import React, { useEffect, useMemo, useState } from "react";
import {
  ActivityIndicator,
  Pressable,
  TextInput,
  StyleSheet,
  View,
} from "react-native";
import { useSirouRouter } from "@sirou/react-native";
import { useColorScheme } from "nativewind";
import { useLocalSearchParams } from "expo-router";

import { api } from "@/lib/api";
import { AppRoutes } from "@/lib/routes";
import { toast } from "@/lib/toast-store";

import { ScreenWrapper } from "@/components/ScreenWrapper";
import { FormFlow } from "@/components/FormFlow";
import { PickerModal, SelectOption } from "@/components/PickerModal";
import { CalendarGrid } from "@/components/CalendarGrid";
import { CustomerPicker } from "@/components/CustomerPicker";
import { Text } from "@/components/ui/text";

import { ChevronDown, Plus, Trash2 } from "@/lib/icons";

type Item = { id: number; description: string; quantity: string; unitPrice: string };

const S = StyleSheet.create({
  input: {
    paddingHorizontal: 12,
    paddingVertical: 12,
    fontSize: 12,
    fontWeight: "500",
    borderRadius: 6,
    borderWidth: 1,
    textAlignVertical: "center",
  },
  inputCenter: {
    paddingHorizontal: 12,
    paddingVertical: 10,
    fontSize: 14,
    fontWeight: "500",
    borderRadius: 6,
    borderWidth: 1,
    textAlign: "center",
    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,
  center = false,
  flex,
  multiline = false,
  keyboardType,
}: {
  label: string;
  value: string;
  onChangeText: (v: string) => void;
  placeholder: string;
  numeric?: boolean;
  center?: boolean;
  flex?: number;
  multiline?: boolean;
  keyboardType?: "default" | "numeric" | "email-address" | "phone-pad";
}) {
  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={[
          center ? S.inputCenter : 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={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-11 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 CHANNELS = ["EMAIL", "PHONE"];

const STEPS = [
  { key: "details", label: "Details" },
  { key: "customer", label: "Customer" },
  { key: "schedule", label: "Schedule" },
  { key: "items", label: "Items" },
  { key: "paymentMethod", label: "Payment" },
  { key: "summary", label: "Summary" },
];

function formatDate(d: string | null | undefined): string {
  if (!d) return "";
  try {
    return new Date(d).toISOString().split("T")[0];
  } catch {
    return "";
  }
}

export default function EditPaymentRequestScreen() {
  const nav = useSirouRouter<AppRoutes>();
  const { id } = useLocalSearchParams<{ id: string }>();
  const [step, setStep] = useState(0);
  const [submitting, setSubmitting] = useState(false);
  const [loadingData, setLoadingData] = useState(true);

  const [paymentRequestNumber, setPaymentRequestNumber] = useState("");
  const [description, setDescription] = useState("");

  const [customerName, setCustomerName] = useState("");
  const [customerEmail, setCustomerEmail] = useState("");
  const [customerId, setCustomerId] = useState("");

  const [channel, setChannel] = useState("EMAIL");
  const [recipient, setRecipient] = useState("");

  const [amount, setAmount] = useState("");
  const [currency, setCurrency] = useState("ETB");

  const [issueDate, setIssueDate] = useState(
    new Date().toISOString().split("T")[0],
  );
  const [dueDate, setDueDate] = useState("");

  const [companyPaymentMethodId, setCompanyPaymentMethodId] = useState("");
  const [paymentMethods, setPaymentMethods] = useState<any[]>([]);
  const [loadingPaymentMethods, setLoadingPaymentMethods] = useState(false);

  const [items, setItems] = useState<Item[]>([
    { id: 1, description: "", quantity: "1", unitPrice: "" },
  ]);

  const c = useInputColors();

  const [showCurrency, setShowCurrency] = useState(false);
  const [showIssueDate, setShowIssueDate] = useState(false);
  const [showDueDate, setShowDueDate] = useState(false);
  const [showChannel, setShowChannel] = useState(false);
  const [showPaymentMethod, setShowPaymentMethod] = useState(false);

  useEffect(() => {
    (async () => {
      try {
        setLoadingData(true);
        const reqId = Array.isArray(id) ? id[0] : id;
        if (!reqId) return;
        const data = await api.paymentRequests.getById({ params: { id: reqId } });
        setPaymentRequestNumber(data.paymentRequestNumber || "");
        setDescription(data.description || "");
        setCustomerName(data.customerName || "");
        setCustomerEmail(data.customerEmail || "");
        setCustomerId(data.customerId || "");
        setChannel(data.channel || "EMAIL");
        setRecipient(data.recipient || data.customerEmail || "");
        setAmount(data.amount != null ? String(data.amount) : "");
        setCurrency(data.currency || "ETB");
        setIssueDate(formatDate(data.issueDate) || new Date().toISOString().split("T")[0]);
        setDueDate(formatDate(data.dueDate));
        setCompanyPaymentMethodId(data.companyPaymentMethodId || "");
        if (data.items?.length) {
          setItems(
            data.items.map((it: any, idx: number) => ({
              id: idx + 1,
              description: it.description || "",
              quantity: String(it.quantity ?? 1),
              unitPrice: String(it.unitPrice ?? ""),
            })),
          );
        }
      } catch {
        toast.error("Error", "Failed to load payment request");
      } finally {
        setLoadingData(false);
      }
    })();
  }, [id]);

  useEffect(() => {
    (async () => {
      setLoadingPaymentMethods(true);
      try {
        const res = await api.company.paymentMethods();
        const list = Array.isArray(res) ? res : res?.data || [];
        setPaymentMethods(list);
      } catch {
        setPaymentMethods([]);
      } finally {
        setLoadingPaymentMethods(false);
      }
    })();
  }, []);

  useEffect(() => {
    if (channel === "EMAIL" && customerEmail && !recipient) {
      setRecipient(customerEmail);
    }
  }, [channel, customerEmail]);

  const updateItem = (id: number, field: keyof Item, value: string) =>
    setItems((prev) =>
      prev.map((it) => (it.id === id ? { ...it, [field]: value } : it)),
    );

  const addItem = () =>
    setItems((prev) => [
      ...prev,
      { id: Date.now(), description: "", quantity: "1", unitPrice: "" },
    ]);

  const removeItem = (id: number) => {
    if (items.length > 1) setItems((prev) => prev.filter((it) => it.id !== id));
  };

  const subtotal = useMemo(
    () =>
      items.reduce(
        (sum, item) =>
          sum +
          (parseFloat(item.quantity) || 0) * (parseFloat(item.unitPrice) || 0),
        0,
      ),
    [items],
  );

  const handleNext = () => {
    if (step === 0 && !paymentRequestNumber.trim()) {
      toast.error("Validation", "Payment request number is required");
      return;
    }
    if (step === 1 && !customerName.trim()) {
      toast.error("Validation", "Customer name is required");
      return;
    }
    setStep(step + 1);
  };

  const handleSubmit = async () => {
    if (!customerName) {
      toast.error("Validation", "Please select a customer");
      return;
    }

    const body = {
      paymentRequestNumber,
      customerName,
      customerEmail: customerEmail || undefined,
      channel,
      recipient,
      amount: amount ? Number(amount) : Number(subtotal.toFixed(2)),
      currency,
      issueDate: new Date(issueDate).toISOString(),
      dueDate: dueDate ? new Date(dueDate).toISOString() : undefined,
      companyPaymentMethodId: companyPaymentMethodId || undefined,
      customerId: customerId || undefined,
      ...(description ? { description } : {}),
      items: items.map((i) => ({
        description: i.description || "Item",
        quantity: parseFloat(i.quantity) || 0,
        unitPrice: parseFloat(i.unitPrice) || 0,
        total: Number(
          ((parseFloat(i.quantity) || 0) * (parseFloat(i.unitPrice) || 0)).toFixed(2),
        ),
      })),
    };

    try {
      setSubmitting(true);
      const reqId = Array.isArray(id) ? id[0] : id;
      await api.paymentRequests.update({
        params: { id: reqId },
        body,
        headers: { "Content-Type": "application/json" },
      });
      toast.success("Success", "Payment request updated successfully!");
      nav.back();
    } catch (err: any) {
      console.error("[PaymentRequestEdit] Error:", err);
      toast.error("Error", err?.message || "Failed to update payment request");
    } finally {
      setSubmitting(false);
    }
  };

  const paymentMethodLabel = companyPaymentMethodId
    ? paymentMethods.find((pm: any) => pm.id === companyPaymentMethodId)
        ?.label || paymentMethods.find((pm: any) => pm.id === companyPaymentMethodId)
        ?.providerName || "Selected"
    : "Select";

  if (loadingData) {
    return (
      <ScreenWrapper className="bg-background">
        <View className="flex-1 items-center justify-center">
          <ActivityIndicator size="large" color="#E46212" />
        </View>
      </ScreenWrapper>
    );
  }

  return (
    <ScreenWrapper className="bg-background">
      <FormFlow
        steps={STEPS}
        currentStep={step}
        onNext={handleNext}
        onBack={() => setStep(step - 1)}
        onComplete={handleSubmit}
        loading={submitting}
        completeLabel="Update Request"
      >
        {step === 0 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Request Details
            </Text>
            <View className="bg-card rounded-[6px] gap-4">
              <Field
                label="Request Number"
                value={paymentRequestNumber}
                onChangeText={setPaymentRequestNumber}
                placeholder="e.g. PAYREQ-2024-001"
              />
              <Field
                label="Description"
                value={description}
                onChangeText={setDescription}
                placeholder="e.g. Payment request for services"
                multiline
              />
            </View>
          </View>
        )}

        {step === 1 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Customer Information
            </Text>
            <View className="bg-card rounded-[6px] gap-4">
              <View>
                <Text className="text-[14px] font-sans-bold mb-1.5 ml-1 text-foreground">
                  Customer
                </Text>
                <CustomerPicker
                  selectedIds={customerId ? [customerId] : []}
                  selectedCustomers={
                    customerId
                      ? [
                          {
                            id: customerId,
                            name: customerName,
                            email: customerEmail,
                            phone: "",
                          },
                        ]
                      : []
                  }
                  onSelect={(ids, customers) => {
                    setCustomerId(ids[0] || "");
                    setCustomerName(customers[0]?.name || "");
                    setCustomerEmail(customers[0]?.email || "");
                  }}
                  placeholder="Select a customer"
                />
              </View>
              <PickerField
                label="Invite Channel"
                value={channel}
                onPress={() => setShowChannel(true)}
              />
              <Field
                label={channel === "EMAIL" ? "Recipient Email" : "Recipient Phone"}
                value={recipient}
                onChangeText={setRecipient}
                placeholder={
                  channel === "EMAIL"
                    ? "email@example.com"
                    : "912345678"
                }
                keyboardType={channel === "EMAIL" ? "email-address" : "phone-pad"}
              />
            </View>
          </View>
        )}

        {step === 2 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Schedule & Currency
            </Text>
            <View className="bg-card rounded-[6px] gap-4">
              <View className="flex-row gap-4">
                <PickerField
                  label="Issue Date"
                  value={issueDate}
                  onPress={() => setShowIssueDate(true)}
                />
                <PickerField
                  label="Due Date"
                  value={dueDate || "Select"}
                  onPress={() => setShowDueDate(true)}
                />
              </View>
              <View className="flex-row gap-4">
                <PickerField
                  label="Currency"
                  value={currency}
                  onPress={() => setShowCurrency(true)}
                />
              </View>
              <Field
                label="Amount"
                value={amount}
                onChangeText={setAmount}
                placeholder={subtotal > 0 ? `${currency} ${subtotal.toFixed(2)}` : "Enter amount"}
                numeric
              />
            </View>
          </View>
        )}

        {step === 3 && (
          <View className="gap-5">
            <View className="flex-row items-center justify-between">
              <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
                Items
              </Text>
              <Pressable
                onPress={addItem}
                className="flex-row items-center gap-1 px-3 py-1.5 rounded-[6px] bg-primary/10 border border-primary/20"
              >
                <Plus color="#ea580c" size={14} strokeWidth={2.5} />
                <Text className="text-primary text-[10px] font-sans-bold">
                  Add
                </Text>
              </Pressable>
            </View>
            <View className="gap-3">
              {items.map((item, index) => (
                <View
                  key={item.id}
                  className={`bg-card pb-4 ${index < items.length - 1 ? "border-b border-border" : ""}`}
                >
                  <View className="flex-row justify-between items-center mb-3">
                    <Text className="text-[16px] font-sans-bold text-foreground">
                      Item {index + 1}
                    </Text>
                    <Pressable onPress={() => removeItem(item.id)} hitSlop={8}>
                      <Trash2 color="#ef4444" size={16} />
                    </Pressable>
                  </View>
                  <Field
                    label="Description"
                    placeholder="e.g. Web Development"
                    value={item.description}
                    onChangeText={(v) => updateItem(item.id, "description", v)}
                  />
                  <View className="flex-row gap-3 mt-4">
                    <Field
                      label="Qty"
                      placeholder="1"
                      numeric
                      center
                      value={item.quantity}
                      onChangeText={(v) => updateItem(item.id, "quantity", v)}
                      flex={1}
                    />
                    <Field
                      label="Unit Price"
                      placeholder="0.00"
                      numeric
                      value={item.unitPrice}
                      onChangeText={(v) => updateItem(item.id, "unitPrice", v)}
                      flex={3}
                    />
                  </View>
                  {parseFloat(item.quantity) > 0 && parseFloat(item.unitPrice) > 0 && (
                    <View className="flex-row justify-end mt-2">
                      <Text className="text-[12px] text-muted-foreground font-sans-medium">
                        = {currency}{" "}
                        {(
                          (parseFloat(item.quantity) || 0) *
                          (parseFloat(item.unitPrice) || 0)
                        ).toFixed(2)}
                      </Text>
                    </View>
                  )}
                </View>
              ))}
            </View>
            {subtotal > 0 && (
              <View className="flex-row justify-end items-center gap-2 pt-2 border-t border-border">
                <Text className="text-[14px] text-muted-foreground font-sans-medium">
                  Subtotal
                </Text>
                <Text className="text-[15px] text-foreground font-sans-bold">
                  {currency} {subtotal.toFixed(2)}
                </Text>
              </View>
            )}
          </View>
        )}

        {step === 4 && (
          <View className="gap-5">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Payment Method
            </Text>
            <View className="bg-card rounded-[6px] gap-4">
              <View>
                <Text className="text-[14px] font-sans-bold mb-1.5 ml-1 text-foreground">
                  Company Payment Method
                </Text>
                <Pressable
                  onPress={() => {
                    if (paymentMethods.length > 0) {
                      setShowPaymentMethod(true);
                    } else {
                      toast.error(
                        "No Methods",
                        "No payment methods available. Please configure one in company settings.",
                      );
                    }
                  }}
                  className="h-11 px-3 border border-border rounded-[6px] flex-row items-center justify-between"
                  style={{ backgroundColor: c.bg, borderColor: c.border }}
                >
                  {loadingPaymentMethods ? (
                    <ActivityIndicator color="#ea580c" size="small" />
                  ) : (
                    <>
                      <Text
                        className="text-xs font-sans-medium flex-1"
                        style={{
                          color: companyPaymentMethodId ? c.text : c.placeholder,
                        }}
                        numberOfLines={1}
                      >
                        {paymentMethodLabel}
                      </Text>
                      <ChevronDown size={14} color={c.text} strokeWidth={3} />
                    </>
                  )}
                </Pressable>
              </View>
            </View>
          </View>
        )}

        {step === 5 && (
          <View className="gap-5 pb-4">
            <Text className="text-[18px] font-sans-bold text-foreground tracking-tight">
              Summary
            </Text>
            <View className="bg-card rounded-[6px] gap-3">
              <SummaryRow label="Request Number" value={paymentRequestNumber} />
              {description ? (
                <SummaryRow label="Description" value={description} multiline />
              ) : null}
              <SummaryRow label="Customer" value={customerName} />
              <SummaryRow label="Channel" value={channel} />
              <SummaryRow label="Recipient" value={recipient} />
              <View className="border-t border-border/40 my-1" />
              <SummaryRow label="Issue Date" value={issueDate} />
              <SummaryRow label="Due Date" value={dueDate || "Not set"} />
              <SummaryRow label="Currency" value={currency} />
              {items.length > 0 && (
                <View className="border-t border-border/40 pt-3">
                  <Text className="text-[12px] text-muted-foreground font-sans-bold uppercase tracking-widest mb-2">
                    Items ({items.length})
                  </Text>
                  {items.map((item, i) => (
                    <View
                      key={item.id}
                      className="flex-row justify-between py-1"
                    >
                      <Text
                        className="text-[13px] text-foreground font-sans-medium flex-1"
                        numberOfLines={1}
                      >
                        {item.description || `Item ${i + 1}`}
                      </Text>
                      <Text className="text-[13px] text-foreground font-sans-bold">
                        {item.quantity} × {currency}{" "}
                        {parseFloat(item.unitPrice || "0").toFixed(2)}
                      </Text>
                    </View>
                  ))}
                </View>
              )}
              {paymentMethodLabel !== "Select" && (
                <SummaryRow label="Payment Method" value={paymentMethodLabel} />
              )}
              <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}{" "}
                  {(amount ? Number(amount) : subtotal).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={showChannel}
        onClose={() => setShowChannel(false)}
        title="Invite Channel"
      >
        {CHANNELS.map((ch) => (
          <SelectOption
            key={ch}
            label={ch}
            value={ch}
            selected={channel === ch}
            onSelect={(v) => {
              setChannel(v);
              setShowChannel(false);
            }}
          />
        ))}
      </PickerModal>

      <PickerModal
        visible={showPaymentMethod}
        onClose={() => setShowPaymentMethod(false)}
        title="Payment Method"
      >
        {paymentMethods.map((pm: any) => (
          <SelectOption
            key={pm.id}
            label={pm.label || pm.providerName || pm.bankName || "Method"}
            value={pm.id}
            selected={companyPaymentMethodId === pm.id}
            onSelect={(v) => {
              setCompanyPaymentMethodId(v);
              setShowPaymentMethod(false);
            }}
          />
        ))}
      </PickerModal>

      <PickerModal
        visible={showIssueDate}
        onClose={() => setShowIssueDate(false)}
        title="Select Issue Date"
      >
        <CalendarGrid
          selectedDate={issueDate}
          onSelect={(v) => {
            setIssueDate(v);
            setShowIssueDate(false);
          }}
        />
      </PickerModal>

      <PickerModal
        visible={showDueDate}
        onClose={() => setShowDueDate(false)}
        title="Select Due Date"
      >
        <CalendarGrid
          selectedDate={dueDate}
          onSelect={(v) => {
            setDueDate(v);
            setShowDueDate(false);
          }}
        />
      </PickerModal>
    </ScreenWrapper>
  );
}

function SummaryRow({
  label,
  value,
  multiline,
}: {
  label: string;
  value: string;
  multiline?: boolean;
}) {
  return (
    <View className="flex-row justify-between">
      <Text className="text-[14px] text-foreground font-sans-medium">
        {label}
      </Text>
      <Text
        className="text-[14px] text-foreground font-sans-bold text-right flex-1 ml-4"
        numberOfLines={multiline ? undefined : 2}
      >
        {value}
      </Text>
    </View>
  );
}