from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.dependencies import get_current_admin
from app.database import get_db
from app.models import Follow
from app.models.user import User
from app.schemas.schemas import UserResponse

router = APIRouter()


# ── User Management ───────────────────────────────────────────────────────────

class UserWithStats(UserResponse):
    follow_count: int


@router.get("/users", response_model=list[UserWithStats])
async def list_users(
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_admin),
):
    """List all users with their follow counts."""
    users_result = await db.execute(select(User).order_by(User.created_at))
    users = users_result.scalars().all()

    counts_result = await db.execute(
        select(Follow.user_id, func.count(Follow.id).label("cnt"))
        .group_by(Follow.user_id)
    )
    counts = {row.user_id: row.cnt for row in counts_result}

    return [
        UserWithStats(
            id=u.id,
            email=u.email,
            is_admin=u.is_admin,
            notification_prefs=u.notification_prefs or {},
            created_at=u.created_at,
            follow_count=counts.get(u.id, 0),
        )
        for u in users
    ]


@router.delete("/users/{user_id}", status_code=204)
async def delete_user(
    user_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_admin),
):
    """Delete a user account (cascades to their follows). Cannot delete yourself."""
    if user_id == current_user.id:
        raise HTTPException(status_code=400, detail="Cannot delete your own account")
    user = await db.get(User, user_id)
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    await db.delete(user)
    await db.commit()


@router.patch("/users/{user_id}/toggle-admin", response_model=UserResponse)
async def toggle_admin(
    user_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_admin),
):
    """Promote or demote a user's admin status."""
    if user_id == current_user.id:
        raise HTTPException(status_code=400, detail="Cannot change your own admin status")
    user = await db.get(User, user_id)
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    user.is_admin = not user.is_admin
    await db.commit()
    await db.refresh(user)
    return user


# ── Celery Tasks ──────────────────────────────────────────────────────────────

@router.post("/trigger-poll")
async def trigger_poll(current_user: User = Depends(get_current_admin)):
    from app.workers.congress_poller import poll_congress_bills
    task = poll_congress_bills.delay()
    return {"task_id": task.id, "status": "queued"}


@router.post("/trigger-member-sync")
async def trigger_member_sync(current_user: User = Depends(get_current_admin)):
    from app.workers.congress_poller import sync_members
    task = sync_members.delay()
    return {"task_id": task.id, "status": "queued"}


@router.post("/trigger-trend-scores")
async def trigger_trend_scores(current_user: User = Depends(get_current_admin)):
    from app.workers.trend_scorer import calculate_all_trend_scores
    task = calculate_all_trend_scores.delay()
    return {"task_id": task.id, "status": "queued"}


@router.get("/task-status/{task_id}")
async def get_task_status(task_id: str, current_user: User = Depends(get_current_admin)):
    from app.workers.celery_app import celery_app
    result = celery_app.AsyncResult(task_id)
    return {
        "task_id": task_id,
        "status": result.status,
        "result": result.result if result.ready() else None,
    }