admin / Syanpse-Vanguard

"""ClickHouse scale-out backend — placeholder implementing the same interface.

Wired into build_engine() so `SV_STORAGE_BACKEND=clickhouse` selects it without
any caller changes. Bodies are intentionally left for the scale-out milestone;
the point here is that the abstraction boundary already exists and the rest of
the app is decoupled from the driver."""
from __future__ import annotations

from datetime import datetime
from typing import AsyncIterator, Sequence

import pyarrow as pa

from sv.models.event import EventModel
from sv.storage.base import Query, StorageEngine


class ClickHouseEngine(StorageEngine):
    def __init__(self, dsn: str | None):
        if not dsn:
            raise ValueError("SV_CLICKHOUSE_DSN is required for the clickhouse backend")
        self._dsn = dsn

    async def init_schema(self) -> None:
        raise NotImplementedError("ClickHouse backend lands in the scale-out milestone")

    async def write_batch(self, events: Sequence[EventModel]) -> int:
        raise NotImplementedError

    async def execute(self, query: Query) -> pa.Table:
        raise NotImplementedError

    async def stream(self, query: Query, batch_rows: int = 10_000
                     ) -> AsyncIterator[pa.RecordBatch]:
        raise NotImplementedError
        yield  # pragma: no cover  (makes this an async generator)

    async def retention_sweep(self, older_than: datetime) -> int:
        raise NotImplementedError

    async def fetchone(self, query: Query) -> dict | None:
        raise NotImplementedError

    async def fetchall(self, query: Query) -> list[dict]:
        raise NotImplementedError

    async def run(self, query: Query) -> None:
        raise NotImplementedError

    async def close(self) -> None:
        return None