import React, { useEffect, useState } from "react";
import {
  View,
  Text,
  TouchableOpacity,
  StyleSheet,
  SafeAreaView,
  Alert,
  Share,
  Linking,
  BackHandler,
} from "react-native";
import * as FileSystem from "expo-file-system";
import * as MediaLibrary from "expo-media-library";
import * as Sharing from "expo-sharing";
import { Image } from "expo-image";
import { useSelector, useDispatch } from "react-redux";
import { RootState } from "@/store";
import { updatePaymentStatus } from "@/store/paymentSlice";
import Header from "@/components/common/Header";
import ShareIcon from "@/assets/icons/share.svg";
import { useSafeAreaInsets } from "react-native-safe-area-context";
import { useSnackbar } from "@/contexts/Snackbar";

import DownloadIcon from "@/assets/icons/download.svg";
import { payments } from "@/constants/config";
import { useRouter } from "expo-router";
import { useSocket } from "@/contexts/SocketContext";

const UpiPaymentScreen = () => {
  const dispatch = useDispatch();
  const paymentOrder = useSelector(
    (state: RootState) => state.payments.paymentOrder
  );

  const router = useRouter();
  const { onPaymentConfirmation, offPaymentConfirmation } = useSocket();
  const [isListening, setIsListening] = useState(false);

  const { showSnackbar } = useSnackbar();

  const insets = useSafeAreaInsets();

  useEffect(() => {
    const handlePaymentConfirmation = (data: any) => {
      console.log("Payment confirmation received:", data);

      Alert.alert(
        "Payment Successful!",
        "Your payment has been confirmed successfully.",
        [
          {
            text: "Continue",
            onPress: () => {
              router.replace("/payments/Confirmation");
            },
          },
        ],
        { cancelable: false }
      );
    };

    onPaymentConfirmation(handlePaymentConfirmation);
    setIsListening(true);

    const backAction = () => {
      Alert.alert(
        "Cancel Payment?",
        "Are you sure you want to cancel this payment?",
        [
          {
            text: "No",
            onPress: () => null,
            style: "cancel",
          },
          {
            text: "Yes",
            onPress: () => {
              offPaymentConfirmation();
              router.back();
            },
          },
        ]
      );
      return true;
    };

    const backHandler = BackHandler.addEventListener(
      "hardwareBackPress",
      backAction
    );

    // Cleanup on unmount
    return () => {
      offPaymentConfirmation();
      setIsListening(false);
      backHandler.remove();
    };
  }, [onPaymentConfirmation, offPaymentConfirmation, router]);

  // Format amount with currency symbol
  const formatAmount = (amount: number): string => {
    return `₹${amount.toLocaleString("en-IN")}`;
  };

  // Check if payment is expired
  const isPaymentExpired = (): boolean => {
    const expiryDate = new Date(paymentOrder.expiry_date);
    const currentDate = new Date();
    return currentDate > expiryDate;
  };

  // Get formatted expiry time
  const getExpiryTime = (): string => {
    const expiryDate = new Date(paymentOrder.expiry_date);
    return expiryDate.toLocaleString("en-IN");
  };

  const getUpiUrl = (): string => {
    const upiString = paymentOrder.ppayment_link;

    const upiMatch = upiString.match(/upi_string=([^&]+)/);
    if (upiMatch) {
      return decodeURIComponent(upiMatch[1]);
    }
    return `upi://pay?pa=${paymentOrder.upi_handle}&am=${paymentOrder.amount}&cu=INR&tr=${paymentOrder.order_id}`;
  };

  const payUsingUpiApp = async (): Promise<void> => {
    try {
      if (isPaymentExpired()) {
        showSnackbar(payments.LINK_EXPIRED, "error");
        return;
      }

      const upiUrl = getUpiUrl();
      console.log("Opening UPI URL:", upiUrl);

      dispatch(updatePaymentStatus("processing"));

      const canOpenUrl = await Linking.canOpenURL(upiUrl);

      if (canOpenUrl) {
        await Linking.openURL(upiUrl);
      } else {
        Alert.alert(
          "UPI App Required",
          "Please install a UPI-enabled app like PhonePe, Paytm, Google Pay, or BHIM to make payments.",
          [
            {
              text: "Share Payment Details",
              onPress: () => sharePaymentDetails(),
            },
            { text: "Cancel", style: "cancel" },
          ]
        );
      }
    } catch (error) {
      console.error("Error opening UPI app:", error);
      dispatch(updatePaymentStatus("failed"));
      Alert.alert(
        "Error",
        "Unable to open UPI app. Would you like to share payment details instead?",
        [
          {
            text: "Share Details",
            onPress: () => sharePaymentDetails(),
          },
          { text: "Cancel", style: "cancel" },
        ]
      );
    }
  };

  const sharePaymentDetails = async (): Promise<void> => {
    try {
      const shareMessage =
        `Payment Request\n\n` +
        `Amount: ${formatAmount(paymentOrder.amount)}\n` +
        `UPI ID: ${paymentOrder.upi_handle}\n` +
        `Order ID: ${paymentOrder.order_id}\n` +
        `Transaction ID: ${paymentOrder.transaction_id}\n` +
        `Expires: ${getExpiryTime()}\n\n` +
        `UPI Link: ${getUpiUrl()}`;

      await Share.share({
        message: shareMessage,
        title: "UPI Payment Details",
      });
    } catch (error) {
      Alert.alert("Error", "Failed to share payment details");
    }
  };

  const shareQR = async (): Promise<void> => {
    try {
      if (await Sharing.isAvailableAsync()) {
        await Share.share({
          message: `Pay ${formatAmount(
            paymentOrder.amount
          )} using this QR code`,
          url: paymentOrder.qr_code_url,
        });
      } else {
        Alert.alert("Error", "Sharing is not available on this device");
      }
    } catch (error) {
      Alert.alert("Error", "Failed to share QR code");
    }
  };

  const downloadQR = async (): Promise<void> => {
    try {
      const { status } = await MediaLibrary.requestPermissionsAsync();
      if (status !== "granted") {
        Alert.alert(
          "Permission Required",
          "Please grant permission to save images"
        );
        return;
      }

      const fileUri =
        FileSystem.documentDirectory + `qr-${paymentOrder.order_id}.png`;
      const downloadResult = await FileSystem.downloadAsync(
        paymentOrder.qr_code_url,
        fileUri
      );

      if (downloadResult.status === 200) {
        const asset = await MediaLibrary.createAssetAsync(downloadResult.uri);
        await MediaLibrary.createAlbumAsync("Payment QR Codes", asset, false);
        Alert.alert("Success", "QR code saved to gallery");
      } else {
        Alert.alert("Error", "Failed to download QR code");
      }
    } catch (error) {
      Alert.alert("Error", "Failed to download QR code");
    }
  };

  return (
    <SafeAreaView style={styles.container}>
      <Header title="Pay EMI" showBackButton={false} />

      <View style={styles.content}>
        <View style={styles.qrFrame}>
          <View style={styles.amountSection}>
            <Text style={styles.amountLabel}>Amount to be paid</Text>
            <Text style={styles.amount}>
              {formatAmount(paymentOrder.amount)}
            </Text>
          </View>

          <View style={styles.qrCodeContainer}>
            <Image
              source={{ uri: paymentOrder.qr_code_url }}
              style={styles.qrCode}
              contentFit="contain"
            />
          </View>

          <View style={styles.buttonsContainer}>
            <TouchableOpacity onPress={shareQR} style={styles.secondaryButton}>
              <ShareIcon />
              <Text style={styles.secondaryButtonText}>Share QR</Text>
            </TouchableOpacity>

            <TouchableOpacity
              onPress={downloadQR}
              style={styles.secondaryButton}
            >
              <DownloadIcon />
              <Text style={styles.secondaryButtonText}>Download QR</Text>
            </TouchableOpacity>
          </View>
        </View>

        <TouchableOpacity
          onPress={payUsingUpiApp}
          style={[styles.primaryButton, { marginBottom: insets.bottom || 20 }]}
        >
          <Text style={[styles.primaryButtonText]}>Pay using UPI app</Text>
        </TouchableOpacity>
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "#F3F5F8",
  },
  loadingContainer: {
    flex: 1,
    justifyContent: "center",
    alignItems: "center",
  },
  loadingText: {
    marginTop: 16,
    fontSize: 16,
    color: "#253342",
  },
  header: {
    flexDirection: "row",
    alignItems: "center",
    paddingHorizontal: 16,
    paddingVertical: 12,
    backgroundColor: "#FFFFFF",
  },
  backButton: {
    padding: 8,
    marginRight: 8,
  },
  headerTitle: {
    fontSize: 18,
    fontWeight: "600",
    color: "#253342",
  },
  content: {
    flex: 1,
    justifyContent: "space-between",
    paddingHorizontal: 16,
    paddingBottom: 16,
  },
  qrFrame: {
    backgroundColor: "#FCFCFC",
    borderRadius: 8,
    padding: 16,
    alignItems: "center",
    marginTop: 16,
  },
  amountSection: {
    alignItems: "center",
    marginBottom: 16,
  },
  amountLabel: {
    fontSize: 14,
    color: "#253342",
    textAlign: "center",
    marginBottom: 4,
  },
  amount: {
    fontSize: 20,
    fontWeight: "600",
    color: "#253342",
    textAlign: "center",
    marginBottom: 8,
  },
  statusBadge: {
    paddingHorizontal: 12,
    paddingVertical: 4,
    borderRadius: 12,
  },
  statusText: {
    fontSize: 12,
    fontWeight: "600",
    color: "#FFFFFF",
  },
  qrCodeContainer: {
    width: 200,
    height: 200,
    justifyContent: "center",
    alignItems: "center",
    marginBottom: 16,
    borderWidth: 2,
    borderColor: "#E5E9F0",
    padding: 12,
    borderRadius: 8,
  },
  qrCode: {
    width: "100%",
    height: "100%",
  },
  upiIdSection: {
    flexDirection: "row",
    alignItems: "center",
    justifyContent: "center",
    marginBottom: 12,
    padding: 8,
    backgroundColor: "#F3F5F8",
    borderRadius: 4,
  },
  upiIdText: {
    fontSize: 14,
    color: "#253342",
    marginRight: 8,
    fontWeight: "500",
  },
  expirySection: {
    alignItems: "center",
    marginBottom: 16,
  },
  expiryLabel: {
    fontSize: 12,
    color: "#6C757D",
    marginBottom: 2,
  },
  expiryTime: {
    fontSize: 14,
    color: "#253342",
    fontWeight: "500",
  },
  buttonsContainer: {
    flexDirection: "row",
    gap: 8,
    width: "100%",
  },
  secondaryButton: {
    flex: 1,
    flexDirection: "row",
    alignItems: "center",
    justifyContent: "center",
    paddingVertical: 10,
    paddingHorizontal: 16,
    backgroundColor: "#F3F5F8",
    borderColor: "#D8DDE7",
    borderWidth: 1,
    borderRadius: 4,
    gap: 4,
  },
  secondaryButtonText: {
    fontSize: 14,
    fontWeight: "500",
    color: "#253342",
  },
  primaryButton: {
    backgroundColor: "#00876F",
    paddingVertical: 12,
    paddingHorizontal: 16,
    borderRadius: 4,
    alignItems: "center",
  },
  primaryButtonText: {
    fontSize: 14,
    fontWeight: "500",
    color: "#FCFCFC",
  },
  disabledButton: {
    backgroundColor: "#D8DDE7",
  },
  disabledButtonText: {
    color: "#6C757D",
  },
});

export default UpiPaymentScreen;
