$state_values = array_map( 'wc_strtoupper', array_flip( array_map( 'wc_strtoupper', $states ) ) );

			if ( isset( $state_values[ $state ] ) ) {
				// Convert to state code if a state name was provided.
				return $state_values[ $state ];
			}
		}

		return $state;
	}

	/**
	 * Validate the given address object.
	 *
	 * @see rest_validate_value_from_schema
	 *
	 * @param array            $address Value being sanitized.
	 * @param \WP_REST_Request $request The Request.
	 * @param string           $param The param being sanitized.
	 * @return true|\WP_Error
	 */
	public function validate_callback( $address, $request, $param ) {
		$errors  = new \WP_Error();
		$address = $this->sanitize_callback( $address, $request, $param );

		if ( empty( $address['country'] ) ) {
			$errors->add(
				'missing_country',
				__( 'Country is required', 'woocommerce' )
			);
			return $errors;
		}

		if ( ! in_array( $address['country'], array_keys( wc()->countries->get_countries() ), true ) ) {
			$errors->add(
				'invalid_country',
				sprintf(
					/* translators: %s valid country codes */
					__( 'Invalid country code provided. Must be one of: %s', 'woocommerce' ),
					implode( ', ', array_keys( wc()->countries->get_countries() ) )
				)
			);
			return $errors;
		}

		$states = array_filter( array_keys( (array) wc()->countries->get_states( $address['country'] ) ) );

		if ( ! empty( $address['state'] ) && count( $states ) && ! in_array( $address['state'], $states, true ) ) {
			$errors->add(
				'invalid_state',
				sprintf(
					/* translators: %s valid states */
					__( 'The provided state is not valid. Must be one of: %s', 'woocommerce' ),
					implode( ', ', $states )
				)
			);
		}

		if ( ! empty( $address['postcode'] ) && ! \WC_Validation::is_postcode( $address['postcode'], $address['country'] ) ) {
			$errors->add(
				'invalid_postcode',
				__( 'The provided postcode / ZIP is not valid', 'woocommerce' )
			);
		}

		return $errors->has_errors( $errors ) ? $errors : true;
	}
}