<div class="solar-calculator">

  <h2>Calcula tu ahorro</h2>
  <p>Desliza para estimar tu recibo mensual</p>

  <input type="range" id="bill" min="500" max="15000" step="100" value="2000">

  <div class="value">$<span id="billValue">2,000</span> MXN / mes</div>

  <div class="results">
    <div class="card">
      <p>Ahorro anual</p>
      <h3>$<span id="savings">20,400</span></h3>
    </div>

    <div class="card">
      <p>Retorno</p>
      <h3><span id="roi">3.5</span> años</h3>
    </div>
  </div>

  <a id="whatsappBtn" target="_blank" class="cta">
    Quiero mi ahorro exacto
  </a>

  <p class="note">Estimación basada en promedios. El cálculo real puede variar.</p>

</div>

<style>
.solar-calculator{
  max-width:500px;
  margin:auto;
  padding:30px;
  border-radius:20px;
  background:#0D0C22;
  color:#fff;
  font-family:sans-serif;
  text-align:center;
}

.solar-calculator input{
  width:100%;
  margin:20px 0;
}

.value{
  font-size:18px;
  margin-bottom:20px;
}

.results{
  display:flex;
  gap:15px;
  justify-content:center;
  margin-bottom:20px;
}

.card{
  flex:1;
  background:#1a1835;
  padding:15px;
  border-radius:12px;
}

.card h3{
  margin:5px 0;
}

.cta{
  display:block;
  padding:14px;
  background:#25D366;
  color:#000;
  border-radius:999px;
  text-decoration:none;
  font-weight:bold;
}

.note{
  font-size:12px;
  opacity:0.7;
  margin-top:10px;
}
</style>

<script>
document.addEventListener("DOMContentLoaded", function(){

  const slider = document.getElementById("bill");
  const billValue = document.getElementById("billValue");
  const savings = document.getElementById("savings");
  const roi = document.getElementById("roi");
  const whatsappBtn = document.getElementById("whatsappBtn");

  const phone = "8115835501"; // 👉 CAMBIA por tu número

  function format(num){
    return num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
  }

  function calculate() {
    let monthly = parseFloat(slider.value);

    billValue.innerText = format(monthly);

    let annualSavings = monthly * 12 * 0.85;
    let systemCost = monthly * 12 * 3;
    let payback = systemCost / annualSavings;

    savings.innerText = format(Math.round(annualSavings));
    roi.innerText = payback.toFixed(1);

    let message = `Hola, quiero mi cálculo solar.\nPago aprox $${monthly} MXN al mes.\nAhorro estimado: $${Math.round(annualSavings)} MXN al año.`;

    let url = `https://wa.me/${phone}?text=${encodeURIComponent(message)}`;
    whatsappBtn.href = url;
  }

  slider.addEventListener("input", calculate);

  calculate();

});
</script>