Quote freshness

import { useEffect, useRef, useState } from "react";

interface QuoteState {
  quoteId: string;
  expectedOut: bigint;
  minOut: bigint;
  expiresAt: number;
}

function useLiveQuote(params: QuoteParams, isOpen: boolean) {
  const [quote, setQuote] = useState<QuoteState | null>(null);
  const isFreezingRef = useRef(false);

  useEffect(() => {
    if (!isOpen) return;

    let cancelled = false;
    const tick = async () => {
      if (cancelled || isFreezingRef.current) return;
      try {
        const q = await fetch(`${API_URL}/quote`, {
          method: "POST",
          headers: { "x-api-key": API_KEY, "content-type": "application/json" },
          body: JSON.stringify(params),
        }).then((r) => r.json());
        if (!cancelled && q.quoteId) {
          setQuote({
            quoteId: q.quoteId,
            expectedOut: BigInt(q.routePlan.expectedAmountOut),
            minOut: BigInt(q.routePlan.minAmountOut),
            expiresAt: q.expiresAt,
          });
        }
      } catch (e) {
        // ignore transient failures; next tick will retry
      }
    };

    tick();
    const id = setInterval(tick, 6000);
    return () => {
      cancelled = true;
      clearInterval(id);
    };
  }, [isOpen, JSON.stringify(params)]);

  const freeze = () => { isFreezingRef.current = true; };
  const unfreeze = () => { isFreezingRef.current = false; };

  return { quote, freeze, unfreeze };
}

async function onSwap() {
  if (!quote) return;
  freeze(); // stop background re-quoting

  try {
    const submit = await fetch(`${API_URL}/submit`, {
      method: "POST",
      headers: { "x-api-key": API_KEY, "content-type": "application/json" },
      body: JSON.stringify({ quoteId: quote.quoteId, user: walletAddress }),
    }).then(async (r) => {
      if (r.status === 404) {
        // Quote expired between the freeze and the submit. Re-quote and retry.
        const fresh = await refreshQuote(params);
        return fetch(`${API_URL}/submit`, {
          method: "POST",
          headers: { "x-api-key": API_KEY, "content-type": "application/json" },
          body: JSON.stringify({ quoteId: fresh.quoteId, user: walletAddress }),
        }).then((r2) => r2.json());
      }
      return r.json();
    });

    const txHash = await walletClient.sendTransaction({
      to: submit.to,
      data: submit.data,
      value: BigInt(submit.value),
    });
    onSuccess(txHash);
  } finally {
    unfreeze();
  }
}