API: publish forecast as arrays with unix timestamps (BC) (#32391)

core/site_tariffs.go

@@ -10,6 +10,7 @@ import (
 	"github.com/evcc-io/evcc/tariff"
 	"github.com/evcc-io/evcc/util"
 	"github.com/jinzhu/now"
+	"github.com/samber/lo"
 )
 
 type solarDetails struct {
@@ -25,6 +26,20 @@ type dailyDetails struct {
 	Complete bool    `json:"complete"`
 }
 
+// forecastRates publishes rates as [start, end, value] with the timestamps in
+// unix seconds. The forecast is the largest payload evcc sends and RFC3339
+// timestamps are two thirds of it.
+func forecastRates(rr api.Rates) [][]float64 {
+	// keep nil for empty rates: shards are published without omitempty
+	if len(rr) == 0 {
+		return nil
+	}
+
+	return lo.Map(rr, func(r api.Rate, _ int) []float64 {
+		return []float64{float64(r.Start.Unix()), float64(r.End.Unix()), r.Value}
+	})
+}
+
 // greenShare returns
 //   - the current green share, calculated for the part of the consumption between powerFrom and powerTo
 //     the consumption below powerFrom will get the available green power first
@@ -101,18 +116,18 @@ func (site *Site) publishTariffs(greenShareHome float64, greenShareLoadpoints fl
 	}
 
 	fc := struct {
-		Co2         api.Rates     `json:"co2,omitempty"`
-		FeedIn      api.Rates     `json:"feedin,omitempty"`
-		Grid        api.Rates     `json:"grid,omitempty"`
-		Planner     api.Rates     `json:"planner,omitempty"`
+		Co2         [][]float64   `json:"co2,omitempty"`
+		FeedIn      [][]float64   `json:"feedin,omitempty"`
+		Grid        [][]float64   `json:"grid,omitempty"`
+		Planner     [][]float64   `json:"planner,omitempty"`
 		Solar       *solarDetails `json:"solar,omitempty"`
-		Temperature api.Rates     `json:"temperature,omitempty"`
+		Temperature [][]float64   `json:"temperature,omitempty"`
 	}{
-		Co2:         tariff.Rates(site.GetTariff(api.TariffUsageCo2)),
-		FeedIn:      tariff.Rates(site.GetTariff(api.TariffUsageFeedIn)),
-		Planner:     tariff.Rates(site.GetTariff(api.TariffUsagePlanner)),
-		Grid:        tariff.Rates(site.GetTariff(api.TariffUsageGrid)),
-		Temperature: tariff.Rates(site.GetTariff(api.TariffUsageTemperature)),
+		Co2:         forecastRates(tariff.Rates(site.GetTariff(api.TariffUsageCo2))),
+		FeedIn:      forecastRates(tariff.Rates(site.GetTariff(api.TariffUsageFeedIn))),
+		Planner:     forecastRates(tariff.Rates(site.GetTariff(api.TariffUsagePlanner))),
+		Grid:        forecastRates(tariff.Rates(site.GetTariff(api.TariffUsageGrid))),
+		Temperature: forecastRates(tariff.Rates(site.GetTariff(api.TariffUsageTemperature))),
 	}
 
 	// calculate adjusted solar rates

core/site_tariffs_test.go

@@ -0,0 +1,69 @@
+package core
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+
+	"github.com/evcc-io/evcc/api"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestForecastRates(t *testing.T) {
+	start := time.Unix(1735689600, 0)
+
+	for _, tc := range []struct {
+		desc  string
+		rates api.Rates
+		want  string
+	}{
+		{desc: "nil", rates: nil, want: "null"},
+		{desc: "empty", rates: api.Rates{}, want: "null"},
+		{
+			desc: "slots",
+			rates: api.Rates{
+				{Start: start, End: start.Add(time.Hour), Value: 0.25},
+				{Start: start.Add(time.Hour), End: start.Add(2 * time.Hour), Value: -0.1},
+			},
+			want: "[[1735689600,1735693200,0.25],[1735693200,1735696800,-0.1]]",
+		},
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			b, err := json.Marshal(forecastRates(tc.rates))
+			require.NoError(t, err)
+			assert.Equal(t, tc.want, string(b))
+		})
+	}
+}
+
+func TestTimeseriesMarshal(t *testing.T) {
+	start := time.Unix(1735689600, 0)
+
+	for _, tc := range []struct {
+		desc string
+		ts   timeseries
+		want string
+	}{
+		{desc: "nil", ts: nil, want: "null"},
+		{desc: "empty", ts: timeseries{}, want: "[]"},
+		{
+			desc: "entries",
+			ts: timeseries{
+				{Timestamp: start, Value: 1000},
+				{Timestamp: start.Add(time.Hour), Value: 0},
+			},
+			want: "[[1735689600,1000],[1735693200,0]]",
+		},
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			b, err := json.Marshal(tc.ts)
+			require.NoError(t, err)
+			assert.Equal(t, tc.want, string(b))
+
+			b, err = tc.ts.MarshalBytes()
+			require.NoError(t, err)
+			assert.Equal(t, tc.want, string(b))
+		})
+	}
+}

core/solar.go

@@ -17,6 +17,20 @@ func (ts timeseries) MarshalBytes() ([]byte, error) {
 	return json.Marshal(ts)
 }
 
+// MarshalJSON publishes entries as [ts, val] with the timestamp in unix seconds
+func (ts timeseries) MarshalJSON() ([]byte, error) {
+	if ts == nil {
+		return []byte("null"), nil
+	}
+
+	res := make([][]float64, 0, len(ts))
+	for _, e := range ts {
+		res = append(res, []float64{float64(e.Timestamp.Unix()), e.Value})
+	}
+
+	return json.Marshal(res)
+}
+
 type tsEntry struct {
 	Timestamp time.Time `json:"ts"`
 	Value     float64   `json:"val"`