"""
Backtest API endpoints.
"""

from typing import List

from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.orm import Session, joinedload

from app.core.database import get_db
from app.api.deps import CurrentUser
from app.models.backtest import (
    Backtest,
    BacktestResult,
    BacktestEquityCurve,
    BacktestHolding,
    BacktestTransaction,
    BacktestStatus,
    WalkForwardResult,
)
from app.schemas.backtest import (
    BacktestCreate,
    BacktestResponse,
    BacktestListItem,
    BacktestMetrics,
    EquityCurvePoint,
    RebalanceHoldings,
    HoldingItem,
    TransactionItem,
    WalkForwardRequest,
    WalkForwardWindowResult,
    WalkForwardResponse,
)
from app.services.backtest import submit_backtest
from app.services.backtest.walkforward_engine import WalkForwardEngine
from app.services.rebalance import RebalanceService

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


@router.post("", response_model=dict)
async def create_backtest(
    request: BacktestCreate,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Create and start a new backtest."""
    # Create backtest record
    backtest = Backtest(
        user_id=current_user.id,
        strategy_type=request.strategy_type,
        strategy_params=request.strategy_params,
        start_date=request.start_date,
        end_date=request.end_date,
        rebalance_period=request.rebalance_period,
        initial_capital=request.initial_capital,
        commission_rate=request.commission_rate,
        slippage_rate=request.slippage_rate,
        benchmark=request.benchmark,
        top_n=request.top_n,
        status=BacktestStatus.PENDING,
    )
    db.add(backtest)
    db.commit()
    db.refresh(backtest)

    # Submit for background execution
    submit_backtest(backtest.id)

    return {"id": backtest.id, "status": "pending"}


@router.get("", response_model=List[BacktestListItem])
async def list_backtests(
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """List all backtests for current user."""
    backtests = (
        db.query(Backtest)
        .options(joinedload(Backtest.result))
        .filter(Backtest.user_id == current_user.id)
        .order_by(Backtest.created_at.desc())
        .all()
    )

    result = []
    for bt in backtests:
        item = BacktestListItem(
            id=bt.id,
            strategy_type=bt.strategy_type,
            start_date=bt.start_date,
            end_date=bt.end_date,
            rebalance_period=bt.rebalance_period.value,
            status=bt.status.value,
            created_at=bt.created_at,
            total_return=bt.result.total_return if bt.result else None,
            cagr=bt.result.cagr if bt.result else None,
            mdd=bt.result.mdd if bt.result else None,
        )
        result.append(item)

    return result


@router.get("/{backtest_id}", response_model=BacktestResponse)
async def get_backtest(
    backtest_id: int,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Get backtest details and results."""
    backtest = (
        db.query(Backtest)
        .filter(Backtest.id == backtest_id, Backtest.user_id == current_user.id)
        .first()
    )

    if not backtest:
        raise HTTPException(status_code=404, detail="Backtest not found")

    result_metrics = None
    if backtest.result:
        result_metrics = BacktestMetrics(
            total_return=backtest.result.total_return,
            cagr=backtest.result.cagr,
            mdd=backtest.result.mdd,
            sharpe_ratio=backtest.result.sharpe_ratio,
            volatility=backtest.result.volatility,
            benchmark_return=backtest.result.benchmark_return,
            excess_return=backtest.result.excess_return,
        )

    return BacktestResponse(
        id=backtest.id,
        user_id=backtest.user_id,
        strategy_type=backtest.strategy_type,
        strategy_params=backtest.strategy_params or {},
        start_date=backtest.start_date,
        end_date=backtest.end_date,
        rebalance_period=backtest.rebalance_period.value,
        initial_capital=backtest.initial_capital,
        commission_rate=backtest.commission_rate,
        slippage_rate=backtest.slippage_rate,
        benchmark=backtest.benchmark,
        status=backtest.status.value,
        created_at=backtest.created_at,
        completed_at=backtest.completed_at,
        error_message=backtest.error_message,
        result=result_metrics,
    )


@router.get("/{backtest_id}/equity-curve", response_model=List[EquityCurvePoint])
async def get_equity_curve(
    backtest_id: int,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Get equity curve data for chart."""
    backtest = (
        db.query(Backtest)
        .filter(Backtest.id == backtest_id, Backtest.user_id == current_user.id)
        .first()
    )

    if not backtest:
        raise HTTPException(status_code=404, detail="Backtest not found")

    curve = (
        db.query(BacktestEquityCurve)
        .filter(BacktestEquityCurve.backtest_id == backtest_id)
        .order_by(BacktestEquityCurve.date)
        .all()
    )

    return [
        EquityCurvePoint(
            date=point.date,
            portfolio_value=point.portfolio_value,
            benchmark_value=point.benchmark_value,
            drawdown=point.drawdown,
        )
        for point in curve
    ]


@router.get("/{backtest_id}/holdings", response_model=List[RebalanceHoldings])
async def get_holdings(
    backtest_id: int,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Get holdings at each rebalance date."""
    backtest = (
        db.query(Backtest)
        .filter(Backtest.id == backtest_id, Backtest.user_id == current_user.id)
        .first()
    )

    if not backtest:
        raise HTTPException(status_code=404, detail="Backtest not found")

    holdings = (
        db.query(BacktestHolding)
        .filter(BacktestHolding.backtest_id == backtest_id)
        .order_by(BacktestHolding.rebalance_date, BacktestHolding.weight.desc())
        .all()
    )

    # Group by rebalance date
    grouped = {}
    for h in holdings:
        if h.rebalance_date not in grouped:
            grouped[h.rebalance_date] = []
        grouped[h.rebalance_date].append(
            HoldingItem(
                ticker=h.ticker,
                name=h.name,
                weight=h.weight,
                shares=h.shares,
                price=h.price,
            )
        )

    return [
        RebalanceHoldings(rebalance_date=date, holdings=items)
        for date, items in sorted(grouped.items())
    ]


@router.get("/{backtest_id}/transactions", response_model=List[TransactionItem])
async def get_transactions(
    backtest_id: int,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Get all transactions."""
    backtest = (
        db.query(Backtest)
        .filter(Backtest.id == backtest_id, Backtest.user_id == current_user.id)
        .first()
    )

    if not backtest:
        raise HTTPException(status_code=404, detail="Backtest not found")

    transactions = (
        db.query(BacktestTransaction)
        .filter(BacktestTransaction.backtest_id == backtest_id)
        .order_by(BacktestTransaction.date, BacktestTransaction.id)
        .all()
    )

    # Resolve stock names
    tickers = list({t.ticker for t in transactions})
    name_service = RebalanceService(db)
    names = name_service.get_stock_names(tickers)

    return [
        TransactionItem(
            id=t.id,
            date=t.date,
            ticker=t.ticker,
            name=names.get(t.ticker),
            action=t.action,
            shares=t.shares,
            price=t.price,
            commission=t.commission,
        )
        for t in transactions
    ]


@router.post("/{backtest_id}/walkforward", response_model=dict)
async def run_walkforward(
    backtest_id: int,
    request: WalkForwardRequest,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Run walk-forward analysis on a completed backtest."""
    backtest = (
        db.query(Backtest)
        .filter(Backtest.id == backtest_id, Backtest.user_id == current_user.id)
        .first()
    )

    if not backtest:
        raise HTTPException(status_code=404, detail="Backtest not found")

    if backtest.status != BacktestStatus.COMPLETED:
        raise HTTPException(
            status_code=400,
            detail="백테스트가 완료된 상태에서만 walk-forward 분석이 가능합니다",
        )

    engine = WalkForwardEngine(db)
    try:
        engine.run(
            backtest_id=backtest_id,
            train_months=request.train_months,
            test_months=request.test_months,
            step_months=request.step_months,
        )
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))

    return {"status": "completed", "backtest_id": backtest_id}


@router.get("/{backtest_id}/walkforward", response_model=WalkForwardResponse)
async def get_walkforward(
    backtest_id: int,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Get walk-forward analysis results."""
    backtest = (
        db.query(Backtest)
        .filter(Backtest.id == backtest_id, Backtest.user_id == current_user.id)
        .first()
    )

    if not backtest:
        raise HTTPException(status_code=404, detail="Backtest not found")

    results = (
        db.query(WalkForwardResult)
        .filter(WalkForwardResult.backtest_id == backtest_id)
        .order_by(WalkForwardResult.window_index)
        .all()
    )

    return WalkForwardResponse(
        backtest_id=backtest_id,
        windows=[
            WalkForwardWindowResult(
                window_index=r.window_index,
                train_start=r.train_start,
                train_end=r.train_end,
                test_start=r.test_start,
                test_end=r.test_end,
                test_return=r.test_return,
                test_sharpe=r.test_sharpe,
                test_mdd=r.test_mdd,
            )
            for r in results
        ],
    )


@router.delete("/{backtest_id}")
async def delete_backtest(
    backtest_id: int,
    current_user: CurrentUser,
    db: Session = Depends(get_db),
):
    """Delete a backtest and all its data."""
    backtest = (
        db.query(Backtest)
        .filter(Backtest.id == backtest_id, Backtest.user_id == current_user.id)
        .first()
    )

    if not backtest:
        raise HTTPException(status_code=404, detail="Backtest not found")

    # Delete related data
    db.query(WalkForwardResult).filter(
        WalkForwardResult.backtest_id == backtest_id
    ).delete()
    db.query(BacktestTransaction).filter(
        BacktestTransaction.backtest_id == backtest_id
    ).delete()
    db.query(BacktestHolding).filter(
        BacktestHolding.backtest_id == backtest_id
    ).delete()
    db.query(BacktestEquityCurve).filter(
        BacktestEquityCurve.backtest_id == backtest_id
    ).delete()
    db.query(BacktestResult).filter(BacktestResult.backtest_id == backtest_id).delete()
    db.delete(backtest)
    db.commit()

    return {"message": "Backtest deleted"}