from __future__ import annotations

import os
from dataclasses import dataclass
from typing import Literal, cast


TradingMode = Literal["schwab_live", "alpaca_paper", "tradier_live", "tradier_sandbox"]


@dataclass(frozen=True)
class TradingModeSettings:
    execution_mode: TradingMode = "alpaca_paper"

    @classmethod
    def from_env(cls, env: dict[str, str] | None = None) -> "TradingModeSettings":
        values = dict(os.environ)
        if env is not None:
            values.update(env)
        # BROKER=tradier swaps the execution client, so the default mode label
        # must follow it — else the Tradier stack reports "alpaca_paper".
        if values.get("BROKER", "alpaca").strip().lower() == "tradier":
            sandbox = values.get("TRADIER_ENV", "sandbox").strip().lower() != "live"
            default = "tradier_sandbox" if sandbox else "tradier_live"
        else:
            default = "alpaca_paper"
        mode = values.get("TRADING_EXECUTION_MODE", default)
        if mode not in {"schwab_live", "alpaca_paper", "tradier_live", "tradier_sandbox"}:
            mode = default
        return cls(execution_mode=cast(TradingMode, mode))