src/lib/prices.ts

// src/lib/prices.ts
type PriceMap = Record<string, number>

// Map your asset code -> provider + symbol
const MAP: Record<string, { p: 'binance'|'stooq'; s: string }> = {
  // crypto (USDT pairs)
  BTC: { p: 'binance', s: 'BTCUSDT' },
  ETH: { p: 'binance', s: 'ETHUSDT' },
  SOL: { p: 'binance', s: 'SOLUSDT' },
  BNB: { p: 'binance', s: 'BNBUSDT' },
  DOGE:{ p: 'binance', s: 'DOGEUSDT' },
  XRP: { p: 'binance', s: 'XRPUSDT' },

  // equities (stooq wants .us)
  AAPL:{ p: 'stooq',   s: 'aapl.us' },
  MSFT:{ p: 'stooq',   s: 'msft.us' },
  BMRN:{ p: 'stooq',   s: 'bmrn.us' },
  MRNA:{ p: 'stooq',   s: 'mrna.us' },
  TSLA:{ p: 'stooq',   s: 'tsla.us' },
};

// --- simple cache + pub/sub
let latest: PriceMap = {};
const subs = new Set<(m: PriceMap)=>void>();
const push = () => subs.forEach(fn => fn({ ...latest }));

export function subscribePrices(fn: (m: PriceMap)=>void) {
  subs.add(fn); fn({ ...latest });
  return () => subs.delete(fn);
}

async function fetchBinance(symbol: string) {
  const r = await fetch(`https://api.binance.com/api/v3/ticker/price?symbol=${encodeURIComponent(symbol)}`);
  const j = await r.json(); const n = Number(j?.price);
  return Number.isFinite(n) ? n : undefined;
}

async function fetchStooq(symbol: string) {
  const url = `https://stooq.com/q/l/?s=${encodeURIComponent(symbol)}&f=sd2t2ohlcv&h&e=csv`;
  const r = await fetch(url);
  const txt = await r.text(); // first line is header; second line has data, column 'Close'
  const line = txt.split('\n')[1] || '';
  const cols = line.split(','); // Symbol,Date,Time,Open,High,Low,Close,Volume
  const n = Number(cols[6]);
  return Number.isFinite(n) ? n : undefined;
}

export async function pollPrices(codes: string[], intervalMs = 30000) {
  const uniq = [...new Set(codes)].filter(c => MAP[c]);
  async function tick() {
    await Promise.all(uniq.map(async code => {
      const { p, s } = MAP[code];
      const px = p === 'binance' ? await fetchBinance(s) : await fetchStooq(s);
      if (px !== undefined) latest[code] = px;
    }));
    push();
  }
  await tick();
  setInterval(tick, intervalMs);
}

export const fmtUSD = (n?: number) =>
  typeof n === 'number'
    ? n.toLocaleString(undefined, { style: 'currency', currency: 'USD', maximumFractionDigits: 2 })
    : '—';