import { useCallback } from 'react';
import { Treemap as RechartsTreemap, ResponsiveContainer, Tooltip } from 'recharts';
import { rechartsTheme } from '@cameleer/design-system';

export interface TreemapItem {
  id: string;
  label: string;
  value: number;
  /** 0-100, drives green→yellow→red color */
  slaCompliance: number;
}

interface TreemapProps {
  items: TreemapItem[];
  onItemClick?: (id: string) => void;
}

function slaColor(pct: number): string {
  if (pct >= 99) return 'hsl(120, 45%, 85%)';
  if (pct >= 97) return 'hsl(90, 45%, 85%)';
  if (pct >= 95) return 'hsl(60, 50%, 85%)';
  if (pct >= 90) return 'hsl(30, 55%, 85%)';
  return 'hsl(0, 55%, 85%)';
}

function slaBorderColor(pct: number): string {
  if (pct >= 99) return 'hsl(120, 40%, 45%)';
  if (pct >= 97) return 'hsl(90, 40%, 50%)';
  if (pct >= 95) return 'hsl(60, 45%, 45%)';
  if (pct >= 90) return 'hsl(30, 50%, 45%)';
  return 'hsl(0, 50%, 45%)';
}

function slaTextColor(pct: number): string {
  if (pct >= 95) return 'hsl(120, 20%, 25%)';
  return 'hsl(0, 40%, 30%)';
}

/** Custom cell renderer for the Recharts Treemap */
function CustomCell(props: Record<string, unknown>) {
  const { x, y, width, height, name, slaCompliance, onItemClick } = props as {
    x: number; y: number; width: number; height: number;
    name: string; slaCompliance: number; onItemClick?: (id: string) => void;
  };

  const w = width ?? 0;
  const h = height ?? 0;
  if (w < 2 || h < 2) return null;

  const showLabel = w > 40 && h > 20;
  const showSla = w > 60 && h > 34;
  const sla = slaCompliance ?? 100;

  return (
    <g
      onClick={() => onItemClick?.(name)}
      style={{ cursor: onItemClick ? 'pointer' : 'default' }}
    >
      <rect
        x={x + 1} y={y + 1} width={w - 2} height={h - 2}
        rx={3}
        fill={slaColor(sla)}
        stroke={slaBorderColor(sla)}
        strokeWidth={1}
      />
      {showLabel && (
        <text
          x={x + 5} y={y + 15}
          fill={slaTextColor(sla)}
          fontSize={11} fontWeight={600}
          style={{ pointerEvents: 'none' }}
        >
          {name.length > w / 6.5 ? name.slice(0, Math.floor(w / 6.5)) + '\u2026' : name}
        </text>
      )}
      {showSla && (
        <text
          x={x + 5} y={y + 28}
          fill={slaTextColor(sla)}
          fontSize={10} fontWeight={400}
          style={{ pointerEvents: 'none' }}
        >
          {sla.toFixed(1)}% SLA
        </text>
      )}
    </g>
  );
}

export function Treemap({ items, onItemClick }: TreemapProps) {
  // Recharts Treemap expects { name, size, ...extra }
  const data = items.map(i => ({
    name: i.label,
    size: i.value,
    slaCompliance: i.slaCompliance,
  }));

  const renderContent = useCallback(
    (props: Record<string, unknown>) => <CustomCell {...props} onItemClick={onItemClick} />,
    [onItemClick],
  );

  if (items.length === 0) {
    return <div style={{ color: 'var(--text-muted)', textAlign: 'center', padding: '2rem' }}>No data</div>;
  }

  return (
    <ResponsiveContainer width="100%" height={300}>
      <RechartsTreemap
        data={data}
        dataKey="size"
        nameKey="name"
        stroke="none"
        content={renderContent}
        isAnimationActive={false}
      >
        <Tooltip
          contentStyle={rechartsTheme.tooltip.contentStyle}
          labelStyle={rechartsTheme.tooltip.labelStyle}
          itemStyle={rechartsTheme.tooltip.itemStyle}
          formatter={(value: number, _name: string, entry: { payload?: { slaCompliance?: number } }) => {
            const sla = entry.payload?.slaCompliance ?? 0;
            return [`${value.toLocaleString()} exchanges · ${sla.toFixed(1)}% SLA`];
          }}
        />
      </RechartsTreemap>
    </ResponsiveContainer>
  );
}