import { useMemo, useState } from 'react';
import {
  ScatterChart, Scatter, XAxis, YAxis, Tooltip,
  ResponsiveContainer, Rectangle,
} from 'recharts';
import { rechartsTheme } from '@cameleer/design-system';
import styles from './DashboardTab.module.css';

export interface PunchcardCell {
  weekday: number;
  hour: number;
  totalCount: number;
  failedCount: number;
}

interface PunchcardHeatmapProps {
  cells: PunchcardCell[];
}

type Mode = 'transactions' | 'errors';

const DAYS = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];

function transactionColor(ratio: number): string {
  if (ratio === 0) return 'var(--bg-inset)';
  const lightness = 90 - ratio * 55;
  return `hsl(220, 60%, ${Math.round(lightness)}%)`;
}

function errorColor(ratio: number): string {
  if (ratio === 0) return 'var(--bg-inset)';
  const lightness = 90 - ratio * 55;
  return `hsl(0, 65%, ${Math.round(lightness)}%)`;
}

interface HeatmapPoint {
  weekday: number;
  hour: number;
  value: number;
  fill: string;
}

function HeatmapCell(props: Record<string, unknown>) {
  const { cx, cy, payload } = props as {
    cx: number; cy: number; payload: HeatmapPoint;
  };
  if (!payload) return null;
  const cellW = 32;
  const cellH = 10;
  return (
    <Rectangle
      x={cx - cellW / 2}
      y={cy - cellH / 2}
      width={cellW}
      height={cellH}
      fill={payload.fill}
      radius={2}
    />
  );
}

function formatDay(value: number): string {
  return DAYS[value] ?? '';
}

function formatHour(value: number): string {
  return String(value).padStart(2, '0');
}

function buildGrid(cells: PunchcardCell[], mode: Mode): HeatmapPoint[] {
  const values = cells.map(c => mode === 'errors' ? c.failedCount : c.totalCount);
  const maxVal = Math.max(...values, 1);

  const cellMap = new Map<string, PunchcardCell>();
  for (const c of cells) cellMap.set(`${c.weekday}-${c.hour}`, c);

  const points: HeatmapPoint[] = [];
  for (let d = 0; d < 7; d++) {
    for (let h = 0; h < 24; h++) {
      const cell = cellMap.get(`${d}-${h}`);
      const val = cell ? (mode === 'errors' ? cell.failedCount : cell.totalCount) : 0;
      const ratio = maxVal > 0 ? val / maxVal : 0;
      points.push({
        weekday: d,
        hour: h,
        value: val,
        fill: mode === 'errors' ? errorColor(ratio) : transactionColor(ratio),
      });
    }
  }
  return points;
}

export function PunchcardHeatmap({ cells }: PunchcardHeatmapProps) {
  const [mode, setMode] = useState<Mode>('transactions');

  const data = useMemo(() => buildGrid(cells, mode), [cells, mode]);

  return (
    <div>
      <div className={styles.toggleRow}>
        <button
          className={`${styles.toggleBtn} ${mode === 'transactions' ? styles.toggleActive : ''}`}
          onClick={() => setMode('transactions')}
        >
          Transactions
        </button>
        <button
          className={`${styles.toggleBtn} ${mode === 'errors' ? styles.toggleActive : ''}`}
          onClick={() => setMode('errors')}
        >
          Errors
        </button>
      </div>
      <ResponsiveContainer width="100%" height={280}>
        <ScatterChart margin={{ top: 10, right: 10, bottom: 10, left: 10 }}>
          <XAxis
            type="number"
            dataKey="weekday"
            domain={[0, 6]}
            ticks={[0, 1, 2, 3, 4, 5, 6]}
            tickFormatter={formatDay}
            {...rechartsTheme.xAxis}
          />
          <YAxis
            type="number"
            dataKey="hour"
            domain={[0, 23]}
            ticks={[0, 4, 8, 12, 16, 20]}
            tickFormatter={formatHour}
            reversed
            {...rechartsTheme.yAxis}
          />
          <Tooltip
            contentStyle={rechartsTheme.tooltip.contentStyle}
            labelStyle={rechartsTheme.tooltip.labelStyle}
            itemStyle={rechartsTheme.tooltip.itemStyle}
            cursor={false}
            formatter={(_val: unknown, _name: string, entry: { payload?: HeatmapPoint }) => {
              const p = entry.payload;
              if (!p) return '';
              return [`${p.value.toLocaleString()} ${mode}`, `${DAYS[p.weekday]} ${formatHour(p.hour)}:00`];
            }}
            labelFormatter={() => ''}
          />
          <Scatter
            data={data}
            shape={(props: unknown) => <HeatmapCell {...(props as Record<string, unknown>)} />}
            isAnimationActive={false}
          />
        </ScatterChart>
      </ResponsiveContainer>
    </div>
  );
}