ecpay_expo/app/(tabs)/scanner.tsx

import React, { useState, useEffect, useRef } from "react";
import { Modal, View, Text, Button, TextInput, SafeAreaView, StatusBar, Platform, StyleSheet, AppState } from "react-native";
import { CameraView } from "expo-camera";
import { Stack, useNavigation } from "expo-router"; // Updated import for navigation
import { Overlay } from "./Overlay";
import { ethers } from "ethers";
import { CHAIN_ID, CONTRACT_ADDRESS, contractABI } from "./shared";
import { useWalletConnectModal } from "@walletconnect/modal-react-native";

export default function Home() {
  const qrLock = useRef(false);
  const appState = useRef(AppState.currentState);
  const navigation = useNavigation(); // Hook for navigation

  const [modalVisible, setModalVisible] = useState(false);
  const [scannedAddress, setScannedAddress] = useState("");
  const [dollarValue, setDollarValue] = useState("");

  useEffect(() => {
    const subscription = AppState.addEventListener("change", (nextAppState) => {
      if (appState.current.match(/inactive|background/) && nextAppState === "active") {
        qrLock.current = false;
      }
      appState.current = nextAppState;
    });

    return () => {
      subscription.remove();
    };
  }, []);

  const { open, isConnected, address, provider } = useWalletConnectModal();

  const isValidEthAddress = (address:string) => /^0x[a-fA-F0-9]{40}$/.test(address);

  const transferEth = async () => {
    if (!provider || !isConnected) {
      console.error("Wallet not connected.");
      return;
    }

    try {
      const ethersProvider = new ethers.providers.Web3Provider(provider);
      const network = await ethersProvider.getNetwork();

      if (network.chainId !== CHAIN_ID) {
        console.log(`Switching from ${network.chainId} to ${CHAIN_ID} (Arbitrum Sepolia)...`);
        await provider.request({
          method: "wallet_switchEthereumChain",
          params: [{ chainId: `0x${CHAIN_ID.toString(16)}` }],
        });
        console.log(`Switched to chain ID: ${CHAIN_ID}`);
      }

      const signer = ethersProvider.getSigner();
      const contract = new ethers.Contract(CONTRACT_ADDRESS, contractABI, signer);
      const priceResponse = await fetch("http://vps.playpoolstudios.com:28328/getMarkPriceETH");
      const priceJson = await priceResponse.json();
      const price = priceJson['price'];

      const ethValue = parseFloat(dollarValue) / price; // Convert dollars to ETH assuming 1 ETH = $3600
      console.log(`Converted ${dollarValue} THB to ${ethValue} ETH`);

      console.log("Requesting contract call");
      const tx = await contract.transferETH(scannedAddress, {
        value: ethers.utils.parseEther(ethValue.toFixed(18).toString()),
      });

      console.log("Transaction sent:", tx.hash);
      await tx.wait();
      console.log("Transaction confirmed:", tx.hash);

      // Navigate back after the transaction is confirmed
      navigation.goBack();
    } catch (error) {
      console.error("Transfer failed:", error);
    }
  };

  return (
    <SafeAreaView style={StyleSheet.absoluteFillObject}>
      <Stack.Screen
        options={{
          title: "Overview",
          headerShown: false,
        }}
      />
      {Platform.OS === "android" ? <StatusBar hidden /> : null}
      <CameraView
        style={StyleSheet.absoluteFillObject}
        facing="back"
        onBarcodeScanned={({ data }) => {
          if (data && !qrLock.current) {
            qrLock.current = true;
            setScannedAddress(data); // Save the scanned address
            setModalVisible(true); // Open the popup/modal
          }
        }}
      />
      <Overlay />

      <Modal
        animationType="slide"
        transparent={true}
        visible={modalVisible}
        onRequestClose={() => setModalVisible(false)} // Close modal on back action
      >
        <View style={styles.modalContainer}>
          <View style={styles.modalContent}>
            <Text style={styles.title}>Enter Amount</Text>

            <View style={styles.inputContainer}>
              <TextInput
                style={styles.input}
                placeholder="0.00"
                keyboardType="numeric"
                value={dollarValue}
                onChangeText={setDollarValue}
              />
              <Text style={styles.dollarSign}> THB</Text>

            </View>

            <Button title="Transfer ETH" onPress={transferEth} color="#4CAF50" />

            <View style={styles.spacer} />
            <Button title="Close" onPress={() => setModalVisible(false)} color="#F44336" />
          </View>
        </View>
      </Modal>
    </SafeAreaView>
  );
}

const styles = StyleSheet.create({
  modalContainer: {
    flex: 1,
    justifyContent: "center",
    alignItems: "center",
    backgroundColor: "rgba(0,0,0,0.5)",
  },
  modalContent: {
    width: "80%",
    backgroundColor: "white",
    borderRadius: 10,
    padding: 20,
    alignItems: "center",
    elevation: 5,
    shadowColor: "#000",
    shadowOffset: { width: 0, height: 2 },
    shadowOpacity: 0.25,
    shadowRadius: 3.84,
  },
  title: {
    fontSize: 20,
    fontWeight: "bold",
    marginBottom: 10,
  },
  inputContainer: {
    flexDirection: "row",
    alignItems: "center",
    marginBottom: 20,
  },
  dollarSign: {
    fontSize: 18,
    marginRight: 5,
    color: "#333",
  },
  input: {
    borderWidth: 1,
    borderColor: "#ccc",
    borderRadius: 5,
    padding: 10,
    width: "70%",
    fontSize: 16,
    textAlign: "left",
  },
  spacer: {
    height: 10,
  },
});