/**
 * 백테스팅 워밍업 — 차트(표시 200 + 워밍업)와 동일하게 지표 수렴 후 평가 구간만 시그널 생성
 */
import type { OHLCVBar, Timeframe } from '../types';
import { API_BASE } from './backendApi';
import { timeframeToCandleType } from './chartCandleType';
import { toHistoryApiIso } from './analysisChartData';
import { INDICATOR_WARMUP } from './upbitApi';

/** 차트 초기 표시·백테스트 평가 구간 기본 봉 수 (워밍업 제외) */
export const BACKTEST_DISPLAY_BAR_COUNT = 200;

const HISTORY_PAGE_SIZE = 200;
const MAX_BACKTEST_FETCH = 800;

const MA_FIELD_RE = /^MA(\d+)$/;
const EMA_FIELD_RE = /^EMA(\d+)$/;

function collectPeriodFromField(field: unknown, out: Set<number>): void {
  if (typeof field !== 'string') return;
  const ma = MA_FIELD_RE.exec(field);
  if (ma) {
    out.add(parseInt(ma[1], 10));
    return;
  }
  const ema = EMA_FIELD_RE.exec(field);
  if (ema) out.add(parseInt(ema[1], 10));
}

/** 전략 DSL 트리에서 MA/EMA 기간 추출 */
function walkStrategyDsl(node: unknown, out: Set<number>): void {
  if (!node || typeof node !== 'object') return;
  const n = node as Record<string, unknown>;

  const cond = n.condition;
  if (cond && typeof cond === 'object') {
    const c = cond as Record<string, unknown>;
    collectPeriodFromField(c.leftField, out);
    collectPeriodFromField(c.rightField, out);
    const p = Number(c.period ?? c.leftPeriod ?? c.rightPeriod);
    if (Number.isFinite(p) && p > 0) out.add(Math.floor(p));
  }

  for (const ch of (n.children as unknown[]) ?? []) walkStrategyDsl(ch, out);
}

function maxFromIndicatorParams(
  params: Record<string, Record<string, unknown>> | undefined,
): number {
  if (!params) return 0;
  let max = 0;

  const sma = params.SMA ?? params.sma;
  if (sma) {
    for (let i = 1; i <= 11; i++) {
      const v = Number(sma[`period${i}`]);
      if (Number.isFinite(v) && v > 0) max = Math.max(max, Math.floor(v));
    }
  }

  const ichimoku = params.IchimokuCloud ?? params.ICHIMOKU;
  if (ichimoku) {
    for (const key of ['basePeriods', 'laggingSpan2Periods', 'conversionPeriods', 'displacement']) {
      const v = Number(ichimoku[key]);
      if (Number.isFinite(v) && v > 0) max = Math.max(max, Math.floor(v));
    }
  }

  const macd = params.MACD ?? params.macd;
  if (macd) {
    for (const key of ['fastLength', 'slowLength', 'signalLength']) {
      const v = Number(macd[key]);
      if (Number.isFinite(v) && v > 0) max = Math.max(max, Math.floor(v));
    }
    const slow = Number(macd.slowLength ?? 26);
    const sig = Number(macd.signalLength ?? 9);
    if (Number.isFinite(slow) && Number.isFinite(sig)) {
      max = Math.max(max, Math.floor(slow + sig));
    }
  }

  for (const key of ['RSI', 'CCI', 'ADX', 'Stochastic']) {
    const block = params[key];
    if (!block) continue;
    const len = Number(block.length ?? block.period);
    if (Number.isFinite(len) && len > 0) max = Math.max(max, Math.floor(len));
  }

  return max;
}

/**
 * 전략·지표 설정 기준 워밍업 봉 수.
 * 차트 INDICATOR_WARMUP(100)과 동일한 안전 마진을 포함한다.
 */
export function computeBacktestWarmupBars(
  buyDsl?: unknown,
  sellDsl?: unknown,
  indicatorParams?: Record<string, Record<string, unknown>>,
): number {
  const periods = new Set<number>();
  walkStrategyDsl(buyDsl, periods);
  walkStrategyDsl(sellDsl, periods);
  let maxPeriod = periods.size > 0 ? Math.max(...periods) : 0;
  maxPeriod = Math.max(maxPeriod, maxFromIndicatorParams(indicatorParams));
  // Ta4j SMA unstable + cross 1봉 여유
  const strategyNeed = maxPeriod > 0 ? maxPeriod + 5 : 0;
  return Math.max(INDICATOR_WARMUP, strategyNeed);
}

/** 백엔드 history API — count>200 페이지네이션 */
export async function fetchBacktestHistoryCandles(
  market: string,
  timeframe: Timeframe,
  totalCount: number,
  toTimeSec?: number,
): Promise<OHLCVBar[]> {
  const type = timeframeToCandleType(timeframe);
  const want = Math.min(Math.max(totalCount, 1), MAX_BACKTEST_FETCH);
  let remaining = want;
  let toIso: string | undefined = toTimeSec && toTimeSec > 0
    ? toHistoryApiIso(toTimeSec)
    : undefined;

  const byTime = new Map<number, OHLCVBar>();

  while (remaining > 0) {
    const batch = Math.min(remaining, HISTORY_PAGE_SIZE);
    const params = new URLSearchParams({
      market,
      type,
      count: String(batch),
    });
    if (toIso) params.set('to', toIso);

    const res = await fetch(`${API_BASE}/candles/history?${params.toString()}`);
    if (!res.ok) throw new Error(`캔들 로딩 실패 (${res.status})`);

    const raw = (await res.json()) as OHLCVBar[];
    if (raw.length === 0) break;

    const before = byTime.size;
    for (const b of raw) byTime.set(b.time, b);
    if (byTime.size === before) break;

    remaining -= raw.length;

    const oldest = raw[0]?.time;
    if (!oldest || oldest <= 0) break;
    toIso = toHistoryApiIso(oldest);

    if (remaining > 0) {
      await new Promise(r => setTimeout(r, 110));
    }
  }

  const sorted = [...byTime.values()].sort((a, b) => a.time - b.time);
  if (sorted.length <= want) return sorted;
  return sorted.slice(sorted.length - want);
}

export interface BacktestCandleBundle {
  bars: OHLCVBar[];
  evaluationBarCount: number;
  warmupBarCount: number;
}

/**
 * 표시 구간(displayCount) + 워밍업을 포함한 캔들 묶음.
 * 백엔드 evaluationBarCount 로 마지막 displayCount 봉만 시그널 평가.
 */
export async function fetchBacktestCandleBundle(opts: {
  market: string;
  timeframe: Timeframe;
  displayCount?: number;
  buyDsl?: unknown;
  sellDsl?: unknown;
  indicatorParams?: Record<string, Record<string, unknown>>;
  toTimeSec?: number;
}): Promise<BacktestCandleBundle> {
  const displayCount = opts.displayCount ?? BACKTEST_DISPLAY_BAR_COUNT;
  const warmupBarCount = computeBacktestWarmupBars(
    opts.buyDsl,
    opts.sellDsl,
    opts.indicatorParams,
  );
  const total = displayCount + warmupBarCount;
  const bars = await fetchBacktestHistoryCandles(
    opts.market,
    opts.timeframe,
    total,
    opts.toTimeSec,
  );
  const evaluationBarCount = Math.min(displayCount, bars.length);
  return { bars, evaluationBarCount, warmupBarCount };
}

/** 이미 로드된 캔들(차트 rawBars)에 대한 평가·워밍업 구간 계산 */
export function resolveEvaluationFromLoadedBars(
  barCount: number,
  buyDsl?: unknown,
  sellDsl?: unknown,
  indicatorParams?: Record<string, Record<string, unknown>>,
): { evaluationBarCount: number; warmupBarCount: number } {
  const warmupBarCount = computeBacktestWarmupBars(buyDsl, sellDsl, indicatorParams);
  if (barCount <= warmupBarCount) {
    return { evaluationBarCount: Math.max(1, barCount), warmupBarCount: 0 };
  }
  return {
    evaluationBarCount: barCount - warmupBarCount,
    warmupBarCount,
  };
}