package services

import (
	"context"
	"fmt"
	"time"

	"github.com/google/uuid"
	"go.uber.org/zap"
	"gorm.io/gorm"
)

// GearWarrantyNotifier sends notifications for gear items with expiring warranty
type GearWarrantyNotifier struct {
	db                 *gorm.DB
	notificationService *NotificationService
	logger             *zap.Logger
	interval           time.Duration
}

// NewGearWarrantyNotifier creates a new warranty notifier
func NewGearWarrantyNotifier(db *gorm.DB, notificationService *NotificationService, logger *zap.Logger) *GearWarrantyNotifier {
	return &GearWarrantyNotifier{
		db:                  db,
		notificationService: notificationService,
		logger:              logger,
		interval:            24 * time.Hour,
	}
}

// Start runs the notifier loop
func (n *GearWarrantyNotifier) Start(ctx context.Context) {
	if n.notificationService == nil {
		n.logger.Info("Gear warranty notifier: notification service not configured, skipping")
		return
	}

	ticker := time.NewTicker(n.interval)
	defer ticker.Stop()

	n.logger.Info("Gear warranty notifier started", zap.Duration("interval", n.interval))

	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			if err := n.runCheck(ctx); err != nil {
				n.logger.Error("Gear warranty check failed", zap.Error(err))
			}
		}
	}
}

func (n *GearWarrantyNotifier) runCheck(ctx context.Context) error {
	var items []struct {
		ID             uuid.UUID
		UserID         uuid.UUID
		Name           string
		WarrantyExpire *time.Time
	}
	err := n.db.WithContext(ctx).Raw(`
		SELECT id, user_id, name, warranty_expire
		FROM gear_items
		WHERE warranty_expire IS NOT NULL
		  AND warranty_expire > NOW()
		  AND warranty_expire <= NOW() + INTERVAL '30 days'
		  AND deleted_at IS NULL
	`).Scan(&items).Error
	if err != nil {
		return fmt.Errorf("query expiring gear: %w", err)
	}

	for _, item := range items {
		if item.WarrantyExpire == nil {
			continue
		}
		daysLeft := int(time.Until(*item.WarrantyExpire).Hours() / 24)
		if daysLeft < 0 {
			daysLeft = 0
		}
		msg := fmt.Sprintf("Warranty for %s expires in %d days", item.Name, daysLeft)
		link := fmt.Sprintf("/inventory/gear/%s", item.ID)
		if err := n.notificationService.CreateNotification(item.UserID, "gear_warranty", "Warranty expiring soon", msg, link); err != nil {
			n.logger.Warn("failed to send warranty notification", zap.String("gear_id", item.ID.String()), zap.Error(err))
		}
	}

	if len(items) > 0 {
		n.logger.Info("Gear warranty notifications sent", zap.Int("count", len(items)))
	}
	return nil
}