main.go

package main

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

	"github.com/Harshjosh361/GopherPing/config"
	"github.com/Harshjosh361/GopherPing/migrations"
	"github.com/Harshjosh361/GopherPing/routes"
	"github.com/Harshjosh361/GopherPing/service"
	"github.com/gin-contrib/cors"
	"github.com/gin-gonic/gin"
	"github.com/joho/godotenv"
)

func main() {
	appEnv := os.Getenv("APP_ENV")
	if appEnv == "" {
		appEnv = "development"
	}
	
	// Only load .env file in development environment
	if appEnv == "development" {
		if err := godotenv.Load(); err != nil {
			log.Fatal("Failed to load env")
		}
		log.Println("Loaded .env file for development environment")
	} else {
		log.Printf("Running in %s environment - skipping .env file loading", appEnv)
	}

	// db
	config.ConnectDb()
	// migrate tables
	migrations.Run()
	config.InitSendGrid()

	// Monitoring - start worker in a goroutine to avoid blocking
	log.Println("Starting monitoring worker...")
	worker := service.GetMonitorWorker()
	go worker.Start()
	log.Println("Monitoring worker started in background")

	r := gin.Default()

    // CORS configuration: allow localhost dev and Vercel domains
    frontendBase := os.Getenv("FRONTEND_BASE_URL")
    allowed := []string{"http://localhost:3000", "https://gopher-ping.vercel.app"}
    if frontendBase != "" {
        allowed = append(allowed, frontendBase)
    }
    corsConfig := cors.Config{
        AllowOrigins:     allowed,
        AllowMethods:     []string{"GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"},
        AllowHeaders:     []string{"Origin", "Content-Type", "Authorization"},
        ExposeHeaders:    []string{"Content-Length"},
        AllowCredentials: true,
    }
    // Also allow any *.vercel.app preview deployments
    corsConfig.AllowOriginFunc = func(origin string) bool {
        if strings.HasSuffix(origin, ".vercel.app") {
            return true
        }
        for _, o := range allowed {
            if origin == o {
                return true
            }
        }
        return false
    }
	r.Use(cors.New(corsConfig))
	api := r.Group("/api")
	// register routes
	routes.AuthRoute(api)
	routes.MonitorRoutes(api)
	log.Println("Routes registered successfully")

	port := os.Getenv("PORT")
	if port == "" {
		port = "8000"
	}

	// http server with graceful shutdown
	srv := &http.Server{
		Addr:    "0.0.0.0:" + port,
		Handler: r,
	}

	// channel to catch server errors
	serverErrors := make(chan error, 1)

	// start server in a separate goroutine
	go func() {
		log.Printf("Server listening on %s", srv.Addr)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			serverErrors <- err
		}
	}()

	// wait for termination signal or server error
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)

	select {
	case err := <-serverErrors:
		log.Fatalf("Server failed to start: %v", err)
	case <-quit:
		log.Println("Shutdown signal received, shutting down server...")
		
		// graceful shutdown with timeout
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		if err := srv.Shutdown(ctx); err != nil {
			log.Fatalf("Server forced to shutdown: %v", err)
		}
		log.Println("Server exited gracefully")
	}
}