tercul-backend/internal/app/application_builder.go

package app

import (
	"tercul/cache"
	"tercul/config"
	"tercul/db"
	"tercul/linguistics"
	"tercul/logger"
	"tercul/repositories"
	"tercul/services"
	"time"

	"github.com/hibiken/asynq"
	"github.com/weaviate/weaviate-go-client/v5/weaviate"
	"gorm.io/gorm"
)

// ApplicationBuilder handles the initialization of all application components
type ApplicationBuilder struct {
	dbConn         *gorm.DB
	redisCache     cache.Cache
	weaviateClient *weaviate.Client
	asynqClient    *asynq.Client
	repositories   *RepositoryContainer
	services       *ServiceContainer
	linguistics    *linguistics.LinguisticsFactory
}

// RepositoryContainer holds all repository instances
type RepositoryContainer struct {
	WorkRepository        repositories.WorkRepository
	UserRepository        repositories.UserRepository
	AuthorRepository      repositories.AuthorRepository
	TranslationRepository repositories.TranslationRepository
	CommentRepository     repositories.CommentRepository
	LikeRepository        repositories.LikeRepository
	BookmarkRepository    repositories.BookmarkRepository
	CollectionRepository  repositories.CollectionRepository
	TagRepository         repositories.TagRepository
	CategoryRepository    repositories.CategoryRepository
	CopyrightRepository   repositories.CopyrightRepository
}

// ServiceContainer holds all service instances
type ServiceContainer struct {
	WorkService         services.WorkService
	CopyrightService    services.CopyrightService
	LocalizationService services.LocalizationService
	AuthService         services.AuthService
}

// NewApplicationBuilder creates a new ApplicationBuilder
func NewApplicationBuilder() *ApplicationBuilder {
	return &ApplicationBuilder{}
}

// BuildDatabase initializes the database connection
func (b *ApplicationBuilder) BuildDatabase() error {
	logger.LogInfo("Initializing database connection")

	dbConn, err := db.InitDB()
	if err != nil {
		logger.LogFatal("Failed to initialize database - application cannot start without database connection",
			logger.F("error", err),
			logger.F("host", config.Cfg.DBHost),
			logger.F("database", config.Cfg.DBName))
		return err
	}

	b.dbConn = dbConn
	logger.LogInfo("Database initialized successfully",
		logger.F("host", config.Cfg.DBHost),
		logger.F("database", config.Cfg.DBName))

	return nil
}

// BuildCache initializes the Redis cache
func (b *ApplicationBuilder) BuildCache() error {
	logger.LogInfo("Initializing Redis cache")

	redisCache, err := cache.NewDefaultRedisCache()
	if err != nil {
		logger.LogWarn("Failed to initialize Redis cache, continuing without caching - performance may be degraded",
			logger.F("error", err),
			logger.F("redisAddr", config.Cfg.RedisAddr))
	} else {
		b.redisCache = redisCache
		logger.LogInfo("Redis cache initialized successfully",
			logger.F("redisAddr", config.Cfg.RedisAddr))
	}

	return nil
}

// BuildWeaviate initializes the Weaviate client
func (b *ApplicationBuilder) BuildWeaviate() error {
	logger.LogInfo("Connecting to Weaviate",
		logger.F("host", config.Cfg.WeaviateHost),
		logger.F("scheme", config.Cfg.WeaviateScheme))

	wClient, err := weaviate.NewClient(weaviate.Config{
		Scheme: config.Cfg.WeaviateScheme,
		Host:   config.Cfg.WeaviateHost,
	})
	if err != nil {
		logger.LogFatal("Failed to create Weaviate client - vector search capabilities will not be available",
			logger.F("error", err),
			logger.F("host", config.Cfg.WeaviateHost),
			logger.F("scheme", config.Cfg.WeaviateScheme))
		return err
	}

	b.weaviateClient = wClient
	logger.LogInfo("Weaviate client initialized successfully")

	return nil
}

// BuildBackgroundJobs initializes Asynq for background job processing
func (b *ApplicationBuilder) BuildBackgroundJobs() error {
	logger.LogInfo("Setting up background job processing",
		logger.F("redisAddr", config.Cfg.RedisAddr))

	redisOpt := asynq.RedisClientOpt{
		Addr:     config.Cfg.RedisAddr,
		Password: config.Cfg.RedisPassword,
		DB:       config.Cfg.RedisDB,
	}

	asynqClient := asynq.NewClient(redisOpt)
	b.asynqClient = asynqClient

	logger.LogInfo("Background job client initialized successfully")

	return nil
}

// BuildRepositories initializes all repositories
func (b *ApplicationBuilder) BuildRepositories() error {
	logger.LogInfo("Initializing repositories")

	// Initialize base repositories
	baseWorkRepo := repositories.NewWorkRepository(b.dbConn)
	userRepo := repositories.NewUserRepository(b.dbConn)
	authorRepo := repositories.NewAuthorRepository(b.dbConn)
	translationRepo := repositories.NewTranslationRepository(b.dbConn)
	commentRepo := repositories.NewCommentRepository(b.dbConn)
	likeRepo := repositories.NewLikeRepository(b.dbConn)
	bookmarkRepo := repositories.NewBookmarkRepository(b.dbConn)
	collectionRepo := repositories.NewCollectionRepository(b.dbConn)
	tagRepo := repositories.NewTagRepository(b.dbConn)
	categoryRepo := repositories.NewCategoryRepository(b.dbConn)
	copyrightRepo := repositories.NewCopyrightRepository(b.dbConn)

	// Wrap work repository with cache if available
	var workRepo repositories.WorkRepository
	if b.redisCache != nil {
		workRepo = repositories.NewCachedWorkRepository(
			baseWorkRepo,
			b.redisCache,
			nil,
			30*time.Minute, // Cache work data for 30 minutes
		)
		logger.LogInfo("Using cached work repository")
	} else {
		workRepo = baseWorkRepo
		logger.LogInfo("Using non-cached work repository")
	}

	b.repositories = &RepositoryContainer{
		WorkRepository:        workRepo,
		UserRepository:        userRepo,
		AuthorRepository:      authorRepo,
		TranslationRepository: translationRepo,
		CommentRepository:     commentRepo,
		LikeRepository:        likeRepo,
		BookmarkRepository:    bookmarkRepo,
		CollectionRepository:  collectionRepo,
		TagRepository:         tagRepo,
		CategoryRepository:    categoryRepo,
		CopyrightRepository:   copyrightRepo,
	}

	logger.LogInfo("Repositories initialized successfully")

	return nil
}

// BuildLinguistics initializes the linguistics components
func (b *ApplicationBuilder) BuildLinguistics() error {
	logger.LogInfo("Initializing linguistic analyzer")

	b.linguistics = linguistics.NewLinguisticsFactory(
		b.dbConn,
		b.redisCache,
		4,    // Default concurrency
		true, // Cache enabled
	)

	logger.LogInfo("Linguistics components initialized successfully")

	return nil
}

// BuildServices initializes all services
func (b *ApplicationBuilder) BuildServices() error {
	logger.LogInfo("Initializing service layer")

	workService := services.NewWorkService(b.repositories.WorkRepository, b.linguistics.GetAnalyzer())
	copyrightService := services.NewCopyrightService(b.repositories.CopyrightRepository)
	localizationService := services.NewLocalizationService(b.repositories.TranslationRepository)
	authService := services.NewAuthService(b.repositories.UserRepository)

	b.services = &ServiceContainer{
		WorkService:         workService,
		CopyrightService:    copyrightService,
		LocalizationService: localizationService,
		AuthService:         authService,
	}

	logger.LogInfo("Services initialized successfully")

	return nil
}

// Build initializes all components in the correct order
func (b *ApplicationBuilder) Build() error {
	// Build components in dependency order
	if err := b.BuildDatabase(); err != nil {
		return err
	}

	if err := b.BuildCache(); err != nil {
		return err
	}

	if err := b.BuildWeaviate(); err != nil {
		return err
	}

	if err := b.BuildBackgroundJobs(); err != nil {
		return err
	}

	if err := b.BuildRepositories(); err != nil {
		return err
	}

	if err := b.BuildLinguistics(); err != nil {
		return err
	}

	if err := b.BuildServices(); err != nil {
		return err
	}

	logger.LogInfo("Application builder completed successfully")
	return nil
}

// GetDatabase returns the database connection
func (b *ApplicationBuilder) GetDatabase() *gorm.DB {
	return b.dbConn
}

// GetCache returns the cache instance
func (b *ApplicationBuilder) GetCache() cache.Cache {
	return b.redisCache
}

// GetWeaviateClient returns the Weaviate client
func (b *ApplicationBuilder) GetWeaviateClient() *weaviate.Client {
	return b.weaviateClient
}

// GetAsynqClient returns the Asynq client
func (b *ApplicationBuilder) GetAsynqClient() *asynq.Client {
	return b.asynqClient
}

// GetRepositories returns the repository container
func (b *ApplicationBuilder) GetRepositories() *RepositoryContainer {
	return b.repositories
}

// GetServices returns the service container
func (b *ApplicationBuilder) GetServices() *ServiceContainer {
	return b.services
}

// GetLinguistics returns the linguistics factory
func (b *ApplicationBuilder) GetLinguistics() *linguistics.LinguisticsFactory {
	return b.linguistics
}

// Close closes all resources
func (b *ApplicationBuilder) Close() error {
	if b.asynqClient != nil {
		b.asynqClient.Close()
	}

	if b.dbConn != nil {
		sqlDB, err := b.dbConn.DB()
		if err == nil {
			sqlDB.Close()
		}
	}

	return nil
}