turash/bugulma/backend/internal/service/translation_cache.go

package service

import (
	"bugulma/backend/internal/domain"
	"context"
	"fmt"
	"strings"
	"sync"
)

// TranslationCache provides caching for translations to avoid redundant API calls
// DEPRECATED: This cache is kept for backward compatibility but should not be used in new code.
// Use TranslationCacheService instead, which provides better features (LRU eviction, stats, context support).
// TranslationCache will be removed in a future version.
type TranslationCache struct {
	repo        domain.LocalizationRepository
	cache       map[string]map[string]string // [russianText][targetLocale] -> translation
	mu          sync.RWMutex
	commonTerms map[string]map[string]string // Pre-populated common terms
}

// NewTranslationCache creates a new translation cache
func NewTranslationCache(repo domain.LocalizationRepository) *TranslationCache {
	cache := &TranslationCache{
		repo:        repo,
		cache:       make(map[string]map[string]string),
		commonTerms: make(map[string]map[string]string),
	}
	cache.initCommonTerms()
	return cache
}

// initCommonTerms initializes common translation terms that appear frequently
func (tc *TranslationCache) initCommonTerms() {
	// Common materials
	tc.commonTerms["кирпич"] = map[string]string{
		"en": "brick",
		"tt": "кирпич", // Keep same for Tatar or translate if needed
	}

	// Common architectural styles
	tc.commonTerms["модерн"] = map[string]string{
		"en": "modern",
		"tt": "модерн",
	}

	tc.commonTerms["эклектика"] = map[string]string{
		"en": "eclecticism",
		"tt": "эклектика",
	}

	// Common building types
	tc.commonTerms["доходный дом"] = map[string]string{
		"en": "income-producing house",
		"tt": "доходный дом",
	}

	tc.commonTerms["мельница"] = map[string]string{
		"en": "mill",
		"tt": "тегермән",
	}

	// Common roles
	tc.commonTerms["купец"] = map[string]string{
		"en": "merchant",
		"tt": "сәүдәгәр",
	}

	tc.commonTerms["архитектор"] = map[string]string{
		"en": "architect",
		"tt": "архитектор",
	}
}

// GetCachedTranslation checks cache and database for existing translation
// Returns (translation, found, error)
func (tc *TranslationCache) GetCachedTranslation(ctx context.Context, russianText, targetLocale, entityType, field string) (string, bool, error) {
	if russianText == "" {
		return "", false, nil
	}

	// Normalize text for cache lookup (trim whitespace, lowercase for common terms)
	normalized := strings.TrimSpace(russianText)

	// Check in-memory cache first
	tc.mu.RLock()
	if localeMap, ok := tc.cache[normalized]; ok {
		if translation, found := localeMap[targetLocale]; found && translation != "" {
			tc.mu.RUnlock()
			return translation, true, nil
		}
	}
	tc.mu.RUnlock()

	// Check common terms (exact match)
	if localeMap, ok := tc.commonTerms[normalized]; ok {
		if translation, found := localeMap[targetLocale]; found && translation != "" {
			// Cache it
			tc.mu.Lock()
			if tc.cache[normalized] == nil {
				tc.cache[normalized] = make(map[string]string)
			}
			tc.cache[normalized][targetLocale] = translation
			tc.mu.Unlock()
			return translation, true, nil
		}
	}

	// Check database for existing translation of the same Russian text
	// Search for any entity with the same Russian source text translated to target locale
	existing, err := tc.findExistingTranslation(ctx, normalized, targetLocale, entityType, field)
	if err == nil && existing != "" {
		// Cache it
		tc.mu.Lock()
		if tc.cache[normalized] == nil {
			tc.cache[normalized] = make(map[string]string)
		}
		tc.cache[normalized][targetLocale] = existing
		tc.mu.Unlock()
		return existing, true, nil
	}

	return "", false, nil
}

// findExistingTranslation searches the database for an existing translation
// by looking for the same Russian text pattern in source entities
func (tc *TranslationCache) findExistingTranslation(ctx context.Context, russianText, targetLocale, entityType, field string) (string, error) {
	if russianText == "" {
		return "", nil
	}

	normalized := strings.TrimSpace(russianText)
	if normalized == "" {
		return "", nil
	}

	// Search for Russian localizations with matching text
	ruLocalizations, err := tc.repo.SearchLocalizations(ctx, normalized, "ru", 10)
	if err != nil {
		return "", err
	}

	// Find a matching Russian localization and check for target locale translation
	for _, ruLoc := range ruLocalizations {
		if ruLoc.EntityType == entityType && ruLoc.Field == field && ruLoc.Value == normalized {
			// Found matching Russian text, check for target locale translation
			targetLoc, err := tc.repo.GetByEntityAndField(ctx, ruLoc.EntityType, ruLoc.EntityID, ruLoc.Field, targetLocale)
			if err == nil && targetLoc != nil && targetLoc.Value != "" {
				return targetLoc.Value, nil
			}
		}
	}

	return "", nil
}

// SetCachedTranslation stores a translation in the cache
func (tc *TranslationCache) SetCachedTranslation(russianText, targetLocale, translation string) {
	if russianText == "" || translation == "" {
		return
	}

	normalized := strings.TrimSpace(russianText)
	tc.mu.Lock()
	defer tc.mu.Unlock()

	if tc.cache[normalized] == nil {
		tc.cache[normalized] = make(map[string]string)
	}
	tc.cache[normalized][targetLocale] = translation
}

// ClearCache clears the in-memory cache
func (tc *TranslationCache) ClearCache() {
	tc.mu.Lock()
	defer tc.mu.Unlock()
	tc.cache = make(map[string]map[string]string)
}

// PreloadCache preloads common translations from the database
func (tc *TranslationCache) PreloadCache(ctx context.Context, entityType, field, targetLocale string) error {
	// Get all localizations for this entity type and locale
	localizations, err := tc.repo.GetByEntityTypeAndLocale(ctx, entityType, targetLocale)
	if err != nil {
		return fmt.Errorf("failed to get localizations: %w", err)
	}

	// Filter by field and cache translations with their Russian source
	for _, loc := range localizations {
		if loc.Field == field {
			// Get the Russian source text for this entity/field
			ruLoc, err := tc.repo.GetByEntityAndField(ctx, loc.EntityType, loc.EntityID, loc.Field, "ru")
			if err == nil && ruLoc != nil && ruLoc.Value != "" {
				// Cache the translation with its Russian source
				tc.SetCachedTranslation(ruLoc.Value, targetLocale, loc.Value)
			}
		}
	}

	return nil
}