test(pkg/storage): add test for compression and rounding

pkg/storage/storage.go

@@ -0,0 +1,70 @@
+package storage
+
+import (
+	"math"
+	"sort"
+
+	"github.com/go-flucky/flucky/pkg/internal/format"
+	"github.com/go-flucky/flucky/pkg/types"
+)
+
+// Compression the measured values. The system checks whether the measured values
+// of the same type correspond to those of the predecessor. If this is the case,
+// the current value is discarded and the validity date of the previous value is
+// set to that of the current value. This means that no information is lost.
+// Only the validity period of the measured value is increased.
+func Compression(measuredValues []*types.MeasuredValue) []*types.MeasuredValue {
+	compressedMeasuredValues := make([]*types.MeasuredValue, 0)
+	lastMeasuredValuesBySensors := make(map[string]map[types.MeasuredValueType]*types.MeasuredValue, 0)
+
+	// Sort all measured values according to the start time of the validity date
+	// in order to successfully implement the subsequent compression.
+	sort.SliceStable(measuredValues, func(i int, j int) bool {
+		return measuredValues[i].FromDate.Before(measuredValues[j].TillDate)
+	})
+
+	now := format.FormatedTime()
+
+	for _, measuredValue := range measuredValues {
+		if _, ok := lastMeasuredValuesBySensors[measuredValue.SensorID]; !ok {
+			lastMeasuredValuesBySensors[measuredValue.SensorID] = make(map[types.MeasuredValueType]*types.MeasuredValue, 0)
+		}
+
+		if _, ok := lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType]; !ok {
+			lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType] = measuredValue
+			continue
+		}
+
+		if lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].Value == measuredValue.Value {
+			lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].TillDate = measuredValue.TillDate
+			lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].UpdateDate = &now
+		} else if lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].Value != measuredValue.Value {
+			compressedMeasuredValues = append(compressedMeasuredValues, lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType])
+			delete(lastMeasuredValuesBySensors[measuredValue.SensorID], measuredValue.ValueType)
+			lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType] = measuredValue
+		}
+	}
+
+	// Copy all remaining entries from the map into the cache array
+	for _, lastMeasuredValuesBySensor := range lastMeasuredValuesBySensors {
+		for _, measuredValueType := range types.MeasuredValueTypes {
+			if measuredValue, ok := lastMeasuredValuesBySensor[measuredValueType]; ok {
+				compressedMeasuredValues = append(compressedMeasuredValues, measuredValue)
+			}
+		}
+	}
+
+	// Sort all measured values again to include the measured values from the
+	// cache.
+	sort.SliceStable(compressedMeasuredValues, func(i int, j int) bool {
+		return compressedMeasuredValues[i].FromDate.Before(compressedMeasuredValues[j].FromDate)
+	})
+
+	return compressedMeasuredValues
+}
+
+func Round(measuredValues []*types.MeasuredValue, round float64) {
+	for _, measuredValue := range measuredValues {
+		measuredValue.Value = math.Round(measuredValue.Value/round) * round
+	}
+}