package repositories

import (
	"errors"
	"time"

	"gorm.io/gorm"

	"github.com/treytartt/casera-api/internal/models"
)

// NotificationRepository handles database operations for notifications
type NotificationRepository struct {
	db *gorm.DB
}

// NewNotificationRepository creates a new notification repository
func NewNotificationRepository(db *gorm.DB) *NotificationRepository {
	return &NotificationRepository{db: db}
}

// === Notifications ===

// FindByID finds a notification by ID
func (r *NotificationRepository) FindByID(id uint) (*models.Notification, error) {
	var notification models.Notification
	err := r.db.First(&notification, id).Error
	if err != nil {
		return nil, err
	}
	return &notification, nil
}

// FindByUser finds all notifications for a user
func (r *NotificationRepository) FindByUser(userID uint, limit, offset int) ([]models.Notification, error) {
	var notifications []models.Notification
	query := r.db.Where("user_id = ?", userID).
		Order("created_at DESC")

	if limit > 0 {
		query = query.Limit(limit)
	}
	if offset > 0 {
		query = query.Offset(offset)
	}

	err := query.Find(&notifications).Error
	return notifications, err
}

// Create creates a new notification
func (r *NotificationRepository) Create(notification *models.Notification) error {
	return r.db.Create(notification).Error
}

// MarkAsRead marks a notification as read
func (r *NotificationRepository) MarkAsRead(id uint) error {
	now := time.Now().UTC()
	return r.db.Model(&models.Notification{}).
		Where("id = ?", id).
		Updates(map[string]interface{}{
			"read":    true,
			"read_at": now,
		}).Error
}

// MarkAllAsRead marks all notifications for a user as read
func (r *NotificationRepository) MarkAllAsRead(userID uint) error {
	now := time.Now().UTC()
	return r.db.Model(&models.Notification{}).
		Where("user_id = ? AND read = ?", userID, false).
		Updates(map[string]interface{}{
			"read":    true,
			"read_at": now,
		}).Error
}

// MarkAsSent marks a notification as sent
func (r *NotificationRepository) MarkAsSent(id uint) error {
	now := time.Now().UTC()
	return r.db.Model(&models.Notification{}).
		Where("id = ?", id).
		Updates(map[string]interface{}{
			"sent":    true,
			"sent_at": now,
		}).Error
}

// SetError sets an error message on a notification
func (r *NotificationRepository) SetError(id uint, errorMsg string) error {
	return r.db.Model(&models.Notification{}).
		Where("id = ?", id).
		Update("error_message", errorMsg).Error
}

// CountUnread counts unread notifications for a user
func (r *NotificationRepository) CountUnread(userID uint) (int64, error) {
	var count int64
	err := r.db.Model(&models.Notification{}).
		Where("user_id = ? AND read = ?", userID, false).
		Count(&count).Error
	return count, err
}

// GetPendingNotifications gets notifications that need to be sent
func (r *NotificationRepository) GetPendingNotifications(limit int) ([]models.Notification, error) {
	var notifications []models.Notification
	err := r.db.Where("sent = ?", false).
		Order("created_at ASC").
		Limit(limit).
		Find(&notifications).Error
	return notifications, err
}

// === Notification Preferences ===

// FindPreferencesByUser finds notification preferences for a user
func (r *NotificationRepository) FindPreferencesByUser(userID uint) (*models.NotificationPreference, error) {
	var prefs models.NotificationPreference
	err := r.db.Where("user_id = ?", userID).First(&prefs).Error
	if err != nil {
		return nil, err
	}
	return &prefs, nil
}

// CreatePreferences creates notification preferences for a user
func (r *NotificationRepository) CreatePreferences(prefs *models.NotificationPreference) error {
	return r.db.Create(prefs).Error
}

// UpdatePreferences updates notification preferences
func (r *NotificationRepository) UpdatePreferences(prefs *models.NotificationPreference) error {
	return r.db.Omit("User").Save(prefs).Error
}

// GetOrCreatePreferences gets or creates notification preferences for a user.
// Uses a transaction to avoid TOCTOU race conditions on concurrent requests.
func (r *NotificationRepository) GetOrCreatePreferences(userID uint) (*models.NotificationPreference, error) {
	var prefs models.NotificationPreference

	err := r.db.Transaction(func(tx *gorm.DB) error {
		err := tx.Where("user_id = ?", userID).First(&prefs).Error
		if err == nil {
			return nil // Found existing preferences
		}
		if !errors.Is(err, gorm.ErrRecordNotFound) {
			return err // Unexpected error
		}

		// Record not found -- create with defaults
		prefs = models.NotificationPreference{
			UserID:             userID,
			TaskDueSoon:        true,
			TaskOverdue:        true,
			TaskCompleted:      true,
			TaskAssigned:       true,
			ResidenceShared:    true,
			WarrantyExpiring:   true,
			EmailTaskCompleted: true,
		}
		return tx.Create(&prefs).Error
	})
	if err != nil {
		return nil, err
	}
	return &prefs, nil
}

// === Device Registration ===

// FindAPNSDeviceByID finds an APNS device by ID
func (r *NotificationRepository) FindAPNSDeviceByID(id uint) (*models.APNSDevice, error) {
	var device models.APNSDevice
	err := r.db.First(&device, id).Error
	if err != nil {
		return nil, err
	}
	return &device, nil
}

// FindGCMDeviceByID finds a GCM device by ID
func (r *NotificationRepository) FindGCMDeviceByID(id uint) (*models.GCMDevice, error) {
	var device models.GCMDevice
	err := r.db.First(&device, id).Error
	if err != nil {
		return nil, err
	}
	return &device, nil
}

// FindAPNSDeviceByToken finds an APNS device by registration token
func (r *NotificationRepository) FindAPNSDeviceByToken(token string) (*models.APNSDevice, error) {
	var device models.APNSDevice
	err := r.db.Where("registration_id = ?", token).First(&device).Error
	if err != nil {
		return nil, err
	}
	return &device, nil
}

// FindAPNSDevicesByUser finds all APNS devices for a user
func (r *NotificationRepository) FindAPNSDevicesByUser(userID uint) ([]models.APNSDevice, error) {
	var devices []models.APNSDevice
	err := r.db.Where("user_id = ? AND active = ?", userID, true).Find(&devices).Error
	return devices, err
}

// CreateAPNSDevice creates a new APNS device
func (r *NotificationRepository) CreateAPNSDevice(device *models.APNSDevice) error {
	return r.db.Create(device).Error
}

// UpdateAPNSDevice updates an APNS device
func (r *NotificationRepository) UpdateAPNSDevice(device *models.APNSDevice) error {
	return r.db.Save(device).Error
}

// DeleteAPNSDevice deletes an APNS device
func (r *NotificationRepository) DeleteAPNSDevice(id uint) error {
	return r.db.Delete(&models.APNSDevice{}, id).Error
}

// DeactivateAPNSDevice deactivates an APNS device
func (r *NotificationRepository) DeactivateAPNSDevice(id uint) error {
	return r.db.Model(&models.APNSDevice{}).
		Where("id = ?", id).
		Update("active", false).Error
}

// FindGCMDeviceByToken finds a GCM device by registration token
func (r *NotificationRepository) FindGCMDeviceByToken(token string) (*models.GCMDevice, error) {
	var device models.GCMDevice
	err := r.db.Where("registration_id = ?", token).First(&device).Error
	if err != nil {
		return nil, err
	}
	return &device, nil
}

// FindGCMDevicesByUser finds all GCM devices for a user
func (r *NotificationRepository) FindGCMDevicesByUser(userID uint) ([]models.GCMDevice, error) {
	var devices []models.GCMDevice
	err := r.db.Where("user_id = ? AND active = ?", userID, true).Find(&devices).Error
	return devices, err
}

// CreateGCMDevice creates a new GCM device
func (r *NotificationRepository) CreateGCMDevice(device *models.GCMDevice) error {
	return r.db.Create(device).Error
}

// UpdateGCMDevice updates a GCM device
func (r *NotificationRepository) UpdateGCMDevice(device *models.GCMDevice) error {
	return r.db.Save(device).Error
}

// DeleteGCMDevice deletes a GCM device
func (r *NotificationRepository) DeleteGCMDevice(id uint) error {
	return r.db.Delete(&models.GCMDevice{}, id).Error
}

// DeactivateGCMDevice deactivates a GCM device
func (r *NotificationRepository) DeactivateGCMDevice(id uint) error {
	return r.db.Model(&models.GCMDevice{}).
		Where("id = ?", id).
		Update("active", false).Error
}

// GetActiveTokensForUser gets all active push tokens for a user
func (r *NotificationRepository) GetActiveTokensForUser(userID uint) (iosTokens []string, androidTokens []string, err error) {
	apnsDevices, err := r.FindAPNSDevicesByUser(userID)
	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, nil, err
	}

	gcmDevices, err := r.FindGCMDevicesByUser(userID)
	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, nil, err
	}

	iosTokens = make([]string, 0, len(apnsDevices))
	for _, d := range apnsDevices {
		iosTokens = append(iosTokens, d.RegistrationID)
	}

	androidTokens = make([]string, 0, len(gcmDevices))
	for _, d := range gcmDevices {
		androidTokens = append(androidTokens, d.RegistrationID)
	}

	return iosTokens, androidTokens, nil
}