from datetime import datetime, timedelta
from fastapi import APIRouter, Depends, Header, HTTPException, Query
from sqlalchemy.orm import Session

from app.database import get_db
from app.models.db_models import Device, StockPosition, Recommendation
from app.models.schemas import RecommendationResponse, RecommendationWithSignals
from app.services.signal_engine import compute_signals
from app.services.recommendation_engine import build_recommendation
from app.config import settings

router = APIRouter(prefix="/recommendations", tags=["recommendations"])


def _get_device(x_device_token: str = Header(...), db: Session = Depends(get_db)) -> Device:
    device = db.query(Device).filter(Device.apns_token == x_device_token).first()
    if not device:
        raise HTTPException(status_code=404, detail="Device not registered.")
    return device


@router.get("", response_model=list[RecommendationResponse])
def get_recommendations(
    time_horizon: str | None = Query(None),
    device: Device = Depends(_get_device),
    db: Session = Depends(get_db),
):
    """Return latest cached recommendations for all portfolio tickers."""
    query = db.query(Recommendation).filter(Recommendation.device_id == device.id)
    if time_horizon:
        query = query.filter(Recommendation.time_horizon == time_horizon)
    return query.order_by(Recommendation.created_at.desc()).all()


@router.get("/{ticker}", response_model=RecommendationWithSignals)
def get_recommendation_for_ticker(
    ticker: str,
    time_horizon: str = Query("weekly"),
    strategy: str = Query("covered_call"),
    device: Device = Depends(_get_device),
    db: Session = Depends(get_db),
):
    """Return fresh recommendation + signals for a specific ticker."""
    ticker = ticker.upper()

    snap = compute_signals(ticker)
    if snap is None:
        raise HTTPException(status_code=503, detail=f"Could not fetch market data for {ticker}")

    rec = build_recommendation(
        device_id=device.id,
        ticker=ticker,
        strategy=strategy,
        time_horizon=time_horizon,
        snapshot=snap,
    )
    if rec is None:
        raise HTTPException(
            status_code=404,
            detail=f"No qualifying options found for {ticker} {strategy} {time_horizon}",
        )

    # Persist recommendation
    existing = (
        db.query(Recommendation)
        .filter(
            Recommendation.device_id == device.id,
            Recommendation.ticker == ticker,
            Recommendation.strategy == strategy,
            Recommendation.time_horizon == time_horizon,
        )
        .first()
    )
    if existing:
        db.delete(existing)
    db.add(rec)
    db.commit()
    db.refresh(rec)

    return RecommendationWithSignals(recommendation=RecommendationResponse.model_validate(rec), signals=snap)


@router.post("/refresh", response_model=list[RecommendationResponse])
def refresh_recommendations(
    device: Device = Depends(_get_device),
    db: Session = Depends(get_db),
):
    """
    On-demand recalculation for all portfolio tickers.
    Throttled: no-ops if last refresh was less than THROTTLE_MINUTES ago.
    """
    throttle = timedelta(minutes=settings.recommendation_throttle_minutes)
    most_recent = (
        db.query(Recommendation)
        .filter(Recommendation.device_id == device.id)
        .order_by(Recommendation.created_at.desc())
        .first()
    )
    if most_recent and (datetime.utcnow() - most_recent.created_at) < throttle:
        return db.query(Recommendation).filter(Recommendation.device_id == device.id).all()

    stock_positions = db.query(StockPosition).filter(StockPosition.device_id == device.id).all()
    if not stock_positions:
        return []

    results = []
    for sp in stock_positions:
        snap = compute_signals(sp.ticker)
        if snap is None:
            continue
        for strategy in ("covered_call", "cash_secured_put"):
            for horizon in ("weekly", "monthly"):
                rec = build_recommendation(
                    device_id=device.id,
                    ticker=sp.ticker,
                    strategy=strategy,
                    time_horizon=horizon,
                    snapshot=snap,
                )
                if rec is None:
                    continue

                existing = (
                    db.query(Recommendation)
                    .filter(
                        Recommendation.device_id == device.id,
                        Recommendation.ticker == sp.ticker,
                        Recommendation.strategy == strategy,
                        Recommendation.time_horizon == horizon,
                    )
                    .first()
                )
                if existing:
                    db.delete(existing)
                db.add(rec)
                results.append(rec)

    db.commit()
    for r in results:
        db.refresh(r)
    return results