from __future__ import annotations

import backtrader as bt


class SmaCrossStrategy(bt.Strategy):
    params = (
        ("fast", 3),
        ("slow", 8),
        ("stake", 1),
    )

    def __init__(self) -> None:
        self.fast_sma = bt.indicators.SMA(self.data.close, period=self.params.fast)
        self.slow_sma = bt.indicators.SMA(self.data.close, period=self.params.slow)
        self.cross_signal = bt.indicators.CrossOver(self.fast_sma, self.slow_sma)

    def next(self) -> None:
        if not self.position and self.cross_signal > 0:
            self.buy(size=self.params.stake)
        elif self.position and self.cross_signal < 0:
            self.close()