"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 } 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');

  useEffect(() => {
    productService.getProducts({ limit: 999 }).then(res => setDbProducts(res.data));
  }, []);

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

    try {
      // 1. Register the order in the backend
      const orderId = await addOrder({
        items: [...items],
        total: getTotal(),
        charityDonation: charityDonation,
        petId: activePet?.id
      });

      // 2. Update user charity total
      if (charityDonation > 0) {
        updateProfile({
          charityDonationTotal: (profile.charityDonationTotal || 0) + charityDonation
        });
      }

      // 3. 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-12">
          {/* Main Form */}
          <div className="lg:col-span-8 space-y-8">
            {/* Step 1: Shipping */}
            <section className="bg-white rounded-[3rem] border border-medical-gray-200 p-10 overflow-hidden relative">
               <div className="absolute top-0 right-0 w-3 h-full bg-canina-blue opacity-20" />
               <div className="flex items-center gap-4 mb-10">
                 <div className="w-12 h-12 bg-medical-gray-900 text-white rounded-2xl flex items-center justify-center font-black">۱</div>
                 <h2 className="text-2xl font-black text-medical-gray-900 italic">اطلاعات ارسال</h2>
               </div>
               
               <div className="grid md:grid-cols-2 gap-6">
                  <div className="space-y-2">
                    <label className="text-[10px] font-black text-medical-gray-400 uppercase tracking-widest block">نام و نام خانوادگی</label>
                    <input type="text" className="w-full bg-medical-gray-50 border border-medical-gray-200 rounded-2xl py-4 px-6 text-sm focus:outline-none focus:ring-2 focus:ring-canina-blue/20" placeholder="مثلاً: پارسا آقایی" />
                  </div>
                  <div className="space-y-2">
                    <label className="text-[10px] font-black text-medical-gray-400 uppercase tracking-widest block">شماره تماس</label>
                    <input type="text" className="w-full bg-medical-gray-50 border border-medical-gray-200 rounded-2xl py-4 px-6 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 className="text-[10px] font-black text-medical-gray-400 uppercase tracking-widest block">آدرس دقیق پستی</label>
                    <textarea className="w-full bg-medical-gray-50 border border-medical-gray-200 rounded-2xl py-4 px-6 text-sm focus:outline-none focus:ring-2 focus:ring-canina-blue/20 h-32" placeholder="استان، شهر، خیابان..." />
                  </div>
               </div>
            </section>

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

                <div className="grid md:grid-cols-3 gap-4">
                  {[
                    { id: 'online', label: 'پرداخت آنلاین', desc: 'کارت‌های بانکی', icon: <CreditCard className="w-6 h-6" /> },
                    { id: 'wallet', label: 'اعتبار حساب', desc: 'شارژ شده اختصاصی', icon: <Wallet className="w-6 h-6" /> },
                    { id: 'cod', label: 'پرداخت در محل', desc: 'فقط تهران', icon: <Truck className="w-6 h-6" /> }
                  ].map((pay) => (
                    <div 
                      key={pay.id} 
                      onClick={async () => {
                        setPaymentMethod(pay.id);
                        try {
                          // In a real scenario, this would call api.post('/payment/init', { method: pay.id, amount: getTotal() })
                          // and redirect to the returned gatewayUrl.
                        } catch (err) {
                          console.error("Payment init failed");
                        }
                      }}
                      className={cn("p-6 rounded-3xl border-2 cursor-pointer transition-all group", paymentMethod === pay.id ? "border-canina-blue bg-canina-blue/5" : "border-medical-gray-100 hover:border-canina-blue")}
                    >
                       <div className="w-12 h-12 bg-medical-gray-50 rounded-2xl flex items-center justify-center text-medical-gray-400 group-hover:text-canina-blue group-hover:bg-canina-blue/10 mb-4 transition-all">
                          {pay.icon}
                       </div>
                       <h4 className="font-black text-sm text-medical-gray-900 mb-1">{pay.label}</h4>
                       <p className="text-[10px] text-medical-gray-400 font-bold">{pay.desc}</p>
                    </div>
                  ))}
               </div>
            </section>

            {/* Step 3: Charity Section */}
            <section className="bg-white rounded-[3rem] border border-medical-gray-200 p-10 overflow-hidden relative">
               <div className="absolute top-0 right-0 w-3 h-full bg-pink-500 opacity-20" />
               <div className="flex items-center justify-between mb-8">
                 <div className="flex items-center gap-4">
                   <div className="w-12 h-12 bg-pink-500 text-white rounded-2xl flex items-center justify-center">
                     <Heart className="w-6 h-6 fill-white" />
                   </div>
                   <div>
                     <h2 className="text-2xl font-black text-medical-gray-900 italic">ردپای مهربانی</h2>
                     <p className="text-xs font-bold text-pink-500 mt-1">سهم شما در حمایت از حیوانات بی‌پناه</p>
                   </div>
                 </div>
               </div>

               <div className="bg-pink-50 rounded-[2.5rem] p-8 border border-pink-100">
                  <div className="flex flex-wrap items-center justify-between gap-6">
                    <div className="flex-1 min-w-[280px]">
                      <h4 className="text-lg font-black text-medical-gray-900 italic mb-2">رند کردن مبلغ و کمک به پناهگاه</h4>
                      <p className="text-sm text-medical-gray-600 leading-relaxed font-medium"> با انتخاب این گزینه، مابقی مبلغ تا ده هزار تومان بعدی یا ۱٪ از خرید شما (هر کدام بیشتر باشد) صرف تامین غذا و دارو برای حیوانات بی-سرپرست تحت حمایت کانینا می‌شود.</p>
                      <div className="mt-4 flex items-center gap-3 text-pink-600">
                        <ShieldCheck className="w-4 h-4" />
                        <span className="text-[10px] font-black uppercase tracking-widest">گزارش شفاف هزینه‌کرد در داشبورد شما</span>
                      </div>
                    </div>
                    
                    <button 
                      onClick={handleCharityToggle}
                      className={cn(
                        "w-20 h-20 rounded-full flex items-center justify-center transition-all shadow-xl hover:scale-110 active:scale-95",
                        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-10 h-10", useRoundUp ? "rotate-45" : "rotate-0")} />
                    </button>
                  </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>
                  )}
               </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/10 pb-4">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/90 leading-tight">{item.product.name}</p>
                        <p className="text-[10px] text-white/40 font-bold mt-1">تعداد: {toPersian(item.quantity)} بسته</p>
                      </div>
                      <span className="text-xs font-mono font-bold font-vazir">{toPersian((item.product.priceValue * item.quantity).toLocaleString())}</span>
                   </div>
                 ))}
               </div>

               <div className="space-y-4 pt-8 border-t border-white/10">
                  <div className="flex justify-between text-sm font-bold text-white/60">
                    <span>مجموع اقلام</span>
                    <span className="font-vazir">{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">{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">{toPersian(charityDonation.toLocaleString())} تومان+</span>
                    </div>
                  )}
                  <div className="flex justify-between text-sm font-bold text-white/60">
                    <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">مبلغ نهایی</span>
                    <div className="text-left">
                       <p className="text-3xl font-black text-canina-blue leading-none font-vazir">{toPersian(getTotal().toLocaleString())}</p>
                       <p className="text-[10px] text-white/30 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 
                      name="coupon"
                      type="text" 
                      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
                      const fullProduct = dbProducts.find(p => p.id === item.product.id) || item.product;
                      const dose = activePet ? fullProduct.calculateDosage(activePet.weight, activePet.age <= 1) : { quantity: 1 };
                      const days = Math.floor(fullProduct.packageSize / (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>
  );
}