package main

import (
	"context"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"time"
)

func makeServer(addr string) *http.Server {
	srv := &http.Server{Addr: addr}

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		proto := r.Header.Get("X-Forwarded-Proto")

		if !strings.HasSuffix(proto, "://") {
			if !strings.HasSuffix(proto, ":") {
				proto = proto + ":"
			}
			proto = proto + "//"
		}

		newURL := strings.ToLower(proto + r.Host + r.RequestURI)

		if os.Getenv("DEBUG") != "true" {
			log.Print(newURL)
		}

		http.Redirect(w, r, newURL, http.StatusMovedPermanently)
	})

	return srv
}

func main() {
	stop := make(chan os.Signal, 1)

	signal.Notify(stop, os.Interrupt)

	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
	}
	addr := os.Getenv("ADDR")
	if addr == "" {
		addr = "127.0.0.1"
	}

	srv := makeServer(addr + ":" + port)

	go func() {
		log.Print("listening on http://" + addr + ":" + port)

		if err := srv.ListenAndServe(); err != nil {
			log.Fatal(err)
		}
	}()

	<-stop

	log.Print("Shutting down...")
	ctx, _ := context.WithTimeout(context.Background(), 5*time.Second)

	srv.Shutdown(ctx)

	log.Print("Shut Down")
}