import logging
from datetime import datetime, timezone, timedelta

from sqlalchemy import select, create_engine
from sqlalchemy.orm import sessionmaker

from backend.config import settings
from backend.models.post import Post
from backend.models.metric_snapshot import MetricSnapshot
from backend.models.subreddit import MonitoredSubreddit

logger = logging.getLogger(__name__)

_engine = create_engine(settings.database_url_sync, pool_size=2, pool_recycle=3600)
SyncSession = sessionmaker(_engine)


def take_metric_snapshots():
    """Snapshot current metrics for recent posts."""
    now = datetime.now(timezone.utc)

    with SyncSession() as db:
        # Posts < 48h old: snapshot every run (every 30 min)
        cutoff_recent = now - timedelta(hours=48)
        stmt = (
            select(Post.id, Post.score, Post.num_comments, Post.upvote_ratio)
            .join(MonitoredSubreddit)
            .where(
                MonitoredSubreddit.is_active == True,  # noqa: E712
                Post.created_utc >= cutoff_recent,
            )
        )
        result = db.execute(stmt)
        snapshots = []
        for post_id, score, num_comments, upvote_ratio in result:
            snapshots.append(MetricSnapshot(
                post_id=post_id,
                score=score,
                num_comments=num_comments,
                upvote_ratio=upvote_ratio,
                snapshot_at=now,
            ))

        if snapshots:
            db.add_all(snapshots)
            db.commit()
            logger.info(f"Took {len(snapshots)} metric snapshots")