Heat-Tracker/public/scripts/trends.js

// Timeframes
const tfConfig = [
  { unit:'hours',  count:24,  label:'Last 24 Hours'  },
  { unit:'days',   count:7,   label:'Last 7 Days'    },
  { unit:'weeks',  count:4,   label:'Last 4 Weeks'   },
  { unit:'months', count:12,  label:'Last 12 Months' },
  { unit:'years',  count:1,   label:'All Time'        }
];

let readings = [];
let chart;

//  Subtract helper
function subtract(date, count, unit) {
  const d = new Date(date);
  switch(unit) {
    case 'hours':  d.setHours(d.getHours() - count);    break;
    case 'days':   d.setDate(d.getDate() - count);      break;
    case 'weeks':  d.setDate(d.getDate() - 7*count);    break;
    case 'months': d.setMonth(d.getMonth() - count);    break;
    case 'years':  d.setFullYear(d.getFullYear() - count); break;
  }
  return d;
}

document.addEventListener('DOMContentLoaded', () => {
  // 1) Grab the server‐injected readings
  const data = window.__INITIAL_READINGS__ || [];
  if (!data.length) {
    console.warn('No initial readings found.');
  }

  // 2) Map into local array with Date objs & formatted strings
  readings = data.map(r => {
    const dt = new Date(r.epoch_ms);
    return {
      stationDockDoor: r.stationDockDoor,
      location:        r.location,
      temperature:     r.temperature,
      humidity:        r.humidity,
      heatIndex:       r.heatIndex,
      dateObj:         dt,
      formattedTs: dt.toLocaleString('en-US', {
        timeZone: 'America/New_York',
        month:    'numeric',
        day:      'numeric',
        year:     '2-digit',
        hour:     '2-digit',
        minute:   '2-digit',
        hour12:   false
      }).replace(',', ' @')
    };
  });

  setupUI();
  initChart();
  updateView();
});

function setupUI() {
  // Slider + label
  const slider = document.getElementById('timeframe-slider');
  const label  = document.getElementById('timeframe-label');
  slider.addEventListener('input', () => {
    label.textContent = tfConfig[slider.value].label;
    updateView();
  });
  label.textContent = tfConfig[slider.value].label;

  // Metric checkboxes
  document.getElementsByName('metric').forEach(cb => {
    cb.addEventListener('change', updateView);
  });

  // Table sorting
  document.querySelectorAll('#trends-table thead th.sortable').forEach(th => {
    th.addEventListener('click', () => {
      const idx = th.cellIndex;
      const asc = !th.classList.contains('asc');
      const tbody = document.getElementById('trends-table-body');
      Array.from(tbody.rows)
        .sort((a,b) => asc
          ? a.cells[idx].textContent.localeCompare(b.cells[idx].textContent, undefined, {numeric:true})
          : b.cells[idx].textContent.localeCompare(a.cells[idx].textContent, undefined, {numeric:true})
        )
        .forEach(r => tbody.appendChild(r));
      th.classList.toggle('asc', asc);
    });
  });
}

function initChart() {
  const ctx = document.getElementById('trend-chart').getContext('2d');
  chart = new Chart(ctx, {
    type: 'line',
    data: { labels: [], datasets: [] },
    options: {
      scales: {
        x: { title: { display:true, text:'Time (EST)' } },
        y: { title: { display:true, text:'Value' } }
      },
      interaction: { mode:'index', intersect:false },
      plugins: { legend:{ position:'top' } },
      maintainAspectRatio: false
    }
  });
}

function updateView() {
  if (!chart) return;

  // Determine "now" from the latest reading, not the browser clock
  const maxEpoch = Math.max(...readings.map(r => r.dateObj.getTime()));
  const nowDate  = new Date(maxEpoch);

  // Compute cutoff
  const idx    = +document.getElementById('timeframe-slider').value;
  const { unit, count } = tfConfig[idx];
  const cutoff = (idx === 4)
    ? new Date(0)                       // "All Time"
    : subtract(nowDate, count, unit);

  // Filter
  const filtered = readings.filter(r => r.dateObj >= cutoff);

  // Which metrics?
  const selected = Array.from(document.getElementsByName('metric'))
    .filter(cb => cb.checked)
    .map(cb => cb.value);

  // Update chart
  chart.data.labels   = filtered.map(r => r.formattedTs);
  chart.data.datasets = [];
  if (selected.includes('temperature')) {
    chart.data.datasets.push({
      label: 'Temperature (°F)',
      data:  filtered.map(r => r.temperature),
      tension: 0.3
    });
  }
  if (selected.includes('humidity')) {
    chart.data.datasets.push({
      label: 'Humidity (%)',
      data:  filtered.map(r => r.humidity),
      tension: 0.3
    });
  }
  if (selected.includes('heatIndex')) {
    chart.data.datasets.push({
      label: 'Heat Index (°F)',
      data:  filtered.map(r => r.heatIndex),
      tension: 0.3
    });
  }
  chart.update();

  // Populate table
  const tbody = document.getElementById('trends-table-body');
  tbody.innerHTML = '';
  filtered.forEach(r => {
    const tr = document.createElement('tr');
    tr.innerHTML = `
      <td>${r.formattedTs}</td>
      <td>${r.temperature.toFixed(1)}</td>
      <td>${r.humidity.toFixed(1)}</td>
      <td>${r.heatIndex.toFixed(2)}</td>
      <td>${r.stationDockDoor}</td>
      <td>${r.location}</td>
    `;
    tbody.appendChild(tr);
  });
}