From b58f3ae2ebb8b50ebf2a2d6e49cca34ddbc6d9a3 Mon Sep 17 00:00:00 2001
From: fanatix <43752712+djfanatix@users.noreply.github.com>
Date: Sun, 14 Sep 2025 19:16:32 +0200
Subject: [PATCH] Tariff: Add Stekker (Market prices  + AI Forecast) (#23356)

---
 tariff/stekker.go                        | 164 +++++++++++++++++++++++
 templates/definition/tariff/stekker.yaml |  54 ++++++++
 2 files changed, 218 insertions(+)
 create mode 100644 tariff/stekker.go
 create mode 100644 templates/definition/tariff/stekker.yaml

diff --git a/tariff/stekker.go b/tariff/stekker.go
new file mode 100644
index 000000000..ad46ed875
--- /dev/null
+++ b/tariff/stekker.go
@@ -0,0 +1,164 @@
+package tariff
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"slices"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/PuerkitoBio/goquery"
+	"github.com/evcc-io/evcc/api"
+	"github.com/evcc-io/evcc/util"
+	"github.com/evcc-io/evcc/util/request"
+)
+
+// Supported regions
+var supportedRegions = []string{
+	"BE", "NL", "DE-LU", "FR", "CH",
+	"SE4", "SE3", "SE1", "DK1", "DK2",
+	"FI", "NO1", "NO2", "NO3", "NO4", "NO5",
+	"LV", "LT", "PL", "PT", "RO", "RS",
+	"SI", "SK", "HU", "AT", "CZ", "HR", "EE",
+}
+
+// Stekker provider
+type Stekker struct {
+	*embed
+	region string
+	log    *util.Logger
+	data   *util.Monitor[api.Rates]
+}
+
+var _ api.Tariff = (*Stekker)(nil)
+
+func init() {
+	registry.Add("stekker", NewStekkerFromConfig)
+}
+
+const stekkerURI = "https://stekker.app/epex-forecast"
+
+// NewStekkerFromConfig creates provider from config
+func NewStekkerFromConfig(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 !slices.Contains(supportedRegions, cc.Region) {
+		return nil, fmt.Errorf("unsupported region: %s", cc.Region)
+	}
+
+	t := &Stekker{
+		embed:  &cc.embed,
+		region: cc.Region,
+		log:    util.NewLogger("stekker"),
+		data:   util.NewMonitor[api.Rates](2 * time.Hour),
+	}
+
+	return runOrError(t)
+}
+
+func (t *Stekker) run(done chan error) {
+	var once sync.Once
+	client := request.NewHelper(t.log)
+
+	for tick := time.Tick(time.Hour); ; <-tick {
+		url := fmt.Sprintf("%s?advanced_view=&region=%s&unit=MWh", stekkerURI, t.region)
+
+		resp, err := client.Get(url)
+		if err != nil {
+			once.Do(func() { done <- err })
+			t.log.ERROR.Println("http error:", err)
+			continue
+		}
+
+		if resp.StatusCode != http.StatusOK {
+			once.Do(func() { done <- fmt.Errorf("http status %d", resp.StatusCode) })
+			t.log.ERROR.Printf("http status %d", resp.StatusCode)
+			resp.Body.Close()
+			continue
+		}
+
+		doc, err := goquery.NewDocumentFromReader(resp.Body)
+		if err != nil {
+			resp.Body.Close()
+			once.Do(func() { done <- err })
+			t.log.ERROR.Println("parse error:", err)
+			continue
+		}
+		resp.Body.Close()
+
+		val, ok := doc.Find("[data-epex-forecast-graph-data-value]").Attr("data-epex-forecast-graph-data-value")
+		if !ok {
+			once.Do(func() { done <- fmt.Errorf("no forecast attribute found") })
+			t.log.ERROR.Println("no forecast attribute found")
+			continue
+		}
+
+		raw := strings.ReplaceAll(val, "&quot;", "\"")
+
+		var data []map[string]interface{}
+		if err := json.Unmarshal([]byte(raw), &data); err != nil {
+			once.Do(func() { done <- err })
+			t.log.ERROR.Println("unmarshal error:", err)
+			continue
+		}
+
+		var res api.Rates
+		for _, series := range data {
+			name, _ := series["name"].(string)
+			if !(strings.Contains(name, "Market") || strings.Contains(name, "Forecast")) {
+				continue
+			}
+
+			xs, _ := series["x"].([]interface{})
+			ys, _ := series["y"].([]interface{})
+
+			for i := range xs {
+				xt, ok1 := xs[i].(string)
+				yt, ok2 := ys[i].(float64)
+				if !ok1 || !ok2 {
+					continue
+				}
+
+				start, err := time.Parse(time.RFC3339, xt)
+				if err != nil {
+					continue
+				}
+
+				start = start.UTC()
+				end := start.Add(time.Hour)
+
+				res = append(res, api.Rate{
+					Start: start,
+					End:   end,
+					Value: t.totalPrice(yt/1000.0, start), // €/MWh → €/kWh
+				})
+			}
+		}
+
+		mergeRates(t.data, res)
+		once.Do(func() { close(done) })
+	}
+}
+
+// Rates implements api.Tariff
+func (t *Stekker) Rates() (api.Rates, error) {
+	var res api.Rates
+	err := t.data.GetFunc(func(val api.Rates) {
+		res = slices.Clone(val)
+	})
+	return res, err
+}
+
+// Type implements api.Tariff
+func (t *Stekker) Type() api.TariffType {
+	return api.TariffTypePriceForecast
+}
diff --git a/templates/definition/tariff/stekker.yaml b/templates/definition/tariff/stekker.yaml
new file mode 100644
index 000000000..a86288404
--- /dev/null
+++ b/templates/definition/tariff/stekker.yaml
@@ -0,0 +1,54 @@
+template: stekker
+products:
+  - brand: Stekker spot prices and AI Forecast
+requirements:
+  description:
+    en: "Stekker.app spot prices in day-ahead market and 24h AI price Forecast"
+  evcc: ["skiptest"]
+group: price
+countries: ["EU"]
+params:
+  - name: region
+    example: BE
+    type: choice
+    choice:
+      [
+        "DE-LU",
+        "EE",
+        "LT",
+        "LV",
+        "AT",
+        "BE",
+        "FR",
+        "GER",
+        "NL",
+        "PL",
+        "DK1",
+        "DK2",
+        "FI",
+        "NO1",
+        "NO2",
+        "NO3",
+        "NO4",
+        "NO5",
+        "SE1",
+        "SE2",
+        "SE3",
+        "SE4",
+        "TEL",
+        "SYS",
+        "CH",
+        "RO",
+        "PT",
+        "RS",
+        "SI",
+        "SK",
+        "HU",
+        "CZ",
+        "HR",
+      ]
+  - preset: tariff-base
+render: |
+  type: stekker
+  region: {{ .region }}
+  {{ include "tariff-base" . }}