// Command mwse is the MWSE engine: a WebSocket relay that virtualizes connected
// peers so they can exchange data through rooms, pairings and data tunnels without
// knowing one another's real identity. It is the Go rewrite of the original
// Node.js engine; the on-the-wire SDK contract is unchanged.
package main

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

	"git.saqut.com/saqut/mwse/internal/config"
	"git.saqut.com/saqut/mwse/internal/httpserver"
	"git.saqut.com/saqut/mwse/internal/services"
	"git.saqut.com/saqut/mwse/internal/ws"
)

func main() {
	cfg := config.Load()

	hub := ws.NewHub()
	reg := services.Register(hub)

	// The notify and datastore stores hold entries with a TTL; their janitors
	// reclaim expired ones so memory cannot grow without bound. They are stopped
	// during shutdown so no goroutine is leaked.
	stopNotify := reg.Notify.StartJanitor(time.Minute)
	stopData := reg.Data.StartJanitor(time.Minute)
	defer stopNotify()
	defer stopData()

	srv := httpserver.New(hub, cfg)

	// Run the listener in the background so main can wait for a shutdown signal.
	serverErr := make(chan error, 1)
	go func() {
		log.Printf("MWSE engine listening on %s", cfg.Addr())
		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			serverErr <- err
		}
	}()

	// Wait for SIGINT/SIGTERM or a fatal listener error.
	stop := make(chan os.Signal, 1)
	signal.Notify(stop, syscall.SIGINT, syscall.SIGTERM)

	select {
	case err := <-serverErr:
		log.Fatalf("MWSE engine failed: %v", err)
	case sig := <-stop:
		log.Printf("received %s, shutting down gracefully", sig)
	}

	// Graceful shutdown: stop accepting new HTTP work, then close every live
	// WebSocket connection so peers receive a clean close frame.
	ctx, cancel := context.WithTimeout(context.Background(), cfg.ShutdownTimeout)
	defer cancel()

	if err := srv.Shutdown(ctx); err != nil {
		log.Printf("http shutdown error: %v", err)
	}
	hub.CloseAll()

	log.Printf("MWSE engine stopped")
}