package domain

import (
	"context"
	"time"

	"gorm.io/gorm"
)

// Localizable defines an interface for entities that support localization
type Localizable interface {
	GetEntityType() string
	GetEntityID() string
}

// EntityLoadOptions contains options for loading entities for localization
type EntityLoadOptions struct {
	IncludeAllSites bool
}

// EntityHandler defines the interface for handling entity-specific operations for localization
// This interface is implemented by handlers in the localization/handlers package
type EntityHandler[T any] interface {
	// GetEntityID returns the unique identifier for an entity
	GetEntityID(entity T) string

	// GetFieldValue returns the value of a specific field from an entity
	GetFieldValue(entity T, field string) string

	// GetLocalizableFields returns the list of fields that can be localized
	GetLocalizableFields() []string

	// LoadEntities loads entities from the database with optional filtering
	LoadEntities(db *gorm.DB, options EntityLoadOptions) ([]T, error)

	// BuildFieldQuery builds a GORM query for finding entities with specific field values
	BuildFieldQuery(db *gorm.DB, field, value string) *gorm.DB

	// GetEntityType returns the entity type string
	GetEntityType() string
}

// Localization represents localized strings for any entity and field
type Localization struct {
	ID         string `gorm:"primaryKey;type:text"`
	EntityType string `gorm:"type:varchar(50);index"` // 'site', 'organization', 'business', 'user'
	EntityID   string `gorm:"type:text;index"`
	Field      string `gorm:"type:varchar(50);index"` // 'name', 'description'
	Locale     string `gorm:"type:varchar(10);index"` // 'ru', 'en', 'tt'
	Value      string `gorm:"type:text"`

	// Timestamps
	CreatedAt time.Time `gorm:"autoCreateTime"`
	UpdatedAt time.Time `gorm:"autoUpdateTime"`
}

// TableName specifies the table name for GORM
func (Localization) TableName() string {
	return "localizations"
}

// LocalizationService provides methods for managing localized content
type LocalizationService interface {
	GetLocalizedValue(entityType, entityID, field, locale string) (string, error)
	SetLocalizedValue(entityType, entityID, field, locale, value string) error
	GetAllLocalizedValues(entityType, entityID string) (map[string]map[string]string, error) // field -> locale -> value
	GetLocalizedEntity(entityType, entityID, locale string) (map[string]string, error)
	GetSupportedLocalesForEntity(entityType, entityID string) ([]string, error)
	DeleteLocalizedValue(entityType, entityID, field, locale string) error
	BulkSetLocalizedValues(entityType, entityID string, values map[string]map[string]string) error
	GetAllLocales() ([]string, error)
	SearchLocalizations(query, locale string, limit int) ([]*Localization, error)
	ApplyLocalizationToEntity(entity Localizable, locale string) error
}

// Helper methods for models to implement Localizable
func (s *Site) GetEntityType() string { return "site" }
func (s *Site) GetEntityID() string   { return s.ID }

func (o *Organization) GetEntityType() string { return "organization" }
func (o *Organization) GetEntityID() string   { return o.ID }

func (u *User) GetEntityType() string { return "user" }
func (u *User) GetEntityID() string   { return u.ID }

// GetLocalizedName retrieves the localized name for an entity, falling back to primary name
func GetLocalizedName(entity Localizable, locale string, service LocalizationService) string {
	if locale == "ru" {
		// Return primary name for Russian
		switch e := entity.(type) {
		case *Site:
			return e.Name
		case *Organization:
			return e.Name
		case *User:
			return e.Name
		}
	}

	// Try to get localized value
	value, err := service.GetLocalizedValue(entity.GetEntityType(), entity.GetEntityID(), "name", locale)
	if err != nil || value == "" {
		// Fallback to primary name
		switch e := entity.(type) {
		case *Site:
			return e.Name
		case *Organization:
			return e.Name
		case *User:
			return e.Name
		}
	}
	return value
}

// SetLocalizedName sets the localized name for an entity
func SetLocalizedName(entity Localizable, locale, value string, service LocalizationService) error {
	return service.SetLocalizedValue(entity.GetEntityType(), entity.GetEntityID(), "name", locale, value)
}

// TranslationStats represents overall translation statistics
type TranslationStats struct {
	TotalEntities     int
	TotalFields       int
	TotalTranslations int
	EntityStats       map[string]*EntityTranslationStats
}

// EntityTranslationStats represents translation statistics for a specific entity type
type EntityTranslationStats struct {
	EntityType        string
	TotalEntities     int
	TotalFields       int
	RussianCount      int
	EnglishCount      int
	TatarCount        int
	TotalTranslations int
}

type LocalizationRepository interface {
	Create(ctx context.Context, loc *Localization) error
	GetByEntityAndField(ctx context.Context, entityType, entityID, field, locale string) (*Localization, error)
	GetAllByEntity(ctx context.Context, entityType, entityID string) ([]*Localization, error)
	Update(ctx context.Context, loc *Localization) error
	Delete(ctx context.Context, id string) error
	GetByEntityTypeAndLocale(ctx context.Context, entityType, locale string) ([]*Localization, error)
	GetAllLocales(ctx context.Context) ([]string, error)
	GetSupportedLocalesForEntity(ctx context.Context, entityType, entityID string) ([]string, error)
	BulkCreate(ctx context.Context, localizations []*Localization) error
	BulkDelete(ctx context.Context, ids []string) error
	SearchLocalizations(ctx context.Context, query string, locale string, limit int) ([]*Localization, error)
	GetTranslationReuseCandidates(ctx context.Context, entityType, field, locale string) ([]ReuseCandidate, error)
	GetEntitiesNeedingTranslation(ctx context.Context, entityType, field, targetLocale string, limit int) ([]string, error)
	FindExistingTranslationByRussianText(ctx context.Context, entityType, field, targetLocale, russianText string) (string, error)
	GetTranslationCountsByEntity(ctx context.Context) (map[string]map[string]int, error)
}

// ReuseCandidate represents a piece of Russian text that appears in multiple entities
type ReuseCandidate struct {
	RussianValue string
	EntityCount  int
}