import type { Quote } from "../../types/financials";
import { canonicalExchange } from "../../utils/exchanges";
import { quoteFutureToleranceMs } from "./clock";
import {
  activeUsExtendedHoursSession,
  isTimestampStaleForExchangeSession,
  isUsPriorSessionPremarketQuote,
} from "../market/freshness";

const EXTENDED_HOURS_EXCHANGES = new Set(["NASDAQ", "NYSE", "AMEX", "ARCA", "BATS"]);

/**
 * Receipt time cannot establish when the source observed a quoted price. A
 * stamp slightly ahead of local time is clock skew, not a bad observation.
 */
export function hasValidQuoteObservationTime(quote: Pick<Quote, "lastUpdated">, now = Date.now()): boolean {
  const timestamp = quote.lastUpdated;
  return typeof timestamp === "number" && Number.isFinite(timestamp) && timestamp > 0
    && Number.isFinite(now) && timestamp <= now + quoteFutureToleranceMs()
    && Number.isFinite(new Date(timestamp).getTime()) && Number.isFinite(new Date(now).getTime());
}

export function isExtendedHoursExchange(quote: Quote): boolean {
  return EXTENDED_HOURS_EXCHANGES.has(canonicalExchange(quote.listingExchangeName || quote.exchangeName));
}

function isQuoteMissingActiveSessionPrice(quote: Quote, now: number): boolean {
  if (!isExtendedHoursExchange(quote)) return false;
  const activeSession = activeUsExtendedHoursSession(now);
  if (!activeSession) return false;
  if (quote.marketState !== activeSession) return true;
  if (activeSession === "POST") return quote.postMarketPrice == null;
  // No pre-market trade yet: the previous session's close is the current price.
  return quote.preMarketPrice == null && !isUsPriorSessionPremarketQuote(
    quote.lastUpdated, quote.listingExchangeName || quote.exchangeName, quote.marketState, now,
  );
}

export function isQuoteStaleForCurrentSession(quote: Quote | null | undefined, now = Date.now()): boolean {
  if (!quote) return false;
  if (quote.stale === true) return true;
  if (!hasValidQuoteObservationTime(quote, now)) return true;
  if (isQuoteMissingActiveSessionPrice(quote, now)) return true;

  // A tolerated future stamp belongs to the session in progress, not the next one.
  return isTimestampStaleForExchangeSession(
    Math.min(quote.lastUpdated, now),
    quote.listingExchangeName || quote.exchangeName,
    now,
    quote.marketState,
  );
}

export function hasFreshQuoteForCurrentSession(
  quotes: Iterable<Quote | null | undefined>,
  now = Date.now(),
): boolean {
  for (const quote of quotes) {
    if (quote && !isQuoteStaleForCurrentSession(quote, now)) {
      return true;
    }
  }
  return false;
}