package indicator

import (
	"sig-pub/pkg/types"
)

// EMA stateful indicator
type EMA struct {
}

func (c *EMA) Name() string {
	return "ema"
}

func (c *EMA) RequiredSeries(window int16, in types.Input) int16 {
	return window + 1
}

// Calculate 计算单根k线sma指标
func (c *EMA) Calculate(ctx IIndicatorContext, window int16) (vector float64) {
	alpha := 2.0 / float64(window+1)

	close := ctx.Get(0).CloseF64()
	prevSMA := ctx.Series(1, window).Close().Avg()

	vector = ((close - prevSMA) * alpha) + prevSMA

	// ctx.GetSelf(0) // 自己计算的上一个值

	// 计算eam
	// closeSeries := ctx.Series(0, window).Close().Reverse()
	// ema := talib.Ema(closeSeries, int(window))
	// vector = ema[len(ema)-1]
	return
}