From 9d4bc2aea74a21a5c6d3bac4dae6d7f03c64f68d Mon Sep 17 00:00:00 2001
From: Martin Valov <marval@users.noreply.github.com>
Date: Mon, 3 Jul 2023 10:33:37 +0200
Subject: [PATCH] Add support for Energinet (#8717)

---
 evcc.dist.yaml            |   5 ++
 tariff/energinet.go       | 109 ++++++++++++++++++++++++++++++++++++++
 tariff/energinet/types.go |  15 ++++++
 3 files changed, 129 insertions(+)
 create mode 100644 tariff/energinet.go
 create mode 100644 tariff/energinet/types.go

diff --git a/evcc.dist.yaml b/evcc.dist.yaml
index 60f99834b..03151fc08 100644
--- a/evcc.dist.yaml
+++ b/evcc.dist.yaml
@@ -179,6 +179,11 @@ tariffs:
     # region: ee # or lt, lv, fi
     # charges: # optional, additional charges per kWh
     # tax: # optional, additional tax (0.1 for 10%)
+
+    # type: energinet # Energinet using the price in DKK
+    # region: dk1 # or dk2
+    # charges: # optional, additional charges per kWh
+    # tax: # optional, additional tax (0.1 for 10%)
   feedin:
     # rate for feeding excess (pv) energy to the grid
     type: fixed
diff --git a/tariff/energinet.go b/tariff/energinet.go
new file mode 100644
index 000000000..a41cff590
--- /dev/null
+++ b/tariff/energinet.go
@@ -0,0 +1,109 @@
+package tariff
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/evcc-io/evcc/api"
+	"github.com/evcc-io/evcc/tariff/energinet"
+	"github.com/evcc-io/evcc/util"
+	"github.com/evcc-io/evcc/util/request"
+	"golang.org/x/exp/slices"
+)
+
+type Energinet struct {
+	*embed
+	mux     sync.Mutex
+	log     *util.Logger
+	region  string
+	data    api.Rates
+	updated time.Time
+}
+
+var _ api.Tariff = (*Energinet)(nil)
+
+func init() {
+	registry.Add("energinet", NewEnerginetFromConfig)
+}
+
+func NewEnerginetFromConfig(other map[string]interface{}) (api.Tariff, error) {
+	var cc struct {
+		embed  `mapstructure:",squash"`
+		Region string
+	}
+
+	if err := util.DecodeOther(other, &cc); err != nil {
+		return nil, err
+	}
+
+	if cc.Region == "" {
+		return nil, errors.New("missing region")
+	}
+
+	t := &Energinet{
+		embed:  &cc.embed,
+		log:    util.NewLogger("energinet"),
+		region: strings.ToLower(cc.Region),
+	}
+
+	done := make(chan error)
+	go t.run(done)
+	err := <-done
+
+	return t, err
+}
+
+func (t *Energinet) run(done chan error) {
+	var once sync.Once
+	client := request.NewHelper(t.log)
+
+	for ; true; <-time.Tick(time.Hour) {
+		var res energinet.Prices
+
+		ts := time.Now().Truncate(time.Hour)
+		uri := fmt.Sprintf(energinet.URI,
+			ts.Format(time.RFC3339),
+			ts.Add(24*time.Hour).Format(time.RFC3339),
+			t.region)
+
+		if err := client.GetJSON(uri, &res); err != nil {
+			once.Do(func() { done <- err })
+
+			t.log.ERROR.Println(err)
+			continue
+		}
+
+		once.Do(func() { close(done) })
+
+		t.mux.Lock()
+		t.updated = time.Now()
+
+		t.data = make(api.Rates, 0, len(res.Records))
+		for _, r := range res.Records {
+			date, _ := time.Parse("2006-01-02T15:04:05", r.HourUTC)
+			ar := api.Rate{
+				Start: date.Local(),
+				End:   date.Add(time.Hour).Local(),
+				Price: t.totalPrice(r.SpotPriceDKK / 1e3),
+			}
+			t.data = append(t.data, ar)
+		}
+
+		t.mux.Unlock()
+	}
+}
+
+// Rates implements the api.Tariff interface
+func (t *Energinet) Rates() (api.Rates, error) {
+	t.mux.Lock()
+	defer t.mux.Unlock()
+	return slices.Clone(t.data), outdatedError(t.updated, time.Hour)
+}
+
+// Type returns the tariff type
+func (t *Energinet) Type() api.TariffType {
+	return api.TariffTypePriceDynamic
+}
diff --git a/tariff/energinet/types.go b/tariff/energinet/types.go
new file mode 100644
index 000000000..06062f330
--- /dev/null
+++ b/tariff/energinet/types.go
@@ -0,0 +1,15 @@
+package energinet
+
+const URI = "https://api.energidataservice.dk/dataset/Elspotprices?offset=0&start=%s&end=%s&filter={\"PriceArea\":[\"%s\"]}&timezone=dk&limit=48"
+
+type Prices struct {
+	Records []PriceInfo `json:"records"`
+}
+
+type PriceInfo struct {
+	HourUTC      string
+	HourDK       string
+	PriceArea    string
+	SpotPriceDKK float64
+	SpotPriceEUR float64
+}