/**
 * KRW ticker 조회 — 백엔드 /api/markets/tickers 우선 (1회·캐시), 실패 시 /upbit-api 폴백
 */
import { API_BASE } from './backendApi';
import { UPBIT_API } from './upbitApi';

export interface UpbitTickerRaw {
  market?: string;
  code?: string;
  trade_price: number;
  signed_change_rate: number;
  signed_change_price: number;
  acc_trade_price_24h: number;
  acc_trade_volume_24h?: number;
  opening_price: number;
  high_price: number;
  low_price: number;
  change?: 'RISE' | 'FALL' | 'EVEN';
}

const CHUNK_SIZE = 40;
const CHUNK_DELAY_MS = 200;
const MAX_CHUNK_ATTEMPTS = 4;

function sleep(ms: number): Promise<void> {
  return new Promise(r => setTimeout(r, ms));
}

/** 백엔드 일괄 ticker (권장) */
async function fetchTickersFromBackend(markets: string[]): Promise<UpbitTickerRaw[] | null> {
  try {
    const qs = markets.length > 0
      ? `?markets=${encodeURIComponent(markets.join(','))}`
      : '';
    const res = await fetch(`${API_BASE}/markets/tickers${qs}`);
    if (res.status === 429) {
      await sleep(1500);
      const retry = await fetch(`${API_BASE}/markets/tickers${qs}`);
      if (!retry.ok) return null;
      const data = (await retry.json()) as UpbitTickerRaw[];
      return Array.isArray(data) ? data : null;
    }
    if (!res.ok) return null;
    const data = (await res.json()) as UpbitTickerRaw[];
    return Array.isArray(data) ? data : null;
  } catch {
    return null;
  }
}

/** 레거시: nginx /upbit-api 직접 (청크·지연) */
async function fetchTickersFromUpbitDirect(markets: string[]): Promise<UpbitTickerRaw[]> {
  const unique = [...new Set(markets.filter(m => m?.startsWith('KRW-')))];
  if (unique.length === 0) return [];

  const results: UpbitTickerRaw[] = [];
  for (let i = 0; i < unique.length; i += CHUNK_SIZE) {
    const chunk = unique.slice(i, i + CHUNK_SIZE);
    let done = false;
    for (let attempt = 0; attempt < MAX_CHUNK_ATTEMPTS && !done; attempt++) {
      try {
        const res = await fetch(`${UPBIT_API}/ticker?markets=${chunk.join(',')}`);
        if (res.status === 429) {
          await sleep(800 * (attempt + 1));
          continue;
        }
        if (res.ok) {
          const data = (await res.json()) as UpbitTickerRaw[];
          if (Array.isArray(data)) results.push(...data);
        }
        done = true;
      } catch {
        await sleep(400 * (attempt + 1));
      }
    }
    if (i + CHUNK_SIZE < unique.length) await sleep(CHUNK_DELAY_MS);
  }
  return results;
}

/**
 * ticker 조회 — 전 종목은 백엔드 1회, 소량은 markets 쿼리
 */
export async function fetchTickersThrottled(markets: string[]): Promise<UpbitTickerRaw[]> {
  const unique = [...new Set(markets.filter(m => m?.startsWith('KRW-')))];

  const fromBackend = await fetchTickersFromBackend(unique);
  if (fromBackend != null && fromBackend.length > 0) return fromBackend;

  if (unique.length === 0) {
    const all = await fetchTickersFromBackend([]);
    if (all != null && all.length > 0) return all;
  }

  return fetchTickersFromUpbitDirect(unique);
}