Add initial backend implementation

- Go module with Gin, GORM, JWT, excelize dependencies
- Configuration loading from YAML with all settings
- GORM models for users, categories, components, configurations, alerts
- Repository layer for all entities
- Services: auth (JWT), pricing (median/average/weighted), components,
  quotes, configurations, export (CSV/XLSX), alerts
- Middleware: JWT auth, role-based access, CORS
- HTTP handlers for all API endpoints
- Main server with dependency injection and graceful shutdown

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/services/alerts/service.go

@@ -0,0 +1,199 @@
+package alerts
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/mchus/quoteforge/internal/config"
+	"github.com/mchus/quoteforge/internal/models"
+	"github.com/mchus/quoteforge/internal/repository"
+)
+
+type Service struct {
+	alertRepo     *repository.AlertRepository
+	componentRepo *repository.ComponentRepository
+	priceRepo     *repository.PriceRepository
+	statsRepo     *repository.StatsRepository
+	config        config.AlertsConfig
+	pricingConfig config.PricingConfig
+}
+
+func NewService(
+	alertRepo *repository.AlertRepository,
+	componentRepo *repository.ComponentRepository,
+	priceRepo *repository.PriceRepository,
+	statsRepo *repository.StatsRepository,
+	alertCfg config.AlertsConfig,
+	pricingCfg config.PricingConfig,
+) *Service {
+	return &Service{
+		alertRepo:     alertRepo,
+		componentRepo: componentRepo,
+		priceRepo:     priceRepo,
+		statsRepo:     statsRepo,
+		config:        alertCfg,
+		pricingConfig: pricingCfg,
+	}
+}
+
+func (s *Service) List(filter repository.AlertFilter, page, perPage int) ([]models.PricingAlert, int64, error) {
+	if page < 1 {
+		page = 1
+	}
+	if perPage < 1 || perPage > 100 {
+		perPage = 20
+	}
+	offset := (page - 1) * perPage
+
+	return s.alertRepo.List(filter, offset, perPage)
+}
+
+func (s *Service) Acknowledge(id uint) error {
+	return s.alertRepo.UpdateStatus(id, models.AlertStatusAcknowledged)
+}
+
+func (s *Service) Resolve(id uint) error {
+	return s.alertRepo.UpdateStatus(id, models.AlertStatusResolved)
+}
+
+func (s *Service) Ignore(id uint) error {
+	return s.alertRepo.UpdateStatus(id, models.AlertStatusIgnored)
+}
+
+func (s *Service) GetNewAlertsCount() (int64, error) {
+	return s.alertRepo.CountByStatus(models.AlertStatusNew)
+}
+
+// CheckAndGenerateAlerts scans components and creates alerts
+func (s *Service) CheckAndGenerateAlerts() error {
+	if !s.config.Enabled {
+		return nil
+	}
+
+	// Get top components by usage
+	topComponents, err := s.statsRepo.GetTopComponents(100)
+	if err != nil {
+		return err
+	}
+
+	for _, stats := range topComponents {
+		component, err := s.componentRepo.GetByLotName(stats.LotName)
+		if err != nil {
+			continue
+		}
+
+		// Check high demand + stale price
+		if err := s.checkHighDemandStalePrice(component, &stats); err != nil {
+			continue
+		}
+
+		// Check trending without price
+		if err := s.checkTrendingNoPrice(component, &stats); err != nil {
+			continue
+		}
+
+		// Check no recent quotes
+		if err := s.checkNoRecentQuotes(component, &stats); err != nil {
+			continue
+		}
+	}
+
+	return nil
+}
+
+func (s *Service) checkHighDemandStalePrice(comp *models.LotMetadata, stats *models.ComponentUsageStats) error {
+	// high_demand_stale_price: >= 5 quotes/month AND price > 60 days old
+	if stats.QuotesLast30d < s.config.HighDemandThreshold {
+		return nil
+	}
+
+	if comp.PriceUpdatedAt == nil {
+		return nil
+	}
+
+	daysSinceUpdate := int(time.Since(*comp.PriceUpdatedAt).Hours() / 24)
+	if daysSinceUpdate <= s.pricingConfig.FreshnessYellowDays {
+		return nil
+	}
+
+	// Check if alert already exists
+	exists, _ := s.alertRepo.ExistsByLotAndType(comp.LotName, models.AlertHighDemandStalePrice)
+	if exists {
+		return nil
+	}
+
+	alert := &models.PricingAlert{
+		LotName:   comp.LotName,
+		AlertType: models.AlertHighDemandStalePrice,
+		Severity:  models.SeverityCritical,
+		Message:   fmt.Sprintf("Компонент %s: высокий спрос (%d КП/мес), но цена устарела (%d дней)", comp.LotName, stats.QuotesLast30d, daysSinceUpdate),
+		Details: models.AlertDetails{
+			"quotes_30d":     stats.QuotesLast30d,
+			"days_since_update": daysSinceUpdate,
+		},
+	}
+
+	return s.alertRepo.Create(alert)
+}
+
+func (s *Service) checkTrendingNoPrice(comp *models.LotMetadata, stats *models.ComponentUsageStats) error {
+	// trending_no_price: trend > 50% AND no price
+	if stats.TrendDirection != models.TrendUp || stats.TrendPercent < float64(s.config.TrendingThresholdPercent) {
+		return nil
+	}
+
+	if comp.CurrentPrice != nil && *comp.CurrentPrice > 0 {
+		return nil
+	}
+
+	exists, _ := s.alertRepo.ExistsByLotAndType(comp.LotName, models.AlertTrendingNoPrice)
+	if exists {
+		return nil
+	}
+
+	alert := &models.PricingAlert{
+		LotName:   comp.LotName,
+		AlertType: models.AlertTrendingNoPrice,
+		Severity:  models.SeverityHigh,
+		Message:   fmt.Sprintf("Компонент %s: рост спроса +%.0f%%, но цена не установлена", comp.LotName, stats.TrendPercent),
+		Details: models.AlertDetails{
+			"trend_percent": stats.TrendPercent,
+		},
+	}
+
+	return s.alertRepo.Create(alert)
+}
+
+func (s *Service) checkNoRecentQuotes(comp *models.LotMetadata, stats *models.ComponentUsageStats) error {
+	// no_recent_quotes: popular component, no supplier quotes > 90 days
+	if stats.QuotesLast30d < 3 {
+		return nil
+	}
+
+	quoteCount, err := s.priceRepo.GetQuoteCount(comp.LotName, s.pricingConfig.FreshnessRedDays)
+	if err != nil {
+		return err
+	}
+
+	if quoteCount > 0 {
+		return nil
+	}
+
+	exists, _ := s.alertRepo.ExistsByLotAndType(comp.LotName, models.AlertNoRecentQuotes)
+	if exists {
+		return nil
+	}
+
+	alert := &models.PricingAlert{
+		LotName:   comp.LotName,
+		AlertType: models.AlertNoRecentQuotes,
+		Severity:  models.SeverityMedium,
+		Message:   fmt.Sprintf("Компонент %s: популярный (%d КП), но нет новых котировок >%d дней", comp.LotName, stats.QuotesLast30d, s.pricingConfig.FreshnessRedDays),
+		Details: models.AlertDetails{
+			"quotes_30d":       stats.QuotesLast30d,
+			"no_quotes_days": s.pricingConfig.FreshnessRedDays,
+		},
+	}
+
+	return s.alertRepo.Create(alert)
+}