backend-service/internal/app/app.go

package app

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

	"attune-heart-therapy/internal/config"
	"attune-heart-therapy/internal/container"
	"attune-heart-therapy/internal/logger"
	"attune-heart-therapy/internal/server"
)

// Application represents the main application
type Application struct {
	config    *config.Config
	container *container.Container
	server    *server.Server
	log       *logger.Logger
}

// New creates a new application instance
func New() (*Application, error) {
	// Initialize logger first
	log := logger.New("application")

	// Load configuration
	cfg, err := config.Load()
	if err != nil {
		return nil, fmt.Errorf("failed to load configuration: %w", err)
	}

	// Set log level based on configuration
	logLevel := logger.INFO
	switch cfg.Logging.Level {
	case "DEBUG":
		logLevel = logger.DEBUG
	case "INFO":
		logLevel = logger.INFO
	case "WARN":
		logLevel = logger.WARN
	case "ERROR":
		logLevel = logger.ERROR
	case "FATAL":
		logLevel = logger.FATAL
	}
	logger.SetGlobalLevel(logLevel)

	log.Info("Application configuration loaded", map[string]interface{}{
		"server_host": cfg.Server.Host,
		"server_port": cfg.Server.Port,
		"db_host":     cfg.Database.Host,
		"db_name":     cfg.Database.Name,
	})

	// Initialize dependency injection container
	cont := container.New(cfg)

	// Initialize server
	srv := server.New(cfg)

	return &Application{
		config:    cfg,
		container: cont,
		server:    srv,
		log:       log,
	}, nil
}

// Initialize performs application initialization
func (app *Application) Initialize() error {
	app.log.Info("Initializing application...")

	// Initialize all dependencies through the container
	if err := app.container.Initialize(); err != nil {
		return fmt.Errorf("failed to initialize dependencies: %w", err)
	}

	// Wire the container to the server
	app.server.SetContainer(app.container)

	app.log.Info("Application initialization completed successfully")
	return nil
}

// Run starts the application and handles graceful shutdown
func (app *Application) Run() error {
	// Initialize the application
	if err := app.Initialize(); err != nil {
		return fmt.Errorf("application initialization failed: %w", err)
	}

	// Setup graceful shutdown
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)

	// Start server in a goroutine
	serverErrors := make(chan error, 1)
	go func() {
		app.log.Info("Starting HTTP server...")
		if err := app.server.Start(); err != nil {
			serverErrors <- fmt.Errorf("server start failed: %w", err)
		}
	}()

	// Wait for either shutdown signal or server error
	select {
	case err := <-serverErrors:
		return err
	case sig := <-quit:
		app.log.Info("Received shutdown signal", map[string]interface{}{
			"signal": sig.String(),
		})
	}

	// Graceful shutdown
	return app.shutdown()
}

// shutdown performs graceful shutdown of all components
func (app *Application) shutdown() error {
	app.log.Info("Initiating graceful shutdown...")

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

	var shutdownErrors []error

	// Shutdown server first
	if app.server != nil {
		app.log.Info("Shutting down HTTP server...")
		if err := app.server.Shutdown(ctx); err != nil {
			app.log.Error("Error shutting down server", err)
			shutdownErrors = append(shutdownErrors, fmt.Errorf("server shutdown error: %w", err))
		} else {
			app.log.Info("HTTP server shutdown completed")
		}
	}

	// Shutdown application dependencies
	if app.container != nil {
		app.log.Info("Shutting down application dependencies...")
		if err := app.container.Shutdown(); err != nil {
			app.log.Error("Error shutting down dependencies", err)
			shutdownErrors = append(shutdownErrors, err)
		} else {
			app.log.Info("Dependencies shutdown completed")
		}
	}

	// Wait for context deadline or completion
	select {
	case <-ctx.Done():
		if ctx.Err() == context.DeadlineExceeded {
			app.log.Warn("Shutdown timeout exceeded, forcing exit")
			shutdownErrors = append(shutdownErrors, fmt.Errorf("shutdown timeout exceeded"))
		}
	default:
		// Shutdown completed before timeout
	}

	if len(shutdownErrors) > 0 {
		app.log.Error("Graceful shutdown completed with errors", nil, map[string]interface{}{
			"error_count": len(shutdownErrors),
		})
		return fmt.Errorf("shutdown completed with %d errors: %v", len(shutdownErrors), shutdownErrors)
	}

	app.log.Info("Graceful shutdown completed successfully")
	return nil
}

// GetConfig returns the application configuration
func (app *Application) GetConfig() *config.Config {
	return app.config
}

// GetContainer returns the dependency injection container
func (app *Application) GetContainer() *container.Container {
	return app.container
}

// HealthCheck performs a comprehensive health check
func (app *Application) HealthCheck() map[string]interface{} {
	health := map[string]interface{}{
		"status":    "ok",
		"timestamp": time.Now().UTC().Format(time.RFC3339),
		"service":   "Video Conference Booking System",
		"version":   "1.0.0",
	}

	// Check container health
	if app.container != nil {
		containerHealth := app.container.HealthCheck()
		health["components"] = containerHealth

		// Update overall status based on component health
		if status, ok := containerHealth["status"].(string); ok && status != "ok" {
			health["status"] = status
		}
	} else {
		health["status"] = "error"
		health["error"] = "Container not initialized"
	}

	return health
}