import React, { useCallback, useEffect, useMemo, useState } from "react";
import {
  View,
  Text,
  StyleSheet,
  FlatList,
  RefreshControl,
  TouchableOpacity,
  SafeAreaView,
} from "react-native";
import { apiCall } from "../../utils/ApiHelper";
import { TRANSACTION } from "../../utils/ApiUrls";
import colors from "../../components/colors";
import AppView from "../../components/AppView";
import Header from "../../components/common/Header";

type Transaction = {
  id: string;
  fundGroupId: string;
  fundGroupName: string;
  amount: number;
  status: string;
  payerMobile?: string;
  transactionDate: number[];
};

type ApiResponse = {
  message: string;
  status: string;
  statusCode: number;
  data: Transaction[];
};

// Helper: convert the array-style date into a JS Date
const parseTransactionDate = (arr: number[] | undefined): Date | null => {
  if (!arr || arr.length < 6) return null;
  const [year, month, day, hour = 0, minute = 0, second = 0, sub = 0] = arr;

  let milli = 0;
  if (sub > 999999999) {
    milli = Math.floor(sub / 1e6);
  } else if (sub > 1000) {
    milli = Math.floor(sub / 1e6);
  } else {
    milli = sub;
  }

  return new Date(year, month - 1, day, hour, minute, second, milli);
};

const formatINR = (amount: number) => {
  try {
    return new Intl.NumberFormat("en-IN", { style: "currency", currency: "INR" }).format(amount);
  } catch (e) {
    return `₹${amount.toFixed(2)}`;
  }
};

const StatusBadge: React.FC<{ status?: string }> = ({ status }) => {
  const text = status ?? "UNKNOWN";
  const color =
    text === "SUCCESS" ? styles.statusSuccess : text === "PENDING" ? styles.statusPending : styles.statusFailed;

  return (
    <View style={[styles.statusBadge, color]}>
      <Text style={styles.statusText}>{text}</Text>
    </View>
  );
};

const TransactionItem: React.FC<{ item: Transaction }> = ({ item }) => {
  const date = useMemo(() => parseTransactionDate(item.transactionDate), [item.transactionDate]);
  const dateStr = date ? date.toLocaleString("en-IN") : "-";

  return (
    <TouchableOpacity activeOpacity={0.8} style={styles.card}>
      <View style={styles.cardLeft}>
        <Text style={styles.fundName}>{item.fundGroupName}</Text>
        <Text style={styles.payer}>Payer: {item.payerMobile ?? "-"}</Text>
        <Text style={styles.date}>{dateStr}</Text>
      </View>

      <View style={styles.cardRight}>
        <Text style={styles.amount}>{formatINR(item.amount)}</Text>
        <StatusBadge status={item.status} />
      </View>
    </TouchableOpacity>
  );
};

const TransactionsList: React.FC = () => {
  const [refreshing, setRefreshing] = useState(false);
  const [transactions, setTransactions] = useState<Transaction[]>([]);
  const [message, setMessage] = useState("");

  const handleTransactionList = async () => {
    try {
      const res = (await apiCall(TRANSACTION, "GET")) as ApiResponse;
      console.log("transaction list response : ", res);
      if (res.statusCode === 200) {
        setTransactions(res.data);
        setMessage(res.message);
      }
    } catch (error) {
      console.error("Error fetching transactions:", error);
    }
  };

  useEffect(() => {
    handleTransactionList();
  }, []);

  const handleRefresh = useCallback(async () => {
    try {
      setRefreshing(true);
      await handleTransactionList();
    } catch (e) {
      console.warn("Refresh failed", e);
    } finally {
      setRefreshing(false);
    }
  }, []);

  const renderEmpty = () => (
    <View style={styles.emptyContainer}>
      <Text style={styles.emptyTitle}>No transactions</Text>
      <Text style={styles.emptySubtitle}>Transactions will appear here when available.</Text>
    </View>
  );

  return (
    <AppView>
      <Header title="transactions" titleColor={colors.Home} arrowColor={colors.Home}/>

      <Text style={styles.headerTitle}>{message}</Text>


      <FlatList
        data={transactions}
        keyExtractor={(item) => item.id}
        renderItem={({ item }) => <TransactionItem item={item} />}
        ListEmptyComponent={renderEmpty}
        contentContainerStyle={transactions.length === 0 ? { flex: 1 } : undefined}
        refreshControl={<RefreshControl refreshing={refreshing} onRefresh={handleRefresh} />}
      />
    </AppView>
  );
};

export default TransactionsList;

const styles = StyleSheet.create({
  container: { flex: 1, backgroundColor: "#f7f7fb" },
  headerTitle: { fontSize: 18, fontWeight: "500", color: colors.primary },
  headerSubtitle: { marginTop: 4, color: "#6b7280" },

  card: {
    flexDirection: "row",
    justifyContent: "space-between",
    padding: 16,
    // marginHorizontal: 12,
    marginVertical: 8,
    backgroundColor: "#fff",
    borderRadius: 12,
    shadowColor: "#000",
    shadowOpacity: 0.03,
    shadowRadius: 8,
    elevation: 2,
  },

  cardLeft: { flex: 1 },
  fundName: { fontSize: 16, fontWeight: "600" },
  payer: { marginTop: 6, color: "#6b7280" },
  date: { marginTop: 6, color: "#9ca3af" },

  cardRight: { alignItems: "flex-end", justifyContent: "space-between" },
  amount: { fontSize: 16, fontWeight: "700" },

  statusBadge: {
    marginTop: 8,
    paddingHorizontal: 8,
    paddingVertical: 4,
    borderRadius: 999,
  },
  statusText: { fontSize: 12, fontWeight: "600", color: "#fff" },
  statusSuccess: { backgroundColor: "#10b981" },
  statusPending: { backgroundColor: "#f59e0b" },
  statusFailed: { backgroundColor: "#ef4444" },

  emptyContainer: { alignItems: "center", justifyContent: "center", },
  emptyTitle: { fontSize: 18, fontWeight: "600", color: "#374151" },
  emptySubtitle: { marginTop: 8, color: "#6b7280" },
});