Donut Chart with Central KPI Radial Stat

import { type ChartPoint, defineChart } from "@tanstack/charts";
import { motion } from "@tanstack/charts/motion";
import { pie, polar, radialArc, radialText } from "@tanstack/charts/polar";
import { tooltip } from "@tanstack/charts/tooltip";
import { Chart } from "@tanstack/react-charts/core";
import { useMemo } from "react";

import { scaleLinear } from "d3-scale";
import { Donut } from "lucide-react";

import { Card, CardContent, CardDescription, CardFooter, CardHeader, CardTitle } from "@/components/ui/card";

interface DonutSegment {
    category: string;
    value: number;
}

const motionRenderer = motion({
    initial: "always",
    transition: { type: "spring", stiffness: 170, damping: 18, mass: 1 },
});

const tau = Math.PI * 2;
const categories = ["Desktop", "Mobile", "Tablet"];
const colors = ["var(--chart-1)", "var(--chart-2)", "var(--chart-3)"];

function generateDemoData(): DonutSegment[] {
    return [
        { category: "Desktop", value: 55 },
        { category: "Mobile", value: 35 },
        { category: "Tablet", value: 10 },
    ];
}

function shadcnTooltipContent<TDatum>(points: readonly ChartPoint<TDatum>[]) {
    if (points.length === 0) return { title: "", rows: [] };
    const d = points[0].datum as DonutSegment;
    if (!d || !d.category) return { title: "", rows: [] };
    return {
        title: d.category,
        rows: [{ label: "Device Share", value: `${d.value}%`, color: "var(--chart-1)" }],
    };
}

export function CenterDonut() {
    const data = useMemo(() => generateDemoData(), []);
    const totalValue = useMemo(() => data.reduce((acc, curr) => acc + curr.value, 0), [data]);

    const definition = useMemo(() => {
        const arcs = pie(data, { value: "value" });
        const center = [{ id: "total", angle: 0, radius: 0, text: `${totalValue}%` }];

        return defineChart(
            {
                renderer: motionRenderer,
                scales: {
                    x: null,
                    y: null,
                },
                marks: [
                    polar({
                        radiusRatio: 0.75,
                        scales: {
                            angle: { scale: scaleLinear().domain([0, tau]) },
                            radius: { scale: scaleLinear().domain([0, 1]) },
                        },
                        marks: [
                            radialArc(arcs, {
                                id: "segment-slices",
                                key: "category",
                                innerRadius: ({ radius }) => radius * 0.65,
                                color: "category",
                            }),
                            radialText(center, {
                                id: "center-total",
                                angle: "angle",
                                radius: "radius",
                                key: "id",
                                text: "text",
                                fill: "var(--foreground)",
                                fontSize: 24,
                                fontWeight: 700,
                            }),
                        ],
                    }),
                ],
                color: { domain: categories, range: colors },
                margin: { top: 20, right: 20, bottom: 20, left: 20 },
                theme: {
                    foreground: "var(--muted-foreground)",
                    grid: "var(--border)",
                    background: "transparent",
                },
            },
            {
                keyboard: true,
                tooltip: {
                    use: tooltip,
                    className: "font-sans shadow-none rounded-md bg-popover text-popover-foreground border p-2 text-xs",
                    anchor: "pointer",
                    placement: "auto",
                    content: (points) => shadcnTooltipContent(points),
                },
            },
        );
    }, [data, totalValue]);

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Donut Chart with Central KPI Radial Text Metric</CardTitle>
                <CardDescription>
                    Hollow inner radius donut chart displaying total aggregate KPI metric in center origin
                </CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Donut Chart with Central KPI Radial Text Metric Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    Total aggregated metric volume centered in hole <Donut className="h-4 w-4 text-emerald-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    `radialText` positioned at origin (radius: 0) anchors central KPI typography
                </div>
            </CardFooter>
        </Card>
    );
}

export default CenterDonut;