'use client'

import Image from 'next/image'
import { useState, useEffect, useRef, useCallback, useMemo } from 'react'
import SuitableButton from './SuitableButton'
import SuitableNoData from './SuitableNoData'
import { useSuitable } from '@/hooks/useSuitable'
import { useSuitableStore } from '@/store/useSuitableStore'
import { SUITABLE_HEAD_CODE, type SuitableMain, type SuitableDetail } from '@/types/Suitable'

// 한 번에 로드할 아이템 수
const ITEMS_PER_PAGE = 100

export default function SuitableList() {
  const { toCodeName, suitableSearchResults, isSearchLoading, toSuitableDetail } = useSuitable()
  const { selectedItems, addSelectedItem, removeSelectedItem } = useSuitableStore()

  const [openItems, setOpenItems] = useState<Set<number>>(new Set())
  const [visibleItems, setVisibleItems] = useState<SuitableMain[]>([])
  const [page, setPage] = useState(1)
  const [isLoadingMore, setIsLoadingMore] = useState(false)
  const observerTarget = useRef<HTMLDivElement>(null)

  // 선택된 아이템 확인 함수 메모이제이션
  const isItemSelected = useCallback(
    (itemId: number) => {
      return selectedItems.some((selected) => selected === itemId)
    },
    [selectedItems],
  )

  // 초기 데이터 로드
  useEffect(() => {
    if (suitableSearchResults) {
      const initialItems = suitableSearchResults.suitable.slice(0, ITEMS_PER_PAGE)
      setVisibleItems(initialItems)
      setPage(1)
    }
  }, [suitableSearchResults])

  // Intersection Observer 설정
  useEffect(() => {
    const observer = new IntersectionObserver(
      (entries) => {
        if (entries[0].isIntersecting && suitableSearchResults && !isLoadingMore) {
          const nextPage = page + 1
          const startIndex = (nextPage - 1) * ITEMS_PER_PAGE
          const endIndex = startIndex + ITEMS_PER_PAGE
          const nextItems = suitableSearchResults.suitable.slice(startIndex, endIndex)

          if (nextItems.length > 0) {
            setIsLoadingMore(true)
            setVisibleItems((prev) => [...prev, ...nextItems])
            setPage(nextPage)
            setIsLoadingMore(false)
          }
        }
      },
      {
        threshold: 0.2,
      },
    )

    if (observerTarget.current) {
      observer.observe(observerTarget.current)
    }

    return () => observer.disconnect()
  }, [page, suitableSearchResults, isLoadingMore])

  const handleItemClick = useCallback(
    (itemId: number) => {
      isItemSelected(itemId) ? removeSelectedItem(itemId) : addSelectedItem(itemId)
    },
    [isItemSelected, addSelectedItem, removeSelectedItem],
  )

  const toggleItemOpen = useCallback((itemId: number) => {
    setOpenItems((prev) => {
      const newOpenItems = new Set(prev)
      newOpenItems.has(itemId) ? newOpenItems.delete(itemId) : newOpenItems.add(itemId)
      return newOpenItems
    })
  }, [])

  // TODO: 추후 지붕재 적합성 데이터 CUD 구현 시 ×, ー 데이터 관리 필요
  const suitableCheck = useCallback((value: string) => {
    if (value === '×') {
      return (
        <div className="compliance-icon">
          <Image src={'/assets/images/sub/compliance_x_icon.svg'} width={22} height={22} alt=""></Image>
        </div>
      )
    } else if (value === 'ー') {
      return (
        <div className="compliance-icon">
          <Image src={'/assets/images/sub/compliance_quest_icon.svg'} width={22} height={22} alt=""></Image>
        </div>
      )
    } else {
      return (
        <div className="compliance-icon">
          <Image src={'/assets/images/sub/compliance_check_icon.svg'} width={22} height={22} alt=""></Image>
        </div>
      )
    }
  }, [])

  // 메모이제이션된 아이템 렌더링
  const renderItem = useCallback(
    (item: SuitableMain) => {
      const isSelected = isItemSelected(item.id)
      const isOpen = openItems.has(item.id)

      return (
        <div className={`compliance-check-bx ${isOpen ? 'act' : ''}`} key={item.id}>
          <div className="check-name-wrap">
            <div className="check-form-box ">
              <input type="checkbox" id={`ch${item.id}`} checked={isSelected} onChange={() => handleItemClick(item.id)} />
              <label htmlFor={`ch${item.id}`}>{item.productName}</label>
            </div>
            <div className="check-name-btn">
              <button className="bx-btn" onClick={() => toggleItemOpen(item.id)}></button>
            </div>
          </div>
          <ul className="reference-list check">
            {toSuitableDetail(item.id).map((subItem: SuitableDetail) => (
              <li className="reference-item" key={subItem.id}>
                <div className="check-item-wrap">
                  <div className="check-form-box light">
                    <input type="checkbox" id={`ch${subItem.id}`} />
                    <label htmlFor={`ch${subItem.id}`}>{toCodeName(SUITABLE_HEAD_CODE.TRESTLE_MFPC_CD, subItem.trestleMfpcCd)}</label>
                  </div>
                  <div className="compliance-icon-wrap">
                    {suitableCheck(subItem.trestleManufacturerProductName)}
                    {subItem.memo && (
                      <div className="compliance-icon">
                        <Image src={'/assets/images/sub/compliance_tip_icon.svg'} width={22} height={22} alt=""></Image>
                      </div>
                    )}
                  </div>
                </div>
              </li>
            ))}
          </ul>
        </div>
      )
    },
    [isItemSelected, openItems, handleItemClick, toggleItemOpen, suitableCheck, toCodeName, toSuitableDetail],
  )

  // 메모이제이션된 아이템 리스트
  const renderedItems = useMemo(() => {
    return visibleItems.map(renderItem)
  }, [visibleItems, renderItem])

  if (isSearchLoading) {
    return <div>Loading...</div>
  }

  if (!suitableSearchResults?.suitable.length) {
    return <SuitableNoData />
  }

  return (
    <>
      {renderedItems}
      <div ref={observerTarget} className="loading-indicator">
        {isLoadingMore && <div className="loading-more">데이터를 불러오는 중...</div>}
      </div>
      <SuitableButton />
    </>
  )
}