from fastapi import Request, status

from fastapi.exceptions import RequestValidationError

from fastapi.responses import JSONResponse

from src.core.schemas.response import ErrorDetail, ErrorResponse

from src.modules.todo import (

TodoNotFoundError,

UnauthorizedTodoAccessError,

)

from src.modules.user import UserAlreadyExistsError

from src.shared.exceptions.credential_exception import (

InvalidCredentialsError,

InvalidRefreshTokenError,

)

# Map domain exceptions to HTTP status codes and error codes

DOMAIN_EXCEPTION_MAP = {

UserAlreadyExistsError: (status.HTTP_400_BAD_REQUEST, "USER_ALREADY_EXISTS"),

InvalidCredentialsError: (status.HTTP_401_UNAUTHORIZED, "INVALID_CREDENTIALS"),

InvalidRefreshTokenError: (status.HTTP_401_UNAUTHORIZED, "INVALID_REFRESH_TOKEN"),

TodoNotFoundError: (status.HTTP_404_NOT_FOUND, "TODO_NOT_FOUND"),

UnauthorizedTodoAccessError: (

status.HTTP_403_FORBIDDEN,

"UNAUTHORIZED_TODO_ACCESS",

),

}

async def validation_exception_handler(request: Request, exc: RequestValidationError):

"""Handles Pydantic validation errors (e.g., missing fields, wrong types)"""

details = [

ErrorDetail(field=".".join(str(loc) for loc in err["loc"]), message=err["msg"])

for err in exc.errors()

]

response, status_code = ErrorResponse.create(

code="VALIDATION_ERROR",

message="Request payload validation failed",

details=details,

http_status=status.HTTP_422_UNPROCESSABLE_ENTITY,

)

return JSONResponse(status_code=status_code, content=response.model_dump())

async def http_exception_handler(request: Request, exc):

"""Handles standard FastAPI HTTPExceptions"""

response, status_code = ErrorResponse.create(

code="HTTP_ERROR", message=exc.detail, http_status=exc.status_code

)

return JSONResponse(status_code=status_code, content=response.model_dump())

async def domain_exception_handler(request: Request, exc: Exception):

"""Handles custom Domain Exceptions"""

exc_type = type(exc)

if exc_type in DOMAIN_EXCEPTION_MAP:

status_code, code = DOMAIN_EXCEPTION_MAP[exc_type]

else:

status_code, code = (

status.HTTP_500_INTERNAL_SERVER_ERROR,

"UNKNOWN_DOMAIN_ERROR",

)

response, _ = ErrorResponse.create(

code=code, message=str(exc), http_status=status_code

)

return JSONResponse(status_code=status_code, content=response.model_dump())

async def global_exception_handler(request: Request, exc: Exception):

"""Fallback for any unhandled exceptions (e.g., Database errors, 3rd party API failures)"""

# Log the actual error here in production (e.g., Sentry, Datadog)

# logger.error(f"Unhandled exception: {exc}", exc_info=True)

response, status_code = ErrorResponse.create(

code="INTERNAL_SERVER_ERROR",

message="An unexpected error occurred. Please try again later.",

http_status=status.HTTP_500_INTERNAL_SERVER_ERROR,

)

return JSONResponse(status_code=status_code, content=response.model_dump())