Redis sorted sets for leaderboard and ranking

import json
from redis.asyncio import Redis

LEADERBOARD_KEY = 'leaderboard:contributors'

# Update score
async def update_contributor_score(redis: Redis, user_id: str, score: float) -> None:
    await redis.zadd(LEADERBOARD_KEY, {user_id: score})

# Get top N with scores
async def get_top_contributors(redis: Redis, n: int = 10) -> list[dict]:
    # ZRANGE with REV=True and WITHSCORES
    entries = await redis.zrange(
        LEADERBOARD_KEY, 0, n - 1,
        rev=True, withscores=True
    )
    return [
        {'user_id': member.decode(), 'score': score}
        for member, score in entries
    ]

# Get rank of a specific user (0-indexed)
async def get_user_rank(redis: Redis, user_id: str) -> int | None:
    rank = await redis.zrevrank(LEADERBOARD_KEY, user_id)
    return rank  # None if not in leaderboard

# Increment score atomically
async def increment_score(redis: Redis, user_id: str, delta: float) -> float:
    new_score = await redis.zincrby(LEADERBOARD_KEY, delta, user_id)
    return new_score

# Sync from PostgreSQL (run on startup and periodically)
async def sync_leaderboard(redis: Redis, session: AsyncSession) -> None:
    result = await session.execute(
        select(User.id, User.reputation_score)
        .where(User.reputation_score > 0)
        .order_by(User.reputation_score.desc())
        .limit(1000)
    )
    users = result.all()
    if users:
        await redis.zadd(
            LEADERBOARD_KEY,
            {str(user.id): user.reputation_score for user in users}
        )