fix(lightning): calculate blocktank limits (#1030)

pwltr · web-flow · commit a3ca5db6d656 · 2023-05-08T20:27:19.000+02:00
* fix(lightning): calculate blocktank limits

* fix(lightning): fix calculate blocktank limits
diff --git a/src/screens/Lightning/CustomSetup.tsx b/src/screens/Lightning/CustomSetup.tsx
@@ -190,24 +190,40 @@ const CustomSetup = ({
 					satoshis: satoshisCapped,
 				};
 			} else {
-				const convertedAmount = convertCurrency({
+				const amount = convertCurrency({
 					amount: blocktankService.max_chan_receiving_usd,
 					from: 'USD',
 					to: selectedCurrency,
 				});
-				const satoshis = convertToSats(
-					convertedAmount.fiatValue,
+				const amountSatoshis = convertToSats(
+					amount.fiatValue,
 					EBalanceUnit.fiat,
 				);
-				// Ensure the conversion still puts us below the max_chan_receiving
-				const satoshisCapped = Math.min(
-					satoshis,
+				// subtract a buffer to ensure we don't land right on the max channel size
+				// also avoids exchange rate deltas with Blocktank
+				const buffer = convertCurrency({
+					amount: 10,
+					from: 'USD',
+					to: selectedCurrency,
+				});
+				const bufferSatoshis = convertToSats(
+					buffer.fiatValue,
+					EBalanceUnit.fiat,
+				);
+
+				// Ensure the amount is below the max channel size
+				const receiveLimit = amountSatoshis - spendingAmount! - bufferSatoshis;
+				let satoshisCapped = Math.min(amountSatoshis, receiveLimit);
+
+				// Ensure the amount is below max_chan_receiving
+				satoshisCapped = Math.min(
+					satoshisCapped,
 					blocktankService.max_chan_receiving,
 				);
 
 				return {
 					...p,
-					fiatAmount: convertedAmount.fiatValue,
+					fiatAmount: amount.fiatValue,
 					satoshis: satoshisCapped,
 				};
 			}
@@ -218,6 +234,7 @@ const CustomSetup = ({
 		blocktankService.max_chan_receiving,
 		blocktankService.max_chan_receiving_usd,
 		selectedCurrency,
+		spendingAmount,
 	]);
 
 	// set initial spending/receiving amount
@@ -247,7 +264,7 @@ const CustomSetup = ({
 					? blocktankService.min_channel_size
 					: 0;
 
-			const result = getNumberPadText(amount, unit, true);
+			const result = getNumberPadText(amount, unit);
 			setTextFieldValue(result);
 		}
 		// eslint-disable-next-line react-hooks/exhaustive-deps
@@ -272,7 +289,7 @@ const CustomSetup = ({
 	// fetch approximate channel open cost on ReceiveAmount screen
 	useEffect(() => {
 		if (!spending && receivingPackages.length) {
-			const defaultPackage = receivingPackages.find((p) => p.id === 'medium')!;
+			const defaultPackage = receivingPackages.find((p) => p.id === 'big')!;
 			const getChannelOpenCost = async (): Promise<void> => {
 				const response = await startChannelPurchase({
 					productId,
diff --git a/src/screens/Lightning/QuickSetup.tsx b/src/screens/Lightning/QuickSetup.tsx
@@ -30,7 +30,7 @@ import {
 	startChannelPurchase,
 } from '../../store/actions/blocktank';
 import { showErrorNotification } from '../../utils/notifications';
-import { convertToSats } from '../../utils/exchange-rate';
+import { convertToSats, getFiatDisplayValues } from '../../utils/exchange-rate';
 import { SPENDING_LIMIT_RATIO } from '../../utils/wallet/constants';
 import type { LightningScreenProps } from '../../navigation/types';
 import {
@@ -78,7 +78,11 @@ const QuickSetup = ({
 		return convertToSats(textFieldValue, unit);
 	}, [textFieldValue, unit]);
 
-	const blocktankSpendingLimit = blocktankService.max_chan_spending;
+	const diff = 0.01;
+	const btSpendingLimit = blocktankService.max_chan_spending;
+	const btSpendingLimitBalanced = Math.round(
+		btSpendingLimit / 2 - btSpendingLimit * diff,
+	);
 	const spendableBalance = Math.round(onchainBalance * SPENDING_LIMIT_RATIO);
 	const savingsAmount = onchainBalance - spendingAmount;
 	const savingsPercentage = Math.round((savingsAmount / onchainBalance) * 100);
@@ -87,8 +91,17 @@ const QuickSetup = ({
 	);
 
 	const spendingLimit = useMemo(() => {
-		return Math.min(spendableBalance, blocktankSpendingLimit);
-	}, [spendableBalance, blocktankSpendingLimit]);
+		return Math.min(spendableBalance, btSpendingLimitBalanced);
+	}, [spendableBalance, btSpendingLimitBalanced]);
+
+	const btSpendingLimitBalancedUsd = useMemo((): string => {
+		const { fiatWhole } = getFiatDisplayValues({
+			satoshis: btSpendingLimitBalanced,
+			currency: 'USD',
+		});
+
+		return fiatWhole;
+	}, [btSpendingLimitBalanced]);
 
 	// BTC -> satoshi -> fiat
 	const nextUnit = useMemo(() => {
@@ -135,7 +148,7 @@ const QuickSetup = ({
 
 		// Ensure local balance is bigger than remote balance
 		const localBalance = Math.max(
-			Math.round(spendingAmount * 1.1),
+			Math.round(spendingAmount + spendingAmount * diff),
 			blocktankService.min_channel_size,
 		);
 		const purchaseResponse = await startChannelPurchase({
@@ -211,13 +224,17 @@ const QuickSetup = ({
 							</View>
 						</AnimatedView>
 
-						{spendingAmount === Math.round(blocktankSpendingLimit) && (
+						{spendingAmount === Math.round(btSpendingLimitBalanced) && (
 							<AnimatedView
 								style={styles.note}
 								entering={FadeIn}
 								exiting={FadeOut}
 								testID="QuickSetupBlocktankNote">
-								<Text02S color="gray1">{t('note_blocktank_limit')}</Text02S>
+								<Text02S color="gray1">
+									{t('note_blocktank_limit', {
+										usdValue: btSpendingLimitBalancedUsd,
+									})}
+								</Text02S>
 							</AnimatedView>
 						)}
 
diff --git a/src/screens/Transfer/Setup.tsx b/src/screens/Transfer/Setup.tsx
@@ -28,7 +28,7 @@ import {
 } from '../../store/actions/blocktank';
 import { useSelector } from 'react-redux';
 import { SPENDING_LIMIT_RATIO } from '../../utils/wallet/constants';
-import { convertToSats } from '../../utils/exchange-rate';
+import { convertToSats, getFiatDisplayValues } from '../../utils/exchange-rate';
 import {
 	resetOnChainTransaction,
 	setupOnChainTransaction,
@@ -72,8 +72,12 @@ const Setup = ({ navigation }: TransferScreenProps<'Setup'>): ReactElement => {
 		return convertToSats(textFieldValue, unit);
 	}, [textFieldValue, unit]);
 
+	const diff = 0.01;
+	const btSpendingLimit = blocktankService.max_chan_spending;
+	const btSpendingLimitBalanced = Math.round(
+		btSpendingLimit / 2 - btSpendingLimit * diff,
+	);
 	const totalBalance = onchainBalance + lightningBalance;
-	const blocktankSpendingLimit = blocktankService.max_chan_spending;
 	const spendableBalance = Math.round(totalBalance * SPENDING_LIMIT_RATIO);
 	const savingsAmount = totalBalance - spendingAmount;
 	const spendingPercentage = Math.round((spendingAmount / totalBalance) * 100);
@@ -82,9 +86,18 @@ const Setup = ({ navigation }: TransferScreenProps<'Setup'>): ReactElement => {
 	const isButtonDisabled = spendingAmount === lightningBalance;
 
 	const spendingLimit = useMemo(() => {
-		const min = Math.min(spendableBalance, blocktankSpendingLimit);
+		const min = Math.min(spendableBalance, btSpendingLimitBalanced);
 		return min < lightningBalance ? lightningBalance : min;
-	}, [spendableBalance, blocktankSpendingLimit, lightningBalance]);
+	}, [spendableBalance, btSpendingLimitBalanced, lightningBalance]);
+
+	const btSpendingLimitBalancedUsd = useMemo((): string => {
+		const { fiatWhole } = getFiatDisplayValues({
+			satoshis: btSpendingLimitBalanced,
+			currency: 'USD',
+		});
+
+		return fiatWhole;
+	}, [btSpendingLimitBalanced]);
 
 	// set initial value
 	useEffect(() => {
@@ -144,10 +157,11 @@ const Setup = ({ navigation }: TransferScreenProps<'Setup'>): ReactElement => {
 		// buy an additional channel from Blocktank with the difference
 		setLoading(true);
 		const remoteBalance = spendingAmount - lightningBalance;
-		const localBalance =
-			Math.round(remoteBalance * 1.1) > blocktankService.min_channel_size
-				? Math.round(remoteBalance * 1.1)
-				: blocktankService.min_channel_size;
+		// Ensure local balance is bigger than remote balance
+		const localBalance = Math.max(
+			Math.round(remoteBalance + remoteBalance * diff),
+			blocktankService.min_channel_size,
+		);
 
 		const purchaseResponse = await startChannelPurchase({
 			selectedNetwork,
@@ -231,12 +245,16 @@ const Setup = ({ navigation }: TransferScreenProps<'Setup'>): ReactElement => {
 								</View>
 							</AnimatedView>
 
-							{spendingAmount === Math.round(blocktankSpendingLimit) && (
+							{spendingAmount === Math.round(btSpendingLimitBalanced) && (
 								<AnimatedView
 									style={styles.note}
 									entering={FadeIn}
 									exiting={FadeOut}>
-									<Text02S color="gray1">{t('note_blocktank_limit')}</Text02S>
+									<Text02S color="gray1">
+										{t('note_blocktank_limit', {
+											usdValue: btSpendingLimitBalancedUsd,
+										})}
+									</Text02S>
 								</AnimatedView>
 							)}
 
diff --git a/src/utils/i18n/locales/en/lightning.json b/src/utils/i18n/locales/en/lightning.json
@@ -16,7 +16,7 @@
 	"savings": "Savings",
 	"spending_label": "Spending balance",
 	"receiving_label": "Receiving capacity",
-	"note_blocktank_limit": "The amount you can transfer to your spending balance is currently limited to $999.",
+	"note_blocktank_limit": "The amount you can transfer to your spending balance is currently limited to ${{usdValue}}.",
 	"note_reserve_limit": "The amount you can transfer to your spending balance is limited to 80%. You need to keep funds in reserve to move this bitcoin back to savings.",
 	"quick_confirm_header": "Please\nConfirm.",
 	"quick_confirm_cost": "It costs <white>{{amount}}</white> to connect you to Lightning and set up your spending balance.",
