from datetime import UTC, date, datetime

import sqlalchemy as sa
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.db_models import DailyStat, InterestCategoryCount
from app.services.session_service import count_active_sessions


async def get_stats(db: AsyncSession) -> dict:
    """Return anonymised aggregate stats for the admin dashboard."""
    today = date.today()

    row = await db.scalar(
        sa.select(DailyStat).where(DailyStat.date == today)
    )

    top_categories_rows = await db.scalars(
        sa.select(InterestCategoryCount)
        .where(InterestCategoryCount.date == today)
        .order_by(InterestCategoryCount.count.desc())
        .limit(5)
    )
    top_categories = [r.category for r in top_categories_rows]
    active = await count_active_sessions()

    return {
        "total_sessions_today": row.total_sessions if row else 0,
        "total_matches_today": row.total_matches if row else 0,
        "active_sessions_now": active,
        "top_interest_categories": top_categories,
    }


async def increment_sessions(db: AsyncSession) -> None:
    """Increment daily session counter. Called when a new session is created."""
    today = date.today()
    await db.execute(
        sa.dialects.postgresql.insert(DailyStat)
        .values(date=today, total_sessions=1, total_matches=0)
        .on_conflict_do_update(
            index_elements=["date"],
            set_={"total_sessions": DailyStat.total_sessions + 1},
        )
    )
    await db.commit()


async def increment_matches(db: AsyncSession) -> None:
    """Increment daily match counter. Called on a successful match."""
    today = date.today()
    await db.execute(
        sa.dialects.postgresql.insert(DailyStat)
        .values(date=today, total_sessions=0, total_matches=1)
        .on_conflict_do_update(
            index_elements=["date"],
            set_={"total_matches": DailyStat.total_matches + 1},
        )
    )
    await db.commit()