$w.onReady(function () {
  const toNum = (v) => Number(String(v ?? "").replace(",", "."));
  const r0 = (x) => Math.round(+x);             // integer bars
  const r2 = (x) => (Math.round((+x) * 100) / 100).toFixed(2); // 2 decimals for %

  // -----------------------
  // CONFIG: average fill gas temperatures (°C)
  // -----------------------
  const TFILL_GRAVITY_C = 45;   // typical "gravity" fill (medium-fast)
  const TFILL_BOOSTER_C = 65;  // booster ~1:20 (average conservative value)

  $w("#button1").onClick(() => {
    // --- Inputs ---
    const V       = toNum($w("#input6").value);
    const xEAN    = toNum($w("#input5").value) / 100;

    // Current mix
    const O2v = toNum($w("#input4").value) / 100;
    const Hev = toNum($w("#input7").value) / 100;
    const P0  = toNum($w("#input8").value);

    // Target mix
    const O2t = toNum($w("#input9").value) / 100;
    const Het = toNum($w("#input10").value) / 100;
    const Pt  = toNum($w("#input11").value); // target at cold (final stabilized pressure)

    // --- New controls ---
    const useTemp    = Array.isArray($w("#checkboxGroup2").value) && $w("#checkboxGroup2").value.length > 0;
    const useBooster = Array.isArray($w("#checkboxGroup3").value) && $w("#checkboxGroup3").value.length > 0;
    const Tamb_C     = toNum($w("#input12").value);

    // --- Validations ---
    if ([xEAN,O2v,Hev,P0,O2t,Het,Pt].some(isNaN)) {
      $w("#text17").text = "Error: please fill all numeric fields.";
      return;
    }
    if (O2v + Hev > 1 || O2t + Het > 1) {
      $w("#text17").text = "Error: O₂% + He% must be ≤ 100%.";
      return;
    }
    if (Pt <= P0) {
      $w("#text17").text = "Error: target pressure must be higher than current pressure.";
      return;
    }
    if (useTemp && isNaN(Tamb_C)) {
      $w("#text17").text = "Error: please enter ambient temperature (°C).";
      return;
    }

    // -----------------------
    // MOLAR CALCULATION (cold) — base math unchanged
    // -----------------------
    const O2pp0 = P0 * O2v;
    const Hepp0 = P0 * Hev;
    const N2pp0 = P0 * (1 - O2v - Hev);

    // 1) Helium
    const He_pp_tar = Pt * Het;
    let addHe = He_pp_tar - Hepp0;
    if (addHe < -1e-9) {
      $w("#text17").text = "Impossible: current He already above target.";
      return;
    }
    addHe = Math.max(0, addHe);
    const P1 = P0 + addHe;

    // 2) Oxygen
    let addO2;
    if (Math.abs(1 - xEAN) < 1e-9) {
      addO2 = Pt * O2t - O2pp0;
    } else {
      addO2 = (Pt*O2t - O2pp0 - xEAN*Pt + xEAN*P1) / (1 - xEAN);
    }
    if (addO2 < -1e-9) addO2 = 0;
    const P2 = P1 + addO2;

    // 3) Air/EAN
    const addEAN = Pt - P2;
    if (addEAN < -1e-9) {
      $w("#text17").text = "Impossible: final pressure exceeded.";
      return;
    }

    // Final mix check (cold)
    const O2ppF = O2pp0 + addO2 + addEAN * xEAN;
    const HeppF = Hepp0 + addHe;
    const N2ppF = N2pp0 + addEAN * (1 - xEAN);
    const O2f = O2ppF / Pt;
    const Hef = HeppF / Pt;
    const N2f = 1 - O2f - Hef;

    // -----------------------
    // BASIC ISOTHERMAL OUTPUT (no temperature correction)
    // -----------------------
    if (!useTemp) {
      const heBars  = r0(addHe);
      const o2Bars  = r0(addO2);
      const eanBars = r0(addEAN);
      const pStart  = r0(P0);
      const pAfterHe= r0(P0 + addHe);
      const pAfterO2= r0(P1 + addO2);
      const pFinal  = r0(Pt);

      const line1 = `STEP 1 — Helium (He): add ${heBars} bar → from ${pStart} to ${pAfterHe} bar \n`;
      const line2 = `STEP 2 — Oxygen (O₂): add ${o2Bars} bar → from ${pAfterHe} to ${pAfterO2} bar \n`;
      const line3 = `STEP 3 — Air/EAN (${(xEAN*100).toFixed(0)}% O₂): add ${eanBars} bar → from ${pAfterO2} to ${pFinal} bar \n`;

      $w("#text17").text =
        `${line1}\n${line2}\n${line3}\n\n` +
        `Final mix @ ${pFinal} bar:\n` +
        `• O₂ ≈ ${r2(O2f*100)}% | He ≈ ${r2(Hef*100)}% | N₂ ≈ ${r2(N2f*100)}%`;
      return;
    }

    // -----------------------
    // TEMPERATURE CORRECTION (continuous fill, no pauses)
    // -----------------------
    const Tfill_C = useBooster ? TFILL_BOOSTER_C : TFILL_GRAVITY_C;
    const Tamb_K  = Tamb_C + 273.15;
    const Tfill_K = Tfill_C + 273.15;
    const k       = Tfill_K / Tamb_K; // >1 → what the gauge shows while filling

    // Convert to "hot" bars seen on the gauge
    let P_hot = P0; // current gauge pressure
    const addHe_hot  = addHe  * k;
    P_hot += addHe_hot;
    const P1_hot = P_hot;

    const addO2_hot  = addO2  * k;
    P_hot += addO2_hot;
    const P2_hot = P_hot;

    const addEAN_hot = addEAN * k;
    P_hot += addEAN_hot;
    const P3_hot = P_hot;

    // Predicted cold pressure after cooling down to Tamb
    const P_final_cold = P3_hot * (Tamb_K / Tfill_K);

    // Rounded values for display
    const heBarsHot   = r0(addHe_hot);
    const o2BarsHot   = r0(addO2_hot);
    const eanBarsHot  = r0(addEAN_hot);
    const pStartHot   = r0(P0);
    const pAfterHeHot = r0(P1_hot);
    const pAfterO2Hot = r0(P2_hot);
    const pFinalHot   = r0(P3_hot);
    const pFinalCold  = r0(P_final_cold);

    // Output text
    const modeTxt = useBooster ? "booster (~1:20)" : "gravity fill";
    const line1 = `STEP 1 — Helium (He): add ${heBarsHot} bar (hot) → from ${pStartHot} to ${pAfterHeHot} bar \n`;
    const line2 = `STEP 2 — Oxygen (O₂): add ${o2BarsHot} bar (hot) → up to ${pAfterO2Hot} bar \n`;
    const line3 = `STEP 3 — Air/EAN (${(xEAN*100).toFixed(0)}% O₂): add ${eanBarsHot} bar (hot) → up to ${pFinalHot} bar \n`;

    $w("#text17").text =
      `${line1}\n${line2}\n${line3}\n\n` +
      `Thermal assumptions: Tₐₘb = ${r0(Tamb_C)}°C, T_fill ≈ ${r0(Tfill_C)}°C, mode = ${modeTxt}\n` +
      `Predicted stabilized (cold) pressure: ${pFinalCold} bar (target: ${r0(Pt)} bar)\n` +
      `Expected final mix @ cold:\n` +
      `• O₂ ≈ ${r2(O2f*100)}% | He ≈ ${r2(Hef*100)}% | N₂ ≈ ${r2(N2f*100)}%`;
  });
});