import { useEffect, useRef, memo, type RefObject } from 'react'
import { useMeQuery } from '@/apis'
import { useChatStore } from '@/features/chat/stores/useChatStore'
import { useChatInitStore } from '@/features/chat/stores/useChatInitStore'
import type { ChatMessage as ChatMessageType } from '@/features/chat/types'
import { renderEmphasis } from '@/features/chat/lib/emphasis'
import { Indicator } from '@/features/chat/components/templates/Indicator'
import { Summary } from '@/features/chat/components/templates/Summary'
import { ExtraInfoForm } from '@/features/chat/components/templates/ExtraInfoForm'
import { BidSummary } from '@/features/chat/components/templates/BidSummary'
import { RejectRSP } from '@/features/chat/components/templates/RejectRSP'
import { RejectCM } from '@/features/chat/components/templates/RejectCM'

const AI_LABEL = '아이마켓코리아 (구매 MD)'

export function ChatMessage() {
  const scrollRef = useRef<HTMLDivElement | null>(null)
  return (
    <div className="flex-1 w-full min-h-0">
      {/* lg:pt-[64px]: 첫 메시지를 우측 협상절차 카드 상단과 맞추는 값 — 그 카드가 없는 lg 미만에선
          스텝바 바로 아래 여백으로만 남아 첫 메시지가 위로 안 붙으므로 뺀다.
          스크롤 시 여백도 함께 밀려 올라가도록 스크롤 컨테이너 안쪽에 둔다 */}
      <div
        ref={scrollRef}
        className="chat-scroll h-full overflow-y-auto flex flex-col pt-4 lg:pt-[64px] pb-6 px-4 sm:px-6 min-[1180px]:pl-[80px] min-[1180px]:pr-[72px] min-[1350px]:pl-[140px] min-[1350px]:pr-[126px]"
      >
        <ChatList scrollRef={scrollRef} />
      </div>
    </div>
  )
}

function ChatList({ scrollRef }: { scrollRef: RefObject<HTMLDivElement | null> }) {
  const isFirstRef = useRef(true)
  const chats = useChatStore((s) => s.messages)
  const isLoading = useChatStore((s) => s.isLoading)

  // 메시지 추가/타이핑 표시 시 항상 맨 아래로 스크롤.
  // 스크롤 컨테이너를 직접 내린다 — scrollIntoView 는 요약/부가정보 폼처럼 큰 블록이 뒤늦게
  // 레이아웃되면 애니메이션 도중 목표 위치가 밀려 중간에 멈춘다.
  // 진입 첫 렌더는 즉시(auto) — 히스토리를 복원하며 위에서부터 훑어 내려가는 연출을 막는다.
  useEffect(() => {
    const scroller = scrollRef.current
    if (!scroller) return
    const behavior: ScrollBehavior = isFirstRef.current ? 'auto' : 'smooth'
    isFirstRef.current = false
    const id = requestAnimationFrame(() => {
      scroller.scrollTo({ top: scroller.scrollHeight, behavior })
    })
    return () => cancelAnimationFrame(id)
  }, [chats, isLoading])

  if (!chats || chats.length === 0) {
    return (
      <div className="flex items-center justify-center h-full">
        <p className="text-sm text-neutral-60">채팅 내역이 없습니다.</p>
      </div>
    )
  }

  return (
    <div className="flex flex-col w-full">
      {chats.map((message, index) => (
        <MessageItem key={message.chat_id || index} message={message} messages={chats} currentIndex={index} />
      ))}
      {isLoading && <TypingBubble />}
    </div>
  )
}

// agent 응답을 기다리는 동안(협상 중) 대화 흐름에 표시하는 타이핑 인디케이터(AI 말풍선 톤).
function TypingBubble() {
  return (
    <div className="mb-6 flex flex-col items-start gap-1.5" aria-label="협상 중" role="status">
      <span className="text-xs font-bold text-neutral-80">{AI_LABEL}</span>
      <div className="inline-flex items-center gap-1.5 rounded-2xl rounded-tl-none border border-[#D2E6FF] bg-brand-light/70 px-4 py-3.5 shadow-sm">
        <span className="size-2 rounded-full bg-brand-500 animate-bounce [animation-delay:-0.3s]" />
        <span className="size-2 rounded-full bg-brand-500 animate-bounce [animation-delay:-0.15s]" />
        <span className="size-2 rounded-full bg-brand-500 animate-bounce" />
      </div>
    </div>
  )
}

const MessageItem = memo(function MessageItem({
  message,
  messages,
  currentIndex,
}: {
  message: ChatMessageType
  messages: ChatMessageType[]
  currentIndex: number
}) {
  const isBot = message.sender === 'bot'

  // 직전이 reject 폼이면 사용자 답변 말풍선은 숨긴다(폼 자체가 답변을 담고 있음)
  if (!isBot && currentIndex > 0) {
    const prev = messages[currentIndex - 1]
    if (prev?.bot_chat_type === 'rejectRSP' || prev?.bot_chat_type === 'rejectCM') {
      return null
    }
  }

  return isBot ? <BotMessage message={message} /> : <UserMessage text={message.script || ''} />
})

const BotMessage = memo(function BotMessage({ message }: { message: ChatMessageType }) {
  // 인디케이터는 이번 방문에서 '협상중'이었던 세션에서만 표시.
  const showIndicator = useChatInitStore((s) => s.wasInProgress)
  const hasScript = Boolean(message.script && message.script.trim())

  return (
    <div className="mb-5 animate-fade-in">
      <div className="flex flex-col items-start gap-1.5">
        <span className="text-xs font-bold text-neutral-80">{AI_LABEL}</span>
        {hasScript && (
          <div className="max-w-[80%] rounded-2xl rounded-tl-none border border-[#D2E6FF] bg-brand-light/70 p-4 text-sm leading-relaxed text-neutral-90 shadow-sm break-keep">
            {renderEmphasis(message.script || '')}
          </div>
        )}
      </div>

      <div className="flex flex-col gap-4 w-full mt-4">
        {showIndicator && message.bot_chat_type === 'indicator' && message.indicator_value != null && (
          <Indicator number={message.indicator_value} />
        )}
        {message.bot_chat_type === 'summaryRSP' && message.summary && (
          <>
            <Summary data={message.summary} />
            <ExtraInfoForm />
          </>
        )}
        {message.bot_chat_type === 'summaryCM' && message.summary && (
          <BidSummary
            itemName={message.summary.item_name}
            itemCode={message.summary.item_code}
            bidPrice={message.summary.final_price}
            deliveryType={message.summary.delivery_type || ''}
            isVAT={message.summary.item_isVAT}
          />
        )}
        {message.bot_chat_type === 'rejectRSP' && <RejectRSP />}
        {message.bot_chat_type === 'rejectCM' && <RejectCM />}
      </div>
    </div>
  )
})

const UserMessage = memo(function UserMessage({ text }: { text: string }) {
  const { data: user } = useMeQuery()
  const label = `${user?.supplierName ?? '공급사'} (나)`
  return (
    <div className="mb-5 flex flex-col items-end gap-1.5 animate-fade-in">
      <span className="text-xs font-bold text-neutral-80">{label}</span>
      <div className="max-w-[80%] rounded-2xl rounded-tr-none border border-border bg-white p-4 text-sm leading-relaxed text-neutral-90 shadow-sm break-keep">
        {text}
      </div>
    </div>
  )
})