import pytest

from trademind.broker import InsufficientFunds, OrderRejected, PaperBroker
from trademind.config import PaperConfig
from trademind.models import Side


@pytest.fixture
def broker(paper_config) -> PaperBroker:
    return PaperBroker(paper_config)


async def test_buy_applies_slippage_and_fee(broker):
    fill = await broker.execute("BTC/USDT", Side.BUY, 0.1, 30_000.0)
    assert fill.price == pytest.approx(30_000.0 * 1.0005)      # 5 bps Slippage
    assert fill.fee_quote == pytest.approx(fill.notional * 0.001)
    assert await broker.cash() == pytest.approx(10_000.0 - fill.notional - fill.fee_quote)
    assert await broker.holdings("BTC/USDT") == pytest.approx(0.1)


async def test_sell_applies_slippage_in_the_other_direction(broker):
    await broker.execute("BTC/USDT", Side.BUY, 0.1, 30_000.0)
    fill = await broker.execute("BTC/USDT", Side.SELL, 0.1, 31_000.0)
    assert fill.price == pytest.approx(31_000.0 * 0.9995)
    assert await broker.holdings("BTC/USDT") == 0.0


async def test_round_trip_at_constant_price_loses_exactly_the_costs(broker):
    price = 30_000.0
    await broker.execute("BTC/USDT", Side.BUY, 0.1, price)
    await broker.execute("BTC/USDT", Side.SELL, 0.1, price)
    # 2 × 0,1 % Gebühr + 2 × 5 bps Slippage auf ein Volumen von ~3000
    assert await broker.cash() == pytest.approx(10_000.0 - 9.0, abs=0.2)


async def test_buy_is_scaled_down_to_available_cash(broker):
    fill = await broker.execute("BTC/USDT", Side.BUY, 10.0, 30_000.0)  # 300k gewünscht
    assert fill.amount < 10.0
    assert await broker.cash() == pytest.approx(0.0, abs=1e-6)


async def test_buy_without_any_cash_raises():
    broker = PaperBroker(PaperConfig(starting_balance=1.0, fee_rate=0.001))
    broker.market_info = {"BTC/USDT": {"amount_precision": 4}}
    with pytest.raises(InsufficientFunds):
        await broker.execute("BTC/USDT", Side.BUY, 1.0, 30_000.0)


async def test_sell_without_position_raises(broker):
    with pytest.raises(OrderRejected):
        await broker.execute("BTC/USDT", Side.SELL, 1.0, 30_000.0)


async def test_sell_is_capped_at_held_amount(broker):
    await broker.execute("BTC/USDT", Side.BUY, 0.1, 30_000.0)
    fill = await broker.execute("BTC/USDT", Side.SELL, 5.0, 30_000.0)
    assert fill.amount == pytest.approx(0.1)


async def test_volume_participation_caps_the_order(broker):
    fill = await broker.execute("BTC/USDT", Side.BUY, 0.1, 30_000.0, bar_volume=0.2)
    assert fill.amount == pytest.approx(0.02)  # 10 % von 0,2
    assert fill.requested_amount == pytest.approx(0.1)


async def test_amount_precision_rounds_down(broker):
    broker.market_info = {"BTC/USDT": {"amount_precision": 3}}
    fill = await broker.execute("BTC/USDT", Side.BUY, 0.123456, 30_000.0)
    assert fill.amount == pytest.approx(0.123)


async def test_step_size_precision_is_supported(broker):
    broker.market_info = {"BTC/USDT": {"amount_precision": 0.05}}
    fill = await broker.execute("BTC/USDT", Side.BUY, 0.17, 100.0)
    assert fill.amount == pytest.approx(0.15)


async def test_invalid_inputs_are_rejected(broker):
    with pytest.raises(OrderRejected):
        await broker.execute("BTC/USDT", Side.BUY, 0.0, 30_000.0)
    with pytest.raises(OrderRejected):
        await broker.execute("BTC/USDT", Side.BUY, 1.0, 0.0)


async def test_state_round_trip(broker):
    await broker.execute("BTC/USDT", Side.BUY, 0.05, 30_000.0)
    state = broker.state()

    restored = PaperBroker(broker.config)
    restored.restore(state["cash"], state["holdings"], state["total_fees"])
    assert await restored.cash() == pytest.approx(await broker.cash())
    assert await restored.holdings("BTC/USDT") == pytest.approx(0.05)