//+------------------------------------------------------------------+
//|                                                           app.js |
//| Interfaz: carga el .bin, muestra la ficha del evento y la tabla  |
//| de valores con lista virtual (solo se dibujan las filas cerca    |
//| de la pantalla; el resto se lee del buffer cuando se hace scroll)|
//+------------------------------------------------------------------+
(function () {
  'use strict';

  const ROW_H = 28;          // alto fijo de fila (px): permite calcular que filas ver sin medirlas
  const RENDER_SCREENS = 4;  // se dibujan ~4 pantallas de filas alrededor de la vista, el resto on-demand

  const $ = (id) => document.getElementById(id);
  const el = {
    file: $('file'), drop: $('drop'), msg: $('msg'), info: $('info'), title: $('title'), sub: $('sub'),
    chips: $('chips'), stats: $('stats'), warn: $('warn'), tableWrap: $('tableWrap'), scroller: $('scroller'),
    body: $('body'), rows: $('rows'), order: $('order'), count: $('count')
  };

  let H = null;            // cabecera parseada
  let desc = true;         // true = mas reciente primero
  let start = 0, end = 0;  // rango de filas dibujado [start, end)
  let ticking = false;

  //--- Utilidades
  function esc(s) {
    return String(s).replace(/[&<>"']/g, (c) => ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' }[c]));
  }
  function setMsg(text, isErr) { el.msg.textContent = text; el.msg.className = isErr ? 'err' : ''; }

  //--- Carga del archivo
  async function loadFile(file) {
    if (!file) return;
    const t0 = performance.now();
    try {
      const buf = await file.arrayBuffer();
      H = CalFmt.parseHeader(buf);
    } catch (e) {
      H = null;
      el.info.hidden = true; el.tableWrap.hidden = true;
      setMsg('No se pudo leer "' + file.name + '": ' + e.message, true);
      return;
    }
    setMsg(file.name + ' — ' + (file.size / 1024).toFixed(1) + ' KB, cabecera leida en ' + (performance.now() - t0).toFixed(1) + ' ms', false);
    showInfo(file);
    resetTable();
  }

  function chip(k, v) { return '<span class="chip"><b>' + esc(k) + '</b> ' + esc(v) + '</span>'; }

  function showInfo(file) {
    const C = CalFmt;
    el.title.textContent = H.name || '(sin nombre)';
    let sub = esc(H.code);
    if (/^https?:\/\//i.test(H.url)) sub += ' · <a href="' + esc(H.url) + '" target="_blank" rel="noopener noreferrer">' + esc(H.url) + '</a>';
    else if (H.url) sub += ' · ' + esc(H.url);
    el.sub.innerHTML = sub;

    el.chips.innerHTML = [
      chip('Pais', (C.COUNTRY[H.countryId] || 'Desconocido') + ' (' + H.countryId + ')'),
      chip('Importancia', C.label(C.IMPORTANCE, H.importance)),
      chip('Tipo', C.label(C.TYPE, H.type)),
      chip('Sector', C.label(C.SECTOR, H.sector)),
      chip('Frecuencia', C.label(C.FREQUENCY, H.frequency)),
      chip('Hora', C.label(C.TIMEMODE, H.timeMode)),
      chip('Unidad', C.label(C.UNIT, H.unit)),
      chip('Multiplicador', C.label(C.MULT_NAME, H.multiplier)),
      chip('Decimales', H.digits),
      chip('ID evento', H.id)
    ].join('');

    let first = '—', last = '—';
    if (H.count > 0) {
      first = C.fmtTime(C.readRow(H, 0).time);
      last = C.fmtTime(C.readRow(H, H.count - 1).time);
    }
    el.stats.textContent = H.count.toLocaleString() + ' registros · ' + first + ' → ' + last + ' (hora del servidor)';
    el.warn.hidden = !H.warning;
    el.warn.textContent = H.warning || '';
    el.info.hidden = false;
  }

  //--- Tabla virtual
  function resetTable() {
    el.tableWrap.hidden = H.count === 0;
    el.count.textContent = H.count.toLocaleString() + ' filas';
    el.body.style.height = H.count * ROW_H + 'px';
    el.scroller.scrollTop = 0;
    start = end = 0;
    el.rows.innerHTML = '';
    render(true);
  }

  function visibleRows() { return Math.max(1, Math.ceil(el.scroller.clientHeight / ROW_H)); }

  function rowHtml(k) {
    const C = CalFmt;
    const i = desc ? H.count - 1 - k : k;      // k = posicion en pantalla, i = indice en el archivo
    const r = C.readRow(H, i);
    const imp = r.impact === 1 ? 'pos' : (r.impact === 2 ? 'neg' : '');
    return '<div class="row ' + (k % 2 ? 'alt' : '') + '" style="height:' + ROW_H + 'px">' +
      '<span class="c-n">' + (i + 1) + '</span>' +
      '<span class="c-t">' + C.fmtTime(r.time) + '</span>' +
      '<span class="c-v">' + C.fmtValue(r.actual, H) + '</span>' +
      '<span class="c-v">' + C.fmtValue(r.forecast, H) + '</span>' +
      '<span class="c-v">' + C.fmtValue(r.previous, H) + '</span>' +
      '<span class="c-v">' + C.fmtValue(r.revised, H) + '</span>' +
      '<span class="c-i ' + imp + '">' + C.label(C.IMPACT, r.impact) + '</span>' +
      '<span class="c-id">' + r.id + '</span>' +
      '<span class="c-m">' + r.countryIdx + ' / ' + r.eventIdx + (r.processed ? ' · proc.' : '') + '</span>' +
      '</div>';
  }

  // Dibuja ~RENDER_SCREENS pantallas alrededor de la vista. Solo vuelve a dibujar cuando la vista
  // se acerca al borde de lo ya dibujado (o con force).
  function render(force) {
    if (!H || H.count === 0) return;
    const vis = visibleRows();
    const first = Math.min(H.count - 1, Math.floor(el.scroller.scrollTop / ROW_H));
    const last = Math.min(H.count, first + vis);

    // Se redibuja solo si la vista se sale de lo dibujado o se acerca a un borde (margen = media pantalla)
    const margin = Math.floor(vis * 0.5);
    const nearTop = start > 0 && first < start + margin;
    const nearBottom = end < H.count && last > end - margin;
    if (!force && !nearTop && !nearBottom && first >= start && last <= end) return;

    const extra = Math.ceil(vis * (RENDER_SCREENS - 1) / 2);
    start = Math.max(0, first - extra);
    end = Math.min(H.count, last + extra);

    let html = '';
    for (let k = start; k < end; k++) html += rowHtml(k);
    el.rows.style.top = start * ROW_H + 'px';
    el.rows.innerHTML = html;
  }

  function onScroll() {
    if (ticking) return;
    ticking = true;
    requestAnimationFrame(() => { ticking = false; render(false); });
  }

  //--- Eventos
  el.file.addEventListener('change', () => loadFile(el.file.files[0]));
  el.scroller.addEventListener('scroll', onScroll, { passive: true });
  window.addEventListener('resize', () => render(true));
  el.order.addEventListener('click', () => {
    desc = !desc;
    el.order.textContent = desc ? 'Mas reciente primero' : 'Mas antiguo primero';
    if (H) { el.scroller.scrollTop = 0; render(true); }
  });

  ['dragenter', 'dragover'].forEach((ev) => el.drop.addEventListener(ev, (e) => { e.preventDefault(); el.drop.classList.add('over'); }));
  ['dragleave', 'drop'].forEach((ev) => el.drop.addEventListener(ev, (e) => { e.preventDefault(); el.drop.classList.remove('over'); }));
  el.drop.addEventListener('drop', (e) => loadFile(e.dataTransfer.files[0]));
})();