"use client";

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import {
  CandlestickSeries,
  ColorType,
  HistogramSeries,
  createChart,
  type IChartApi,
  type ISeriesApi,
  type Time,
} from "lightweight-charts";
import { ChevronDown } from "lucide-react";
import { toast } from "sonner";
import { fetchStockChart } from "@/features/dashboard/apis/kis-stock.api";
import type { KisRuntimeCredentials } from "@/features/dashboard/store/use-kis-runtime-store";
import type {
  DashboardChartTimeframe,
  DashboardRealtimeTradeTick,
  StockCandlePoint,
} from "@/features/dashboard/types/dashboard.types";
import { cn } from "@/lib/utils";
import {
  type ChartBar,
  formatKstCrosshairTime,
  formatKstTickMark,
  formatPrice,
  formatSignedPercent,
  isMinuteTimeframe,
  mergeBars,
  normalizeCandles,
  toRealtimeTickBar,
  upsertRealtimeBar,
} from "./chart-utils";

const UP_COLOR = "#ef4444";
const DOWN_COLOR = "#2563eb";
const MINUTE_SYNC_INTERVAL_MS = 5000;
const REALTIME_STALE_THRESHOLD_MS = 12000;

const MINUTE_TIMEFRAMES: Array<{
  value: DashboardChartTimeframe;
  label: string;
}> = [
  { value: "1m", label: "1분" },
  { value: "30m", label: "30분" },
  { value: "1h", label: "1시간" },
];

const PERIOD_TIMEFRAMES: Array<{
  value: DashboardChartTimeframe;
  label: string;
}> = [
  { value: "1d", label: "일" },
  { value: "1w", label: "주" },
];

interface StockLineChartProps {
  symbol?: string;
  candles: StockCandlePoint[];
  credentials?: KisRuntimeCredentials | null;
  latestTick?: DashboardRealtimeTradeTick | null;
}

/**
 * @description TradingView 스타일 캔들 차트를 렌더링하고, timeframe별 KIS 차트 API를 조회합니다.
 * @see features/dashboard/apis/kis-stock.api.ts fetchStockChart
 * @see lib/kis/domestic.ts getDomesticChart
 */
export function StockLineChart({
  symbol,
  candles,
  credentials,
  latestTick,
}: StockLineChartProps) {
  const containerRef = useRef<HTMLDivElement | null>(null);
  const chartRef = useRef<IChartApi | null>(null);
  const candleSeriesRef = useRef<ISeriesApi<"Candlestick", Time> | null>(null);
  const volumeSeriesRef = useRef<ISeriesApi<"Histogram", Time> | null>(null);

  const [timeframe, setTimeframe] = useState<DashboardChartTimeframe>("1d");
  const [isMinuteDropdownOpen, setIsMinuteDropdownOpen] = useState(false);
  const [bars, setBars] = useState<ChartBar[]>([]);
  const [nextCursor, setNextCursor] = useState<string | null>(null);
  const [isLoading, setIsLoading] = useState(false);
  const [isLoadingMore, setIsLoadingMore] = useState(false);
  const [isChartReady, setIsChartReady] = useState(false);
  const lastRealtimeKeyRef = useRef<string>("");
  const lastRealtimeAppliedAtRef = useRef(0);

  // 복수 이벤트에서 중복 로드를 막기 위한 ref 상태
  const loadingMoreRef = useRef(false);
  const loadMoreHandlerRef = useRef<() => Promise<void>>(async () => {});
  const initialLoadCompleteRef = useRef(false);

  // API 오류 시 fallback 용도로 유지
  const latestCandlesRef = useRef(candles);
  useEffect(() => {
    latestCandlesRef.current = candles;
  }, [candles]);

  const latest = bars.at(-1);
  const prevClose = bars.length > 1 ? (bars.at(-2)?.close ?? 0) : 0;
  const change = latest ? latest.close - prevClose : 0;
  const changeRate = prevClose > 0 ? (change / prevClose) * 100 : 0;

  const renderableBars = useMemo(() => {
    const dedup = new Map<number, ChartBar>();

    for (const bar of bars) {
      if (
        !Number.isFinite(bar.time) ||
        !Number.isFinite(bar.open) ||
        !Number.isFinite(bar.high) ||
        !Number.isFinite(bar.low) ||
        !Number.isFinite(bar.close) ||
        bar.close <= 0
      ) {
        continue;
      }

      dedup.set(bar.time, bar);
    }

    return [...dedup.values()].sort((a, b) => a.time - b.time);
  }, [bars]);

  /**
   * @description lightweight-charts 시리즈 데이터에 안전한 OHLCV 값을 주입합니다.
   * @see features/dashboard/components/chart/StockLineChart.tsx renderableBars useMemo
   */
  const setSeriesData = useCallback((nextBars: ChartBar[]) => {
    const candleSeries = candleSeriesRef.current;
    const volumeSeries = volumeSeriesRef.current;
    if (!candleSeries || !volumeSeries) return;

    try {
      candleSeries.setData(
        nextBars.map((bar) => ({
          time: bar.time,
          open: bar.open,
          high: bar.high,
          low: bar.low,
          close: bar.close,
        })),
      );

      volumeSeries.setData(
        nextBars.map((bar) => ({
          time: bar.time,
          value: Number.isFinite(bar.volume) ? bar.volume : 0,
          color:
            bar.close >= bar.open
              ? "rgba(239,68,68,0.45)"
              : "rgba(37,99,235,0.45)",
        })),
      );
    } catch (error) {
      console.error("Failed to render chart series data:", error);
    }
  }, []);

  /**
   * @description 좌측 스크롤 시 cursor 기반 과거 캔들을 추가 로드합니다.
   * @see lib/kis/domestic.ts getDomesticChart cursor
   */
  const handleLoadMore = useCallback(async () => {
    if (!symbol || !credentials || !nextCursor || loadingMoreRef.current) return;

    loadingMoreRef.current = true;
    setIsLoadingMore(true);

    try {
      const response = await fetchStockChart(
        symbol,
        timeframe,
        credentials,
        nextCursor,
      );

      const olderBars = normalizeCandles(response.candles, timeframe);
      setBars((prev) => mergeBars(olderBars, prev));
      setNextCursor(response.hasMore ? response.nextCursor : null);
    } catch (error) {
      const message =
        error instanceof Error
          ? error.message
          : "과거 차트 데이터를 불러오지 못했습니다.";
      toast.error(message);
    } finally {
      loadingMoreRef.current = false;
      setIsLoadingMore(false);
    }
  }, [credentials, nextCursor, symbol, timeframe]);

  useEffect(() => {
    loadMoreHandlerRef.current = handleLoadMore;
  }, [handleLoadMore]);

  useEffect(() => {
    lastRealtimeKeyRef.current = "";
    lastRealtimeAppliedAtRef.current = 0;
  }, [symbol, timeframe]);

  useEffect(() => {
    const container = containerRef.current;
    if (!container || chartRef.current) return;

    const chart = createChart(container, {
      width: Math.max(container.clientWidth, 320),
      height: Math.max(container.clientHeight, 340),
      layout: {
        background: { type: ColorType.Solid, color: "#ffffff" },
        textColor: "#475569",
        attributionLogo: true,
      },
      localization: {
        locale: "ko-KR",
        timeFormatter: formatKstCrosshairTime,
      },
      rightPriceScale: {
        borderColor: "#e2e8f0",
        scaleMargins: {
          top: 0.08,
          bottom: 0.24,
        },
      },
      grid: {
        vertLines: { color: "#edf1f5" },
        horzLines: { color: "#edf1f5" },
      },
      crosshair: {
        vertLine: { color: "#94a3b8", width: 1, style: 2 },
        horzLine: { color: "#94a3b8", width: 1, style: 2 },
      },
      timeScale: {
        borderColor: "#e2e8f0",
        timeVisible: true,
        secondsVisible: false,
        rightOffset: 2,
        tickMarkFormatter: formatKstTickMark,
      },
      handleScroll: {
        mouseWheel: true,
        pressedMouseMove: true,
      },
      handleScale: {
        mouseWheel: true,
        pinch: true,
        axisPressedMouseMove: true,
      },
    });

    const candleSeries = chart.addSeries(CandlestickSeries, {
      upColor: UP_COLOR,
      downColor: DOWN_COLOR,
      wickUpColor: UP_COLOR,
      wickDownColor: DOWN_COLOR,
      borderUpColor: UP_COLOR,
      borderDownColor: DOWN_COLOR,
      priceLineVisible: true,
      lastValueVisible: true,
    });

    const volumeSeries = chart.addSeries(HistogramSeries, {
      priceScaleId: "volume",
      priceLineVisible: false,
      lastValueVisible: false,
      base: 0,
    });

    chart.priceScale("volume").applyOptions({
      scaleMargins: {
        top: 0.78,
        bottom: 0,
      },
      borderVisible: false,
    });

    let scrollTimeout: number | undefined;
    chart.timeScale().subscribeVisibleLogicalRangeChange((range) => {
      if (!range || !initialLoadCompleteRef.current) return;
      if (range.from >= 10) return;

      if (scrollTimeout !== undefined) window.clearTimeout(scrollTimeout);
      scrollTimeout = window.setTimeout(() => {
        void loadMoreHandlerRef.current();
      }, 250);
    });

    chartRef.current = chart;
    candleSeriesRef.current = candleSeries;
    volumeSeriesRef.current = volumeSeries;
    setIsChartReady(true);

    const resizeObserver = new ResizeObserver(() => {
      chart.resize(
        Math.max(container.clientWidth, 320),
        Math.max(container.clientHeight, 340),
      );
    });
    resizeObserver.observe(container);

    const rafId = window.requestAnimationFrame(() => {
      chart.resize(
        Math.max(container.clientWidth, 320),
        Math.max(container.clientHeight, 340),
      );
    });

    return () => {
      if (scrollTimeout !== undefined) window.clearTimeout(scrollTimeout);
      window.cancelAnimationFrame(rafId);
      resizeObserver.disconnect();
      chart.remove();
      chartRef.current = null;
      candleSeriesRef.current = null;
      volumeSeriesRef.current = null;
      setIsChartReady(false);
    };
  }, []);

  useEffect(() => {
    if (symbol && credentials) return;

    // 인증 전/종목 미선택 상태는 overview 캔들로 fallback
    setBars(normalizeCandles(candles, "1d"));
    setNextCursor(null);
  }, [candles, credentials, symbol]);

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

    initialLoadCompleteRef.current = false;
    let disposed = false;

    const load = async () => {
      setIsLoading(true);

      try {
        const firstPage = await fetchStockChart(symbol, timeframe, credentials);
        if (disposed) return;

        let mergedBars = normalizeCandles(firstPage.candles, timeframe);
        let resolvedNextCursor = firstPage.hasMore ? firstPage.nextCursor : null;

        // 분봉은 기본 2페이지를 붙여서 "당일만 보이는" 느낌을 줄입니다.
        if (
          isMinuteTimeframe(timeframe) &&
          firstPage.hasMore &&
          firstPage.nextCursor
        ) {
          try {
            const secondPage = await fetchStockChart(
              symbol,
              timeframe,
              credentials,
              firstPage.nextCursor,
            );

            const olderBars = normalizeCandles(secondPage.candles, timeframe);
            mergedBars = mergeBars(olderBars, mergedBars);
            resolvedNextCursor = secondPage.hasMore ? secondPage.nextCursor : null;
          } catch {
            // 2페이지 실패는 치명적이지 않으므로 1페이지 데이터는 유지합니다.
          }
        }

        setBars(mergedBars);
        setNextCursor(resolvedNextCursor);

        window.setTimeout(() => {
          if (!disposed) initialLoadCompleteRef.current = true;
        }, 350);
      } catch (error) {
        if (disposed) return;

        const message =
          error instanceof Error
            ? error.message
            : "차트 조회 중 오류가 발생했습니다.";
        toast.error(message);

        setBars(normalizeCandles(latestCandlesRef.current, timeframe));
        setNextCursor(null);
      } finally {
        if (!disposed) setIsLoading(false);
      }
    };

    void load();

    return () => {
      disposed = true;
    };
  }, [credentials, symbol, timeframe]);

  useEffect(() => {
    if (!isChartReady) return;

    setSeriesData(renderableBars);
    if (!initialLoadCompleteRef.current && renderableBars.length > 0) {
      chartRef.current?.timeScale().fitContent();
    }
  }, [isChartReady, renderableBars, setSeriesData]);

  /**
   * @description WebSocket 체결 틱을 현재 timeframe 캔들에 반영합니다.
   * @see features/dashboard/hooks/useKisTradeWebSocket.ts latestTick
   * @see features/dashboard/components/chart/chart-utils.ts toRealtimeTickBar
   */
  useEffect(() => {
    if (!latestTick) return;
    if (bars.length === 0) return;

    const dedupeKey = `${timeframe}:${latestTick.tickTime}:${latestTick.price}:${latestTick.tradeVolume}`;
    if (lastRealtimeKeyRef.current === dedupeKey) return;

    const realtimeBar = toRealtimeTickBar(latestTick, timeframe);
    if (!realtimeBar) return;

    lastRealtimeKeyRef.current = dedupeKey;
    lastRealtimeAppliedAtRef.current = Date.now();
    setBars((prev) => upsertRealtimeBar(prev, realtimeBar));
  }, [bars.length, latestTick, timeframe]);

  /**
   * @description 분봉(1m/30m/1h)에서는 WS 공백 상황을 대비해 최신 페이지를 주기적으로 동기화합니다.
   * @see features/dashboard/apis/kis-stock.api.ts fetchStockChart
   * @see lib/kis/domestic.ts getDomesticChart
   */
  useEffect(() => {
    if (!symbol || !credentials) return;
    if (!isMinuteTimeframe(timeframe)) return;

    let disposed = false;

    const syncLatestMinuteBars = async () => {
      const now = Date.now();
      const isRealtimeFresh =
        now - lastRealtimeAppliedAtRef.current < REALTIME_STALE_THRESHOLD_MS;
      if (isRealtimeFresh) return;

      try {
        const response = await fetchStockChart(symbol, timeframe, credentials);
        if (disposed) return;

        const latestPageBars = normalizeCandles(response.candles, timeframe);
        const recentBars = latestPageBars.slice(-10);
        if (recentBars.length === 0) return;

        setBars((prev) => mergeBars(prev, recentBars));
      } catch {
        // 폴링 실패는 치명적이지 않으므로 조용히 다음 주기에서 재시도합니다.
      }
    };

    const intervalId = window.setInterval(() => {
      void syncLatestMinuteBars();
    }, MINUTE_SYNC_INTERVAL_MS);

    return () => {
      disposed = true;
      window.clearInterval(intervalId);
    };
  }, [credentials, symbol, timeframe]);

  const statusMessage = (() => {
    if (isLoading && bars.length === 0) {
      return "차트 데이터를 불러오는 중입니다.";
    }
    if (bars.length === 0) {
      return "차트 데이터가 없습니다.";
    }
    if (renderableBars.length === 0) {
      return "차트 데이터 형식이 올바르지 않습니다.";
    }
    return null;
  })();

  return (
    <div className="flex h-full min-h-[340px] flex-col bg-white">
      {/* ========== CHART TOOLBAR ========== */}
      <div className="flex flex-wrap items-center justify-between gap-2 border-b border-slate-200 px-2 py-2 sm:px-3">
        <div className="flex flex-wrap items-center gap-1 text-xs sm:text-sm">
          <div className="relative">
            <button
              type="button"
              onClick={() => setIsMinuteDropdownOpen((prev) => !prev)}
              onBlur={() =>
                window.setTimeout(() => setIsMinuteDropdownOpen(false), 200)
              }
              className={cn(
                "flex items-center gap-1 rounded px-2 py-1 text-slate-600 transition-colors hover:bg-slate-100",
                MINUTE_TIMEFRAMES.some((item) => item.value === timeframe) &&
                  "bg-brand-100 font-semibold text-brand-700",
              )}
            >
              {MINUTE_TIMEFRAMES.find((item) => item.value === timeframe)
                ?.label ?? "분봉"}
              <ChevronDown className="h-3 w-3" />
            </button>

            {isMinuteDropdownOpen && (
              <div className="absolute left-0 top-full z-10 mt-1 rounded border border-slate-200 bg-white shadow-lg">
                {MINUTE_TIMEFRAMES.map((item) => (
                  <button
                    key={item.value}
                    type="button"
                    onClick={() => {
                      setTimeframe(item.value);
                      setIsMinuteDropdownOpen(false);
                    }}
                    className={cn(
                      "block w-full whitespace-nowrap px-3 py-1.5 text-left hover:bg-slate-100",
                      timeframe === item.value &&
                        "bg-brand-50 font-semibold text-brand-700",
                    )}
                  >
                    {item.label}
                  </button>
                ))}
              </div>
            )}
          </div>

          {PERIOD_TIMEFRAMES.map((item) => (
            <button
              key={item.value}
              type="button"
              onClick={() => setTimeframe(item.value)}
              className={cn(
                "rounded px-2 py-1 text-slate-600 transition-colors hover:bg-slate-100",
                timeframe === item.value &&
                  "bg-brand-100 font-semibold text-brand-700",
              )}
            >
              {item.label}
            </button>
          ))}

          {isLoadingMore && (
            <span className="ml-2 text-[11px] text-muted-foreground">
              과거 데이터 로딩 중...
            </span>
          )}
        </div>

        <div className="text-[11px] text-slate-600 sm:text-xs">
          O {formatPrice(latest?.open ?? 0)} H {formatPrice(latest?.high ?? 0)} L{" "}
          {formatPrice(latest?.low ?? 0)} C{" "}
          <span className={cn(change >= 0 ? "text-red-600" : "text-blue-600")}>
            {formatPrice(latest?.close ?? 0)} ({formatSignedPercent(changeRate)})
          </span>
        </div>
      </div>

      {/* ========== CHART BODY ========== */}
      <div className="relative min-h-0 flex-1 overflow-hidden">
        <div ref={containerRef} className="h-full w-full" />

        {statusMessage && (
          <div className="absolute inset-0 flex items-center justify-center bg-white/80 text-sm text-muted-foreground">
            {statusMessage}
          </div>
        )}
      </div>
    </div>
  );
}