"use client";

import Link from "next/link";
import { useRouter } from "next/navigation";
import { useEffect, useState } from "react";
import { formatPrice } from "@/data/sample";
import { useAuth } from "@/lib/auth";
import { useCart } from "@/lib/cart";
import { customerLoginUrl } from "@/lib/customer-auth";

type Address = {
  id: string;
  label?: string;
  province: string;
  city: string;
  address: string;
  postalCode?: string;
  landline?: string;
};

type PaymentMethods = {
  cash?: boolean;
  transfer?: boolean;
  pos?: boolean;
  ePayment?: {
    enabled?: boolean;
    defaultGateway?: string;
    gateways?: string[];
  };
};

export function CheckoutPage() {
  const router = useRouter();
  const { isAuthenticated, ready: authReady, getAccessToken } = useAuth();
  const { items, total, ready: cartReady } = useCart();

  const [addresses, setAddresses] = useState<Address[]>([]);
  const [methods, setMethods] = useState<PaymentMethods | null>(null);
  const [addressId, setAddressId] = useState("");
  const [paymentType, setPaymentType] = useState<"cash" | "transfer" | "e_payment_gate">("cash");
  const [gatewayType, setGatewayType] = useState("zarinpal");
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [shipping, setShipping] = useState({
    province: "",
    city: "",
    address: "",
    postalCode: "",
    landline: "",
  });

  useEffect(() => {
    if (!authReady) return;
    if (!isAuthenticated) {
      window.location.href = customerLoginUrl("/checkout");
    }
  }, [authReady, isAuthenticated]);

  useEffect(() => {
    const token = getAccessToken();
    if (!token) return;

    Promise.all([
      fetch("/api/addresses", { headers: { Authorization: `Bearer ${token}` } }).then((r) =>
        r.ok ? r.json() : { items: [] },
      ),
      fetch("/api/payments/methods", { headers: { Authorization: `Bearer ${token}` } }).then((r) =>
        r.ok ? r.json() : null,
      ),
    ]).then(([addressRes, methodsRes]) => {
      const nextAddresses = (addressRes.items ?? []) as Address[];
      setAddresses(nextAddresses);
      if (nextAddresses[0]) setAddressId(nextAddresses[0].id);

      const nextMethods = (methodsRes ?? methodsRes?.methods ?? methodsRes) as PaymentMethods;
      setMethods(nextMethods);
      if (nextMethods?.ePayment?.enabled) {
        setPaymentType("e_payment_gate");
        setGatewayType(nextMethods.ePayment.defaultGateway ?? nextMethods.ePayment.gateways?.[0] ?? "zarinpal");
      } else if (nextMethods?.cash) {
        setPaymentType("cash");
      } else if (nextMethods?.transfer) {
        setPaymentType("transfer");
      }
    });
  }, [getAccessToken, isAuthenticated]);

  const onSubmit = async (event: React.FormEvent) => {
    event.preventDefault();
    const token = getAccessToken();
    if (!token) return;

    setLoading(true);
    setError(null);

    const payload: Record<string, unknown> = {
      payment: { type: paymentType },
    };

    if (addressId) {
      payload.addressId = addressId;
    } else {
      payload.shippingAddress = shipping;
    }

    if (paymentType === "e_payment_gate") {
      payload.payment = { type: paymentType, gatewayType };
      payload.returnUrl = `${window.location.origin}/checkout/complete`;
    }

    try {
      const res = await fetch("/api/cart/checkout", {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
          Authorization: `Bearer ${token}`,
        },
        body: JSON.stringify(payload),
      });
      const data = await res.json();
      if (!res.ok) throw new Error(data.error ?? "ثبت سفارش ناموفق بود");

      const redirect = data.payment?.redirect;
      if (redirect?.url) {
        if (redirect.method === "POST" && redirect.fields) {
          const form = document.createElement("form");
          form.method = "POST";
          form.action = redirect.url;
          for (const [key, value] of Object.entries(redirect.fields as Record<string, string>)) {
            const input = document.createElement("input");
            input.type = "hidden";
            input.name = key;
            input.value = value;
            form.appendChild(input);
          }
          document.body.appendChild(form);
          form.submit();
          return;
        }
        window.location.href = redirect.url;
        return;
      }

      router.push(`/checkout/complete?orderId=${data.order?.id ?? ""}`);
    } catch (err) {
      setError(err instanceof Error ? err.message : "خطا در ثبت سفارش");
    } finally {
      setLoading(false);
    }
  };

  if (!authReady || !cartReady || !isAuthenticated) {
    return <div className="py-16 text-center text-sm text-muted">در حال بارگذاری...</div>;
  }

  if (items.length === 0) {
    return (
      <div className="rounded-2xl border border-border bg-surface p-10 text-center">
        <p className="mb-4 text-muted">سبد خرید شما خالی است</p>
        <Link href="/products" className="text-sm font-medium text-red hover:text-red-dark">
          بازگشت به فروشگاه
        </Link>
      </div>
    );
  }

  return (
    <form onSubmit={onSubmit} className="grid gap-8 lg:grid-cols-3">
      <div className="space-y-6 lg:col-span-2">
        <section className="rounded-2xl border border-border bg-surface p-5">
          <h2 className="mb-4 text-lg font-bold">آدرس تحویل</h2>
          {addresses.length > 0 ? (
            <div className="space-y-2">
              {addresses.map((address) => (
                <label
                  key={address.id}
                  className={`flex cursor-pointer gap-3 rounded-xl border p-3 ${
                    addressId === address.id ? "border-red bg-red-light/30" : "border-border"
                  }`}
                >
                  <input
                    type="radio"
                    name="address"
                    checked={addressId === address.id}
                    onChange={() => setAddressId(address.id)}
                  />
                  <span className="text-sm leading-relaxed">
                    {address.label ? `${address.label} — ` : ""}
                    {address.province}، {address.city}، {address.address}
                  </span>
                </label>
              ))}
            </div>
          ) : (
            <div className="grid gap-3 sm:grid-cols-2">
              <input
                required
                placeholder="استان"
                value={shipping.province}
                onChange={(e) => setShipping((s) => ({ ...s, province: e.target.value }))}
                className="rounded-xl border border-border px-3 py-2 text-sm"
              />
              <input
                required
                placeholder="شهر"
                value={shipping.city}
                onChange={(e) => setShipping((s) => ({ ...s, city: e.target.value }))}
                className="rounded-xl border border-border px-3 py-2 text-sm"
              />
              <input
                required
                placeholder="آدرس"
                value={shipping.address}
                onChange={(e) => setShipping((s) => ({ ...s, address: e.target.value }))}
                className="rounded-xl border border-border px-3 py-2 text-sm sm:col-span-2"
              />
              <input
                placeholder="کد پستی"
                value={shipping.postalCode}
                onChange={(e) => setShipping((s) => ({ ...s, postalCode: e.target.value }))}
                className="rounded-xl border border-border px-3 py-2 text-sm"
              />
              <input
                placeholder="تلفن ثابت"
                value={shipping.landline}
                onChange={(e) => setShipping((s) => ({ ...s, landline: e.target.value }))}
                className="rounded-xl border border-border px-3 py-2 text-sm"
              />
            </div>
          )}
        </section>

        <section className="rounded-2xl border border-border bg-surface p-5">
          <h2 className="mb-4 text-lg font-bold">روش پرداخت</h2>
          <div className="space-y-2">
            {methods?.cash !== false && (
              <label className="flex items-center gap-2 text-sm">
                <input
                  type="radio"
                  name="payment"
                  checked={paymentType === "cash"}
                  onChange={() => setPaymentType("cash")}
                />
                پرداخت در محل / نقدی
              </label>
            )}
            {methods?.transfer && (
              <label className="flex items-center gap-2 text-sm">
                <input
                  type="radio"
                  name="payment"
                  checked={paymentType === "transfer"}
                  onChange={() => setPaymentType("transfer")}
                />
                کارت به کارت / انتقال
              </label>
            )}
            {methods?.ePayment?.enabled && (
              <label className="flex items-center gap-2 text-sm">
                <input
                  type="radio"
                  name="payment"
                  checked={paymentType === "e_payment_gate"}
                  onChange={() => setPaymentType("e_payment_gate")}
                />
                پرداخت آنلاین
              </label>
            )}
          </div>
          {paymentType === "e_payment_gate" && methods?.ePayment?.gateways?.length ? (
            <select
              value={gatewayType}
              onChange={(e) => setGatewayType(e.target.value)}
              className="mt-3 w-full rounded-xl border border-border px-3 py-2 text-sm"
            >
              {methods.ePayment.gateways.map((gateway) => (
                <option key={gateway} value={gateway}>
                  {gateway}
                </option>
              ))}
            </select>
          ) : null}
        </section>
      </div>

      <aside className="h-fit rounded-2xl border border-border bg-surface p-5">
        <h2 className="mb-4 text-lg font-bold">خلاصه سفارش</h2>
        <div className="mb-4 space-y-2 text-sm">
          {items.map((item) => (
            <div key={item.id} className="flex justify-between gap-3">
              <span className="line-clamp-1 text-muted">{item.name}</span>
              <span>× {new Intl.NumberFormat("fa-IR").format(item.quantity)}</span>
            </div>
          ))}
        </div>
        <div className="mb-4 flex items-center justify-between border-t border-border pt-4">
          <span className="text-muted">جمع کل</span>
          <span className="text-lg font-bold text-red-dark">{formatPrice(total)} تومان</span>
        </div>
        {error && <p className="mb-3 text-sm text-red">{error}</p>}
        <button
          type="submit"
          disabled={loading}
          className="w-full rounded-xl bg-red py-3 text-sm font-medium text-white transition-colors hover:bg-red-dark disabled:cursor-not-allowed disabled:bg-red/60"
        >
          {loading ? "در حال ثبت سفارش..." : "ثبت سفارش"}
        </button>
      </aside>
    </form>
  );
}