import {
  Chart as ChartJS,
  CategoryScale,
  LinearScale,
  PointElement,
  LineElement,
  BarElement,
  ArcElement,
  Title,
  Tooltip,
  Legend,
  Filler
} from 'chart.js';
import ChartDataLabels from 'chartjs-plugin-datalabels';
import Annotation from 'chartjs-plugin-annotation';

// Register ChartJS components once
ChartJS.register(
  CategoryScale,
  LinearScale,
  PointElement,
  LineElement,
  BarElement,
  ArcElement,
  Title,
  Tooltip,
  Legend,
  Filler,
  ChartDataLabels,
  Annotation
);

export const chartColors = {
  primary: '#2563eb',
  secondary: '#7c3aed',
  tertiary: '#0891b2',
  success: '#059669',
  danger: '#dc2626',
  muted: '#94a3b8',
  grid: '#e2e8f0'  // fallback only; use getChartTheme().border at runtime
};

export function getChartTheme() {
  const style = getComputedStyle(document.documentElement);
  const get = (v: string) => style.getPropertyValue(v).trim();
  return {
    surface:     get('--surface')      || '#ffffff',
    textPrimary: get('--text-primary') || '#0f172a',
    textMuted:   get('--text-muted')   || '#64748b',
    border:      get('--border')       || '#e2e8f0',
    textInverse: get('--text-inverse') || '#ffffff',
  };
}

// Extended palette for charts with many categories (events, channels)
export const chartPalette = [
  '#2563eb', // blue
  '#7c3aed', // purple
  '#0891b2', // cyan
  '#059669', // emerald
  '#d97706', // amber
  '#e11d48', // rose
  '#4f46e5', // indigo
  '#0d9488', // teal
  '#c026d3', // fuchsia
  '#ea580c', // orange
];

export const createDataLabelConfig = (showDataLabels: boolean, overrides?: { color?: string; backgroundColor?: string }): any => ({
  display: showDataLabels,
  color: overrides?.color ?? '#1e293b',
  font: { size: 10, weight: 600 },
  anchor: 'end',
  align: 'end',
  offset: 4,
  padding: 4,
  backgroundColor: overrides?.backgroundColor ?? 'rgba(255, 255, 255, 0.85)',
  borderRadius: 3,
  textDirection: 'ltr', // Force LTR for numbers - fixes RTL misalignment
  formatter: (value: number | null) => {
    if (value == null) return '';
    if (value >= 1000000) return (value / 1000000).toFixed(2) + 'M';
    if (value >= 1000) return (value / 1000).toFixed(2) + 'K';
    if (value < 100 && value > 0) return value.toFixed(2);
    return Math.round(value).toLocaleString();
  }
});

export const createBaseOptions = (showDataLabels: boolean): any => {
  const theme = getChartTheme();
  return {
    responsive: true,
    maintainAspectRatio: false,
    locale: 'en-US', // Force LTR number formatting
    layout: {
      padding: {
        top: showDataLabels ? 25 : 5,
        right: 5,
        bottom: 5,
        left: 5
      }
    },
    plugins: {
      legend: { display: false },
      tooltip: {
        backgroundColor: theme.surface,
        titleColor: theme.textPrimary,
        bodyColor: theme.textMuted,
        borderColor: theme.border,
        borderWidth: 1,
        padding: 12,
        cornerRadius: 8,
        titleFont: { size: 12 },
        bodyFont: { size: 11 },
        rtl: false,
        textDirection: 'ltr'
      },
      datalabels: createDataLabelConfig(showDataLabels, {
        color: theme.textPrimary,
        backgroundColor: theme.surface + 'dd',
      })
    },
    scales: {
      x: {
        grid: { display: false },
        ticks: { font: { size: 10 }, color: theme.textMuted }
      },
      y: {
        grid: { color: theme.border },
        ticks: { font: { size: 10 }, color: theme.textMuted },
        border: { display: false }
      }
    }
  };
};

export const lineDatasetDefaults = {
  borderWidth: 2,
  tension: 0.4,
  fill: true,
  pointRadius: 0,
  pointHoverRadius: 4
};

export const barDatasetDefaults = {
  borderRadius: 4
};