// public/scripts/trends.js

// ─── Configuration for 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'        }
];

// ─── Helpers ──────────────────────────────────────────────────────────────────
// Reformat EST SQL timestamp "YYYY-MM-DD HH:mm:ss" → "M/D/YY @HH:mm"
function formatESTTimestamp(ts) {
  const [datePart, timePart] = ts.split(' ');
  const [Y, M, D]            = datePart.split('-').map(n => parseInt(n, 10));
  const [h, m]               = timePart.split(':');
  const YY                    = String(Y).slice(-2);
  return `${M}/${D}/${YY} @${h.padStart(2,'0')}:${m}`;
}

// Subtract count units from a Date
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;
}

// ─── State ────────────────────────────────────────────────────────────────────
let readings = [];
let chart;

// ─── Initialize on page load ─────────────────────────────────────────────────
document.addEventListener('DOMContentLoaded', async () => {
  await loadReadings();
  setupUI();
  initChart();
  updateView();
});

// ─── Load readings from API ───────────────────────────────────────────────────
async function loadReadings() {
  const data = await fetch('/api/readings').then(r => r.json());
  readings = data.map(r => ({
    ...r,
    formattedTs: formatESTTimestamp(r.timestamp),
    dateObj:     new Date(r.timestamp.replace(' ', 'T'))
  }));
}

// ─── UI Wiring ────────────────────────────────────────────────────────────────
function setupUI() {
  // Timeframe 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 toggles
  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');
      const rows   = Array.from(tbody.rows);
      rows.sort((a, b) => {
        const aText = a.cells[idx].textContent;
        const bText = b.cells[idx].textContent;
        return asc
          ? aText.localeCompare(bText, undefined, { numeric: true })
          : bText.localeCompare(aText, undefined, { numeric: true });
      });
      th.classList.toggle('asc', asc);
      rows.forEach(r => tbody.appendChild(r));
    });
  });
}

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

// ─── Update both chart & table based on UI state ─────────────────────────────
function updateView() {
  // Determine timeframe cutoff
  const idx    = +document.getElementById('timeframe-slider').value;
  const { unit, count } = tfConfig[idx];
  const cutoff = subtract(new Date(), count, unit);

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

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

  // Prepare chart labels & datasets
  const labels   = filtered.map(r => r.formattedTs);
  const datasets = [];

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

  chart.data.labels   = labels;
  chart.data.datasets = datasets;
  chart.update();

  populateTable(filtered);
}

// ─── Populate the trends table ────────────────────────────────────────────────
function populateTable(data) {
  const tbody = document.getElementById('trends-table-body');
  tbody.innerHTML = '';
  data.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);
  });
}