from fastapi import APIRouter
from sqlalchemy import select, func
from sqlalchemy.orm import selectinload

from app.api.deps import DbSession, CurrentUser
from app.models import Activity, Participant
from app.schemas import FeedResponse, ActivityResponse, UserPublic

router = APIRouter(tags=["feed"])


@router.get("/marathons/{marathon_id}/feed", response_model=FeedResponse)
async def get_feed(
    marathon_id: int,
    current_user: CurrentUser,
    db: DbSession,
    limit: int = 20,
    offset: int = 0,
):
    """Get activity feed for marathon"""
    # Check user is participant
    result = await db.execute(
        select(Participant).where(
            Participant.user_id == current_user.id,
            Participant.marathon_id == marathon_id,
        )
    )
    if not result.scalar_one_or_none():
        return FeedResponse(items=[], total=0, has_more=False)

    # Get total count
    total = await db.scalar(
        select(func.count()).select_from(Activity).where(Activity.marathon_id == marathon_id)
    )

    # Get activities
    result = await db.execute(
        select(Activity)
        .options(selectinload(Activity.user))
        .where(Activity.marathon_id == marathon_id)
        .order_by(Activity.created_at.desc())
        .limit(limit)
        .offset(offset)
    )
    activities = result.scalars().all()

    items = [
        ActivityResponse(
            id=a.id,
            type=a.type,
            user=UserPublic.model_validate(a.user),
            data=a.data,
            created_at=a.created_at,
        )
        for a in activities
    ]

    return FeedResponse(
        items=items,
        total=total,
        has_more=(offset + limit) < total,
    )