package service

import (
	"context"
	"time"

	"gorm.io/gorm"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
)

// NotificationService provides business logic for notifications and notification preferences.
// Reference: Chatwoot app/services/notification_service.rb
type NotificationService struct {
	db           *gorm.DB
	notifRepo    *repository.NotificationRepo
	prefRepo     *repository.NotificationPreferenceRepo
}

// NewNotificationService creates a new Notification service with required dependencies.
func NewNotificationService(
	db *gorm.DB,
	notifRepo *repository.NotificationRepo,
	prefRepo *repository.NotificationPreferenceRepo,
) *NotificationService {
	return &NotificationService{
		db:        db,
		notifRepo: notifRepo,
		prefRepo:  prefRepo,
	}
}

// --- Notification CRUD operations ---

// GetNotification retrieves a single notification by ID.
func (s *NotificationService) GetNotification(ctx context.Context, id uint) (*model.Notification, error) {
	return s.notifRepo.FindByID(ctx, id)
}

// ListNotifications retrieves all notifications for a user with pagination.
func (s *NotificationService) ListNotifications(ctx context.Context, userID uint, page, perPage int) ([]model.Notification, int64, error) {
	offset := (page - 1) * perPage
	return s.notifRepo.ListByUser(ctx, userID, offset, perPage)
}

// ListNotificationsByAccount retrieves notifications for a user within an account.
func (s *NotificationService) ListNotificationsByAccount(ctx context.Context, userID uint, accountID uint, page, perPage int) ([]model.Notification, int64, error) {
	offset := (page - 1) * perPage
	return s.notifRepo.ListByUserAndAccount(ctx, userID, accountID, offset, perPage)
}

// CreateNotification creates a new notification.
func (s *NotificationService) CreateNotification(ctx context.Context, notification *model.Notification) error {
	return s.notifRepo.Create(ctx, notification)
}

// MarkRead marks a single notification as read.
func (s *NotificationService) MarkRead(ctx context.Context, id uint) error {
	return s.notifRepo.MarkRead(ctx, id)
}

// MarkAllRead marks all unread notifications for a user as read.
func (s *NotificationService) MarkAllRead(ctx context.Context, userID uint) error {
	return s.notifRepo.MarkAllReadByUser(ctx, userID)
}

// MarkAllReadByAccount marks all unread notifications for a user within an account as read.
func (s *NotificationService) MarkAllReadByAccount(ctx context.Context, userID uint, accountID uint) error {
	return s.notifRepo.MarkAllReadByUserAndAccount(ctx, userID, accountID)
}

// DeleteNotification soft-deletes a notification.
func (s *NotificationService) DeleteNotification(ctx context.Context, id uint) error {
	return s.notifRepo.Delete(ctx, id)
}

// GetUnreadCount returns the number of unread notifications for a user.
func (s *NotificationService) GetUnreadCount(ctx context.Context, userID uint) (int64, error) {
	return s.notifRepo.CountUnreadByUser(ctx, userID)
}

// --- Notification Preference operations ---

// GetPreferences retrieves all notification preferences for a user within an account.
func (s *NotificationService) GetPreferences(ctx context.Context, userID uint, accountID uint) ([]model.NotificationPreference, error) {
	return s.prefRepo.ListByUserAndAccount(ctx, userID, accountID)
}

// UpdatePreferences upserts notification preferences for a user within an account.
func (s *NotificationService) UpdatePreferences(ctx context.Context, userID uint, accountID uint, prefs []model.NotificationPreference) error {
	// Enforce userID and accountID on each preference
	for i := range prefs {
		prefs[i].UserID = userID
		prefs[i].AccountID = &accountID
	}
	return s.prefRepo.BatchUpsert(ctx, prefs)
}

// --- Notification extension operations (G8) ---
// Reference: Chatwoot notifications_controller.rb#snooze, #unread, #destroy_all

// SnoozeNotification sets a snooze timestamp on a notification and clears its read_at.
func (s *NotificationService) SnoozeNotification(ctx context.Context, id, userID, accountID uint, snoozedUntil time.Time) (*model.Notification, error) {
	return s.notifRepo.Snooze(ctx, id, userID, accountID, snoozedUntil)
}

// MarkNotificationUnread clears read_at on a notification, marking it as unread.
func (s *NotificationService) MarkNotificationUnread(ctx context.Context, id, userID, accountID uint) (*model.Notification, error) {
	return s.notifRepo.MarkUnread(ctx, id, userID, accountID)
}

// DeleteAllNotifications deletes all notifications for a user within an account.
func (s *NotificationService) DeleteAllNotifications(ctx context.Context, userID, accountID uint) error {
	return s.notifRepo.DeleteAllByUser(ctx, userID, accountID)
}