from fastapi import HTTPException, status

from app.repositories.scheme_versions import get_current_scheme_version
from app.repositories.schemes import get_scheme_record_by_scheme_id


def build_stale_draft_version_detail(
    *,
    expected_scheme_version_id: str,
    actual_scheme_version_id: str,
) -> dict:
    return {
        "code": "stale_draft_version",
        "message": "Draft scheme version is stale. Reload current draft state before applying mutation.",
        "expected_scheme_version_id": expected_scheme_version_id,
        "actual_scheme_version_id": actual_scheme_version_id,
    }


async def get_current_draft_context(
    scheme_id: str,
    expected_scheme_version_id: str | None = None,
):
    scheme = await get_scheme_record_by_scheme_id(scheme_id)
    version = await get_current_scheme_version(
        scheme_id=scheme.scheme_id,
        current_version_number=scheme.current_version_number,
    )

    if version.status != "draft" or scheme.status != "draft":
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail="Current scheme version is not editable because it is not in draft state",
        )

    if expected_scheme_version_id and expected_scheme_version_id != version.scheme_version_id:
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail=build_stale_draft_version_detail(
                expected_scheme_version_id=expected_scheme_version_id,
                actual_scheme_version_id=version.scheme_version_id,
            ),
        )

    return scheme, version


async def validate_expected_draft_version_if_provided(
    scheme_id: str,
    expected_scheme_version_id: str | None,
):
    if not expected_scheme_version_id:
        return None

    scheme, version = await get_current_draft_context(
        scheme_id=scheme_id,
        expected_scheme_version_id=expected_scheme_version_id,
    )
    return scheme, version