WIP: subtract fees from max client balance

src/components/Percentage.tsx

@@ -5,11 +5,17 @@ import { CoinsIcon, SavingsIcon } from '../styles/icons';
 
 type PercentageProps = {
 	value: number;
+	isMax?: boolean;
 	type: 'spending' | 'savings';
 	style?: StyleProp<ViewStyle>;
 };
 
-const Percentage = ({ value, type, style }: PercentageProps): ReactElement => (
+const Percentage = ({
+	value,
+	isMax = false,
+	type,
+	style,
+}: PercentageProps): ReactElement => (
 	<View style={[styles.root, style]}>
 		{type === 'spending' ? (
 			<CoinsIcon color="purple" height={26} width={26} />
@@ -18,8 +24,16 @@ const Percentage = ({ value, type, style }: PercentageProps): ReactElement => (
 		)}
 
 		<Headline lineHeight="40px" style={styles.text}>
-			{value}
-			<Text01S>%</Text01S>
+			{isMax ? (
+				<>
+					Max
+					<Text01S />
+				</>
+			) : (
+				<>
+					{value} <Text01S>%</Text01S>
+				</>
+			)}
 		</Headline>
 	</View>
 );

src/screens/Lightning/QuickSetup.tsx

@@ -26,13 +26,17 @@ import {
 	setupOnChainTransaction,
 } from '../../store/actions/wallet';
 import {
+	getMaxChannelClientBalance,
 	refreshBlocktankInfo,
 	startChannelPurchase,
 } from '../../store/utils/blocktank';
 import { showToast } from '../../utils/notifications';
 import { convertToSats } from '../../utils/conversion';
 import { getFiatDisplayValues } from '../../utils/displayValues';
-import { LIGHTNING_DIFF } from '../../utils/wallet/constants';
+import {
+	LIGHTNING_DIFF,
+	SPENDING_LIMIT_MAX,
+} from '../../utils/wallet/constants';
 import type { LightningScreenProps } from '../../navigation/types';
 import {
 	selectedNetworkSelector,
@@ -76,7 +80,7 @@ const QuickSetup = ({
 		}, []),
 	);
 
-	const spendingAmount = useMemo((): number => {
+	let spendingAmount = useMemo((): number => {
 		return convertToSats(textFieldValue, conversionUnit);
 	}, [textFieldValue, conversionUnit]);
 
@@ -93,6 +97,10 @@ const QuickSetup = ({
 		return fiatWhole;
 	}, [lnSetup.btSpendingLimitBalanced]);
 
+	const isHighBalance = useMemo((): boolean => {
+		return spendingAmount > lnSetup.slider.maxValue * SPENDING_LIMIT_MAX;
+	}, [spendingAmount, lnSetup.slider.maxValue]);
+
 	const setDefaultClientBalance = useCallback(() => {
 		const value = lnSetup.defaultClientBalance;
 		const result = getNumberPadText(value, denomination, unit);
@@ -141,10 +149,33 @@ const QuickSetup = ({
 			Math.round(spendingAmount + spendingAmount * LIGHTNING_DIFF),
 			minUsableLspBalance,
 		);
+
+		// if the spendingAmount is set to max we calculate fees and subtract
+		// them from the final clientBalance passed to BT's createOrder api.
+		// TODO: should move this to an `useEffect`
+		let clientBalanceSat = spendingAmount;
+		const isMax = spendingAmount >= lnSetup.slider.maxValue;
+		if (isMax) {
+			const estimate = await getMaxChannelClientBalance({
+				lspBalance,
+				spendingAmount,
+				channelExpiryWeeks: DEFAULT_CHANNEL_DURATION,
+				lspNodeId: blocktankInfo.nodes[0].pubkey,
+				turboChannel:
+					spendingAmount <= blocktankInfo.options.max0ConfClientBalanceSat,
+			});
+			if (!estimate.isErr()) {
+				clientBalanceSat = estimate.value;
+				// TEMP hack, should be properly done
+				// eslint-disable-next-line react-hooks/exhaustive-deps
+				spendingAmount = clientBalanceSat;
+			}
+		}
+
 		const purchaseResponse = await startChannelPurchase({
 			selectedNetwork,
 			selectedWallet,
-			clientBalanceSat: spendingAmount!,
+			clientBalanceSat: clientBalanceSat!,
 			lspBalanceSat: lspBalance,
 			channelExpiry: DEFAULT_CHANNEL_DURATION,
 			lspNodeId: blocktankInfo.nodes[0].pubkey,
@@ -214,6 +245,7 @@ const QuickSetup = ({
 							<View style={styles.percentages}>
 								<Percentage
 									value={lnSetup.percentage.spendings}
+									isMax={isHighBalance}
 									type="spending"
 								/>
 								<Percentage value={lnSetup.percentage.savings} type="savings" />
@@ -234,13 +266,16 @@ const QuickSetup = ({
 							</AnimatedView>
 						)}
 
-						{spendingAmount >= lnSetup.spendableBalance && (
+						{isHighBalance && (
 							<AnimatedView
 								style={styles.note}
 								entering={FadeIn}
 								exiting={FadeOut}
 								testID="QuickSetupReserveNote">
-								<Text02S color="gray1">{t('note_reserve_limit')}</Text02S>
+								<Text02S color="gray1">
+									{'The fees to setup and connect you to Lightning will be subtracted from your spending balance. \n' +
+										'You will see the final amount before confirming.'}
+								</Text02S>
 							</AnimatedView>
 						)}
 

src/store/utils/blocktank.ts

@@ -23,6 +23,7 @@ import {
 import * as blocktank from '../../utils/blocktank';
 import {
 	createOrder,
+	estimateOrderFee,
 	getBlocktankInfo,
 	getCJitEntry,
 	getMin0ConfTxFee,
@@ -214,6 +215,51 @@ export const refreshBlocktankInfo = async (): Promise<Result<string>> => {
 	return err('Unable to update Blocktank info.');
 };
 
+export const getMaxChannelClientBalance = async ({
+	lspBalance,
+	spendingAmount,
+	channelExpiryWeeks,
+	lspNodeId,
+	turboChannel,
+}: {
+	lspBalance: number;
+	spendingAmount: number;
+	channelExpiryWeeks: number;
+	lspNodeId: string;
+	turboChannel: boolean;
+}): Promise<Result<number>> => {
+	// 1. estimating bt order fee
+	const estimateRes = await estimateOrderFee({
+		lspBalanceSat: lspBalance,
+		channelExpiryWeeks: channelExpiryWeeks,
+		options: {
+			clientBalanceSat: spendingAmount,
+			couponCode: 'bitkit',
+			lspNodeId,
+			turboChannel,
+		},
+	});
+
+	if (estimateRes.isErr()) {
+		return estimateRes;
+	}
+
+	// 2. subtracting bt order fee from client balance
+	const channelOpenFeeEstimate = estimateRes.value;
+	let clientBalanceSat = spendingAmount - channelOpenFeeEstimate;
+
+	// 3. estimating tx fee
+	let { fast: satsPerByte } = getFeesStore().onchain;
+	let transactionFeeEstimate = getTotalFee({ satsPerByte });
+	console.log('transactionFeeEstimate:', transactionFeeEstimate);
+
+	// 4. subtracting tx fee from client balance
+	clientBalanceSat = clientBalanceSat - transactionFeeEstimate;
+	console.log('maxOrderClientBalance:', clientBalanceSat);
+
+	return ok(clientBalanceSat);
+};
+
 /**
  * Attempts to start the purchase of a Blocktank channel.
  *

src/utils/wallet/constants.ts

@@ -14,10 +14,11 @@ export const CHUNK_LIMIT = 15;
 //How much of the users funds we allow to be used for Lightning.
 export const SPENDING_LIMIT_RATIO = 1;
 
+export const SPENDING_LIMIT_MAX = 0.8;
+
 export const LIGHTNING_DIFF = 0.01;
 
-// TODO remote; temp to make it easier for testing 100% cap
-export const LIGHTNING_DEFAULT_SLIDER = 1;
+export const LIGHTNING_DEFAULT_SLIDER = 0.8;
 
 export const TRANSACTION_DEFAULTS = {
 	recommendedBaseFee: 256, // Total recommended tx base fee in sats