initial pipeline for functions processing

pkg/datasource/functions.go

@@ -0,0 +1,40 @@
+package datasource
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/alexanderzobnin/grafana-zabbix/pkg/timeseries"
+)
+
+var errFunctionNotSupported = func(name string) error {
+	return fmt.Errorf("function not supported: %s", name)
+}
+
+type DataProcessingFunc = func(series timeseries.TimeSeries, params ...string) timeseries.TimeSeries
+
+var funcMap map[string]DataProcessingFunc
+
+func init() {
+	funcMap = make(map[string]DataProcessingFunc)
+	funcMap["groupBy"] = applyGroupBy
+}
+
+func applyFunctions(series []*timeseries.TimeSeriesData, functions []QueryFunction) ([]*timeseries.TimeSeriesData, error) {
+	for _, f := range functions {
+		if applyFunc, ok := funcMap[f.Def.Name]; ok {
+			for _, s := range series {
+				s.TS = applyFunc(s.TS, f.Params...)
+			}
+		} else {
+			err := errFunctionNotSupported(f.Def.Name)
+			return series, err
+		}
+	}
+	return series, nil
+}
+
+func applyGroupBy(series timeseries.TimeSeries, params ...string) timeseries.TimeSeries {
+	s := series.GroupBy(time.Minute, "avg")
+	return s
+}