// Fiat prices for every Aegis-supported coin — CoinGecko's free /simple/price
// endpoint, one request covers the lot. Opt-in via Settings so a
// privacy-conscious user isn't quietly telling CoinGecko when Aegis is open.
//
// Cache is in-memory (returned by fullState() → panel). The addon polls
// every 5 min while enabled; each fetch is cheap (~200 B response) and
// the free tier tolerates one call/5 min per client easily.
//
// Trade-off named in the settings copy: CoinGecko sees the browser's IP
// + a User-Agent every poll. Not seed-linked, not address-linked, but a
// data point. Off by default.

const COIN_GECKO_IDS = {
  bch: "bitcoin-cash",
  btc: "bitcoin",
  trx: "tron",
  eth: "ethereum",
  sol: "solana",
  sc:  "siacoin",
  dgb: "digibyte",
};

const ENDPOINT = "https://api.coingecko.com/api/v3/simple/price";
const POLL_MS = 5 * 60 * 1000;

module.exports = function makePriceFeed({ log = () => {}, onChange = () => {} } = {}) {
  const state = {
    enabled: false,
    prices: {},           // { <chain>: usd (number) }
    fetchedAt: null,
    error: null,
    loading: false,
  };
  let timer = null;

  async function fetchOnce() {
    if (!state.enabled) return;
    state.loading = true; state.error = null; onChange();
    try {
      const ids = Object.values(COIN_GECKO_IDS).join(",");
      const url = `${ENDPOINT}?ids=${encodeURIComponent(ids)}&vs_currencies=usd`;
      const r = await fetch(url);
      if (!r.ok) throw new Error(`CoinGecko HTTP ${r.status}`);
      const body = await r.json();
      const next = {};
      for (const [chain, cgId] of Object.entries(COIN_GECKO_IDS)) {
        const usd = body?.[cgId]?.usd;
        if (typeof usd === "number") next[chain] = usd;
      }
      state.prices = next;
      state.fetchedAt = Date.now();
      state.error = null;
    } catch (e) {
      state.error = e?.message || String(e);
      log("price fetch failed:", state.error);
    } finally {
      state.loading = false;
      onChange();
    }
  }

  function schedule() {
    clearTimeout(timer);
    if (!state.enabled) return;
    timer = setTimeout(async () => { await fetchOnce(); schedule(); }, POLL_MS);
  }

  return {
    // Snapshot for the panel: only what the UI needs.
    snapshot() {
      return {
        enabled: state.enabled,
        prices: state.prices,
        fetchedAt: state.fetchedAt,
        error: state.error,
        loading: state.loading,
      };
    },
    // Turn the feed on/off. Enabling triggers an immediate fetch so the
    // panel doesn't wait 5 minutes for the first price.
    async setEnabled(on) {
      const changed = !!on !== state.enabled;
      state.enabled = !!on;
      if (!state.enabled) {
        state.prices = {}; state.fetchedAt = null; state.error = null;
        clearTimeout(timer);
        if (changed) onChange();
        return;
      }
      onChange();
      await fetchOnce();
      schedule();
    },
    // Force-refresh — bound to a manual "refresh" button in the panel.
    refresh() { return fetchOnce(); },
    dispose() { clearTimeout(timer); state.enabled = false; },
  };
};