import React, { useEffect, useState, useMemo } from "react";
import {
  View,
  ScrollView,
  Pressable,
  TextInput,
  StyleSheet,
  ActivityIndicator,
  Platform,
  PermissionsAndroid,
  Switch,
} from "react-native";
import { useColorScheme } from "nativewind";
import { Text } from "@/components/ui/text";
import { ChevronDown, CalendarSearch, Search, Link2 } from "@/lib/icons";
import { ScreenWrapper } from "@/components/ScreenWrapper";
import { useSirouRouter } from "@sirou/react-native";
import { AppRoutes } from "@/lib/routes";
import { api } from "@/lib/api";
import { toast } from "@/lib/toast-store";
import { EmptyState } from "@/components/EmptyState";
import { PickerModal, SelectOption } from "@/components/PickerModal";
import { CalendarGrid } from "@/components/CalendarGrid";
import { FormFlow } from "@/components/FormFlow";
import { getPlaceholderColor } from "@/lib/colors";
import { getScanData } from "@/lib/scan-cache";

let SmsAndroid: any = null;
if (Platform.OS === "android") {
  try {
    const smsModule = require("react-native-get-sms-android");
    SmsAndroid = smsModule.default || smsModule;
  } catch (e) {
    console.log("[CreatePayment] SMS module unavailable");
  }
}

const S = StyleSheet.create({
  input: {
    paddingHorizontal: 12,
    paddingVertical: 12,
    fontSize: 12,
    fontWeight: "500",
    borderRadius: 6,
    borderWidth: 1,
    textAlignVertical: "center",
  },
});

function useInputColors() {
  const { colorScheme } = useColorScheme();
  const dark = colorScheme === "dark";
  return {
    bg: dark ? "rgba(30,30,30,0.8)" : "rgba(241,245,249,0.2)",
    border: dark ? "rgba(255,255,255,0.08)" : "rgba(203,213,225,0.6)",
    text: dark ? "#f1f5f9" : "#0f172a",
    placeholder: "rgba(100,116,139,0.45)",
  };
}

function Field({
  label,
  value,
  onChangeText,
  placeholder,
  numeric = false,
  flex,
  multiline = false,
}: {
  label: string;
  value: string;
  onChangeText: (v: string) => void;
  placeholder: string;
  numeric?: boolean;
  flex?: number;
  multiline?: boolean;
}) {
  const c = useInputColors();
  return (
    <View style={flex != null ? { flex } : undefined}>
      <Text className="text-[14px] font-sans-bold mb-1.5 ml-1 text-foreground">
        {label}
      </Text>
      <TextInput
        style={[
          S.input,
          { backgroundColor: c.bg, borderColor: c.border, color: c.text },
          multiline
            ? { height: 80, paddingTop: 10, textAlignVertical: "top" }
            : {},
        ]}
        placeholder={placeholder}
        placeholderTextColor={c.placeholder}
        value={value}
        onChangeText={onChangeText}
        keyboardType={numeric ? "numeric" : "default"}
        multiline={multiline}
        autoCorrect={false}
        autoCapitalize="none"
      />
    </View>
  );
}

function PickerField({
  label,
  value,
  onPress,
}: {
  label: string;
  value: string;
  onPress: () => void;
}) {
  const c = useInputColors();
  return (
    <View className="flex-1">
      <Text className="text-[14px] font-sans-bold mb-1.5 ml-1 text-foreground">
        {label}
      </Text>
      <Pressable
        onPress={onPress}
        className="h-10 px-3 border border-border rounded-[6px] flex-row items-center justify-between"
        style={{ backgroundColor: c.bg, borderColor: c.border }}
      >
        <Text className="text-xs font-sans-bold" style={{ color: c.text }}>
          {value}
        </Text>
        <ChevronDown size={14} color={c.text} strokeWidth={3} />
      </Pressable>
    </View>
  );
}

const CURRENCIES = ["ETB", "USD", "EUR", "GBP", "KES", "ZAR"];
const PAYMENT_METHODS = [
  "Telebirr",
  "CBE",
  "Dashen",
  "DECSI",
  "Bank Transfer",
  "Cash",
  "Credit Card",
  "Other",
];
const FINANCIAL_INSTITUTIONS = ["CBE", "ABYSSINIA", "TELE", "DASHEN"];

const PROVIDER_ALIASES: Record<string, string> = {
  cbe: "CBE",
  telebirr: "TELE",
  tele: "TELE",
  dashen: "DASHEN",
  abyssinia: "ABYSSINIA",
};

function normalizeFinancialInstitution(input: string | undefined | null): string | null {
  if (!input) return null;
  const key = String(input).trim().toLowerCase();
  return PROVIDER_ALIASES[key] ?? null;
}

function parseSmsMessage(body: string) {
  const text = body.toUpperCase();
  let bank = "";
  let ref = "";
  let amount = "";

  if (text.includes("CBE")) {
    bank = "CBE";
    const dirMatch = body.match(/(debited|credited)\s+with\s+ETB([\d,.]+)/i);
    if (dirMatch) amount = dirMatch[2];
    const refMatch = body.match(/id=(\w+)/i);
    if (refMatch) ref = refMatch[1];
  } else if (text.includes("TELEBIRR")) {
    bank = "Telebirr";
    const dirMatch = body.match(/(received|sent|paid)\s+ETB\s*([\d,.]+)/i);
    if (dirMatch) amount = dirMatch[2];
    const refMatch = body.match(/transaction number\s+(\w+)/i);
    if (refMatch) ref = refMatch[1];
  }

  return { bank, ref, amount };
}

export default function CreatePaymentScreen() {
  const nav = useSirouRouter<AppRoutes>();
  const [step, setStep] = useState(0);
  const [submitting, setSubmitting] = useState(false);
  const [scanRecordId, setScanRecordId] = useState<string | null>(null);

  const [transactionId, setTransactionId] = useState("");
  const [amount, setAmount] = useState("");
  const [currency, setCurrency] = useState("ETB");
  const [paymentMethod, setPaymentMethod] = useState("Telebirr");
  const [financialInstitution, setFinancialInstitution] = useState("CBE");
  const [isReferenceVerified, setIsReferenceVerified] = useState(false);
  const [paymentDate, setPaymentDate] = useState(
    new Date().toISOString().split("T")[0],
  );
  const [notes, setNotes] = useState("");
  const [selectedInvoice, setSelectedInvoice] = useState<any>(null);
  const [customerId, setCustomerId] = useState("");

  const [showCurrency, setShowCurrency] = useState(false);
  const [showPaymentMethod, setShowPaymentMethod] = useState(false);
  const [showFinancialInstitution, setShowFinancialInstitution] =
    useState(false);
  const [showPaymentDate, setShowPaymentDate] = useState(false);
  const [showInvoicePicker, setShowInvoicePicker] = useState(false);

  const [invoices, setInvoices] = useState<any[]>([]);
  const [invoiceSearch, setInvoiceSearch] = useState("");
  const [loadingInvoices, setLoadingInvoices] = useState(false);

  const { colorScheme } = useColorScheme();
  const isDark = colorScheme === "dark";
  const c = useInputColors();

  useEffect(() => {
    if (Platform.OS !== "android" || !SmsAndroid) return;

    (async () => {
      try {
        const granted = await PermissionsAndroid.request(
          PermissionsAndroid.PERMISSIONS.READ_SMS,
        );
        if (granted !== PermissionsAndroid.RESULTS.GRANTED) return;

        const fiveMinsAgo = Date.now() - 5 * 60 * 1000;
        const filter = {
          box: "inbox",
          minDate: fiveMinsAgo,
          maxCount: 30,
        };

        SmsAndroid.list(
          JSON.stringify(filter),
          () => {},
          (_count: number, smsList: string) => {
            const messages = JSON.parse(smsList);
            const match = messages.find((m: any) => {
              const addr = (m.address || "").toUpperCase();
              const body = (m.body || "").toUpperCase();
              return (
                addr === "127" ||
                addr === "CBE" ||
                body.includes("TELEBIRR") ||
                body.includes("CBE")
              );
            });

            if (!match) return;

            const {
              bank,
              ref,
              amount: parsedAmount,
            } = parseSmsMessage(match.body);
            if (ref || parsedAmount) {
              setTransactionId(ref || match.body.slice(0, 20));
              if (parsedAmount) setAmount(parsedAmount.replace(/,/g, ""));
              if (bank) setPaymentMethod(bank);
            }
          },
        );
      } catch {
        // silent
      }
    })();
  }, []);

  useEffect(() => {
    const payload = getScanData();
    if (!payload) return;
    if (payload.type !== "payment" || !payload.id) return;
    setScanRecordId(payload.id);
    const scanData = payload.data || {};
    if (scanData.transactionId)
      setTransactionId(String(scanData.transactionId));
    if (scanData.amount != null) setAmount(String(scanData.amount));
    if (scanData.currency) setCurrency(scanData.currency);
    if (scanData.paymentMethod) setPaymentMethod(scanData.paymentMethod);
    if (scanData.provider) {
      const normalized = normalizeFinancialInstitution(scanData.provider);
      if (normalized) setFinancialInstitution(normalized);
    }
    if (scanData.paymentDate) {
      try {
        setPaymentDate(
          new Date(scanData.paymentDate).toISOString().split("T")[0],
        );
      } catch (_) {}
    }
    if (
      scanData.referenceNumber ||
      scanData.merchantName ||
      scanData.merchantId
    ) {
      const parts: string[] = [];
      if (scanData.referenceNumber)
        parts.push(`Ref: ${scanData.referenceNumber}`);
      if (scanData.merchantName)
        parts.push(`Merchant: ${scanData.merchantName}`);
      if (scanData.merchantId)
        parts.push(`Merchant ID: ${scanData.merchantId}`);
      setNotes((prev) =>
        prev ? `${prev}\n${parts.join(" · ")}` : parts.join(" · "),
      );
    }
  }, []);

  const openInvoicePicker = async () => {
    setLoadingInvoices(true);
    try {
      const response = await api.invoices.getAll({ query: { limit: 50 } });
      const list = Array.isArray(response)
        ? response
        : (response as any).data || [];
      setInvoices(list);
      setInvoiceSearch("");
      setShowInvoicePicker(true);
    } catch (err: any) {
      toast.error("Error", "Failed to fetch invoices.");
    } finally {
      setLoadingInvoices(false);
    }
  };

  const filteredInvoices = useMemo(() => {
    if (!invoiceSearch) return invoices;
    const q = invoiceSearch.toLowerCase();
    return invoices.filter(
      (inv) =>
        (inv.invoiceNumber || "").toLowerCase().includes(q) ||
        (inv.customerName || "").toLowerCase().includes(q),
    );
  }, [invoices, invoiceSearch]);

  const STEPS = [
    { key: "details", label: "Payment Details" },
    { key: "schedule", label: "Schedule" },
    { key: "method", label: "Method" },
    { key: "summary", label: "Summary" },
  ];

  const handleNext = () => {
    if (step === 0) {
      if (!transactionId.trim()) {
        toast.error("Validation Error", "Transaction ID is required");
        return;
      }
      if (!amount || parseFloat(amount) <= 0) {
        toast.error(
          "Validation Error",
          "Amount is required and must be greater than 0",
        );
        return;
      }
    }
    setStep(step + 1);
  };

  const handleSubmit = async () => {
    if (!transactionId.trim()) {
      toast.error("Validation Error", "Transaction ID is required");
      return;
    }
    if (!amount || parseFloat(amount) <= 0) {
      toast.error(
        "Validation Error",
        "Amount is required and must be greater than 0",
      );
      return;
    }

    setSubmitting(true);
    try {
      const payload = {
        transactionId: transactionId.trim(),
        amount: parseFloat(amount),
        currency,
        paymentDate: new Date(paymentDate).toISOString(),
        paymentMethod,
        financialInstitution,
        isReferenceVerified,
        notes: notes.trim() || undefined,
        ...(selectedInvoice?.id ? { invoiceId: selectedInvoice.id } : {}),
        ...(customerId ? { customerId } : {}),
      };

      if (scanRecordId) {
        await api.payments.update({
          params: { id: scanRecordId },
          body: payload,
        });
        toast.success("Success", "Payment updated successfully!");
      } else {
        await api.payments.create({ body: payload });
        toast.success("Success", "Payment created successfully!");
      }
      nav.back();
    } catch (error: any) {
      console.error("[CreatePayment] Error:", error);
      const msg =
        error?.response?.data?.message ||
        error?.data?.message ||
        error?.message ||
        (scanRecordId
          ? "Failed to update payment"
          : "Failed to create payment");
      toast.error("Error", msg);
    } finally {
      setSubmitting(false);
    }
  };

  return (
    <ScreenWrapper className="bg-background">
      <FormFlow
        steps={STEPS}
        currentStep={step}
        onNext={handleNext}
        onBack={() => setStep(step - 1)}
        onComplete={handleSubmit}
        loading={submitting}
        completeLabel={scanRecordId ? "Update Payment" : "Create Payment"}
      >
        {step === 0 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Payment Details
            </Text>
            <View className="bg-card rounded-[6px]  gap-4">
              <Field
                label="Transaction ID"
                value={transactionId}
                onChangeText={setTransactionId}
                placeholder="e.g. TXN-2024-001"
              />
              <View className="flex-row gap-4">
                <Field
                  label="Amount"
                  value={amount}
                  onChangeText={setAmount}
                  placeholder="0.00"
                  numeric
                  flex={1}
                />
                <PickerField
                  label="Currency"
                  value={currency}
                  onPress={() => setShowCurrency(true)}
                />
              </View>
              <PickerField
                label="Payment Date"
                value={paymentDate}
                onPress={() => setShowPaymentDate(true)}
              />
            </View>
          </View>
        )}

        {step === 1 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Link Invoice
            </Text>
            <View className="bg-card rounded-[6px]  gap-4">
              <View>
                <Text className="text-[14px] font-sans-bold mb-1.5 ml-1 text-foreground">
                  Link Invoice
                </Text>
                <Pressable
                  onPress={openInvoicePicker}
                  disabled={loadingInvoices}
                  className="h-11 px-3 border border-border rounded-[6px] flex-row items-center justify-between"
                  style={{ backgroundColor: c.bg, borderColor: c.border }}
                >
                  {loadingInvoices ? (
                    <ActivityIndicator color="#ea580c" size="small" />
                  ) : (
                    <>
                      <Text
                        className="text-xs font-sans-medium flex-1"
                        style={{
                          color: selectedInvoice ? c.text : c.placeholder,
                        }}
                        numberOfLines={1}
                      >
                        {selectedInvoice
                          ? `#${selectedInvoice.invoiceNumber || selectedInvoice.id} — ${selectedInvoice.customerName || ""}`
                          : "Select an invoice (optional)"}
                      </Text>
                      <Link2 size={14} color="#ea580c" strokeWidth={2.5} />
                    </>
                  )}
                </Pressable>
              </View>
              <Field
                label="Notes"
                value={notes}
                onChangeText={setNotes}
                placeholder="e.g. Payment for invoice INV-2024-001"
                multiline
              />
            </View>
          </View>
        )}

        {step === 2 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Method
            </Text>
            <View className="bg-card rounded-[6px] gap-4">
              <PickerField
                label="Payment Method"
                value={paymentMethod}
                onPress={() => setShowPaymentMethod(true)}
              />
              <PickerField
                label="Financial Institution"
                value={financialInstitution}
                onPress={() => setShowFinancialInstitution(true)}
              />
            </View>

            <View className="bg-card rounded-[6px]">
              <View className="flex-row items-center justify-between p-1">
                <View className="flex-1">
                  <Text className="text-[14px] font-sans-bold text-foreground">
                    Reference verified
                  </Text>
                  <Text className="text-[12px] text-muted-foreground mt-0.5 font-sans-medium">
                    Transaction reference has been confirmed
                  </Text>
                </View>
                <Switch
                  value={isReferenceVerified}
                  onValueChange={setIsReferenceVerified}
                  trackColor={{ false: "#334155", true: "#ea580c" }}
                  thumbColor={isReferenceVerified ? "#fff" : "#64748b"}
                />
              </View>
            </View>
          </View>
        )}

        {step === 3 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Summary
            </Text>
            <View className="bg-card rounded-[6px] p-4 border border-border gap-3">
              <View className="flex-row justify-between">
                <Text className="text-[14px] text-foreground font-sans-bold">
                  Transaction ID
                </Text>
                <Text className="text-[14px] text-foreground font-sans-bold">
                  {transactionId}
                </Text>
              </View>
              <View className="flex-row justify-between">
                <Text className="text-[14px] text-foreground font-sans-bold">
                  Amount
                </Text>
                <Text className="text-[14px] text-foreground font-sans-bold">
                  {currency}{" "}
                  {(parseFloat(amount) || 0).toLocaleString("en-US", {
                    minimumFractionDigits: 2,
                    maximumFractionDigits: 2,
                  })}
                </Text>
              </View>
              <View className="flex-row justify-between">
                <Text className="text-[14px] text-foreground font-sans-bold">
                  Payment Method
                </Text>
                <Text className="text-[14px] text-foreground font-sans-bold">
                  {paymentMethod}
                </Text>
              </View>
              <View className="flex-row justify-between">
                <Text className="text-[14px] text-foreground font-sans-bold">
                  Financial Institution
                </Text>
                <Text className="text-[14px] text-foreground font-sans-bold">
                  {financialInstitution}
                </Text>
              </View>
              <View className="flex-row justify-between">
                <Text className="text-[14px] text-foreground font-sans-bold">
                  Reference Verified
                </Text>
                <Text className="text-[14px] text-foreground font-sans-bold">
                  {isReferenceVerified ? "Yes" : "No"}
                </Text>
              </View>
              <View className="flex-row justify-between">
                <Text className="text-[14px] text-foreground font-sans-bold">
                  Payment Date
                </Text>
                <Text className="text-[14px] text-foreground font-sans-bold">
                  {paymentDate}
                </Text>
              </View>
              {selectedInvoice?.customerName ? (
                <View className="flex-row justify-between">
                  <Text className="text-[14px] text-foreground font-sans-bold">
                    Customer
                  </Text>
                  <Text className="text-[14px] text-foreground font-sans-bold">
                    {selectedInvoice?.customerName}
                  </Text>
                </View>
              ) : null}
              <View className="flex-row justify-between">
                <Text className="text-[14px] text-foreground font-sans-bold">
                  Linked Invoice
                </Text>
                <Text className="text-[14px] text-foreground font-sans-bold">
                  {selectedInvoice
                    ? `#${selectedInvoice.invoiceNumber || selectedInvoice.id}`
                    : "None"}
                </Text>
              </View>
              {notes ? (
                <View className="flex-row justify-between">
                  <Text className="text-[14px] text-foreground font-sans-medium">
                    Notes
                  </Text>
                  <Text
                    className="text-[14px] text-foreground font-sans-bold flex-1 text-right ml-4"
                    numberOfLines={2}
                  >
                    {notes}
                  </Text>
                </View>
              ) : null}
              <View className="border-t border-border/40 my-1" />
              <View className="flex-row justify-between">
                <Text className="text-[16px] font-sans-bold text-foreground">
                  Total Amount
                </Text>
                <Text className="text-[16px] font-sans-bold text-primary">
                  {currency}{" "}
                  {(parseFloat(amount) || 0).toLocaleString("en-US", {
                    minimumFractionDigits: 2,
                    maximumFractionDigits: 2,
                  })}
                </Text>
              </View>
            </View>
          </View>
        )}
      </FormFlow>

      <PickerModal
        visible={showCurrency}
        onClose={() => setShowCurrency(false)}
        title="Select Currency"
      >
        {CURRENCIES.map((curr) => (
          <SelectOption
            key={curr}
            label={curr}
            value={curr}
            selected={currency === curr}
            onSelect={(v) => {
              setCurrency(v);
              setShowCurrency(false);
            }}
          />
        ))}
      </PickerModal>

      <PickerModal
        visible={showPaymentMethod}
        onClose={() => setShowPaymentMethod(false)}
        title="Select Payment Method"
      >
        {PAYMENT_METHODS.map((method) => (
          <SelectOption
            key={method}
            label={method}
            value={method}
            selected={paymentMethod === method}
            onSelect={(v) => {
              setPaymentMethod(v);
              setShowPaymentMethod(false);
            }}
          />
        ))}
      </PickerModal>

      <PickerModal
        visible={showFinancialInstitution}
        onClose={() => setShowFinancialInstitution(false)}
        title="Select Financial Institution"
      >
        {FINANCIAL_INSTITUTIONS.map((fi) => (
          <SelectOption
            key={fi}
            label={fi}
            value={fi}
            selected={financialInstitution === fi}
            onSelect={(v) => {
              setFinancialInstitution(v);
              setShowFinancialInstitution(false);
            }}
          />
        ))}
      </PickerModal>

      <PickerModal
        visible={showPaymentDate}
        onClose={() => setShowPaymentDate(false)}
        title="Select Payment Date"
      >
        <CalendarGrid
          selectedDate={paymentDate}
          onSelect={(v) => {
            setPaymentDate(v);
            setShowPaymentDate(false);
          }}
        />
      </PickerModal>

      <PickerModal
        visible={showInvoicePicker}
        onClose={() => setShowInvoicePicker(false)}
        title="Link Invoice (Optional)"
      >
        <View className="px-4 pb-3">
          <View className="flex-row items-center rounded-xl px-3 border border-border h-10">
            <Search size={16} color={isDark ? "#94a3b8" : "#64748b"} />
            <TextInput
              className="flex-1 ml-2 text-foreground py-0 text-sm"
              placeholder="Search by number or customer..."
              placeholderTextColor={getPlaceholderColor(isDark)}
              value={invoiceSearch}
              onChangeText={setInvoiceSearch}
              autoCorrect={false}
              style={{ textAlignVertical: "center" }}
            />
          </View>
        </View>
        {loadingInvoices ? (
          <View className="py-10 items-center">
            <ActivityIndicator color="#ea580c" />
          </View>
        ) : (
          <ScrollView className="max-h-96" keyboardShouldPersistTaps="handled">
            <Pressable
              onPress={() => {
                setSelectedInvoice(null);
                setCustomerId("");
                setShowInvoicePicker(false);
              }}
              className="px-4 py-3 border-b border-border/40 flex-row items-center"
            >
              <Text className="text-muted-foreground text-sm font-sans-medium">
                None — skip linking
              </Text>
            </Pressable>
            {filteredInvoices.length > 0 ? (
              filteredInvoices.map((inv) => (
                <Pressable
                  key={inv.id}
                  onPress={() => {
                    setSelectedInvoice(inv);
                    setCustomerId(inv.customerId || "");
                    setShowInvoicePicker(false);
                  }}
                  className="px-4 py-3 border-b border-border/40 flex-row items-center"
                >
                  <View className="flex-1">
                    <Text className="text-foreground font-sans-bold text-sm">
                      {inv.customerName || "Unknown"}
                    </Text>
                    <Text className="text-muted-foreground text-[10px] font-sans-semibold mt-0.5">
                      #{inv.invoiceNumber || inv.id} · {inv.currency || "ETB"}{" "}
                      {Number(inv.amount || 0).toLocaleString()}
                    </Text>
                  </View>
                  <Link2 size={16} color="#ea580c" strokeWidth={2.5} />
                </Pressable>
              ))
            ) : (
              <EmptyState
                title={
                  invoiceSearch
                    ? "No invoices match your search"
                    : "No invoices available"
                }
              />
            )}
          </ScrollView>
        )}
      </PickerModal>
    </ScreenWrapper>
  );
}