(function() {
  // Default: HKD → JPY
  document.getElementById('fx-from').value = 'HKD';
  document.getElementById('fx-to').value = 'JPY';
  setTimeout(fxInit, 50);
  ['fx-amount','fx-from','fx-to'].forEach(id => {
    document.getElementById(id).addEventListener('input', fxCalc);
    document.getElementById(id).addEventListener('change', fxCalc);
  });
})();

// Static fallback rates (vs HKD = 1) — updated 2026-Q1 estimates
const FX_FALLBACK = {
  HKD: 1.0, USD: 0.128, EUR: 0.117, JPY: 19.2, GBP: 0.099,
  KRW: 175, TWD: 4.12, THB: 4.31, SGD: 0.171, MYR: 0.567,
  CNY: 0.917, AUD: 0.196, NZD: 0.213, CAD: 0.176, CHF: 0.114,
  PHP: 7.32, IDR: 2030, VND: 3220, INR: 10.85, AED: 0.470
};
let fxRates = null;
let fxUpdated = null;

async function fxInit() {
  try {
    // Try Supabase live rates
    const supaUrl = 'https://itawskzbsbjodlljbuwt.supabase.co/functions/v1/fx-rates';
    const r = await fetch(supaUrl, { method: 'POST' });
    if (r.ok) {
      const j = await r.json();
      if (j && j.rates) { fxRates = j.rates; fxUpdated = j.updated; }
    }
  } catch(e) { /* fallback */ }
  if (!fxRates) { fxRates = FX_FALLBACK; fxUpdated = '2026-Q1 (fallback)'; }
  document.getElementById('fx-updated').textContent = '更新：' + fxUpdated;
  fxCalc();
  fxRenderTiles();
}

function fxCalc() {
  try {
    const amount = parseFloat(document.getElementById('fx-amount').value) || 0;
    const from = document.getElementById('fx-from').value;
    const to = document.getElementById('fx-to').value;
    if (!fxRates) return;
    // All rates vs HKD=1
    const hkd = amount / fxRates[from];
    const out = hkd * fxRates[to];
    document.getElementById('fx-out').value = out.toFixed(to === 'JPY' || to === 'KRW' || to === 'IDR' || to === 'VND' ? 0 : 2);
    // Show result
    const result = document.getElementById('fx-result');
    result.style.display = 'block';
    result.innerHTML = '<div class="fx-main">' + formatNumber(out) + ' ' + to + '<small>' + formatNumber(amount) + ' ' + from + ' = ' + formatNumber(out) + ' ' + to + '（1 ' + from + ' = ' + (fxRates[to] / fxRates[from]).toFixed(4) + ' ' + to + '）</small></div>';
  } catch(e) { /* silent */ }
}

function fxRenderTiles() {
  const html = Object.keys(fxRates).filter(k => k !== 'HKD').map(k => {
    const rate = fxRates.HKD / fxRates[k]; // 1 unit k = X HKD
    return '<div class="fx-tile" onclick="fxPick(\'' + k + '\')">' +
      '<div class="fx-tile-name">1 ' + k + ' =</div>' +
      '<div class="fx-tile-rate">HKD ' + rate.toFixed(rate > 10 ? 2 : 4) + '</div>' +
    '</div>';
  }).join('');
  document.getElementById('fx-grid').innerHTML = html;
}

function fxPick(c) {
  document.getElementById('fx-to').value = c;
  fxCalc();
}

function fxSwap() {
  const f = document.getElementById('fx-from');
  const t = document.getElementById('fx-to');
  const tmp = f.value; f.value = t.value; t.value = tmp;
  const a = document.getElementById('fx-amount').value;
  document.getElementById('fx-amount').value = document.getElementById('fx-out').value;
  document.getElementById('fx-out').value = a;
  fxCalc();
}

function fxSetAmount(v) {
  document.getElementById('fx-amount').value = v;
  fxCalc();
}

function formatNumber(n) {
  return Number(n).toLocaleString('en-US', { maximumFractionDigits: 4 });
}