package main

import (
	"fmt"
	"net/http"
	"sync"
)

// mu protects visits.
var mu sync.Mutex
var visits = 0

func nextVisit() int {
	mu.Lock()
	defer mu.Unlock()

	visits = visits + 1
	return visits
}

func handleHome(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "You are visitor number %d.\n", nextVisit())
}

func main() {
	http.HandleFunc("GET /{$}", handleHome)

	fmt.Println("Server running at http://localhost:8080")
	fmt.Println("Press Ctrl+C to stop it.")

	err := http.ListenAndServe("localhost:8080", nil)
	if err != nil {
		fmt.Println("Server stopped:", err)
	}
}