"""
Position sizing API endpoints.
"""
from fastapi import APIRouter, HTTPException

from app.api.deps import CurrentUser
from app.schemas.position_sizing import (
    SizingMethod,
    PositionSizeRequest,
    PositionSizeResponse,
    MethodInfo,
    MethodsResponse,
)
from app.services.position_sizing import fixed_ratio, kelly_criterion, atr_based

router = APIRouter(prefix="/api/position-sizing", tags=["position-sizing"])

METHODS = [
    MethodInfo(
        name="fixed",
        label="균등 분배 (Fixed Ratio)",
        description="자본금을 종목 수로 균등 분배. 현금 비중 설정 가능. quant.md 기본 방식.",
    ),
    MethodInfo(
        name="kelly",
        label="켈리 기준 (Kelly Criterion)",
        description="승률과 손익비를 기반으로 최적 베팅 비율 계산. 보수적 1/4 켈리 기본.",
    ),
    MethodInfo(
        name="atr",
        label="ATR 변동성 (ATR-Based)",
        description="ATR(평균 진폭)을 이용한 변동성 기반 포지션 사이징.",
    ),
]


@router.post("/calculate", response_model=PositionSizeResponse)
async def calculate_position_size(
    request: PositionSizeRequest,
    current_user: CurrentUser,
):
    """Calculate position size based on selected method."""
    try:
        if request.method == SizingMethod.FIXED:
            result = fixed_ratio(
                capital=request.capital,
                num_positions=request.num_positions,
                cash_ratio=request.cash_ratio,
            )
        elif request.method == SizingMethod.KELLY:
            if not all([request.win_rate, request.avg_win, request.avg_loss]):
                raise HTTPException(
                    status_code=422,
                    detail="Kelly method requires win_rate, avg_win, avg_loss",
                )
            result = kelly_criterion(
                win_rate=request.win_rate,
                avg_win=request.avg_win,
                avg_loss=request.avg_loss,
            )
        elif request.method == SizingMethod.ATR:
            if not request.atr:
                raise HTTPException(
                    status_code=422,
                    detail="ATR method requires atr value",
                )
            result = atr_based(
                capital=request.capital,
                atr=request.atr,
                risk_pct=request.risk_pct,
            )
        else:
            raise HTTPException(status_code=422, detail=f"Unknown method: {request.method}")
    except ValueError as e:
        raise HTTPException(status_code=422, detail=str(e))

    return PositionSizeResponse(**result)


@router.get("/methods", response_model=MethodsResponse)
async def get_methods(current_user: CurrentUser):
    """List supported position sizing methods."""
    return MethodsResponse(methods=METHODS)