import { useEffect, useMemo, useRef, useState } from "react";
import type { KisRuntimeCredentials } from "@/features/settings/store/use-kis-runtime-store";
import type { DashboardStockOrderBookResponse } from "@/features/trade/types/trade.types";
import { fetchStockOrderBook } from "@/features/trade/apis/kis-stock.api";
import { toast } from "sonner";

/**
 * @description 초기 REST 호가를 한 번 조회하고, 이후에는 웹소켓 호가를 우선 사용합니다.
 * 웹소켓 호가 데이터는 TradeContainer에서 useKisTradeWebSocket을 통해
 * 단일 WebSocket으로 수신되어 externalRealtimeOrderBook으로 주입됩니다.
 * @see features/trade/components/TradeContainer.tsx 호가 데이터 흐름
 * @see features/trade/components/orderbook/OrderBook.tsx 호가창 렌더링 데이터 공급
 */
export function useOrderBook(
  symbol: string | undefined,
  market: "KOSPI" | "KOSDAQ" | undefined,
  credentials: KisRuntimeCredentials | null,
  isVerified: boolean,
  options: {
    enabled?: boolean;
    /** 체결 WS에서 받은 실시간 호가 데이터 (단일 WS 통합) */
    externalRealtimeOrderBook?: DashboardStockOrderBookResponse | null;
  } = {},
) {
  const { enabled = true, externalRealtimeOrderBook = null } = options;
  const isRequestEnabled = enabled && !!symbol && !!credentials;
  const requestSeqRef = useRef(0);
  const lastErrorToastRef = useRef<string>("");

  const [initialData, setInitialData] =
    useState<DashboardStockOrderBookResponse | null>(null);
  const [lastRealtimeWithLevels, setLastRealtimeWithLevels] =
    useState<DashboardStockOrderBookResponse | null>(null);
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!isRequestEnabled) {
      setLastRealtimeWithLevels(null);
      return;
    }

    if (externalRealtimeOrderBook && hasOrderBookLevelData(externalRealtimeOrderBook)) {
      setLastRealtimeWithLevels(externalRealtimeOrderBook);
    }
  }, [externalRealtimeOrderBook, isRequestEnabled]);

  useEffect(() => {
    if (!isRequestEnabled || !symbol || !credentials) {
      return;
    }

    const requestSeq = ++requestSeqRef.current;
    let isDisposed = false;

    const loadInitialOrderBook = async () => {
      setInitialData(null);
      setIsLoading(true);
      setError(null);

      try {
        const data = await fetchStockOrderBook(symbol, credentials);
        if (isDisposed || requestSeq !== requestSeqRef.current) return;
        setInitialData(data);
      } catch (err) {
        if (isDisposed || requestSeq !== requestSeqRef.current) return;
        console.error("Failed to fetch initial orderbook:", err);
        const message =
          err instanceof Error
            ? err.message
            : "호가 정보를 불러오지 못했습니다. 잠시 후 다시 시도해주세요.";
        setError(message);

        if (lastErrorToastRef.current !== message) {
          lastErrorToastRef.current = message;
          toast.error(message);
        }
      } finally {
        if (isDisposed || requestSeq !== requestSeqRef.current) return;
        setIsLoading(false);
      }
    };

    void loadInitialOrderBook();

    return () => {
      isDisposed = true;
    };
  }, [isRequestEnabled, symbol, credentials]);

  // 외부 실시간 호가가 비어 있으면(가격/잔량 레벨 0) 마지막 정상 실시간 또는 REST 초기값을 유지합니다.
  const orderBook = useMemo(() => {
    if (!isRequestEnabled) return null;

    if (externalRealtimeOrderBook) {
      if (hasOrderBookLevelData(externalRealtimeOrderBook)) {
        return externalRealtimeOrderBook;
      }

      if (lastRealtimeWithLevels) {
        return {
          ...lastRealtimeWithLevels,
          totalAskSize: externalRealtimeOrderBook.totalAskSize,
          totalBidSize: externalRealtimeOrderBook.totalBidSize,
          anticipatedPrice: externalRealtimeOrderBook.anticipatedPrice,
          anticipatedVolume: externalRealtimeOrderBook.anticipatedVolume,
          anticipatedTotalVolume: externalRealtimeOrderBook.anticipatedTotalVolume,
          anticipatedChange: externalRealtimeOrderBook.anticipatedChange,
          anticipatedChangeSign: externalRealtimeOrderBook.anticipatedChangeSign,
          anticipatedChangeRate: externalRealtimeOrderBook.anticipatedChangeRate,
          accumulatedVolume: externalRealtimeOrderBook.accumulatedVolume,
          totalAskSizeDelta: externalRealtimeOrderBook.totalAskSizeDelta,
          totalBidSizeDelta: externalRealtimeOrderBook.totalBidSizeDelta,
          businessHour:
            externalRealtimeOrderBook.businessHour ?? lastRealtimeWithLevels.businessHour,
          hourClassCode:
            externalRealtimeOrderBook.hourClassCode ?? lastRealtimeWithLevels.hourClassCode,
          fetchedAt: externalRealtimeOrderBook.fetchedAt,
          tradingEnv: externalRealtimeOrderBook.tradingEnv,
          source: externalRealtimeOrderBook.source,
        };
      }

      if (initialData && hasOrderBookLevelData(initialData)) {
        return {
          ...initialData,
          totalAskSize: externalRealtimeOrderBook.totalAskSize,
          totalBidSize: externalRealtimeOrderBook.totalBidSize,
          anticipatedPrice: externalRealtimeOrderBook.anticipatedPrice,
          anticipatedVolume: externalRealtimeOrderBook.anticipatedVolume,
          anticipatedTotalVolume: externalRealtimeOrderBook.anticipatedTotalVolume,
          anticipatedChange: externalRealtimeOrderBook.anticipatedChange,
          anticipatedChangeSign: externalRealtimeOrderBook.anticipatedChangeSign,
          anticipatedChangeRate: externalRealtimeOrderBook.anticipatedChangeRate,
          accumulatedVolume: externalRealtimeOrderBook.accumulatedVolume,
          totalAskSizeDelta: externalRealtimeOrderBook.totalAskSizeDelta,
          totalBidSizeDelta: externalRealtimeOrderBook.totalBidSizeDelta,
          businessHour: externalRealtimeOrderBook.businessHour ?? initialData.businessHour,
          hourClassCode: externalRealtimeOrderBook.hourClassCode ?? initialData.hourClassCode,
          fetchedAt: externalRealtimeOrderBook.fetchedAt,
          tradingEnv: externalRealtimeOrderBook.tradingEnv,
          source: externalRealtimeOrderBook.source,
        };
      }

      return externalRealtimeOrderBook;
    }

    return initialData;
  }, [externalRealtimeOrderBook, initialData, isRequestEnabled, lastRealtimeWithLevels]);

  const mergedError = isRequestEnabled ? error : null;
  const mergedLoading = isRequestEnabled ? isLoading && !orderBook : false;

  return {
    orderBook,
    isLoading: mergedLoading,
    error: mergedError,
    isWsConnected: !!externalRealtimeOrderBook,
  };
}

function hasOrderBookLevelData(orderBook: DashboardStockOrderBookResponse) {
  return orderBook.levels.some(
    (level) =>
      level.askPrice > 0 ||
      level.bidPrice > 0 ||
      level.askSize > 0 ||
      level.bidSize > 0,
  );
}