"""Leverage cap server-side per place_order (IBKR Reg-T context).

Cap letto dal secret JSON via campo `max_leverage`. Default 1 (cash) se assente.
IBKR margin accounts default a 4x intraday / 2x overnight (Reg-T).
"""
from __future__ import annotations

from fastapi import HTTPException


def get_max_leverage(creds: dict) -> int:
    """Legge max_leverage dal secret. Default 1 se mancante."""
    raw = creds.get("max_leverage", 1)
    try:
        value = int(raw)
    except (TypeError, ValueError):
        value = 1
    return max(1, value)


def enforce_leverage(
    requested: int | float | None,
    *,
    creds: dict,
    exchange: str,
) -> int:
    """Verifica e applica leverage cap. Ritorna leverage applicabile.

    Solleva HTTPException(403, LEVERAGE_CAP_EXCEEDED) se requested > cap.
    Se requested is None, applica il cap come default.
    """
    cap = get_max_leverage(creds)
    if requested is None:
        return cap
    lev = int(requested)
    if lev < 1:
        raise HTTPException(
            status_code=403,
            detail={
                "error": "LEVERAGE_CAP_EXCEEDED",
                "exchange": exchange,
                "requested": lev,
                "max": cap,
                "reason": "leverage must be >= 1",
            },
        )
    if lev > cap:
        raise HTTPException(
            status_code=403,
            detail={
                "error": "LEVERAGE_CAP_EXCEEDED",
                "exchange": exchange,
                "requested": lev,
                "max": cap,
            },
        )
    return lev