"""Redis-backed cursor for the bridge.

Tracks the highest `kevin_stock_mentions.id` we've already attempted to
process. Stored at key `kevin:bridge:last_mention_id`.
"""

from __future__ import annotations

from typing import Any


class RedisCursor:
    _KEY = "kevin:bridge:last_mention_id"

    def __init__(self, redis: Any) -> None:
        self.redis = redis

    async def last_seen_id(self) -> int:
        v = await self.redis.get(self._KEY)
        if v is None:
            return 0
        return int(v)

    async def advance(self, mention_id: int) -> None:
        # Conservative: only set if mention_id > current
        current = await self.last_seen_id()
        if mention_id > current:
            await self.redis.set(self._KEY, str(mention_id))