"use client";
import React, { useState, useEffect } from "react";
import { motion } from "motion/react";
import { 
  ChevronRight, 
  ChevronLeft,
  MapPin, 
  CreditCard, 
  Truck, 
  ShieldCheck, 
  Calendar,
  Wallet,
  Clock,
  ArrowRight,
  CheckCircle2,
  Heart,
  PlusCircle
} from "lucide-react";
import { toPersian, cn } from "../lib/utils";
import { useCartStore } from "../lib/store/cartStore";
import { usePetStore } from "../lib/store/usePetStore";
import { useUserStore } from "../lib/store/userStore";
import { Product, PRODUCTS } from "../lib/data/products";
import { productService } from "../lib/services/productService";
import { toast } from "sonner";
import { useRouter } from 'next/navigation';

export default function CheckoutPage() {
  const router = useRouter();
  const { items, getTotal, getSubtotal, getDiscount, isSubscribed, charityDonation, setCharityDonation, addOrder, clearCart } = useCartStore();
  const { getActivePet, updatePet } = usePetStore();
  const { profile, updateProfile } = useUserStore();
  const [step, setStep] = useState(1);
  const [loading, setLoading] = useState(false);
  const [useRoundUp, setUseRoundUp] = useState(false);
  const [dbProducts, setDbProducts] = useState<Product[]>([]);
  const [paymentMethod, setPaymentMethod] = useState<string>('online');

  const [selectedAddressId, setSelectedAddressId] = useState<string>('');
  const [showNewAddressForm, setShowNewAddressForm] = useState(false);
  
  // Custom manual address state if guest or not using stored addresses
  const [manualName, setManualName] = useState('');
  const [manualPhone, setManualPhone] = useState('');
  const [manualAddress, setManualAddress] = useState('');

  useEffect(() => {
    productService.getProducts({ limit: 999 }).then(res => setDbProducts(res.data));
    
    // Set default selected address if logged in
    if (profile.addresses && profile.addresses.length > 0) {
      const def = profile.addresses.find(a => a.isDefault) || profile.addresses[0];
      setSelectedAddressId(def.id);
    } else if (profile.firstName) {
      // Pre-fill profile info for manual fields
      setManualName(`${profile.firstName} ${profile.lastName}`.trim());
      setManualPhone(profile.mobile || '');
    }
  }, [profile]);

  const subtotal = getSubtotal();
  const roundedAmount = Math.ceil(subtotal / 10000) * 10000;
  const roundUpDiff = roundedAmount - subtotal;

  const handleCharityToggle = () => {
    if (!useRoundUp) {
      setCharityDonation(Math.max(roundUpDiff, Math.round(subtotal * 0.01)));
      setUseRoundUp(true);
    } else {
      setCharityDonation(0);
      setUseRoundUp(false);
    }
  };

  const handleFinalize = async () => {
    const totalAmount = getTotal();

    if (paymentMethod === 'wallet' && profile.walletBalance < totalAmount) {
      toast.error("اعتبار کیف پول شما کافی نیست. لطفاً ابتدا آن را شارژ کنید یا روش پرداخت دیگری انتخاب کنید.");
      return;
    }

    setLoading(true);
    const activePet = getActivePet();

    try {
      // 1. If using wallet, deduct balance and add purchase transaction
      if (paymentMethod === 'wallet') {
        const newBalance = profile.walletBalance - totalAmount;
        const newTransaction = {
          id: `TR-${Math.floor(Math.random() * 90000) + 10000}`,
          type: 'purchase' as const,
          amount: totalAmount,
          date: new Date().toISOString(),
          status: 'success' as const
        };
        await updateProfile({
          walletBalance: newBalance,
          transactions: [newTransaction, ...(profile.transactions || [])]
        });
      }

      // 2. Register the order in the backend
      const orderId = await addOrder({
        items: [...items],
        total: totalAmount,
        charityDonation: charityDonation,
        petId: activePet?.id
      });

      // 3. Update user charity total
      if (charityDonation > 0) {
        await updateProfile({
          charityDonationTotal: (profile.charityDonationTotal || 0) + charityDonation
        });
      }

      // 4. Update pet consumptions for the refill logic
      if (activePet) {
        const newConsumptions = [...(activePet.consumptions || [])];
        
        items.forEach(item => {
          const existing = newConsumptions.find(c => c.productId === item.product.id);
          if (existing) {
            existing.remaining += item.product.packageSize * item.quantity;
            existing.packageSize = item.product.packageSize;
          } else {
            newConsumptions.push({
              productId: item.product.id,
              packageSize: item.product.packageSize,
              remaining: item.product.packageSize * item.quantity
            });
          }
        });

        updatePet(activePet.id, { consumptions: newConsumptions });
      }

      clearCart();
      toast.success("سفارش شما با موفقیت ثبت شد و به پرونده سلامت همدمتان اضافه شد!");
      router.push('/dashboard');
    } catch (err: any) {
      toast.error(err.message || "خطا در ثبت سفارش. لطفاً مجدداً تلاش کنید.");
    } finally {
      setLoading(false);
    }
  };

  if (items.length === 0) {
    return (
      <div className="min-h-screen bg-medical-gray-50 flex items-center justify-center p-6" dir="rtl">
        <div className="text-center space-y-6">
          <div className="w-24 h-24 bg-white rounded-full flex items-center justify-center mx-auto text-medical-gray-200">
             <ShieldCheck className="w-12 h-12" />
          </div>
          <h2 className="text-2xl font-black text-medical-gray-900 italic">سبد خرید شما خالی است</h2>
          <button onClick={() => router.push('/shop')} className="text-canina-blue font-black underline underline-offset-8">بازگشت به فروشگاه</button>
        </div>
      </div>
    );
  }

  return (
    <div className="min-h-screen bg-medical-gray-50 py-12 px-6 font-vazir" dir="rtl">
      <div className="max-w-7xl mx-auto">
        
        {/* Mobile Navigation & Breadcrumbs */}
        <div className="lg:hidden mb-10 space-y-4">
          <button 
            onClick={() => router.back()}
            className="flex items-center gap-2 text-medical-gray-500 font-bold hover:text-canina-blue transition-colors"
          >
            <ChevronRight className="w-5 h-5" />
            <span>بازگشت به سبد خرید</span>
          </button>
          
          <div className="flex items-center gap-2 text-[10px] font-black text-medical-gray-400 uppercase tracking-widest overflow-x-auto whitespace-nowrap pb-2">
            <span className="cursor-pointer hover:text-canina-blue" onClick={() => router.push('/shop')}>سبد خرید</span>
            <ChevronLeft className="w-2.5 h-2.5" />
            <span className="text-canina-blue">نهایی‌سازی سفارش</span>
          </div>
        </div>

        {/* Desktop Breadcrumbs (Hidden on Mobile) */}
        <div className="hidden lg:flex items-center gap-2 text-[10px] font-black text-medical-gray-400 uppercase tracking-widest mb-10">
           <span className="cursor-pointer hover:text-canina-blue" onClick={() => router.push('/')}>خانه</span>
           <ChevronLeft className="w-2.5 h-2.5" />
           <span className="text-canina-blue">درگاه پرداخت امن و نهایی‌سازی</span>
        </div>

        <div className="grid lg:grid-cols-12 gap-8 lg:gap-12">
          {/* Main Form */}
          <div className="lg:col-span-8 space-y-6 sm:space-y-8">
            {/* Step 1: Shipping */}
            <section className="bg-white rounded-[2rem] sm:rounded-[3rem] border border-medical-gray-200 p-5 sm:p-10 overflow-hidden relative">
               <div className="absolute top-0 right-0 w-2.5 sm:w-3 h-full bg-canina-blue opacity-20" />
               <div className="flex items-center gap-3 sm:gap-4 mb-6 sm:mb-10">
                 <div className="w-10 h-10 sm:w-12 sm:h-12 bg-medical-gray-900 text-white rounded-2xl flex items-center justify-center font-black text-sm sm:text-base">۱</div>
                 <h2 className="text-xl sm:text-2xl font-black text-medical-gray-900 italic">اطلاعات ارسال</h2>
               </div>
               
               {profile.addresses && profile.addresses.length > 0 && !showNewAddressForm ? (
                 <div className="space-y-4">
                   <p className="text-xs font-bold text-medical-gray-500 mb-2">انتخاب از بین آدرس‌های ذخیره‌شده شما:</p>
                   <div className="grid gap-3">
                     {profile.addresses.map((addr) => (
                       <div
                         key={addr.id}
                         onClick={() => setSelectedAddressId(addr.id)}
                         className={cn(
                           "p-4 rounded-2xl border-2 cursor-pointer transition-all flex items-start gap-3",
                           selectedAddressId === addr.id ? "border-canina-blue bg-canina-blue/5" : "border-medical-gray-100 hover:border-medical-gray-200"
                         )}
                       >
                         <input
                           type="radio"
                           name="selectedAddress"
                           checked={selectedAddressId === addr.id}
                           onChange={() => setSelectedAddressId(addr.id)}
                           className="mt-1"
                         />
                         <div className="flex-1 min-w-0">
                           <div className="flex items-center gap-2 mb-1">
                             <span className="font-black text-sm text-medical-gray-900">{addr.title}</span>
                             {addr.isDefault && (
                               <span className="bg-canina-blue/10 text-canina-blue text-[9px] font-black px-2 py-0.5 rounded-full">پیش‌فرض</span>
                             )}
                           </div>
                           <p className="text-xs text-medical-gray-600 leading-relaxed truncate">{addr.province}، {addr.city}، {addr.detail}</p>
                           <p className="text-[10px] text-medical-gray-400 font-bold mt-1">گیرنده: {addr.receptorName} | همراه: {toPersian(addr.phone)}</p>
                         </div>
                       </div>
                     ))}
                   </div>
                   <button
                     onClick={() => setShowNewAddressForm(true)}
                     className="mt-4 flex items-center gap-2 text-canina-blue font-black text-xs hover:underline"
                   >
                     <PlusCircle className="w-4 h-4" />
                     <span>استفاده از آدرس جدید</span>
                   </button>
                 </div>
               ) : (
                 <div className="space-y-4">
                   {profile.addresses && profile.addresses.length > 0 && (
                     <button
                       onClick={() => setShowNewAddressForm(false)}
                       className="mb-4 text-xs font-bold text-canina-blue hover:underline"
                     >
                       ← بازگشت به آدرس‌های ذخیره‌شده
                     </button>
                   )}
                   <div className="grid md:grid-cols-2 gap-4 sm:gap-6">
                     <div className="space-y-2">
                       <label htmlFor="chk-fullname" className="text-[10px] font-black text-medical-gray-400 uppercase tracking-widest block">نام و نام خانوادگی</label>
                       <input
                         id="chk-fullname"
                         name="name"
                         type="text"
                         autoComplete="name"
                         value={manualName}
                         onChange={(e) => setManualName(e.target.value)}
                         className="w-full bg-medical-gray-50 border border-medical-gray-200 rounded-2xl py-3 sm:py-4 px-4 sm:px-6 text-xs sm:text-sm focus:outline-none focus:ring-2 focus:ring-canina-blue/20"
                         placeholder="مثلاً: پارسا آقایی"
                       />
                     </div>
                     <div className="space-y-2">
                       <label htmlFor="chk-tel" className="text-[10px] font-black text-medical-gray-400 uppercase tracking-widest block">شماره تماس</label>
                       <input
                         id="chk-tel"
                         name="tel"
                         type="tel"
                         autoComplete="tel"
                         value={manualPhone}
                         onChange={(e) => setManualPhone(e.target.value.replace(/[^0-9]/g, ''))}
                         className="w-full bg-medical-gray-50 border border-medical-gray-200 rounded-2xl py-3 sm:py-4 px-4 sm:px-6 text-xs sm:text-sm focus:outline-none focus:ring-2 focus:ring-canina-blue/20"
                         placeholder="۰۹۱۲XXXXXXX"
                       />
                     </div>
                     <div className="md:col-span-2 space-y-2">
                       <label htmlFor="chk-street" className="text-[10px] font-black text-medical-gray-400 uppercase tracking-widest block">آدرس دقیق پستی</label>
                       <textarea
                         id="chk-street"
                         name="street-address"
                         autoComplete="street-address"
                         value={manualAddress}
                         onChange={(e) => setManualAddress(e.target.value)}
                         className="w-full bg-medical-gray-50 border border-medical-gray-200 rounded-2xl py-3 sm:py-4 px-4 sm:px-6 text-xs sm:text-sm focus:outline-none focus:ring-2 focus:ring-canina-blue/20 h-28 sm:h-32"
                         placeholder="استان، شهر، خیابان..."
                       />
                     </div>
                   </div>
                 </div>
               )}
            </section>

            {/* Step 2: Payment */}
            <section className="bg-white rounded-[2rem] sm:rounded-[3rem] border border-medical-gray-200 p-5 sm:p-10 overflow-hidden relative">
               <div className="absolute top-0 right-0 w-2.5 sm:w-3 h-full bg-medical-gray-900 opacity-20" />
               <div className="flex items-center gap-3 sm:gap-4 mb-6 sm:mb-10">
                 <div className="w-10 h-10 sm:w-12 sm:h-12 bg-medical-gray-900 text-white rounded-2xl flex items-center justify-center font-black text-sm sm:text-base">۲</div>
                 <h2 className="text-xl sm:text-2xl font-black text-medical-gray-900 italic">شیوه پرداخت</h2>
               </div>

                <div className="grid grid-cols-1 sm:grid-cols-3 gap-3 sm:gap-4">
                  {[
                    { id: 'online', label: 'پرداخت آنلاین', desc: 'کارت‌های بانکی', icon: <CreditCard className="w-5 h-5 sm:w-6 sm:h-6" /> },
                    { id: 'wallet', label: 'اعتبار حساب', desc: 'شارژ شده اختصاصی', icon: <Wallet className="w-5 h-5 sm:w-6 sm:h-6" /> },
                    { id: 'cod', label: 'پرداخت در محل', desc: 'فقط تهران', icon: <Truck className="w-5 h-5 sm:w-6 sm:h-6" /> }
                  ].map((pay) => (
                    <div 
                      key={pay.id} 
                      onClick={async () => {
                        setPaymentMethod(pay.id);
                      }}
                      className={cn("p-4 sm:p-6 rounded-2xl sm:rounded-3xl border-2 cursor-pointer transition-all group flex sm:flex-col items-center sm:items-start gap-4 sm:gap-0", paymentMethod === pay.id ? "border-canina-blue bg-canina-blue/5" : "border-medical-gray-100 hover:border-canina-blue")}
                    >
                       <div className="w-10 h-10 sm:w-12 sm:h-12 bg-medical-gray-50 rounded-xl sm:rounded-2xl flex items-center justify-center text-medical-gray-400 group-hover:text-canina-blue group-hover:bg-canina-blue/10 sm:mb-4 transition-all flex-shrink-0">
                          {pay.icon}
                       </div>
                       <div>
                         <h4 className="font-black text-xs sm:text-sm text-medical-gray-900 mb-0.5 sm:mb-1">{pay.label}</h4>
                         <p className="text-[10px] text-medical-gray-400 font-bold">{pay.desc}</p>
                       </div>
                    </div>
                  ))}
               </div>
            </section>

            {/* Step 3: Charity Section */}
            <section className="bg-white rounded-[2rem] sm:rounded-[3rem] border border-medical-gray-200 p-5 sm:p-10 overflow-hidden relative">
               <div className="absolute top-0 right-0 w-2.5 sm:w-3 h-full bg-pink-500 opacity-20" />
               <div className="flex items-center justify-between mb-6 sm:mb-8">
                 <div className="flex items-center gap-3 sm:gap-4">
                   <div className="w-10 h-10 sm:w-12 sm:h-12 bg-pink-500 text-white rounded-2xl flex items-center justify-center flex-shrink-0">
                     <Heart className="w-5 h-5 sm:w-6 sm:h-6 fill-white" />
                   </div>
                   <div>
                     <h2 className="text-xl sm:text-2xl font-black text-medical-gray-900 italic">ردپای مهربانی</h2>
                     <p className="text-[10px] sm:text-xs font-bold text-pink-500 mt-0.5">سهم شما در حمایت از حیوانات بی‌پناه</p>
                   </div>
                 </div>
               </div>

               <div className="bg-pink-50 rounded-[2rem] sm:rounded-[2.5rem] p-5 sm:p-8 border border-pink-100">
                  <div className="flex flex-col sm:flex-row items-start sm:items-center justify-between gap-4 sm:gap-6">
                    <div className="flex-1">
                      <h4 className="text-base sm:text-lg font-black text-medical-gray-900 italic mb-1 sm:mb-2">رند کردن مبلغ و کمک به پناهگاه</h4>
                      <p className="text-xs sm:text-sm text-medical-gray-600 leading-relaxed font-medium"> مابقی مبلغ تا ۱۰,۰۰۰ تومان بعدی صرف تامین غذا و دارو برای حیوانات بی-سرپرست می‌شود.</p>
                    </div>
                    
                    <button 
                      onClick={handleCharityToggle}
                      className={cn(
                        "w-14 h-14 sm:w-20 sm:h-20 rounded-full flex items-center justify-center transition-all shadow-lg self-end sm:self-center",
                        useRoundUp ? "bg-pink-500 text-white shadow-pink-200" : "bg-white text-medical-gray-300 border-2 border-medical-gray-100"
                      )}
                    >
                      <PlusCircle className={cn("w-7 h-7 sm:w-10 sm:h-10", useRoundUp ? "rotate-45" : "rotate-0")} />
                    </button>
                  </div>
               </div>
                   {useRoundUp && (
                     <motion.div 
                       initial={{ opacity: 0, y: 10 }}
                       animate={{ opacity: 1, y: 0 }}
                       className="mt-6 pt-6 border-t border-pink-100 flex items-center justify-between"
                     >
                       <span className="text-sm font-black text-pink-600 italic">مبلغ اهدایی شما:</span>
                       <span className="text-lg font-black font-vazir text-pink-500">{toPersian(charityDonation.toLocaleString())} تومان</span>
                     </motion.div>
                   )}
                
                <p className="mt-6 text-[10px] text-center text-medical-gray-400 font-bold">«با خرید این محصول، شما هم در درمان یک حیوان پناهگاهی سهیم شدید.»</p>
             </section>
          </div>

          {/* Sidebar Summary */}
          <div className="lg:col-span-4 space-y-8">
            <div className="bg-medical-gray-900 rounded-[3rem] p-10 text-white shadow-2xl sticky top-32">
               <h3 className="text-2xl font-black italic mb-8 border-b border-white/20 pb-4 text-white">خلاصه سفارش</h3>
               
               <div className="space-y-6 mb-10 overflow-y-auto max-h-60 pr-2">
                 {items.map((item) => (
                   <div key={item.product.id} className="flex justify-between items-start gap-4">
                      <div className="flex-1">
                        <p className="text-sm font-black text-white leading-tight">{item.product.name}</p>
                        <p className="text-[10px] text-white/60 font-bold mt-1">تعداد: {toPersian(item.quantity)} بسته</p>
                      </div>
                      <span className="text-xs font-mono font-bold font-vazir text-white">{toPersian((item.product.priceValue * item.quantity).toLocaleString())} تومان</span>
                   </div>
                 ))}
               </div>

               <div className="space-y-4 pt-8 border-t border-white/20">
                  <div className="flex justify-between text-sm font-bold text-white/80">
                    <span>مجموع اقلام</span>
                    <span className="font-vazir text-white">{toPersian(getSubtotal().toLocaleString())} تومان</span>
                  </div>
                  {isSubscribed && (
                    <div className="flex justify-between text-sm font-bold text-green-400">
                      <span>تخفیف اشتراک (۵٪-)</span>
                      <span className="font-vazir text-green-400">{toPersian(getDiscount().toLocaleString())} تومان</span>
                    </div>
                  )}
                  {charityDonation > 0 && (
                    <div className="flex justify-between text-sm font-bold text-pink-400">
                      <span>ردپای مهربانی</span>
                      <span className="font-vazir text-pink-400">{toPersian(charityDonation.toLocaleString())} تومان+</span>
                    </div>
                  )}
                  <div className="flex justify-between text-sm font-bold text-white/80">
                    <span>هزینه ارسال</span>
                    <span className="text-green-400 uppercase tracking-widest text-[10px] font-black">رایگان</span>
                  </div>
                  <div className="flex justify-between items-end pt-4">
                    <span className="text-xl font-black italic text-white">مبلغ نهایی</span>
                    <div className="text-left">
                       <p className="text-3xl font-black text-canina-gold leading-none font-vazir">{toPersian(getTotal().toLocaleString())}</p>
                       <p className="text-[10px] text-white/50 font-bold mt-1">تومان</p>
                    </div>
                  </div>
               </div>

                {/* Discount Code */}
               <div className="mt-8 pt-8 border-t border-white/10">
                  <form 
                    className="flex gap-2"
                    onSubmit={async (e) => {
                      e.preventDefault();
                      const code = (e.currentTarget.elements.namedItem('coupon') as HTMLInputElement).value;
                      const success = await useCartStore.getState().applyCoupon(code);
                      if (success) {
                        toast.success("تبریک! کد تخفیف با موفقیت اعمال شد.");
                      } else {
                        toast.error("کد تخفیف معتبر نیست.");
                      }
                    }}
                  >
                     <input 
                       id="chk-coupon"
                       name="coupon"
                       type="text" 
                       autoComplete="off"
                       placeholder="کد تخفیف (مثلاً: CANINO2024)"
                       className="flex-1 bg-white/5 border border-white/10 rounded-xl px-4 py-3 text-xs focus:ring-1 focus:ring-canina-blue outline-none"
                     />
                    <button type="submit" className="bg-white/10 px-4 py-3 rounded-xl text-[10px] font-black uppercase tracking-widest hover:bg-white/20 transition-all">اعمال</button>
                  </form>
               </div>

               {/* Refill Estimates */}
               <div className="mt-10 p-6 bg-white/5 rounded-3xl border border-white/10 space-y-4">
                 <div className="flex items-center gap-3">
                   <Clock className="w-5 h-5 text-canina-blue" />
                   <h4 className="text-xs font-black uppercase tracking-widest font-vazir">تخمین اتمام مصرف (هوش مصنوعی)</h4>
                 </div>
                 <div className="space-y-2">
                    {items.map(item => {
                      const activePet = usePetStore.getState().getActivePet();
                      // Re-hydrate product to ensure methods like calculateDosage exist from static config
                      const staticProduct = PRODUCTS.find(p => p.id === item.product.id || p.artNo === item.product.artNo);
                      const calculateFn = staticProduct?.calculateDosage || item.product.calculateDosage;
                      
                      const dose = activePet && typeof calculateFn === 'function' 
                        ? calculateFn(activePet.weight, activePet.age <= 1) 
                        : { quantity: 1 };
                        
                      const days = Math.floor((staticProduct?.packageSize || item.product.packageSize || 50) / (dose.quantity || 1));
                      
                      return (
                        <div key={item.product.id} className="flex items-center justify-between text-[10px] font-medium font-vazir">
                           <span className="text-white/40">{item.product.name}</span>
                           <span className="text-canina-blue">~ {toPersian(days)} روز دیگر</span>
                        </div>
                      );
                    })}
                 </div>
               </div>

               <button 
                 onClick={handleFinalize}
                 disabled={loading}
                 className="w-full bg-canina-blue text-white py-6 rounded-2xl font-black text-xl mt-10 hover:scale-[1.02] transition-all shadow-xl shadow-canina-blue/20 flex items-center justify-center gap-3 disabled:opacity-50 disabled:cursor-not-allowed"
               >
                 {loading ? (
                    <>
                      <div className="w-6 h-6 border-4 border-white/20 border-t-white rounded-full animate-spin" />
                      در حال ثبت...
                    </>
                 ) : (
                    <>
                      پرداخت و تکمیل {step === 1 ? 'سفارش' : 'مرحله'}
                      <ArrowRight className="w-6 h-6 rotate-180" />
                    </>
                 )}
               </button>

               <div className="mt-6 flex items-center justify-center gap-2 text-[10px] font-black text-white/20 tracking-widest uppercase">
                  <ShieldCheck className="w-4 h-4" />
                  تضمین امنیت تراکنش بانکی
               </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  );
}