Stateful http handler demo

backend/cmd/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -9,6 +10,26 @@ import (
 	_ "github.com/mattn/go-sqlite3"
 )
 
+// The button state as represented in memory
+type ButtonState struct {
+	pressCount int
+}
+
+// This is what a handler with a receiver looks like
+// Keep in mind that concurrent state access is not (usually) safe
+// And will in pracice be guarded by a mutex
+func (b *ButtonState) pressHandler(w http.ResponseWriter, r *http.Request) {
+	b.pressCount++
+	response, err := json.Marshal(b.pressCount)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	fmt.Println("Request received")
+	io.WriteString(w, string(response))
+}
+
 // This is what a handler looks like
 func handler(w http.ResponseWriter, r *http.Request) {
 	fmt.Println("Request received")
@@ -17,15 +38,18 @@ func handler(w http.ResponseWriter, r *http.Request) {
 
 func main() {
 	database.DbConnect()
+	b := &ButtonState{pressCount: 0}
 
-	// Mounting the handler
+	// Mounting the handlers
 	fs := http.FileServer(http.Dir("static"))
 	http.Handle("/", fs)
 	http.HandleFunc("/hello", handler)
+	http.HandleFunc("/button", b.pressHandler)
 
 	// Start the server on port 8080
 	println("Currently listening on http://localhost:8080")
-	println("Visit http://localhost:8080/hello to see the handler in action")
+	println("Visit http://localhost:8080/hello to see the hello handler in action")
+	println("Visit http://localhost:8080/button to see the button handler in action")
 	println("Press Ctrl+C to stop the server")
 	err := http.ListenAndServe(":8080", nil)
 	if err != nil {