"""Base strategy and example SMA crossover for Chinese equities."""
import backtrader as bt


class SmaCross(bt.Strategy):
    """Simple SMA crossover strategy: buy when fast crosses above slow, sell when below."""

    params = (
        ("fast", 10),
        ("slow", 30),
    )

    def __init__(self):
        self.fast_ma = bt.indicators.SMA(self.data.close, period=self.params.fast)
        self.slow_ma = bt.indicators.SMA(self.data.close, period=self.params.slow)
        self.crossover = bt.indicators.CrossOver(self.fast_ma, self.slow_ma)

    def next(self):
        if not self.position:
            if self.crossover > 0:  # fast crosses above slow
                self.buy()
        elif self.crossover < 0:  # fast crosses below slow
            self.close()