"use client"

import { useState, useMemo } from 'react'
import Link from './LocalizedLink'
import { getCategoryImage, formatPrice, type Product } from '@homaroma/types'
import { useCartStore } from '../store/cartStore'
import { resolveCategoryName, resolveLocalized } from '../lib/localization'
import { useLang } from '../hooks/useLang'

interface Props {
  product: Product
}

export default function AddToCartSection({ product }: Props) {
  const [selectedOptions, setSelectedOptions] = useState<string[]>(() => {
    if (product.variants && product.variants.length > 0) {
      const first = product.variants[0];
      return [first.option1 || '', first.option2 || '', first.option3 || ''];
    }
    return ['', '', ''];
  });

  const { addToCart, toggleCart } = useCartStore()
  const lang = useLang()

  const currentVariant = useMemo(() => {
    if (!product.variants) return undefined;
    return product.variants.find(v => {
      const v1 = v.option1 || '';
      const v2 = v.option2 || '';
      const v3 = v.option3 || '';
      const s1 = selectedOptions[0] || '';
      const s2 = selectedOptions[1] || '';
      const s3 = selectedOptions[2] || '';
      return v1 === s1 && v2 === s2 && v3 === s3;
    });
  }, [product.variants, selectedOptions]);

  const categoryName = resolveCategoryName(product.category, lang)
  const productName = resolveLocalized(product.name, lang) || product.brand.name
  const description = resolveLocalized(product.description, lang)

  const isOptionAvailable = (optionIndex: number, value: string) => {
    if (!product.variants) return false;
    return product.variants.some(v => {
      const vOpts = [v.option1 || '', v.option2 || '', v.option3 || ''];
      if (vOpts[optionIndex] !== value) return false;

      // Check if it matches currently selected options for OTHER indices
      for (let i = 0; i < (product.options?.length || 0); i++) {
        if (i === optionIndex) continue;
        if (vOpts[i] !== (selectedOptions[i] || '')) return false;
      }
      return true;
    });
  };

  const handleOptionChange = (optIndex: number, val: string) => {
    setSelectedOptions(prev => {
      const next = [...prev];
      next[optIndex] = val;
      return next;
    });
  };

  const handleAddToCart = () => {
    if (!currentVariant) return

    const variantName = [currentVariant.option1, currentVariant.option2, currentVariant.option3].filter(Boolean).join(' / ');

    addToCart({
      productId: product.id,
      variantId: currentVariant.id,
      quantity: 1,
      price: currentVariant.price || product.price || 0,
      productName,
      variantSize: variantName || undefined,
      productImage: product.images?.[0]?.url || product.category.imageUrl || getCategoryImage(categoryName),
    })
    toggleCart(true)
  }

  const currentVariantName = currentVariant ? [currentVariant.option1, currentVariant.option2, currentVariant.option3].filter(Boolean).join(' / ') : null;

  return (
    <>
      <div className="space-y-8">
        <div className="space-y-2">
          {categoryName && (
            <p className="ui-eyebrow">{categoryName}</p>
          )}
          <h1 className="text-4xl font-semibold leading-tight text-text-main md:text-6xl">
            {productName}
          </h1>
          <p className="text-sm font-semibold uppercase tracking-widest text-muted-text">
            Premium Collection
          </p>
        </div>

        {description && <p className="leading-relaxed text-muted-text">{description}</p>}

        <div className="flex items-baseline gap-3">
          <span className="text-4xl font-bold text-brand-primary">
            {formatPrice(currentVariant?.price ?? product.price)}
          </span>
          {currentVariantName && <span className="text-sm text-muted-text">/ {currentVariantName}</span>}
        </div>

        {product.options && product.options.length > 0 && (
          <div className="space-y-6">
            {product.options.map((option, optIndex) => (
              <div key={option.name} className="space-y-3">
                <p className="text-xs font-bold uppercase tracking-widest text-muted-text">Select {option.name}</p>
                <div className="flex flex-wrap gap-3">
                  {option.values.map(val => {
                    const isSelected = selectedOptions[optIndex] === val;
                    const isAvailable = isOptionAvailable(optIndex, val);
                    
                    return (
                      <button
                        key={val}
                        disabled={!isAvailable}
                        onClick={() => handleOptionChange(optIndex, val)}
                        className={`rounded-xl border px-5 py-3 text-sm font-bold uppercase tracking-widest transition ${
                          isSelected
                            ? 'border-brand-primary bg-brand-primary text-surface-card shadow-card'
                            : isAvailable
                            ? 'border-line-primary/20 bg-surface-card text-muted-text hover:border-brand-primary hover:text-brand-primary'
                            : 'border-line-primary/10 bg-surface-card/50 text-muted-text/30 cursor-not-allowed'
                        }`}
                      >
                        {val}
                      </button>
                    );
                  })}
                </div>
              </div>
            ))}
          </div>
        )}

        <div className="hidden gap-4 md:flex">
          <button
            onClick={handleAddToCart}
            disabled={!currentVariant}
            className={`ui-form-inline-button flex-1 ${!currentVariant ? 'opacity-50 cursor-not-allowed' : ''}`}
          >
            {currentVariant ? 'Add to Cart' : 'Unavailable'}
          </button>
          {categoryName && (
            <Link
              href={`/category/${product.category.id}`}
              className="rounded-full border border-line-primary/20 bg-surface-card px-8 py-4 font-bold uppercase tracking-widest text-muted-text transition hover:border-brand-primary hover:text-brand-primary"
            >
              {categoryName}
            </Link>
          )}
        </div>

        <div className="grid grid-cols-2 gap-4 border-t border-line-primary/20 pt-6 text-sm text-muted-text">
          <div>
            <span className="mb-1 block text-xs font-bold uppercase tracking-widest text-muted-text/70">Brand</span>
            <span className="font-semibold text-text-main">{product.brand.name}</span>
          </div>
          <div>
            <span className="mb-1 block text-xs font-bold uppercase tracking-widest text-muted-text/70">Category</span>
            <Link href={`/category/${product.category.id}`} className="font-semibold text-text-main transition hover:text-brand-primary">
              {categoryName}
            </Link>
          </div>
        </div>
      </div>

      <div className="fixed bottom-0 left-0 right-0 z-40 border-t border-line-primary/20 bg-surface-card/95 p-4 shadow-[0_-10px_30px_rgba(0,0,0,0.08)] backdrop-blur md:hidden">
        <div className="flex items-center justify-between gap-4">
          <div className="flex flex-col">
            <span className="text-[10px] font-bold uppercase tracking-widest text-muted-text/70">
              {currentVariantName || 'Total Price'}
            </span>
            <span className="text-xl font-bold text-brand-primary">{formatPrice(currentVariant?.price ?? product.price)}</span>
          </div>
          <button
            onClick={handleAddToCart}
            disabled={!currentVariant}
            className={`ui-form-inline-button flex-1 px-5 py-3.5 ${!currentVariant ? 'opacity-50 cursor-not-allowed' : ''}`}
          >
            {currentVariant ? 'Add to Cart' : 'Unavailable'}
          </button>
        </div>
      </div>
    </>
  )
}