woocommerce/plugins/woocommerce-blocks/assets/js/data/payment-methods/set-default-payment-method.ts

/**
 * External dependencies
 */
import { select, dispatch } from '@wordpress/data';
import { PaymentMethods } from '@woocommerce/type-defs/payments';

/**
 * Internal dependencies
 */
import { STORE_KEY as PAYMENT_METHOD_DATA_STORE_KEY } from './constants';

export const setDefaultPaymentMethod = async (
	paymentMethods: PaymentMethods
) => {
	const paymentMethodKeys = Object.keys( paymentMethods );

	const expressPaymentMethodKeys = Object.keys(
		select(
			PAYMENT_METHOD_DATA_STORE_KEY
		).getAvailableExpressPaymentMethods()
	);

	const allPaymentMethodKeys = [
		...paymentMethodKeys,
		...expressPaymentMethodKeys,
	];

	const savedPaymentMethods = select(
		PAYMENT_METHOD_DATA_STORE_KEY
	).getSavedPaymentMethods();

	const savedPaymentMethod =
		Object.keys( savedPaymentMethods ).flatMap(
			( type ) => savedPaymentMethods[ type ]
		)[ 0 ] || undefined;

	if ( savedPaymentMethod ) {
		const token = savedPaymentMethod.tokenId.toString();
		const paymentMethodSlug = savedPaymentMethod.method.gateway;

		const savedTokenKey = `wc-${ paymentMethodSlug }-payment-token`;

		dispatch(
			PAYMENT_METHOD_DATA_STORE_KEY
		).__internalSetActivePaymentMethod( paymentMethodSlug, {
			token,
			payment_method: paymentMethodSlug,
			[ savedTokenKey ]: token,
			isSavedToken: true,
		} );
		return;
	}

	const activePaymentMethod = select(
		PAYMENT_METHOD_DATA_STORE_KEY
	).getActivePaymentMethod();

	// Return if current method is valid.
	if (
		activePaymentMethod &&
		allPaymentMethodKeys.includes( activePaymentMethod )
	) {
		return;
	}

	dispatch( PAYMENT_METHOD_DATA_STORE_KEY ).__internalSetPaymentStatus( {
		isPristine: true,
	} );

	dispatch( PAYMENT_METHOD_DATA_STORE_KEY ).__internalSetActivePaymentMethod(
		paymentMethodKeys[ 0 ]
	);
};