request.url}: "
            f"{exc.error_code} - {exc.message}",
            extra={
                "error_code": exc.error_code,
                "status_code": exc.status_code,
                "details": exc.details,
                "url": str(request.url),
                "method": request.method,
                "exception_type": type(exc).__name__,
            }
        )

        return JSONResponse(
            status_code=exc.status_code,
            content=exc.to_dict()
        )

    @app.exception_handler(HTTPException)
    async def http_exception_handler(request: Request, exc: HTTPException):
        """Handle FastAPI HTTPExceptions with consistent format."""

        logger.error(
            f"HTTP exception in {request.method} {request.url}: "
            f"{exc.status_code} - {exc.detail}",
            extra={
                "status_code": exc.status_code,
                "detail": exc.detail,
                "url": str(request.url),
                "method": request.method,
                "exception_type": "HTTPException",
            }
        )

        return JSONResponse(
            status_code=exc.status_code,
            content={
                "error_code": f"HTTP_{exc.status_code}",
                "message": exc.detail,
                "status_code": exc.status_code,
            }
        )

    @app.exception_handler(RequestValidationError)
    async def validation_exception_handler(request: Request, exc: RequestValidationError):
        """Handle Pydantic validation errors with consistent format."""

        logger.error(
            f"Validation error in {request.method} {request.url}: {exc.errors()}",
            extra={
                "validation_errors": exc.errors(),
                "url": str(request.url),
                "method": request.method,
                "exception_type": "RequestValidationError",
            }
        )

        # Clean up validation errors to ensure JSON serializability
        clean_errors = []
        for error in exc.errors():
            clean_error = {}
            for key, value in error.items():
                if key == 'input' and isinstance(value, bytes):
                    # Convert bytes to string representation for JSON serialization
                    clean_error[key] = f"<bytes: {len(value)} bytes>"
                elif key == 'ctx' and isinstance(value, dict):
                    # Handle the 'ctx' field that contains ValueError objects
                    clean_ctx = {}
                    for ctx_key, ctx_value in value.items():
                        if isinstance(ctx_value, Exception):
                            clean_ctx[ctx_key] = str(ctx_value)  # Convert exception to string
                        else:
                            clean_ctx[ctx_key] = ctx_value
                    clean_error[key] = clean_ctx
                elif isinstance(value, bytes):
                    # Handle any other bytes objects
                    clean_error[key] = f"<bytes: {len(value)} bytes>"
                else:
                    clean_error[key] = value
            clean_errors.append(clean_error)

        return JSONResponse(
            status_code=422,
            content={
                "error_code": "VALIDATION_ERROR",
                "message": "Request validation failed",
                "status_code": 422,
                "details": {
                    "validation_errors": clean_errors  # Use cleaned errors
                }
            }
        )

    @app.exception_handler(Exception)
    async def generic_exception_handler(request: Request, exc: Exception):
        """Handle unexpected exceptions."""

        logger.error(
            f"Unexpected exception in {request.method} {request.url}: {str(exc)}",
            exc_info=True,
            extra={
                "url": str(request.url),
                "method": request.method,
                "exception_type": type(exc).__name__,
            }
        )

        return JSONResponse(
            status_code=500,
            content={
                "error_code": "INTERNAL_SERVER_ERROR",
                "message": "Internal server error",
                "status_code": 500,
            }
        )

    @app.exception_handler(404)
    async def not_found_handler(request: Request, exc):
        """Handle all 404 errors with consistent format."""
        logger.warning(f"404 Not Found: {request.method} {request.url}")

        return JSONResponse(
            status_code=404,
            content={
                "error_code": "ENDPOINT_NOT_FOUND",
                "message": f"Endpoint not found: {request.url.path}",
                "status_code": 404,
                "details": {
                    "path": request.url.path,
                    "method": request.method
                }
            }
        )

# Utility functions for common exception scenarios
def raise_not_found(resource_type: str, identifier: str) -> None:
    """Convenience function to raise ResourceNotFoundException."""
    from .base import ResourceNotFoundException
    raise ResourceNotFoundException(resource_type, identifier)


def raise_validation_error(message: str, field: str = None, details: dict = None) -> None:
    """Convenience function to raise ValidationException."""
    from .base import ValidationException
    raise ValidationException(message, field, details)


def raise_auth_error(message: str = "Authentication failed") -> None:
    """Convenience function to raise AuthenticationException."""
    from .base import AuthenticationException
    raise AuthenticationException(message)


def raise_permission_error(message: str = "Access denied") -> None:
    """Convenience function to raise AuthorizationException."""
    from .base import AuthorizationException
    raise AuthorizationException(message)