From f8573f1123a75799c6986c1c854798a0ec5059c0 Mon Sep 17 00:00:00 2001
From: Will Charczuk <will.charczuk@gmail.com>
Date: Fri, 15 Jul 2016 13:27:45 -0700
Subject: [PATCH] adding GetLastBoundedValue and tests

---
 bollinger_band_series.go      | 28 ++++++++++++++++++++++++++++
 bollinger_band_series_test.go | 19 +++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/bollinger_band_series.go b/bollinger_band_series.go
index 3529aa5..fef8be5 100644
--- a/bollinger_band_series.go
+++ b/bollinger_band_series.go
@@ -81,6 +81,34 @@ func (bbs *BollingerBandsSeries) GetBoundedValue(index int) (x, y1, y2 float64)
 	return
 }
 
+// GetLastBoundedValue returns the last bounded value for the series.
+func (bbs *BollingerBandsSeries) GetLastBoundedValue() (x, y1, y2 float64) {
+	if bbs.InnerSeries == nil {
+		return
+	}
+	windowSize := bbs.GetWindowSize()
+	seriesLength := bbs.InnerSeries.Len()
+	startAt := seriesLength - windowSize
+	if startAt < 0 {
+		startAt = 0
+	}
+
+	vb := NewRingBufferWithCapacity(windowSize)
+	for index := startAt; index < seriesLength; index++ {
+		xn, yn := bbs.InnerSeries.GetValue(index)
+		vb.Enqueue(yn)
+		x = xn
+	}
+
+	ay := bbs.getAverage(vb)
+	std := bbs.getStdDev(vb)
+
+	y1 = ay + (bbs.GetK() * std)
+	y2 = ay - (bbs.GetK() * std)
+
+	return
+}
+
 // Render renders the series.
 func (bbs BollingerBandsSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
 	s := bbs.Style.WithDefaultsFrom(defaults)
diff --git a/bollinger_band_series_test.go b/bollinger_band_series_test.go
index 5394afd..67a34f4 100644
--- a/bollinger_band_series_test.go
+++ b/bollinger_band_series_test.go
@@ -1,6 +1,7 @@
 package chart
 
 import (
+	"math"
 	"testing"
 
 	"github.com/blendlabs/go-assert"
@@ -30,3 +31,21 @@ func TestBollingerBandSeries(t *testing.T) {
 		assert.True(y1values[x] > y2values[x])
 	}
 }
+
+func TestBollingerBandLastValue(t *testing.T) {
+	assert := assert.New(t)
+
+	s1 := mockValueProvider{
+		X: Seq(1.0, 100.0),
+		Y: Seq(1.0, 100.0),
+	}
+
+	bbs := &BollingerBandsSeries{
+		InnerSeries: s1,
+	}
+
+	x, y1, y2 := bbs.GetLastBoundedValue()
+	assert.Equal(100.0, x)
+	assert.Equal(100, math.Floor(y1))
+	assert.Equal(95, math.Floor(y2))
+}