package app

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"git.linuxforward.com/byom/byom-gateway/config"
	"git.linuxforward.com/byom/byom-gateway/handlers"
	"git.linuxforward.com/byom/byom-gateway/logger"
	"git.linuxforward.com/byom/byom-gateway/middleware"
	"git.linuxforward.com/byom/byom-gateway/store"
	"gorm.io/driver/sqlite"
	"gorm.io/gorm"

	"github.com/gin-contrib/cors"
	"github.com/gin-gonic/gin"
	"github.com/sirupsen/logrus"
)

type App struct {
	entry       *logrus.Entry
	cnf         *config.Config
	ctx         context.Context
	cancel      context.CancelFunc
	dbHandler   *store.DataStore
	userHandler *handlers.UserHandler
	router      *gin.Engine
}

func NewApp(cnf *config.Config) (*App, error) {
	ctx, cancel := context.WithCancel(context.Background())

	// Create logger
	entry := logger.NewLogger("app")

	// Create app instance
	app := &App{
		entry:  entry,
		cnf:    cnf,
		ctx:    ctx,
		cancel: cancel,
	}

	// Initialize services
	if err := app.initServices(); err != nil {
		cancel()
		return nil, fmt.Errorf("failed to initialize services: %w", err)
	}

	// Initialize router and middleware
	if err := app.initRouter(); err != nil {
		cancel()
		return nil, fmt.Errorf("init router: %w", err)
	}

	return app, nil
}

func (a *App) initRouter() error {
	rtr := gin.Default()

	coreRtr := rtr.Group("/api/v1/gw")

	// Add core middleware
	coreRtr.Use(middleware.Recovery(a.entry.Logger))
	coreRtr.Use(middleware.RequestID())
	coreRtr.Use(middleware.RequestLogger(a.entry.Logger))
	coreRtr.Use(middleware.ErrorHandler())

	// Add security middleware
	coreRtr.Use(middleware.SecurityHeaders())
	coreRtr.Use(middleware.RequestSanitizer())

	// Configure request timeout
	timeout := 30 * time.Second
	coreRtr.Use(middleware.TimeoutMiddleware(timeout))

	//Configure CORS

	coreRtr.Use(cors.New(cors.Config{
		AllowOrigins:     []string{"http://172.27.28.86:5173"},
		AllowMethods:     []string{"GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"},
		AllowHeaders:     []string{"Origin", "Content-Type", "Accept", "Authorization", "X-Request-ID"},
		ExposeHeaders:    []string{"Content-Length", "Content-Type", "X-Request-ID", "Location"},
		AllowCredentials: true,
	}))

	// Add health check endpoint
	coreRtr.GET("/health", func(c *gin.Context) {
		c.JSON(200, gin.H{"status": "ok"})
	})

	// Add user routes
	// userGroup := rtr.Group("/user", gin.BasicAuth(gin.Accounts{
	// 	a.cnf.BasicAuth.Username: a.cnf.BasicAuth.Password,
	// }))
	userGroup := coreRtr.Group("/user")
	{
		userGroup.GET("/host", a.userHandler.GetUserHost)
		userGroup.POST("/host", a.userHandler.AddUserHost)
		userGroup.DELETE("/host", a.userHandler.DeleteUserHost)
		userGroup.PUT("/host", a.userHandler.UpdateUserHost)
	}

	a.router = rtr

	return nil
}

func (a *App) initServices() error {
	// Initialize database
	dbConn, err := initDBConn(&a.cnf.Database)
	if err != nil {
		return fmt.Errorf("init database: %w", err)
	}

	dbHandler := store.NewDataStore(dbConn)
	a.dbHandler = dbHandler

	// Initialize user handler
	userHandler := handlers.NewUserHandler(dbHandler, a.cnf.Homepage)
	a.userHandler = userHandler

	return nil
}

func initDBConn(cnf *config.DatabaseConfig) (*gorm.DB, error) {

	db, err := gorm.Open(sqlite.Open(cnf.File), &gorm.Config{})
	if err != nil {
		return nil, fmt.Errorf("database: %w", err)
	}

	//Tune the DB
	sqlDB, err := db.DB()
	if err != nil {
		return nil, fmt.Errorf("database: %w", err)
	}

	sqlDB.SetMaxOpenConns(cnf.MaxOpenConns)
	sqlDB.SetMaxIdleConns(cnf.MaxIdleConns)
	sqlDB.SetConnMaxLifetime(time.Duration(cnf.ConnMaxLifetime) * time.Second)

	for _, pragma := range cnf.Pragma {
		tx := db.Exec("PRAGMA " + pragma)
		if tx.Error != nil {
			return nil, fmt.Errorf("database: %w", tx.Error)
		}
	}

	return db, nil
}

func (a *App) Run() error {
	a.entry.Info("Starting server...")

	// Configure server with timeouts
	srv := &http.Server{
		Addr:         ":" + a.cnf.Server.ListeningPort,
		Handler:      a.router,
		ReadTimeout:  15 * time.Second,
		WriteTimeout: 15 * time.Second,
		IdleTimeout:  60 * time.Second,
	}

	// Start server
	go func() {
		var err error
		if a.cnf.Server.TlsConfig.Enabled {
			a.entry.Infof("Starting server on port %s with TLS", a.cnf.Server.ListeningPort)
			err = srv.ListenAndServeTLS(
				a.cnf.Server.TlsConfig.CertFile,
				a.cnf.Server.TlsConfig.KeyFile,
			)
		} else {
			a.entry.Infof("Starting server on port %s without TLS", a.cnf.Server.ListeningPort)
			err = srv.ListenAndServe()
		}

		if err != nil && err != http.ErrServerClosed {
			a.entry.WithError(err).Error("Server error")
			// Signal shutdown on critical error
			a.cancel()
		}
	}()

	// Graceful shutdown
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, os.Interrupt, syscall.SIGTERM)

	select {
	case <-quit:
		a.entry.Info("Shutdown signal received...")
	case <-a.ctx.Done():
		a.entry.Info("Server error occurred, initiating shutdown...")
	}

	// Create shutdown context with timeout
	ctxShutdown, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	// Shutdown server
	if err := srv.Shutdown(ctxShutdown); err != nil {
		a.entry.WithError(err).Error("Server forced to shutdown")
		return fmt.Errorf("server forced to shutdown: %w", err)
	}

	// Close all services
	if err := a.Close(); err != nil {
		a.entry.WithError(err).Error("Error during service cleanup")
		return fmt.Errorf("service cleanup error: %w", err)
	}

	a.entry.Info("Server stopped gracefully")
	return nil
}

func (a *App) Close() error {
	if err := a.dbHandler.Close(); err != nil {
		return err
	}
	return nil
}