import { signRequest, KALSHI_API_BASE } from './auth.js';

const SERIES_TICKER = 'KXBTC15M';
const OPEN_EVENT_STATUSES = new Set(['open', 'active', 'initialized', 'trading']);
const TRADABLE_EVENT_STATUSES = new Set(['open', 'active', 'trading']);

async function kalshiFetch(method, path, body = null) {
  const headers = signRequest(method, path);
  const opts = { method, headers };
  if (body) opts.body = JSON.stringify(body);

  const res = await fetch(`${KALSHI_API_BASE}${path}`, opts);
  if (!res.ok) {
    const text = await res.text();
    throw new Error(`Kalshi API ${method} ${path} → ${res.status}: ${text}`);
  }
  return res.json();
}

function getTimeMs(value) {
  if (!value) return null;
  const ts = new Date(value).getTime();
  return Number.isFinite(ts) ? ts : null;
}

function getEventCloseTimeMs(event) {
  return (
    getTimeMs(event?.close_time) ||
    getTimeMs(event?.expiration_time) ||
    getTimeMs(event?.settlement_time) ||
    getTimeMs(event?.end_date) ||
    null
  );
}

function rankEvents(events = []) {
  const now = Date.now();

  return events
    .filter(Boolean)
    .map((event) => {
      const status = String(event.status || '').toLowerCase();
      const closeTs = getEventCloseTimeMs(event);

      const openLike = OPEN_EVENT_STATUSES.has(status);
      const tradableLike = TRADABLE_EVENT_STATUSES.has(status);
      const notClearlyExpired = closeTs == null || closeTs > now - 60_000;

      // Prefer near-future close times; heavily penalize stale/past
      const delta = closeTs == null ? Number.MAX_SAFE_INTEGER : closeTs - now;
      const closenessScore = delta < 0 ? Math.abs(delta) + 3_600_000 : delta;

      return { event, openLike, tradableLike, notClearlyExpired, closenessScore, closeTs };
    })
    .filter((x) => x.openLike || x.notClearlyExpired)
    .sort((a, b) => {
      if (a.tradableLike !== b.tradableLike) return a.tradableLike ? -1 : 1;
      if (a.openLike !== b.openLike) return a.openLike ? -1 : 1;
      if (a.notClearlyExpired !== b.notClearlyExpired) return a.notClearlyExpired ? -1 : 1;
      return a.closenessScore - b.closenessScore;
    })
    .map((x) => x.event);
}

async function fetchEvents(series, query) {
  const path = `/trade-api/v2/events?series_ticker=${encodeURIComponent(series)}&${query}`;
  const data = await kalshiFetch('GET', path);
  return Array.isArray(data.events) ? data.events : [];
}

/**
 * Return ranked candidate events for BTC 15m.
 */
export async function getActiveBTCEvents(limit = 12) {
  const seriesCandidates = [...new Set([SERIES_TICKER, SERIES_TICKER.toLowerCase()])];
  const eventMap = new Map();

  for (const series of seriesCandidates) {
    for (const query of [
      'status=open&limit=10',
      'status=active&limit=10',
      'status=initialized&limit=10',
      'limit=50'
    ]) {
      try {
        const events = await fetchEvents(series, query);
        for (const event of events) {
          if (event?.event_ticker) eventMap.set(event.event_ticker, event);
        }
      } catch (e) {
        console.error(`[Kalshi] Event fetch failed (${series}, ${query}):`, e.message);
      }
    }
  }

  return rankEvents([...eventMap.values()]).slice(0, limit);
}

/**
 * Backward-compatible: return single best candidate event.
 */
export async function getActiveBTCEvent() {
  const events = await getActiveBTCEvents(1);
  return events[0] || null;
}

/**
 * Get markets for a specific event ticker.
 */
export async function getEventMarkets(eventTicker) {
  const data = await kalshiFetch('GET', `/trade-api/v2/events/${eventTicker}`);
  const markets = data?.event?.markets ?? data?.markets ?? data?.event_markets ?? [];
  return Array.isArray(markets) ? markets : [];
}

/**
 * Get orderbook for a specific market ticker.
 */
export async function getOrderbook(ticker) {
  const data = await kalshiFetch('GET', `/trade-api/v2/markets/${ticker}/orderbook`);
  return data.orderbook || data;
}

/**
 * Get single market details.
 */
export async function getMarket(ticker) {
  const data = await kalshiFetch('GET', `/trade-api/v2/markets/${ticker}`);
  return data.market || data;
}

/**
 * Place a real order on Kalshi. NOT used in paper mode.
 */
export async function placeOrder(params) {
  return kalshiFetch('POST', '/trade-api/v2/portfolio/orders', params);
}

/**
 * Get wallet balance.
 */
export async function getBalance() {
  return kalshiFetch('GET', '/trade-api/v2/portfolio/balance');
}

export { kalshiFetch };