package alerts

import (
	"fmt"
	"time"

	"git.mchus.pro/mchus/quoteforge/internal/config"
	"git.mchus.pro/mchus/quoteforge/internal/models"
	"git.mchus.pro/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)
}