function renderChart(points) {
  const canvas = document.getElementById("consumption-chart");

  const labels = points.map(p => formatPeriod(p.period));
  const data = points.map(p => p.delta_m3);

  new Chart(canvas, {
    type: "bar",
    data: {
      labels,
      datasets: [
        {
          label: "Consommation (m³)",
          data
        },
      ],
    },
    options: {
      responsive: true,
      scales: {
        y: {
          beginAtZero: true,
        },
      },
    },
  });
}

function formatPeriod(isoString) {
  const date = new Date(isoString);
  return date.toLocaleDateString("fr-FR", { day: "2-digit", month: "short" });
}