'use client'

import { useState, useRef, useEffect } from 'react'
import { getImageProps } from 'next/image'
import type { ProductImage } from '@homaroma/types'

interface Props {
  productName: string
  categoryName?: string
  images: ProductImage[]
  stretchDesktop?: boolean
}

interface ResponsiveProductImageProps {
  image: ProductImage
  alt: string
  className: string
  fetchPriority?: 'high' | 'low' | 'auto'
  sizes: string
}

function ResponsiveProductImage({ image, alt, className, fetchPriority, sizes }: ResponsiveProductImageProps) {
  const desktop = getImageProps({
    src: image.url,
    alt,
    width: 1200,
    height: 1600,
    sizes,
    fetchPriority,
  }).props
  const mobile = image.mobileUrl
    ? getImageProps({
        src: image.mobileUrl,
        alt,
        width: 1200,
        height: 1200,
        sizes,
        fetchPriority,
      }).props
    : null

  return (
    <picture className="block h-full w-full">
      {mobile && (
        <source media="(max-width: 767px)" srcSet={mobile.srcSet ?? mobile.src} sizes={mobile.sizes} />
      )}
      <img {...desktop} alt={alt} className={className} />
    </picture>
  )
}

export default function ProductGallery({ productName, categoryName, images, stretchDesktop = false }: Props) {
  const [activeIndex, setActiveIndex] = useState(0)
  const scrollRef = useRef<HTMLDivElement>(null)
  const sortedImages = [...images].sort((a, b) => (a.order ?? 0) - (b.order ?? 0))
  const imageCount = sortedImages.length
  const visibleIndex = Math.min(activeIndex, Math.max(imageCount - 1, 0))

  useEffect(() => {
    const el = scrollRef.current
    if (!el) return
    const onScrollEnd = () => {
      const width = el.clientWidth
      if (width > 0) {
        const newIndex = Math.round(el.scrollLeft / width)
        if (newIndex >= 0 && newIndex < imageCount) setActiveIndex(newIndex)
      }
    }
    el.addEventListener('scrollend', onScrollEnd)
    return () => el.removeEventListener('scrollend', onScrollEnd)
  }, [imageCount])

  const handleThumbnailClick = (idx: number) => {
    setActiveIndex(idx)
    const scroller = scrollRef.current
    const child = scroller?.children[idx] as HTMLElement | undefined
    if (scroller && child) scroller.scrollTo({ left: child.offsetLeft, behavior: 'smooth' })
  }

  if (imageCount === 0) return null

  const frameClass = stretchDesktop
    ? 'relative aspect-square w-full overflow-hidden rounded-3xl bg-surface-card shadow-card md:aspect-auto md:h-full md:min-h-0'
    : 'relative aspect-square w-full overflow-hidden rounded-3xl bg-surface-card shadow-card'
  const mainImageClass = stretchDesktop
    ? 'h-full w-full object-cover md:object-contain'
    : 'h-full w-full object-cover'

  if (imageCount === 1) {
    return (
      <div className={frameClass}>
        <ResponsiveProductImage image={sortedImages[0]} alt={productName} fetchPriority="high" sizes="(min-width: 768px) 50vw, 100vw" className={mainImageClass} />
        {categoryName && (
          <div className="pointer-events-none absolute left-5 top-5 rounded-full bg-surface-card/90 px-4 py-2 text-xs font-bold uppercase tracking-widest text-text-main shadow-sm">
            {categoryName}
          </div>
        )}
      </div>
    )
  }

  return (
    <div className={`flex w-full flex-col-reverse gap-4 md:flex-row ${stretchDesktop ? 'md:h-full md:min-h-0 md:items-stretch' : 'items-start'}`}>
      <div className={`hide-scrollbar flex w-full flex-none snap-x snap-mandatory flex-row gap-2 overflow-x-auto pb-2 md:w-20 md:snap-y md:flex-col md:gap-3 md:overflow-y-auto md:pb-0 md:pr-2 lg:w-24 ${stretchDesktop ? 'md:h-full md:min-h-0' : ''}`}>
        {sortedImages.map((image, idx) => (
          <button
            key={image.id || `${image.url}-${idx}`}
            type="button"
            onClick={() => handleThumbnailClick(idx)}
            aria-label={`View ${productName} image ${idx + 1}`}
            aria-current={visibleIndex === idx ? 'true' : undefined}
            className={`relative aspect-square w-14 flex-none snap-center overflow-hidden rounded-xl border-2 transition-all md:w-full md:rounded-2xl ${visibleIndex === idx ? 'border-brand-primary opacity-100' : 'border-transparent opacity-60 hover:opacity-100'}`}
          >
            <ResponsiveProductImage image={image} alt={`${productName} thumbnail ${idx + 1}`} sizes="96px" className="h-full w-full object-cover" />
          </button>
        ))}
      </div>

      <div className={`${frameClass} flex-1`}>
        <div ref={scrollRef} className="hide-scrollbar flex h-full w-full snap-x snap-mandatory overflow-x-auto">
          {sortedImages.map((image, idx) => (
            <div key={image.id || `${image.url}-${idx}`} className="relative block h-full w-full flex-none snap-center snap-always">
              <ResponsiveProductImage image={image} alt={`${productName} ${idx + 1}`} fetchPriority={idx === 0 ? 'high' : 'auto'} sizes="(min-width: 768px) 46vw, 100vw" className={mainImageClass} />
            </div>
          ))}
        </div>

        {categoryName && (
          <div className="pointer-events-none absolute left-5 top-5 z-10 rounded-full bg-surface-card/90 px-4 py-2 text-xs font-bold uppercase tracking-widest text-text-main shadow-sm">
            {categoryName}
          </div>
        )}

        <div className="pointer-events-none absolute bottom-4 left-0 right-0 z-10 flex justify-center gap-2 md:hidden">
          {sortedImages.map((image, idx) => (
            <div key={image.id || `${image.url}-${idx}`} className={`h-1.5 w-1.5 rounded-full shadow-[0_1px_2px_rgba(0,0,0,0.3)] transition-all ${visibleIndex === idx ? 'scale-125 bg-white' : 'bg-white/50'}`} />
          ))}
        </div>
      </div>
    </div>
  )
}