already in the array.
		if ( ! empty( $this->additional_fields[ $id ] ) || in_array( $id, $this->fields_locations[ $location ], true ) ) {
			wc_get_logger()->warning(
				sprintf( 'Unable to register field with id: "%s". %s', esc_html( $id ), 'The field is already registered.' )
			);
			return;
		}

		// Hidden fields are not supported right now. They will be registered with hidden => false.
		if ( ! empty( $options['hidden'] ) && true === $options['hidden'] ) {
			wc_get_logger()->warning(
				sprintf( 'Registering a field with hidden set to true is not supported. The field "%s" will be registered as visible.', esc_html( $id ) )
			);
		}

		$field_data = array(
			'label'          => $options['label'],
			'hidden'         => false,
			'type'           => $type,
			'optionalLabel'  => empty( $options['optionalLabel'] ) ? '' : $options['optionalLabel'],
			'required'       => empty( $options['required'] ) ? false : $options['required'],
			'autocomplete'   => empty( $options['autocomplete'] ) ? '' : $options['autocomplete'],
			'autocapitalize' => empty( $options['autocapitalize'] ) ? '' : $options['autocapitalize'],
		);

		/**
		 * Handle Checkbox fields.
		 */
		if ( 'checkbox' === $type ) {
			// Checkbox fields are always optional. Log a warning if it's set explicitly as true.
			$field_data['required'] = false;
			if ( isset( $options['required'] ) && true === $options['required'] ) {
				wc_get_logger()->warning(
					sprintf( 'Registering checkbox fields as required is not supported. "%s" will be registered as optional.', esc_html( $id ) )
				);
			}
		}

		/**
		 * Handle Select fields.
		 */
		if ( 'select' === $type ) {
			if ( empty( $options['options'] ) || ! is_array( $options['options'] ) ) {
				wc_get_logger()->warning(
					sprintf( 'Unable to register field with id: "%s". %s', esc_html( $id ), 'Fields of type "select" must have an array of "options".' )
				);
				return;
			}

			// Select fields are always required. Log a warning if it's set explicitly as false.
			$field_data['required'] = true;
			if ( isset( $options['required'] ) && false === $options['required'] ) {
				wc_get_logger()->warning(
					sprintf( 'Registering select fields as optional is not supported. "%s" will be registered as required.', esc_html( $id ) )
				);
			}

			$cleaned_options = array();
			$added_values    = array();

			// Check all entries in $options['options'] has a key and value member.
			foreach ( $options['options'] as $option ) {
				if ( ! isset( $option['value'] ) || ! isset( $option['label'] ) ) {
					wc_get_logger()->warning(
						sprintf( 'Unable to register field with id: "%s". %s', esc_html( $id ), 'Fields of type "select" must have an array of "options" and each option must contain a "value" and "label" member.' )
					);
					return;
				}

				$sanitized_value = sanitize_text_field( $option['value'] );
				$sanitized_label = sanitize_text_field( $option['label'] );

				if ( in_array( $sanitized_value, $added_values, true ) ) {
					wc_get_logger()->warning(
						sprintf( 'Duplicate key found when registering field with id: "%s". The value in each option of "select" fields must be unique. Duplicate value "%s" found. The duplicate key will be removed.', esc_html( $id ), esc_html( $sanitized_value ) )
					);
					continue;
				}

				$added_values[] = $sanitized_value;

				$cleaned_options[] = array(
					'value' => $sanitized_value,
					'label' => $sanitized_label,
				);
			}

			$field_data['options'] = $cleaned_options;
		}

		// Insert new field into the correct location array.
		$this->additional_fields[ $id ] = $field_data;

		$this->fields_locations[ $location ][] = $id;
	}

	/**
	 * Returns an array of all core fields.
	 *
	 * @return array An array of fields.
	 */
	public function get_core_fields() {
		return $this->core_fields;
	}

	/**
	 * Returns an array of all additional fields.
	 *
	 * @return array An array of fields.
	 */
	public function get_additional_fields() {
		return $this->additional_fields;
	}

	/**
	 * Update the default locale with additional fields without country limitations.
	 *
	 * @param array $locale The locale to update.
	 * @return mixed
	 */
	public function update_default_locale_with_fields( $locale ) {
		foreach ( $this->fields_locations['address'] as $field_id => $additional_field ) {
			if ( empty( $locale[ $field_id ] ) ) {
				$locale[ $field_id ] = $additional_field;
			}
		}
		return $locale;
	}

	/**
	 * Returns an array of fields keys for the address group.
	 *
	 * @return array An array of fields keys.
	 */
	public function get_address_fields_keys() {
		return $this->fields_locations['address'];
	}

	/**
	 * Returns an array of fields keys for the contact group.
	 *
	 * @return array An array of fields keys.
	 */
	public function get_contact_fields_keys() {
		return $this->fields_locations['contact'];
	}

	/**
	 * Returns an array of fields keys for the additional area group.
	 *
	 * @return array An array of fields keys.
	 */
	public function get_additional_fields_keys() {
		return $this->fields_locations['additional'];
	}

	/**
	 * Returns an array of fields for a given group.
	 *
	 * @param string $location The location to get fields for (address|contact|additional).
	 *
	 * @return array An array of fields.
	 */
	public function get_fields_for_location( $location ) {
		if ( in_array( $location, array_keys( $this->fields_locations ), true ) ) {
			return $this->fields_locations[ $location ];
		}
	}

	/**
	 * Validates a field value for a given group.
	 *
	 * @param string $key The field key.
	 * @param mixed  $value The field value.
	 * @param string $location The gslocation to validate the field for (address|contact|additional).
	 *
	 * @return true|\WP_Error True if the field is valid, a WP_Error otherwise.
	 */
	public function validate_field_for_location( $key, $value, $location ) {
		if ( ! $this->is_field( $key ) ) {
			return new \WP_Error(
				'woocommerce_blocks_checkout_field_invalid',
				\sprintf(
					// translators: % is field key.
					__( 'The field %s is invalid.', 'woocommerce' ),
					$key
				)
			);
		}

		if ( ! in_array( $key, $this->fields_locations[ $location ], true ) ) {
			return new \WP_Error(
				'woocommerce_blocks_checkout_field_invalid_location',
				\sprintf(
					// translators: %1$s is field key, %2$s location.
					__( 'The field %1$s is invalid for the location %2$s.', 'woocommerce' ),
					$key,
					$location
				)
			);
		}

		$field = $this->additional_fields[ $key ];
		if ( ! empty( $field['required'] ) && empty( $value ) ) {
			return new \WP_Error(
				'woocommerce_blocks_checkout_field_required',
				\sprintf(
					// translators: %s is field key.
					__( 'The field %s is required.', 'woocommerce' ),
					$key
				)
			);
		}

		return true;
	}

	/**
	 * Returns true if the given key is a valid field.
	 *
	 * @param string $key The field key.
	 *
	 * @return bool True if the field is valid, false otherwise.
	 */
	public function is_field( $key ) {
		return array_key_exists( $key, $this->additional_fields );
	}

	/**
	 * Persists a field value for a given order. This would also optionally set the field value on the customer.
	 *
	 * @param string    $key The field key.
	 * @param mixed     $value The field value.
	 * @param \WC_Order $order The order to persist the field for.
	 * @param bool      $set_customer Whether to set the field value on the customer or not.
	 *
	 * @return void
	 */
	public function persist_field_for_order( $key, $value, $order, $set_customer = true ) {
		$this->set_array_meta( $key, $value, $order );
		if ( $set_customer ) {
			if ( isset( wc()->customer ) ) {
				$this->set_array_meta( $key, $value, wc()->customer );
			} elseif ( $order->get_customer_id() ) {
				$customer = new \WC_Customer( $order->get_customer_id() );
				$this->set_array_meta( $key, $value, $customer );
			}
		}
	}

	/**
	 * Persists a field value for a given customer.
	 *
	 * @param string       $key The field key.
	 * @param mixed        $value The field value.
	 * @param \WC_Customer $customer The customer to persist the field for.
	 *
	 * @return void
	 */
	public function persist_field_for_customer( $key, $value, $customer ) {
		$this->set_array_meta( $key, $value, $customer );
	}

	/**
	 * Sets a field value in an array meta, supporting routing things to billing, shipping, or additional fields, based on a prefix for the key.
	 *
	 * @param string                 $key The field key.
	 * @param mixed                  $value The field value.
	 * @param \WC_Customer|\WC_Order $object The object to set the field value for.
	 *
	 * @return void
	 */
	private function set_array_meta( $key, $value, $object ) {
		$meta_key = '';

		if ( 0 === strpos( $key, '/billing/' ) ) {
			$meta_key = self::BILLING_FIELDS_KEY;
			$key      = str_replace( '/billing/', '', $key );
		} elseif ( 0 === strpos( $key, '/shipping/' ) ) {
			$meta_key = self::SHIPPING_FIELDS_KEY;
			$key      = str_replace( '/shipping/', '', $key );
		} else {
			$meta_key = self::ADDITIONAL_FIELDS_KEY;
		}

		if ( $object instanceof \WC_Customer ) {
			if ( ! $object->get_id() ) {
				$meta_data = wc()->session->get( $meta_key, array() );
			} else {
				$meta_data = get_user_meta( $object->get_id(), $meta_key, true );
			}
		} elseif ( $object instanceof \WC_Order ) {
			$meta_data = $object->get_meta( $meta_key, true );
		}

		if ( ! is_array( $meta_data ) ) {
			$meta_data = array();
		}

		$meta_data[ $key ] = $value;
		if ( $object instanceof \WC_Customer ) {
			if ( ! $object->get_id() ) {
				wc()->session->set( $meta_key, $meta_data );
			} else {
				update_user_meta( $object->get_id(), $meta_key, $meta_data );
			}
		} elseif ( $object instanceof \WC_Order ) {
			$object->update_meta_data( $meta_key, $meta_data );
		}

	}

	/**
	 * Returns a field value for a given object.
	 *
	 * @param string       $key The field key.
	 * @param \WC_Customer $customer The customer to get the field value for.
	 * @param string       $group The group to get the field value for (shipping|billing|'') in which '' refers to the additional group.
	 *
	 * @return mixed The field value.
	 */
	public function get_field_from_customer( $key, $customer, $group = '' ) {
		return $this->get_field_from_object( $key, $customer, $group );
	}

	/**
	 * Returns a field value for a given order.
	 *
	 * @param string    $field The field key.
	 * @param \WC_Order $order The order to get the field value for.
	 * @param string    $group The group to get the field value for (shipping|billing|'') in which '' refers to the additional group.
	 *
	 * @return mixed The field value.
	 */
	public function get_field_from_order( $field, $order, $group = '' ) {
		return $this->get_field_from_object( $field, $order, $group );
	}

	/**
	 * Returns a field value for a given object.
	 *
	 * @param string                 $key The field key.
	 * @param \WC_Customer|\WC_Order $object The customer to get the field value for.
	 * @param string                 $group The group to get the field value for (shipping|billing|'') in which '' refers to the additional group.
	 *
	 * @return mixed The field value.
	 */
	private function get_field_from_object( $key, $object, $group = '' ) {
		$meta_key = '';
		if ( 0 === strpos( $key, '/billing/' ) || 'billing' === $group ) {
			$meta_key = self::BILLING_FIELDS_KEY;
			$key      = str_replace( '/billing/', '', $key );
		} elseif ( 0 === strpos( $key, '/shipping/' ) || 'shipping' === $group ) {
			$meta_key = self::SHIPPING_FIELDS_KEY;
			$key      = str_replace( '/shipping/', '', $key );
		} else {
			$meta_key = self::ADDITIONAL_FIELDS_KEY;
		}

		if ( $object instanceof \WC_Customer ) {
			if ( ! $object->get_id() ) {
				$meta_data = wc()->session->get( $meta_key, array() );
			} else {
				$meta_data = get_user_meta( $object->get_id(), $meta_key, true );
			}
		} elseif ( $object instanceof \WC_Order ) {
			$meta_data = $object->get_meta( $meta_key, true );
		}

		if ( ! is_array( $meta_data ) ) {
			return '';
		}

		if ( ! isset( $meta_data[ $key ] ) ) {
			return '';
		}

		return $meta_data[ $key ];
	}

	/**
	 * Returns an array of all fields values for a given customer.
	 *
	 * @param \WC_Customer $customer The customer to get the fields for.
	 * @param bool         $all Whether to return all fields or only the ones that are still registered. Default false.
	 *
	 * @return array An array of fields.
	 */
	public function get_all_fields_from_customer( $customer, $all = false ) {
		$customer_id = $customer->get_id();
		$meta_data   = array(
			'billing'    => array(),
			'shipping'   => array(),
			'additional' => array(),
		);
		if ( ! $customer_id ) {
			if ( isset( wc()->session ) ) {
				$meta_data['billing']    = wc()->session->get( self::BILLING_FIELDS_KEY, array() );
				$meta_data['shipping']   = wc()->session->get( self::SHIPPING_FIELDS_KEY, array() );
				$meta_data['additional'] = wc()->session->get( self::ADDITIONAL_FIELDS_KEY, array() );
			}
		} else {
			$meta_data['billing']    = get_user_meta( $customer_id, self::BILLING_FIELDS_KEY, true );
			$meta_data['shipping']   = get_user_meta( $customer_id, self::SHIPPING_FIELDS_KEY, true );
			$meta_data['additional'] = get_user_meta( $customer_id, self::ADDITIONAL_FIELDS_KEY, true );
		}

		return $this->format_meta_data( $meta_data, $all );
	}

	/**
	 * Returns an array of all fields values for a given order.
	 *
	 * @param \WC_Order $order The order to get the fields for.
	 * @param bool      $all Whether to return all fields or only the ones that are still registered. Default false.
	 *
	 * @return array An array of fields.
	 */
	public function get_all_fields_from_order( $order, $all = false ) {
		$meta_data = array(
			'billing'    => array(),
			'shipping'   => array(),
			'additional' => array(),
		);
		if ( $order instanceof \WC_Order ) {
			$meta_data['billing']    = $order->get_meta( self::BILLING_FIELDS_KEY, true );
			$meta_data['shipping']   = $order->get_meta( self::SHIPPING_FIELDS_KEY, true );
			$meta_data['additional'] = $order->get_meta( self::ADDITIONAL_FIELDS_KEY, true );
		}
		return $this->format_meta_data( $meta_data, $all );
	}

	/**
	 * Returns an array of all fields values for a given meta object. It would add the billing or shipping prefix to the keys.
	 *
	 * @param array $meta The meta data to format.
	 * @param bool  $all Whether to return all fields or only the ones that are still registered. Default false.
	 *
	 * @return array An array of fields.
	 */
	private function format_meta_data( $meta, $all = false ) {
		$billing_fields    = $meta['billing'] ?? array();
		$shipping_fields   = $meta['shipping'] ?? array();
		$additional_fields = $meta['additional'] ?? array();

		$fields = array();

		if ( is_array( $billing_fields ) ) {
			foreach ( $billing_fields as $key => $value ) {
				if ( ! $all && ! $this->is_field( $key ) ) {
					continue;
				}
				$fields[ '/billing/' . $key ] = $value;
			}
		}

		if ( is_array( $shipping_fields ) ) {
			foreach ( $shipping_fields as $key => $value ) {
				if ( ! $all && ! $this->is_field( $key ) ) {
					continue;
				}
				$fields[ '/shipping/' . $key ] = $value;
			}
		}

		if ( is_array( $additional_fields ) ) {
			foreach ( $additional_fields as $key => $value ) {
				if ( ! $all && ! $this->is_field( $key ) ) {
					continue;
				}
				$fields[ $key ] = $value;
			}
		}

		return $fields;
	}

	/**
	 * From a set of fields, returns only the ones that should be saved to the customer.
	 * For now, this only supports fields in address location.
	 *
	 * @param array $fields The fields to filter.
	 *
	 * @return array The filtered fields.
	 */
	public function filter_fields_for_customer( $fields ) {
		$customer_fields_keys = $this->get_address_fields_keys();
		return array_filter(
			$fields,
			function( $key ) use ( $customer_fields_keys ) {
				return in_array( $key, $customer_fields_keys, true );
			},
			ARRAY_FILTER_USE_KEY
		);
	}

}