Document PrettifiedMetrics (#16)

docs/TEMPLATING_REFERENCE.md

@@ -416,6 +416,49 @@ Example:
 }]
 ```
 
+For metrics there is a dedicated method `PrettifiedMetrics` which provided on the Details collection that returns only the details with `metric` tag with pre-formatted values:
+
+- returns them as string type rather than floating numbers;
+- rounds the floating values to 2 decimal digits or none if the fraction is below 0.05 delta
+- converts bit/s unit into the one the most applicable (Kbit/s, Mbit/s, Gbit/s etc.)
+
+**Example - Using PrettifiedMetrics**
+
+```go-template
+{{- if .IsSingleEvent  -}}
+  {{- with .Event -}}
+    {{- .Details.PrettifiedMetrics | toJSON -}}
+  {{- end -}}
+{{- end -}}
+}
+```
+
+For the previous example it would render as:
+
+```json
+[{
+  "Label": "Kbit/s",
+  "Name": "bits",
+  "Tag": "metric",
+  "Value": "46.25"
+},
+{
+  "Label": "Packets/second",
+  "Name": "packets",
+  "Tag": "metric",
+  "Value": "240.26"
+},
+{
+  "Label": "Unique Source IPs",
+  "Name": "unique_src_ip",
+  "Tag": "metric",
+  "Value": "1"
+}]
+```
+
+
+
+
 #### Labels
 
 Tags: `label`, `device_label`

pkg/types.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"math"
 	"strings"
 	"time"
 )
@@ -373,3 +374,70 @@ func (vm *NotificationViewModel) Summary() string {
 	}
 	return strings.Join(segments, ", ")
 }
+
+// filter details to only ones with a metric tag and prettify their
+// values rounding the float values and converting bits to x-bits/s
+func (details EventViewModelDetails) PrettifiedMetrics() EventViewModelDetails {
+	result := make(EventViewModelDetails, 0)
+	for _, detail := range details {
+		if detail.Tag != "metric" {
+			continue
+		}
+
+		floatValue, err := toFloat(detail.Value)
+		if err != nil {
+			result = append(result, detail)
+			continue
+		}
+
+		label := detail.Label
+
+		// format bits with proper unit
+		if strings.HasPrefix(detail.Name, "bits") {
+			var prefix string
+			floatValue, prefix = formatBits(floatValue)
+			label = fmt.Sprintf("%sbits/s", prefix)
+		}
+
+		// prevent showing fractions when unnecessary
+		stringValue := fmt.Sprintf("%.2f", floatValue)
+		if _, fraction := math.Modf(floatValue); fraction < 0.05 {
+			stringValue = fmt.Sprintf("%.0f", floatValue)
+		}
+
+		formatted := &EventViewModelDetail{
+			Name:  detail.Name,
+			Label: label,
+			Tag:   detail.Tag,
+			Value: stringValue,
+		}
+
+		result = append(result, formatted)
+	}
+	return result
+}
+
+func toFloat(value interface{}) (float64, error) {
+	switch v := value.(type) {
+	case float64:
+		return v, nil
+	case int:
+		return float64(v), nil
+	default:
+		return 0, fmt.Errorf("don't know how to convert %T to float64", v)
+	}
+}
+
+func formatBits(bits float64) (float64, string) {
+	const unit = 1024
+	const suffixes = "KMGTPE"
+
+	exp := math.Floor(math.Log(bits) / math.Log(unit))
+	suffix := ""
+	if exp > 0 {
+		suffix = string(suffixes[int(exp)-1])
+	}
+	value := bits / math.Pow(unit, exp)
+
+	return value, suffix
+}

templates/discord.json.tmpl

@@ -40,11 +40,11 @@ Webhook execute parameters: https://discord.com/developers/docs/resources/webhoo
       {{- end -}}
 
 
-      {{- with $metrics := .Details.WithTag "metric" -}}
+      {{- with $metrics := .Details.PrettifiedMetrics -}}
         {{- if gt (len $metrics) 0 -}}
           **Metrics**:\n
           {{- range $index, $detail := $metrics -}}
-            - **{{ $detail.LabelOrName }}**: {{ $detail.Value }}\n
+            - **{{ $detail.Value }} {{ $detail.LabelOrName }}**\n
           {{- end -}}
         {{- end -}}
       {{- end -}}