from __future__ import annotations

from app.broker.base import Broker, Fill
from app.broker.binance import TESTNET_URL, BinanceBroker
from app.broker.coinbase import CoinbaseBroker
from app.broker.paper import PaperBroker
from app.config import Settings
from app.market.binance import BASE_URL

# Exchanges with a live execution adapter. Others fall back to paper and the
# engine surfaces a clear error at start.
_LIVE_BROKERS: dict[str, type[Broker]] = {
    "binance": BinanceBroker,
    "binanceus": BinanceBroker,
    "coinbase": CoinbaseBroker,
}


def build_broker(settings: Settings) -> Broker:
    if settings.mode != "live":
        return PaperBroker(fee_bps=settings.fee_bps, slippage_bps=settings.slippage_bps)

    exchange = settings.exchange.lower()
    if exchange not in _LIVE_BROKERS:
        raise ValueError(
            f"live trading is not supported on '{settings.exchange}' yet; "
            f"use MODE=paper or one of {sorted(_LIVE_BROKERS)}"
        )

    if exchange in {"binance", "binanceus"}:
        return BinanceBroker(
            api_key=settings.exchange_api_key,
            api_secret=settings.exchange_api_secret,
            base_url=TESTNET_URL if settings.exchange_sandbox else BASE_URL,
        )
    return CoinbaseBroker(
        api_key=settings.exchange_api_key,
        api_secret=settings.exchange_api_secret,
    )


__all__ = ["Broker", "Fill", "PaperBroker", "build_broker"]