/**
 * dashboard-stats.js — In-app real-time charts using Chart.js
 * Fetches /pos/api/dashboard/stats and renders hourly + top-products charts.
 */
(function () {
  'use strict';

  const token = localStorage.getItem('pos_token') || '';
  if (!token) return;

  let hourlyChart = null;
  let topProductsChart = null;

  function headers() {
    return { 'Authorization': 'Bearer ' + token, 'Content-Type': 'application/json' };
  }

  function fmt(n) {
    return '$' + parseFloat(n || 0).toLocaleString('es-MX', { minimumFractionDigits: 2, maximumFractionDigits: 2 });
  }

  async function loadStats() {
    try {
      const res = await fetch('/pos/api/dashboard/stats', { headers: headers() });
      if (!res.ok) return;
      const data = await res.json();
      renderHourlyChart(data.hourly_sales || []);
      renderTopProductsChart(data.top_products || []);
    } catch (e) {
      console.error('[dashboard-stats] failed to load', e);
    }
  }

  function renderHourlyChart(hourly) {
    const ctx = document.getElementById('hourlySalesChart');
    if (!ctx) return;
    if (hourlyChart) { hourlyChart.destroy(); hourlyChart = null; }
    const labels = hourly.map(function (h) { return h.hour + ':00'; });
    const totals = hourly.map(function (h) { return h.total; });

    hourlyChart = new Chart(ctx, {
      type: 'bar',
      data: {
        labels: labels,
        datasets: [{
          label: 'Ventas ($)',
          data: totals,
          backgroundColor: 'rgba(245, 166, 35, 0.7)',
          borderColor: 'rgba(245, 166, 35, 1)',
          borderWidth: 1,
          borderRadius: 4,
        }]
      },
      options: {
        responsive: true,
        maintainAspectRatio: false,
        plugins: { legend: { display: false } },
        scales: {
          x: { ticks: { color: '#888', font: { size: 10 } }, grid: { display: false } },
          y: { ticks: { color: '#888', font: { size: 10 }, callback: function (v) { return '$' + (v / 1000).toFixed(0) + 'k'; } }, grid: { color: '#333' } }
        }
      }
    });
  }

  function renderTopProductsChart(topProducts) {
    const ctx = document.getElementById('topProductsChart');
    if (!ctx) return;
    if (topProductsChart) { topProductsChart.destroy(); topProductsChart = null; }
    if (!topProducts || topProducts.length === 0) {
      // No sales today — render a friendly empty-state mini chart so the canvas
      // doesn't collapse or leave a blank hole.
      topProductsChart = new Chart(ctx, {
        type: 'doughnut',
        data: {
          labels: ['Sin ventas hoy'],
          datasets: [{
            data: [1],
            backgroundColor: ['rgba(136, 136, 136, 0.25)'],
            borderWidth: 0,
          }]
        },
        options: {
          responsive: true,
          maintainAspectRatio: false,
          plugins: {
            legend: {
              position: 'right',
              labels: { color: '#888', font: { size: 10 }, boxWidth: 10 }
            }
          }
        }
      });
      return;
    }

    const labels = topProducts.map(function (p) { return p.name.substring(0, 20); });
    const revenues = topProducts.map(function (p) { return p.revenue; });

    topProductsChart = new Chart(ctx, {
      type: 'doughnut',
      data: {
        labels: labels,
        datasets: [{
          data: revenues,
          backgroundColor: [
            '#F5A623', '#E85D75', '#4ECDC4', '#556270', '#C7F464',
            '#FF6B6B', '#45B7D1', '#96CEB4', '#FFEAA7', '#DDA0DD'
          ],
          borderWidth: 0,
        }]
      },
      options: {
        responsive: true,
        maintainAspectRatio: false,
        plugins: {
          legend: {
            position: 'right',
            labels: { color: '#ccc', font: { size: 10 }, boxWidth: 10 }
          }
        }
      }
    });
  }

  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', loadStats);
  } else {
    loadStats();
  }
})();