validate balance before purchase (#50)

public/locales/en/common.json

@@ -55,6 +55,7 @@
  "arrival_airport_not_whitelisted": "Buying protection for flights arriving into {{airport}} is currently not allowed",
  "purchase_protection_not_possible": "To purchase protection, please connect your wallet, choose a flight and departure date and try again.",
  "no_wallet_connected": "Please connect your wallet to view policies",
- "no_policies": "No policies found"
+ "no_policies": "No policies found",
+ "insufficient_balance": "Your wallet balance is insufficient to purchase protection. Please top up your wallet and try again."
  }
 }

src/config/constants.ts

@@ -6,4 +6,6 @@ export const DEPARTURE_DATE_DAYS_MAX = parseInt(process.env.NEXT_PUBLIC_DEPARTUR
 export const DEPARTURE_DATE_DATE_FROM = process.env.NEXT_PUBLIC_DEPARTURE_DATE_DATE_FROM || '';
 export const DEPARTURE_DATE_DATE_TO = process.env.NEXT_PUBLIC_DEPARTURE_DATE_DATE_TO || '';
 export const PREMIUM_TOKEN_SYMBOL = process.env.NEXT_PUBLIC_PREMIUM_TOKEN_SYMBOL || 'USDC';
+export const PREMIUM_TOKEN_DECIMALS = parseInt(process.env.NEXT_PUBLIC_PREMIUM_TOKEN_DECIMALS || '6');
+
 

src/hooks/use_application.tsx

@@ -2,25 +2,41 @@ import { useState } from "react";
 import { useSelector } from "react-redux";
 import { RootState } from "../redux/store";
 import { useTranslation } from "react-i18next";
+import { useERC20Contract } from "./onchain/use_erc20_contract";
+import { PREMIUM_TOKEN_DECIMALS } from "../config/constants";
+import { useEnvContext } from "next-runtime-env";
+import { useWallet } from "./onchain/use_wallet";
 
 export default function useApplication() {
  const { t } = useTranslation();
+ const { NEXT_PUBLIC_ERC20_TOKEN_CONTRACT_ADDRESS } = useEnvContext();
+
+ const { hasBalance } = useERC20Contract(NEXT_PUBLIC_ERC20_TOKEN_CONTRACT_ADDRESS!, PREMIUM_TOKEN_DECIMALS);
+ const { getSigner } = useWallet();
+
  const [error, setError] = useState<string | null>(null);
  const departureAirport = useSelector((state: RootState) => state.flightData.arrivalAirport);
  const isDepartureAirportWhiteListed = useSelector((state: RootState) => state.flightData.departureAirport?.whitelisted || true);
  const isArrivalAirportWhiteListed = useSelector((state: RootState) => state.flightData.arrivalAirport?.whitelisted || true);
+ const premium = useSelector((state: RootState) => state.flightData.premium);
 
  async function purchaseProtection() {
  setError(null);
  // do nothing, just log for now
 
- const canPurchase = departureAirport !== null && isDepartureAirportWhiteListed && isArrivalAirportWhiteListed;
+ const canPurchase = departureAirport !== null && isDepartureAirportWhiteListed && isArrivalAirportWhiteListed && premium !== null;
 
  if (!canPurchase) {
  setError(t("error.purchase_protection_not_possible"));
  return;
  }
 
+
+ if (! await hasBalance(BigInt(premium!), (await getSigner())!)) {
+ setError(t("error.insufficient_balance"));
+ return;
+ }
+
  console.log("purchaseProtection");
 
  // TODO: 1. check wallet balance for payment token

src/redux/slices/flightData.ts

@@ -1,6 +1,5 @@
 import type { PayloadAction } from '@reduxjs/toolkit';
 import { createSlice } from '@reduxjs/toolkit';
-import dayjs from 'dayjs';
 import { ARRIVAL_AIRPORTS_WHITELIST, DEPARTURE_AIRPORTS_WHITELIST } from '../../config/constants';
 import { Reason } from '../../types/errors';
 import { Airport as FsAirport } from '../../types/flightstats/airport';