package main

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

const defaultTargetURL = "https://venueaxe.com"

func getEnv(key, fallback string) string {
	if value := os.Getenv(key); value != "" {
		return value
	}
	return fallback
}

func redirectHandler(targetURL string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		http.Redirect(w, r, targetURL, http.StatusMovedPermanently)
	}
}

func main() {
	port := getEnv("PORT", "8080")
	targetURL := getEnv("TARGET_URL", defaultTargetURL)

	mux := http.NewServeMux()
	mux.HandleFunc("/", redirectHandler(targetURL))

	server := &http.Server{
		Addr:         ":" + port,
		Handler:      mux,
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 10 * time.Second,
		IdleTimeout:  120 * time.Second,
	}

	// Channel to listen for interrupt signals for graceful shutdown
	stop := make(chan os.Signal, 1)
	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)

	go func() {
		log.Printf("Starting redirect server on :%s -> %s", port, targetURL)
		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("HTTP server error: %v\n", err)
		}
	}()

	<-stop
	log.Println("Shutting down server gracefully...")

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	if err := server.Shutdown(ctx); err != nil {
		log.Fatalf("Server shutdown failed: %+v", err)
	}

	log.Println("Server exited")
}