/**
 * useAppSettings
 *
 * 앱 전역 차트 기본 설정을 DB 와 동기화하는 훅.
 *
 * 관리 항목 (하드코딩 대체):
 *  - defaultSymbol    : 기본 종목 (DEFAULT_STATE.symbol)
 *  - defaultTimeframe : 기본 타임프레임 (DEFAULT_STATE.timeframe)
 *  - defaultChartType : 기본 차트 타입
 *  - (테마는 DB 미사용 — localStorage, see localThemeStorage)
 *  - defaultLogScale  : 기본 로그 스케일
 *  - defaultLayoutId  : 기본 레이아웃 ID
 *  - mainChartStyle   : 캔들 색상 (DEFAULT_MAIN_CHART_STYLE)
 *  - syncOptions      : 멀티차트 동기화 옵션 (DEFAULT_SYNC)
 *
 * 사용 예:
 * ```tsx
 * const { settings, isLoaded, save } = useAppSettings();
 *
 * // 기본 심볼 사용
 * const symbol = settings.defaultSymbol ?? 'KRW-BTC';
 *
 * // 테마 변경 시 saveLocalTheme() (App.tsx)
 * ```
 */

import { useCallback, useEffect, useRef, useState } from 'react';
import {
  hasRegisteredUser,
  loadAppSettings,
  loadStrategies,
  saveAppSettings,
  type AppSettingsDto,
} from '../utils/backendApi';
import type { Theme, ChartType, Timeframe, MainChartStyle } from '../types';
import { resolveChartLegendOptions } from '../types/chartLegend';
import type { ChartLegendVisibility } from '../types/chartLegend';
import { DEFAULT_MAIN_CHART_STYLE } from '../utils/storage';
import { DEFAULT_SYNC, type SyncOptions } from '../utils/layoutTypes';
import {
  DEFAULT_CHART_TIME_FORMAT,
  normalizeChartTimeFormat,
  setChartTimeFormat,
} from '../utils/chartTimeFormat';
import {
  DEFAULT_TRADE_ALERT_TIME_FORMAT,
  setTradeAlertTimeFormat,
} from '../utils/tradeAlertTimeFormat';
import { DEFAULT_DISPLAY_TIMEZONE, normalizeTimezone, setDisplayTimezone } from '../utils/timezone';
import {
  clampVirtualTargetMax,
  DEFAULT_VIRTUAL_TARGET_MAX,
} from '../utils/virtualTargetLimits';
import {
  resolveTrendSearchAppSettings,
  type TrendSearchAppSettings,
} from '../utils/trendSearchAppSettings';
import {
  resolveChartPaneSeparatorOptions,
  type ChartPaneSeparatorOptions,
} from '../types/chartPaneSeparator';
import { migrateLocalStorageToUiPreferences } from '../utils/uiPreferencesMigrate';
import { loadLocalTheme } from '../utils/localThemeStorage';

// 전역 캐시 — 여러 컴포넌트에서 공유하여 중복 요청 방지
let _cache: AppSettingsDto | null = null;
let _loadPromise: Promise<AppSettingsDto> | null = null;
/** invalidate 이후 완료된 로드만 캐시에 반영 */
let _loadGeneration = 0;
type AppSettingsListener = () => void;
const _listeners = new Set<AppSettingsListener>();

function notifyAppSettingsListeners() {
  _listeners.forEach(fn => fn());
}

/** 훅 외부에서 최신 캐시 읽기 (추세검색 설정 병합 등) */
export function getAppSettingsCache(): AppSettingsDto {
  return _cache ?? {};
}

/** 낙관적 캐시 패치 — _cache 가 null 일 때도 다음 로드 전까지 임시 보관 */
export function patchAppSettingsCache(patch: Partial<AppSettingsDto>): void {
  if (_cache !== null) {
    Object.assign(_cache, patch);
  }
  // _cache 가 null 이면 현재 로드 중이므로 건너뜀 (로드 완료 후 DB 저장값으로 덮어씌워짐)
}

export function subscribeAppSettings(listener: AppSettingsListener): () => void {
  _listeners.add(listener);
  return () => _listeners.delete(listener);
}

function ensureLoaded(): Promise<AppSettingsDto> {
  if (_cache !== null) return Promise.resolve(_cache);
  if (_loadPromise) return _loadPromise;
  const generation = _loadGeneration;
  _loadPromise = loadAppSettings().then(async data => {
    if (generation !== _loadGeneration) {
      _loadPromise = null;
      return _cache ?? {};
    }
    _cache = data ?? {};
    const migrated = migrateLocalStorageToUiPreferences(_cache);
    if (migrated?.changed) {
      try {
        const saved = await saveAppSettings({ uiPreferences: migrated.uiPreferences });
        if (generation === _loadGeneration) {
          _cache = { ..._cache, ...saved, uiPreferences: migrated.uiPreferences };
        }
      } catch (e) {
        console.warn('[useAppSettings] uiPreferences 마이그레이션 저장 실패:', e);
        if (generation === _loadGeneration) {
          _cache = { ..._cache, uiPreferences: migrated.uiPreferences };
        }
      }
    }
    if (hasRegisteredUser()) {
      try {
        await loadStrategies();
      } catch (e) {
        console.warn('[useAppSettings] strategies preload failed', e);
      }
    }
    _loadPromise = null;
    if (generation === _loadGeneration) {
      notifyAppSettingsListeners();
    }
    // loadStrategies() 등 await 중 invalidateAppSettingsCache()가 호출되면
    // _cache 가 null 로 초기화될 수 있으므로 ?? {} 로 null 반환 방지
    return _cache ?? {};
  });
  return _loadPromise;
}

export function invalidateAppSettingsCache() {
  _cache = null;
  _loadPromise = null;
  _loadGeneration += 1;
}

/** 서버에서 app-settings 재로드 후 캐시 갱신 (모바일 ↻ 동기화 등) */
export function reloadAppSettingsCache(): Promise<AppSettingsDto> {
  invalidateAppSettingsCache();
  return ensureLoaded();
}

// ─────────────────────────────────────────────────────────────────────────────

/** DB 또는 fallback 기본값 접근 헬퍼 */
export function resolveAppDefaults(s: AppSettingsDto) {
  return {
    symbol:        (s.defaultSymbol    ?? 'KRW-BTC')    as string,
    timeframe:     (s.defaultTimeframe ?? '1D')          as Timeframe,
    chartType:     (s.defaultChartType ?? 'candlestick') as ChartType,
    theme:         loadLocalTheme(),
    logScale:      s.defaultLogScale   ?? false,
    layoutId:      s.defaultLayoutId   ?? '1',
    mainChartStyle:(s.mainChartStyle as unknown as MainChartStyle | null) ?? DEFAULT_MAIN_CHART_STYLE,
    syncOptions:   (s.syncOptions as unknown as SyncOptions | null) ?? DEFAULT_SYNC,
    btAutoPopup:      s.btAutoPopup      ?? true,
    btShowPrice:      s.btShowPrice      ?? true,
    chartCandleAreaPriceLabels: s.chartCandleAreaPriceLabels ?? s.chartSeriesPriceLabels ?? true,
    chartSeriesPriceLabels: s.chartSeriesPriceLabels ?? true,
    chartVolumeVisible:     s.chartVolumeVisible ?? true,
    chartLiveReceiveHighlight: s.chartLiveReceiveHighlight ?? true,
    chartCrosshairInfoVisible: s.chartCrosshairInfoVisible ?? true,
    chartHoverToolbarVisible:  s.chartHoverToolbarVisible ?? true,
    chartLegendOptions:     resolveChartLegendOptions(
      s.chartLegendOptions as Partial<ChartLegendVisibility> | null | undefined,
    ),
    chartPaneSeparator:     resolveChartPaneSeparatorOptions(
      s.chartPaneSeparator as Partial<ChartPaneSeparatorOptions> | null | undefined,
      loadLocalTheme(),
    ),
    tradeAlertPopup:  s.tradeAlertPopup  ?? true,
    tradeAlertSoundEnabled: s.tradeAlertSoundEnabled ?? true,
    tradeAlertSound:  s.tradeAlertSound  ?? 'bell',
    tradeAlertPopupPosition: s.tradeAlertPopupPosition ?? 'right',
    tradeAlertPopupLayout:   s.tradeAlertPopupLayout   ?? 'stack',
    tradeAlertPopupGridCols: s.tradeAlertPopupGridCols ?? 2,
    verificationIssueNotify: s.verificationIssueNotify ?? true,
    liveStrategyCheck:  s.liveStrategyCheck  ?? false,
    liveStrategyId:     s.liveStrategyId     ?? null,
    liveExecutionType:  s.liveExecutionType  ?? 'CANDLE_CLOSE',
    livePositionMode:   s.livePositionMode   ?? 'LONG_ONLY',
    paperTradingEnabled:     s.paperTradingEnabled     ?? true,
    paperInitialCapital:     s.paperInitialCapital     ?? 10_000_000,
    paperFeeRatePct:         s.paperFeeRatePct         ?? 0.05,
    paperSlippagePct:        s.paperSlippagePct        ?? 0,
    paperMinOrderKrw:        s.paperMinOrderKrw        ?? 5000,
    paperAutoTradeEnabled:   s.paperAutoTradeEnabled   ?? false,
    paperAutoTradeBudgetPct: s.paperAutoTradeBudgetPct ?? 95,
    paperOrderFillMode:      (s.paperOrderFillMode ?? 'LIMIT_ONLY') as 'LIMIT_ONLY' | 'NEXT_TICK' | 'AUTO_CANCEL',
    paperOrderAutoCancelPct: s.paperOrderAutoCancelPct ?? 1.0,
    virtualTargetMaxCount:   clampVirtualTargetMax(s.virtualTargetMaxCount ?? DEFAULT_VIRTUAL_TARGET_MAX),
    tradingMode:            s.tradingMode            ?? 'PAPER',
    liveAutoTradeEnabled:   s.liveAutoTradeEnabled   ?? false,
    hasUpbitKeys:           s.hasUpbitKeys           ?? false,
    upbitAccessKeyMasked:   s.upbitAccessKeyMasked   ?? null,
    chartRealtimeSource:    s.chartRealtimeSource    ?? 'BACKEND_STOMP',
    liveAutoTradeBudgetPct: s.liveAutoTradeBudgetPct ?? 95,
    fcmPushEnabled:         s.fcmPushEnabled         ?? false,
    displayTimezone:        normalizeTimezone(s.displayTimezone ?? DEFAULT_DISPLAY_TIMEZONE),
    chartTimeFormat:        normalizeChartTimeFormat(s.chartTimeFormat ?? DEFAULT_CHART_TIME_FORMAT),
    tradeAlertTimeFormat:   normalizeChartTimeFormat(s.tradeAlertTimeFormat ?? DEFAULT_TRADE_ALERT_TIME_FORMAT),
    trendSearchSettings:    resolveTrendSearchAppSettings(
      s.trendSearchSettings as Partial<TrendSearchAppSettings> | null | undefined,
    ),
  };
}

// ─────────────────────────────────────────────────────────────────────────────

/** sessionKey 변경 시(로그인/로그아웃) 설정을 DB에서 다시 로드 */
export function useAppSettings(sessionKey = 0) {
  const [settings, setSettings] = useState<AppSettingsDto>(_cache ?? {});
  const [isLoaded, setIsLoaded] = useState(_cache !== null);
  const mountedRef = useRef(true);
  const prevSessionKeyRef = useRef(sessionKey);

  useEffect(() => {
    mountedRef.current = true;
    const sessionChanged = prevSessionKeyRef.current !== sessionKey;
    prevSessionKeyRef.current = sessionKey;

    if (sessionChanged) {
      if (_cache !== null) {
        setSettings(_cache);
        setDisplayTimezone(normalizeTimezone(_cache.displayTimezone ?? DEFAULT_DISPLAY_TIMEZONE));
        setChartTimeFormat(normalizeChartTimeFormat(_cache.chartTimeFormat ?? DEFAULT_CHART_TIME_FORMAT));
        setTradeAlertTimeFormat(normalizeChartTimeFormat(_cache.tradeAlertTimeFormat ?? DEFAULT_TRADE_ALERT_TIME_FORMAT));
        setIsLoaded(true);
      } else {
        setIsLoaded(false);
        invalidateAppSettingsCache();
      }
    } else if (_cache !== null) {
      setSettings(_cache);
      setDisplayTimezone(normalizeTimezone(_cache.displayTimezone ?? DEFAULT_DISPLAY_TIMEZONE));
      setChartTimeFormat(normalizeChartTimeFormat(_cache.chartTimeFormat ?? DEFAULT_CHART_TIME_FORMAT));
      setTradeAlertTimeFormat(normalizeChartTimeFormat(_cache.tradeAlertTimeFormat ?? DEFAULT_TRADE_ALERT_TIME_FORMAT));
      setIsLoaded(true);
    } else {
      setIsLoaded(false);
    }

    ensureLoaded().then(data => {
      const safe = data ?? {};
      if (mountedRef.current) {
        setSettings(safe);
        setDisplayTimezone(normalizeTimezone(safe.displayTimezone ?? DEFAULT_DISPLAY_TIMEZONE));
        setChartTimeFormat(normalizeChartTimeFormat(safe.chartTimeFormat ?? DEFAULT_CHART_TIME_FORMAT));
        setTradeAlertTimeFormat(normalizeChartTimeFormat(safe.tradeAlertTimeFormat ?? DEFAULT_TRADE_ALERT_TIME_FORMAT));
        setIsLoaded(true);
      }
    }).catch(err => {
      console.error('[useAppSettings] load failed', err);
      if (mountedRef.current) setIsLoaded(true);
    });
    const unsub = subscribeAppSettings(() => {
      if (mountedRef.current) setSettings({ ...(getAppSettingsCache()) });
    });
    return () => {
      mountedRef.current = false;
      unsub();
    };
  }, [sessionKey]);

  /**
   * 특정 필드를 DB 에 저장하고 로컬 캐시를 업데이트.
   * 낙관적 업데이트 — DB 저장 실패해도 UI 는 즉시 반영.
   */
  const save = useCallback((patch: AppSettingsDto) => {
    const { defaultTheme: _omitTheme, ...patchWithoutTheme } = patch;
    const apiPatch = 'defaultTheme' in patch ? patchWithoutTheme : patch;
    const merged = { ...(_cache ?? {}), ...apiPatch };
    _cache = merged;
    notifyAppSettingsListeners();
    setSettings(merged);
    if (patch.displayTimezone != null) {
      setDisplayTimezone(normalizeTimezone(patch.displayTimezone));
    }
    if (patch.chartTimeFormat != null) {
      setChartTimeFormat(normalizeChartTimeFormat(patch.chartTimeFormat));
    }
    if (patch.tradeAlertTimeFormat != null) {
      setTradeAlertTimeFormat(normalizeChartTimeFormat(patch.tradeAlertTimeFormat));
    }
    saveAppSettings(apiPatch).then(updated => {
      if (updated) {
        _cache = { ...(_cache ?? {}), ...updated };
        notifyAppSettingsListeners();
        if (mountedRef.current) {
          setSettings(prev => ({ ...prev, ...updated }));
        }
      }
    }).catch(err =>
      console.error('[useAppSettings] save failed', err)
    );
  }, []);

  /** 로드된 설정의 해석된 기본값 */
  const defaults = resolveAppDefaults(settings);

  return { settings, defaults, isLoaded, save };
}

/** 앱 설정 캐시 기준 투자대상 최대 개수 (훅 외부·추가 API 등) */
export function getVirtualTargetMaxCount(): number {
  const n = _cache?.virtualTargetMaxCount;
  return clampVirtualTargetMax(n ?? DEFAULT_VIRTUAL_TARGET_MAX);
}