add otel as separate module (#10)

Reviewed-on: #10
Co-authored-by: andrey <andrey@4devs.io>
Co-committed-by: andrey <andrey@4devs.io>

handler/otel/helpers.go

@@ -0,0 +1,59 @@
+package otel
+
+import (
+	"context"
+
+	"gitoa.ru/go-4devs/log/entry"
+	"gitoa.ru/go-4devs/log/field"
+	"gitoa.ru/go-4devs/log/level"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+const (
+	fieldSeverityNumber = "SeverityNumber"
+	fieldSeverityText   = "SeverityText"
+	levelFields         = 2
+)
+
+func levels(lvl level.Level) Level {
+	switch lvl {
+	case level.Emergency:
+		return levelError3
+	case level.Alert:
+		return levelFatal
+	case level.Critical:
+		return levelError2
+	case level.Error:
+		return levelError
+	case level.Warning:
+		return levelWarn
+	case level.Notice:
+		return levelInfo2
+	case level.Info:
+		return levelInfo
+	case level.Debug:
+		return levelDebug
+	}
+
+	return 0
+}
+
+func addEvent(ctx context.Context, data *entry.Entry) {
+	span := trace.SpanFromContext(ctx)
+	attrs := make([]attribute.KeyValue, 0, data.Fields().Len()+levelFields)
+
+	lvl := levels(data.Level())
+	attrs = append(attrs,
+		attribute.String(fieldSeverityText, lvl.String()),
+		attribute.Int(fieldSeverityNumber, int(lvl)),
+	)
+
+	data.Fields().Fields(func(f field.Field) bool {
+		attrs = append(attrs, attribute.String(f.Key, f.Value.String()))
+
+		return true
+	})
+
+	span.AddEvent(data.Message(), trace.WithAttributes(attrs...))
+}