"use client";

import { useState, useEffect } from "react";
import { useRouter } from "next/navigation";
import Link from "next/link";
import Image from "next/image";
import { useTranslations, useLocale } from "next-intl";
import Header from "@/components/layout/Header";
import Footer from "@/components/layout/Footer";
import { useSaleorCheckoutStore } from "@/stores/saleorCheckoutStore";
import { formatPrice } from "@/lib/saleor";
import { saleorClient } from "@/lib/saleor/client";
import { useAnalytics } from "@/lib/analytics";
import {
  CHECKOUT_SHIPPING_ADDRESS_UPDATE,
} from "@/lib/saleor/mutations/Checkout";
import { PaymentSection } from "./components/PaymentSection";
import { DEFAULT_PAYMENT_METHOD } from "@/lib/config/paymentMethods";
import { GET_CHECKOUT_BY_ID } from "@/lib/saleor/queries/Checkout";
import type { Checkout } from "@/types/saleor";
import { createCheckoutService, type Address } from "@/lib/services/checkoutService";
import { useShippingMethodSelector } from "@/lib/hooks/useShippingMethodSelector";

interface ShippingAddressUpdateResponse {
  checkoutShippingAddressUpdate?: {
    checkout?: Checkout;
    errors?: Array<{ message: string }>;
  };
}

interface CheckoutQueryResponse {
  checkout?: Checkout;
}



interface ShippingMethod {
  id: string;
  name: string;
  price: {
    amount: number;
    currency: string;
  };
}

interface AddressForm {
  firstName: string;
  lastName: string;
  streetAddress1: string;
  streetAddress2: string;
  city: string;
  postalCode: string;
  country: string;
  phone: string;
  email: string;
}

export default function CheckoutPage() {
  const t = useTranslations("Checkout");
  const locale = useLocale();
  const router = useRouter();
  const { checkout, refreshCheckout, clearCheckout, getLines, getTotal } = useSaleorCheckoutStore();
  const { trackCheckoutStarted, trackCheckoutStep, trackOrderCompleted, identifyUser } = useAnalytics();
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [orderComplete, setOrderComplete] = useState(false);
  const [orderNumber, setOrderNumber] = useState<string | null>(null);

  const [sameAsShipping, setSameAsShipping] = useState(true);
  const [selectedPaymentMethod, setSelectedPaymentMethod] = useState<string>(DEFAULT_PAYMENT_METHOD);
  const [shippingAddress, setShippingAddress] = useState<AddressForm>({
    firstName: "",
    lastName: "",
    streetAddress1: "",
    streetAddress2: "",
    city: "",
    postalCode: "",
    country: "RS",
    phone: "",
    email: "",
  });
  const [billingAddress, setBillingAddress] = useState<AddressForm>({
    firstName: "",
    lastName: "",
    streetAddress1: "",
    streetAddress2: "",
    city: "",
    postalCode: "",
    country: "RS",
    phone: "",
    email: "",
  });

  const [shippingMethods, setShippingMethods] = useState<ShippingMethod[]>([]);
  const [selectedShippingMethod, setSelectedShippingMethod] = useState<string>("");
  const [isLoadingShipping, setIsLoadingShipping] = useState(false);

  // Hook to manage shipping method selection (both manual and auto)
  const { selectShippingMethodWithApi } = useShippingMethodSelector({
    checkoutId: checkout?.id ?? null,
    onSelect: setSelectedShippingMethod,
    onRefresh: refreshCheckout,
  });

  const lines = getLines();
  // Use checkout.totalPrice directly for reactive updates when shipping method changes
  const total = checkout?.totalPrice?.gross?.amount || getTotal();

  // Debounced shipping method fetching
  useEffect(() => {
    if (!checkout) return;
    
    // Check if address is complete enough to fetch shipping methods
    const isAddressComplete = 
      shippingAddress.firstName && 
      shippingAddress.lastName && 
      shippingAddress.streetAddress1 && 
      shippingAddress.city && 
      shippingAddress.postalCode && 
      shippingAddress.country;
    
    if (!isAddressComplete) {
      setShippingMethods([]);
      return;
    }

    const timer = setTimeout(async () => {
      setIsLoadingShipping(true);
      try {
        console.log("Fetching shipping methods...");
        
        // First update the shipping address
        await saleorClient.mutate<ShippingAddressUpdateResponse>({
          mutation: CHECKOUT_SHIPPING_ADDRESS_UPDATE,
          variables: {
            checkoutId: checkout.id,
            shippingAddress: {
              firstName: shippingAddress.firstName,
              lastName: shippingAddress.lastName,
              streetAddress1: shippingAddress.streetAddress1,
              streetAddress2: shippingAddress.streetAddress2,
              city: shippingAddress.city,
              postalCode: shippingAddress.postalCode,
              country: shippingAddress.country,
              phone: shippingAddress.phone,
            },
          },
        });

        // Then query for shipping methods
        const checkoutQueryResult = await saleorClient.query<CheckoutQueryResponse>({
          query: GET_CHECKOUT_BY_ID,
          variables: { id: checkout.id },
          fetchPolicy: "network-only",
        });

        const availableMethods = checkoutQueryResult.data?.checkout?.shippingMethods || [];
        console.log("Available shipping methods:", availableMethods);
        
        setShippingMethods(availableMethods);

        // Auto-select first method if none selected
        if (availableMethods.length > 0 && !selectedShippingMethod) {
          const firstMethodId = availableMethods[0].id;
          // Use the hook to both update UI and call API
          await selectShippingMethodWithApi(firstMethodId);
        }
      } catch (err) {
        console.error("Error fetching shipping methods:", err);
      } finally {
        setIsLoadingShipping(false);
      }
    }, 500); // 500ms debounce

    return () => clearTimeout(timer);
  }, [checkout, shippingAddress]);

  useEffect(() => {
    if (!checkout) {
      refreshCheckout();
    }
  }, [checkout, refreshCheckout]);

  // Track checkout started when page loads
  useEffect(() => {
    if (checkout) {
      const lines = getLines();
      const total = getTotal();
      trackCheckoutStarted({
        total,
        currency: "RSD",
        item_count: lines.reduce((sum, line) => sum + line.quantity, 0),
        items: lines.map(line => ({
          id: line.variant.id,
          name: line.variant.product.name,
          quantity: line.quantity,
          price: line.variant.pricing?.price?.gross?.amount || 0,
          currency: line.variant.pricing?.price?.gross?.currency || "RSD",
        })),
      });
    }
  }, [checkout]);

  // Scroll to top when order is complete
  useEffect(() => {
    if (orderComplete) {
      window.scrollTo({ top: 0, behavior: "smooth" });
    }
  }, [orderComplete]);

  const handleShippingChange = (field: keyof AddressForm, value: string) => {
    setShippingAddress((prev) => ({ ...prev, [field]: value }));
    if (sameAsShipping && field !== "email") {
      setBillingAddress((prev) => ({ ...prev, [field]: value }));
    }
  };

  const handleBillingChange = (field: keyof AddressForm, value: string) => {
    setBillingAddress((prev) => ({ ...prev, [field]: value }));
  };

  const handleEmailChange = (value: string) => {
    setShippingAddress((prev) => ({ ...prev, email: value }));
  };

  const handleShippingMethodSelect = async (methodId: string) => {
    await selectShippingMethodWithApi(methodId);
  };

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();

    if (!checkout) {
      setError(t("errorNoCheckout"));
      return;
    }

    // Validate all required fields
    if (!shippingAddress.email || !shippingAddress.email.includes("@")) {
      setError(t("errorEmailRequired"));
      return;
    }

    if (!shippingAddress.phone || shippingAddress.phone.length < 8) {
      setError(t("errorPhoneRequired"));
      return;
    }

    if (!shippingAddress.firstName || !shippingAddress.lastName || !shippingAddress.streetAddress1 || !shippingAddress.city || !shippingAddress.postalCode) {
      setError(t("errorFieldsRequired"));
      return;
    }

    if (!selectedShippingMethod) {
      setError(t("errorSelectShipping"));
      return;
    }

    if (!selectedPaymentMethod) {
      setError(t("errorSelectPayment"));
      return;
    }

    setIsLoading(true);
    setError(null);

    try {
      console.log("Completing order via CheckoutService...");

      // Create checkout service instance
      const checkoutService = createCheckoutService(checkout.id);

      // Transform form data to service types
      const serviceShippingAddress: Address = {
        firstName: shippingAddress.firstName,
        lastName: shippingAddress.lastName,
        streetAddress1: shippingAddress.streetAddress1,
        streetAddress2: shippingAddress.streetAddress2,
        city: shippingAddress.city,
        postalCode: shippingAddress.postalCode,
        country: shippingAddress.country,
        phone: shippingAddress.phone,
      };

      const serviceBillingAddress: Address = {
        firstName: billingAddress.firstName,
        lastName: billingAddress.lastName,
        streetAddress1: billingAddress.streetAddress1,
        streetAddress2: billingAddress.streetAddress2,
        city: billingAddress.city,
        postalCode: billingAddress.postalCode,
        country: billingAddress.country,
        phone: billingAddress.phone,
      };

      // Execute checkout pipeline
      const result = await checkoutService.execute({
        email: shippingAddress.email,
        shippingAddress: serviceShippingAddress,
        billingAddress: serviceBillingAddress,
        shippingMethodId: selectedShippingMethod,
        languageCode: locale.toUpperCase(),
        metadata: {
          phone: shippingAddress.phone,
          shippingPhone: shippingAddress.phone,
          userLanguage: locale,
          userLocale: locale,
        },
      });

      if (!result.success || !result.order) {
        // Handle specific error types
        if (result.error === "CHECKOUT_EXPIRED") {
          console.error("Checkout not found, clearing cart...");
          localStorage.removeItem('cart');
          localStorage.removeItem('checkoutId');
          window.location.href = `/${locale}/products`;
          return;
        }
        throw new Error(result.error || t("errorCreatingOrder"));
      }

      // Success!
      setOrderNumber(result.order.number);
      setOrderComplete(true);
      
      // Track order completion BEFORE clearing checkout
      const lines = getLines();
      const total = getTotal();
      console.log("[Checkout] Order total before tracking:", total, "RSD");
      trackOrderCompleted({
        order_id: checkout.id,
        order_number: result.order.number,
        total,
        currency: "RSD",
        item_count: lines.reduce((sum, line) => sum + line.quantity, 0),
        shipping_cost: shippingMethods.find(m => m.id === selectedShippingMethod)?.price.amount,
        customer_email: shippingAddress.email,
      });
      
      // Clear the checkout/cart from the store
      clearCheckout();
      
      // Identify the user
      identifyUser({
        profileId: shippingAddress.email,
        email: shippingAddress.email,
        firstName: shippingAddress.firstName,
        lastName: shippingAddress.lastName,
      });

      console.log("Order completed successfully:", result.order.number);

    } catch (err: unknown) {
      console.error("Checkout error:", err);
      
      if (err instanceof Error) {
        if (err.name === "AbortError") {
          setError("Request timed out. Please check your connection and try again.");
        } else {
          setError(err.message || t("errorOccurred"));
        }
      } else {
        setError(t("errorOccurred"));
      }
    } finally {
      setIsLoading(false);
    }
  };

  if (orderComplete) {
    return (
      <>
        <Header locale={locale} />
        <main className="min-h-screen">
          <section className="pt-[120px] pb-20 px-4">
            <div className="max-w-2xl mx-auto text-center">
              <div className="mb-6">
                <div className="w-16 h-16 bg-green-100 rounded-full flex items-center justify-center mx-auto mb-4">
                  <svg className="w-8 h-8 text-green-600" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
                  </svg>
                </div>
                <h1 className="text-3xl font-serif mb-2">{t("orderConfirmed")}</h1>
                <p className="text-foreground-muted">{t("thankYou")}</p>
              </div>

              {orderNumber && (
                <div className="bg-background-ice p-6 rounded-lg mb-6">
                  <p className="text-sm text-foreground-muted mb-1">{t("orderNumber")}</p>
                  <p className="text-2xl font-serif">#{orderNumber}</p>
                </div>
              )}

              <p className="text-foreground-muted mb-8">
                {t("confirmationEmail")}
              </p>

              <Link
                href={`/${locale}/products`}
                className="inline-block px-8 py-3 bg-foreground text-white hover:bg-accent-dark transition-colors"
              >
                {t("continueShoppingBtn")}
              </Link>
            </div>
          </section>
        </main>
        <div className="pt-16">
          <Footer locale={locale} />
        </div>
      </>
    );
  }

  return (
    <>
      <Header locale={locale} />
      <main className="min-h-screen">
        <section className="pt-[120px] pb-20 px-4">
          <div className="max-w-7xl mx-auto">
            <h1 className="text-3xl font-serif mb-8">{t("checkout")}</h1>

            {error && (
              <div className="bg-red-50 border border-red-200 text-red-600 p-4 mb-6 rounded">
                {error}
              </div>
            )}

            <div className="grid grid-cols-1 lg:grid-cols-2 gap-12">
              <div>
                <form onSubmit={handleSubmit} className="space-y-6">
                  <div className="border-b border-border pb-6">
                    <h2 className="text-xl font-serif mb-4">{t("contactInfo")}</h2>
                    <div className="grid grid-cols-1 gap-4">
                      <div>
                        <label className="block text-sm font-medium mb-1">{t("email")}</label>
                        <input
                          type="email"
                          required
                          value={shippingAddress.email}
                          onChange={(e) => handleEmailChange(e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                          placeholder="email@example.com"
                        />
                        <p className="text-xs text-foreground-muted mt-1">{t("emailRequired")}</p>
                      </div>
                      <div>
                        <label className="block text-sm font-medium mb-1">{t("phone")}</label>
                        <input
                          type="tel"
                          required
                          value={shippingAddress.phone}
                          onChange={(e) => handleShippingChange("phone", e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                          placeholder="+381..."
                        />
                        <p className="text-xs text-foreground-muted mt-1">{t("phoneRequired")}</p>
                      </div>
                    </div>
                  </div>

                  <div className="border-b border-border pb-6">
                    <h2 className="text-xl font-serif mb-4">{t("shippingAddress")}</h2>
                    <div className="grid grid-cols-2 gap-4">
                      <div>
                        <label className="block text-sm font-medium mb-1">{t("firstName")}</label>
                        <input
                          type="text"
                          required
                          value={shippingAddress.firstName}
                          onChange={(e) => handleShippingChange("firstName", e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                        />
                      </div>
                      <div>
                        <label className="block text-sm font-medium mb-1">{t("lastName")}</label>
                        <input
                          type="text"
                          required
                          value={shippingAddress.lastName}
                          onChange={(e) => handleShippingChange("lastName", e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                        />
                      </div>
                      <div className="col-span-2">
                        <label className="block text-sm font-medium mb-1">{t("country")}</label>
                        <select
                          required
                          value={shippingAddress.country}
                          onChange={(e) => handleShippingChange("country", e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                        >
                          <option value="RS">Serbia (Srbija)</option>
                          <option value="BA">Bosnia and Herzegovina</option>
                          <option value="ME">Montenegro</option>
                          <option value="HR">Croatia</option>
                          <option value="SI">Slovenia</option>
                          <option value="MK">North Macedonia</option>
                          <option value="AL">Albania</option>
                          <option value="XK">Kosovo</option>
                          <option value="BG">Bulgaria</option>
                          <option value="RO">Romania</option>
                          <option value="HU">Hungary</option>
                          <option value="DE">Germany</option>
                          <option value="AT">Austria</option>
                          <option value="CH">Switzerland</option>
                          <option value="FR">France</option>
                          <option value="GB">United Kingdom</option>
                          <option value="US">United States</option>
                          <option value="CA">Canada</option>
                          <option value="AU">Australia</option>
                        </select>
                      </div>
                      <div className="col-span-2">
                        <label className="block text-sm font-medium mb-1">{t("streetAddress")}</label>
                        <input
                          type="text"
                          required
                          value={shippingAddress.streetAddress1}
                          onChange={(e) => handleShippingChange("streetAddress1", e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                        />
                      </div>
                      <div className="col-span-2">
                        <input
                          type="text"
                          value={shippingAddress.streetAddress2}
                          onChange={(e) => handleShippingChange("streetAddress2", e.target.value)}
                          placeholder={t("streetAddressOptional")}
                          className="w-full border border-border px-4 py-2 rounded"
                        />
                      </div>
                      <div>
                        <label className="block text-sm font-medium mb-1">{t("city")}</label>
                        <input
                          type="text"
                          required
                          value={shippingAddress.city}
                          onChange={(e) => handleShippingChange("city", e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                        />
                      </div>
                      <div>
                        <label className="block text-sm font-medium mb-1">{t("postalCode")}</label>
                        <input
                          type="text"
                          required
                          value={shippingAddress.postalCode}
                          onChange={(e) => handleShippingChange("postalCode", e.target.value)}
                          className="w-full border border-border px-4 py-2 rounded"
                        />
                      </div>
                    </div>
                  </div>

                  <div className="border-b border-border pb-6">
                    <label className="flex items-center gap-2 cursor-pointer">
                      <input
                        type="checkbox"
                        checked={sameAsShipping}
                        onChange={(e) => setSameAsShipping(e.target.checked)}
                        className="w-4 h-4"
                      />
                      <span>{t("billingAddressSame")}</span>
                    </label>
                  </div>

                  {/* Shipping Method Selection */}
                  <div className="border-b border-border pb-6">
                    <h2 className="text-xl font-serif mb-4">{t("shippingMethod")}</h2>
                    {isLoadingShipping ? (
                      <div className="flex items-center gap-2 text-foreground-muted">
                        <svg className="animate-spin h-5 w-5" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24">
                          <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4"></circle>
                          <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path>
                        </svg>
                        <span>{t("loadingShippingMethods")}</span>
                      </div>
                    ) : shippingMethods.length > 0 ? (
                      <div className="space-y-3">
                        {shippingMethods.map((method) => (
                          <label
                            key={method.id}
                            className={`flex items-center justify-between p-4 border rounded cursor-pointer transition-colors ${
                              selectedShippingMethod === method.id
                                ? "border-foreground bg-background-ice"
                                : "border-border hover:border-foreground/50"
                            }`}
                          >
                            <div className="flex items-center gap-3">
                              <input
                                type="radio"
                                name="shippingMethod"
                                value={method.id}
                                checked={selectedShippingMethod === method.id}
                                onChange={(e) => handleShippingMethodSelect(e.target.value)}
                                className="w-4 h-4"
                              />
                              <span className="font-medium">{method.name}</span>
                            </div>
                            <span className="text-foreground-muted">
                              {formatPrice(method.price.amount)}
                            </span>
                          </label>
                        ))}
                      </div>
                    ) : (
                      <p className="text-foreground-muted">{t("enterAddressForShipping")}</p>
                    )}
                  </div>

                  {/* Payment Method Section */}
                  <PaymentSection
                    selectedMethodId={selectedPaymentMethod}
                    onSelectMethod={setSelectedPaymentMethod}
                    locale={locale}
                    channel="default-channel"
                    disabled={isLoading}
                  />

                  {/* Money Back Guarantee Trust Badge */}
                  <div className="flex items-center justify-center gap-2 py-3 px-4 bg-green-50 rounded-lg border border-green-100">
                    <svg className="w-5 h-5 text-green-600" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
                      <path strokeLinecap="round" strokeLinejoin="round" d="M9 12l2 2 4-4m6 2a9 9 0 11-18 0 9 9 0 0118 0z" />
                    </svg>
                    <span className="text-sm font-medium text-green-800">{t("moneyBackGuarantee")}</span>
                  </div>

                  <button
                    type="submit"
                    disabled={isLoading || lines.length === 0 || !selectedShippingMethod}
                    className="w-full py-4 bg-foreground text-white font-medium hover:bg-accent-dark transition-colors disabled:opacity-50"
                  >
                    {isLoading ? t("processing") : t("completeOrder", { total: formatPrice(total) })}
                  </button>
                </form>
              </div>

              <div className="bg-background-ice p-6 rounded-lg h-fit">
                <h2 className="text-xl font-serif mb-6">{t("orderSummary")}</h2>

                {lines.length === 0 ? (
                  <p className="text-foreground-muted">{t("yourCartEmpty")}</p>
                ) : (
                  <>
                    <div className="space-y-4 mb-6">
                      {lines.map((line) => (
                        <div key={line.id} className="flex gap-4">
                          <div className="w-16 h-16 bg-white relative flex-shrink-0">
                            {line.variant.product.media[0]?.url && (
                              <Image
                                src={line.variant.product.media[0].url}
                                alt={line.variant.product.name}
                                fill
                                sizes="64px"
                                className="object-cover"
                              />
                            )}
                          </div>
                          <div className="flex-1">
                            <h3 className="font-medium text-sm">{line.variant.product.name}</h3>
                            <p className="text-foreground-muted text-sm">
                              {t("qty")}: {line.quantity}
                            </p>
                            <p className="text-sm">
                              {formatPrice(line.totalPrice.gross.amount)}
                            </p>
                          </div>
                        </div>
                      ))}
                    </div>

                    <div className="border-t border-border pt-4 space-y-2">
                      <div className="flex justify-between">
                        <span className="text-foreground-muted">{t("subtotal")}</span>
                        <span>{formatPrice(checkout?.subtotalPrice?.gross?.amount || 0)}</span>
                      </div>
                      {selectedShippingMethod && (
                        <div className="flex justify-between">
                          <span className="text-foreground-muted">{t("shipping")}</span>
                          <span>{formatPrice(shippingMethods.find(m => m.id === selectedShippingMethod)?.price.amount || 0)}</span>
                        </div>
                      )}
                      <div className="flex justify-between font-medium text-lg pt-2 border-t border-border">
                        <span>{t("total")}</span>
                        <span>{formatPrice(total)}</span>
                      </div>
                    </div>
                  </>
                )}
              </div>
            </div>
          </div>
        </section>
      </main>

      <div className="pt-16">
        <Footer locale={locale} />
      </div>
    </>
  );
}