commit cda74c3d6011614191641f7080a6e1a9faac3815
Author: Thomas Klaehn <thomas.klaehn@perinet.io>
Date:   Wed Mar 1 07:45:34 2023 +0100

    Initial commit

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..19a5929
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,11 @@
+module git.blackfinn.de/apiservice/sauna
+
+go 1.20
+
+require github.com/eclipse/paho.mqtt.golang v1.4.2
+
+require (
+	github.com/gorilla/websocket v1.4.2 // indirect
+	golang.org/x/net v0.0.0-20200425230154-ff2c4b7c35a0 // indirect
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..ddd8ce6
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,12 @@
+github.com/eclipse/paho.mqtt.golang v1.4.2 h1:66wOzfUHSSI1zamx7jR6yMEI5EuHnT1G6rNA5PM12m4=
+github.com/eclipse/paho.mqtt.golang v1.4.2/go.mod h1:JGt0RsEwEX+Xa/agj90YJ9d9DH2b7upDZMK9HRbFvCA=
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20200425230154-ff2c4b7c35a0 h1:Jcxah/M+oLZ/R4/z5RzfPzGbPXnVDPkEDtf2JnuxN+U=
+golang.org/x/net v0.0.0-20200425230154-ff2c4b7c35a0/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/sauna.go b/sauna.go
new file mode 100644
index 0000000..0c542f4
--- /dev/null
+++ b/sauna.go
@@ -0,0 +1,100 @@
+package sauna
+
+import (
+	"encoding/json"
+	"log"
+	"math/rand"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+)
+
+type temperature struct {
+	Value float64   `json:"value"`
+	Unit  string    `json:"unit"`
+	Time  time.Time `json:"time"`
+	Valid bool      `json:"valid"`
+}
+
+var (
+	logger            log.Logger = *log.Default()
+	sauna_mutex       sync.Mutex
+	sauna_temperature = temperature{
+		Value: 0.0,
+		Unit:  "°C",
+	}
+)
+
+var messagePubHandler mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
+	logger.Printf("Received message: %s from topic: %s\n", msg.Payload(), msg.Topic())
+}
+
+var saunaHandler mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
+	log.Printf("Received message: %s from topic: %s\n", msg.Payload(), msg.Topic())
+	sauna_mutex.Lock()
+	err := json.Unmarshal(msg.Payload(), &sauna_temperature)
+	sauna_temperature.Time = time.Now()
+	if err != nil {
+		sauna_temperature.Valid = false
+		sauna_mutex.Unlock()
+		logger.Print(err)
+		return
+	}
+	sauna_temperature.Valid = true
+	sauna_mutex.Unlock()
+}
+
+var connectHandler mqtt.OnConnectHandler = func(client mqtt.Client) {
+	logger.Println("Connected")
+}
+
+var connectLostHandler mqtt.ConnectionLostHandler = func(client mqtt.Client, err error) {
+	logger.Printf("Connect lost: %v", err)
+}
+
+func init() {
+	logger.SetPrefix("apiservice/sauna: ")
+}
+
+func http_endpoint_sauna(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-type", "application/json; charset=utf-8;")
+	if r.Method == http.MethodGet {
+		sauna_mutex.Lock()
+		data, err := json.Marshal(sauna_temperature)
+		sauna_mutex.Unlock()
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write(json.RawMessage(`{"error": "cannot marshal object to json"}`))
+		} else {
+			w.WriteHeader(http.StatusOK)
+			w.Write(data)
+		}
+	} else {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+	}
+}
+
+func Start() {
+	// MQTT connection
+	opts := mqtt.NewClientOptions()
+	opts.AddBroker("tcp://nuc:1883")
+	opts.SetClientID("apiservice/sauna/" + strconv.Itoa(rand.Int()))
+	opts.SetDefaultPublishHandler(messagePubHandler)
+	opts.OnConnect = connectHandler
+	opts.OnConnectionLost = connectLostHandler
+	client := mqtt.NewClient(opts)
+	if token := client.Connect(); token.Wait() && token.Error() != nil {
+		panic(token.Error())
+	}
+
+	// MQTT subscribtion
+	topic := "sauna/temperature"
+	token := client.Subscribe(topic, 1, saunaHandler)
+	token.Wait()
+	logger.Printf("Subscribed to topic %s", topic)
+
+	http.HandleFunc("/api/sauna", http_endpoint_sauna)
+}