functions to find max value of gapi nonsense types

tscli/main.go

@@ -124,10 +124,11 @@ func executeQuery(cmd *cobra.Command, args []string) error {
 		log.Fatal(err)
 	}
 
-	plot, err := tsplot.NewPlotFromTimeSeries(ts)
+	plot, err := tsplot.NewPlotFromTimeSeries(ts, tsplot.WithXTimeTicks(time.Kitchen), tsplot.WithXAxisName("UTC"), tsplot.WithTitle("decodes_raw"))
 	if err != nil {
 		log.Fatal(err)
 	}
+
 	saveFile := fmt.Sprintf("%s/test.png", "/tmp/")
 	return plot.Save(8*vg.Inch, 4*vg.Inch, saveFile)
 }

tsplot/options.go

@@ -115,3 +115,12 @@ func WithLineFromPoints(pts []*monitoringpb.Point) PlotOption {
 		p.Add(line)
 	}
 }
+
+func WithColoredLineFromPoints(pts []*monitoringpb.Point, color color.Color) PlotOption {
+	return func(p *plot.Plot) {
+		line, _ := createLine(pts)
+		line.Width = vg.Points(1)
+		line.Color = color
+		p.Add(line)
+	}
+}

tsplot/plot.go

@@ -1,29 +1,72 @@
 package tsplot
 
 import (
+	"fmt"
 	"gonum.org/v1/plot"
 	"gonum.org/v1/plot/plotter"
+	"google.golang.org/genproto/googleapis/api/metric"
 	monitoringpb "google.golang.org/genproto/googleapis/monitoring/v3"
 )
 
-func NewPlotFromTimeSeries(ts *monitoringpb.TimeSeries, opts ...PlotOption) (*plot.Plot, error) {
-	// todo: how do we determine the type of values in the metric? float? double?
-	// todo: need to abstract max function.
+// findMaxFromPoints finds the maximum value of a list of metric points of the GAPI MetricDescriptor Value type.
+func findMaxFromPoints(gapiValueType metric.MetricDescriptor_ValueType, points []*monitoringpb.Point) (float64, error) {
+	var maximum float64
+
+	switch gapiValueType {
+	case metric.MetricDescriptor_INT64:
+		maximum = findMaxFromInt64Data(points)
+	case metric.MetricDescriptor_DOUBLE:
+		maximum = findMaxFromFloat64Data(points)
+	default:
+		return 0, fmt.Errorf("cannot operate on value type %q", gapiValueType.String())
+	}
+
+	return maximum, nil
+
+}
+
+// findMaxFromFloat64Data is a helper function to findMaxFromPoints but is specific to the data being of type float64.
+// The other helper function findMaxFromInt64Data is also required due to the methods that which Google allows the consumer
+// to fetch the data.
+func findMaxFromFloat64Data(points []*monitoringpb.Point) float64 {
 	var maximum float64
-	points := ts.GetPoints()
 	for _, v := range points {
 		cur := v.GetValue().GetDoubleValue()
 		if cur > maximum {
 			maximum = cur
 		}
 	}
+	return maximum
+}
+
+// findMaxFromInt64Data is a helper function to findMaxFromPoints but is specific to the data being of type float64.
+// The other helper function findMaxFromFloat64Data is also required due to the methods that which Google allows the consumer
+// to fetch the data.
+func findMaxFromInt64Data(points []*monitoringpb.Point) float64 {
+	var maximum int64
+	for _, v := range points {
+		cur := v.GetValue().GetInt64Value()
+		if cur > maximum {
+			maximum = cur
+		}
+	}
+	return float64(maximum)
+}
+
+func NewPlotFromTimeSeries(ts *monitoringpb.TimeSeries, opts ...PlotOption) (*plot.Plot, error) {
+	points := ts.GetPoints()
+	YMax, err := findMaxFromPoints(ts.GetValueType(), points)
+	if err != nil {
+		return nil, err
+	}
+
 	opts = append(opts, WithLineFromPoints(points))
 	p := plot.New()
 	for _, opt := range opts {
 		opt(p)
 	}
 
-	p.Y.Max = maximum + 200
+	p.Y.Max = YMax + 200
 	return p, nil
 }