// public/scripts/trends.js

// --- Timeframe options ---
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'        }
];

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

// --- Helpers ---
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;
}

// --- Load & initialize ---
document.addEventListener('DOMContentLoaded', async () => {
  console.log('📡 Loading readings from /api/readings…');
  try {
    const data = await fetch('/api/readings').then(r => r.json());
    console.log('✅ Received readings:', data);
    readings = data.map(r => ({
      stationDockDoor: r.stationDockDoor,
      location:        r.location,
      temperature:     r.temperature,
      humidity:        r.humidity,
      heatIndex:       r.heatIndex,
      dateObj:         new Date(r.epoch_ms),
      formattedTs: new Date(r.epoch_ms).toLocaleString('en-US', {
        timeZone:'America/New_York',
        month:'numeric', day:'numeric', year:'2-digit',
        hour:'2-digit', minute:'2-digit', hour12:false
      }).replace(',',' @')
    }));
    console.log('✔ Parsed readings:', readings);

    setupUI();
    initChart();
    updateView();
  } catch (err) {
    console.error('❌ Failed to load readings:', err);
  }
});

// --- UI wiring ---
function setupUI() {
  // Slider
  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;

  // Metrics 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');
      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);
    });
  });
}

// --- Chart.js init ---
function initChart() {
  if (typeof Chart === 'undefined') {
    console.error('❌ Chart.js not loaded!');
    return;
  }
  console.log('📊 Initializing Chart.js');
  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
    }
  });
}

// --- Render chart & table ---
function updateView() {
  if (!chart) return;
  console.log('🔄 updateView called');

  // Timeframe cutoff
  const idx = +document.getElementById('timeframe-slider').value;
  const { unit, count } = tfConfig[idx];
  const cutoff = subtract(new Date(), count, unit);
  console.log(`   Showing data since ${cutoff.toISOString()}`);

  // Filter readings
  const filtered = readings.filter(r => r.dateObj >= cutoff);
  console.log(`   ${filtered.length}/${readings.length} points after filtering`);

  // Metrics selected
  const selected = Array.from(document.getElementsByName('metric'))
    .filter(cb => cb.checked).map(cb => cb.value);
  console.log('   Metrics selected:', selected);

  // 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
    });
  }
  console.log('   Chart update:', chart.data);
  chart.update();

  // Update 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);
  });
  console.log('   Table populated with', filtered.length, 'rows');
}