from fastapi_problem.error import (
    BadRequestProblem,
    ConflictProblem,
    ForbiddenProblem,
    NotFoundProblem,
    ServerProblem,
    UnauthorisedProblem,
    UnprocessableProblem,
)

# app/exceptions/resource.py
"""
Resource-related exceptions.
"""

from fastapi_problem.error import ConflictProblem, NotFoundProblem


class ResourceNotFoundError(NotFoundProblem):
    """
    Raised when a resource cannot be found.
    """

    title = "Resource not found"


class ResourceAlreadyExistsError(ConflictProblem):
    """
    Raised when attempting to create a duplicate resource.
    """

    title = "Resource already exists"

from app.exceptions.base import (
    BadRequestProblem,
    ConflictProblem,
    ForbiddenProblem,
    NotFoundProblem,
    ServerProblem,
    UnauthorisedProblem,
    UnprocessableProblem,
)
from app.exceptions.resource import ResourceAlreadyExistsError, ResourceNotFoundError

__all__ = [
    "BadRequestProblem",
    "ConflictProblem",
    "ForbiddenProblem",
    "NotFoundProblem",
    "ResourceAlreadyExistsError",
    "ResourceNotFoundError",
    "ServerProblem",
    "UnauthorisedProblem",
    "UnprocessableProblem",
]

# In routers and services
from app.exceptions import ResourceNotFoundError, ResourceAlreadyExistsError

async def get_resource(self, user_id: str) -> Resource:
    snapshot = await doc_ref.get()
    if not snapshot.exists:
        raise ResourceNotFoundError("Resource not found")
    return Resource(**snapshot.to_dict())

@router.get("/")
async def get_resource(
    current_user: CurrentUser,
    service: ResourceServiceDep,
) -> Resource:
    try:
        return await service.get_resource(current_user.uid)
    except (HTTPException, ResourceNotFoundError):
        raise
    except Exception:
        logger.exception("Error getting resource", extra={"user_id": current_user.uid})
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="Failed to retrieve resource"
        ) from None

{
  "type": "about:blank",
  "title": "Resource not found",
  "status": 404,
  "detail": "Resource not found"
}

raise ResourceNotFoundError(detail="Resource with ID 'abc123' was not found")

def test_returns_404_when_not_found(
    client: TestClient,
    with_fake_user: None,
    mock_resource_service: AsyncMock,
) -> None:
    mock_resource_service.get_resource.side_effect = ResourceNotFoundError()

    response = client.get("/v1/resource")

    assert response.status_code == 404
    body = response.json()
    assert body["title"] == "Resource not found"
    assert body["status"] == 404