Dumbbell Plot

import { type ChartPoint, defineChart, dot, link } from "@tanstack/charts";
import { motion } from "@tanstack/charts/motion";
import { tooltip } from "@tanstack/charts/tooltip";
import { Chart } from "@tanstack/react-charts/core";
import { useMemo } from "react";

import { scaleBand, scaleLinear } from "d3-scale";
import { ArrowLeftRight } from "lucide-react";

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

interface DumbbellDatum {
    city: string;
    v1980: number;
    v2015: number;
}

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

function generateDemoData(): DumbbellDatum[] {
    return [
        { city: "New York", v1980: 4.2, v2015: 7.8 },
        { city: "San Francisco", v1980: 3.8, v2015: 8.4 },
        { city: "Chicago", v1980: 4.0, v2015: 6.2 },
        { city: "Houston", v1980: 3.5, v2015: 5.9 },
        { city: "Boston", v1980: 4.1, v2015: 7.1 },
    ];
}

function shadcnTooltipContent<TDatum>(points: readonly ChartPoint<TDatum>[]) {
    if (points.length === 0) return { title: "", rows: [] };
    const d = points[0].datum as DumbbellDatum;
    if (!d) return { title: "", rows: [] };
    return {
        title: d.city,
        rows: [
            { label: "1980 Ratio", value: d.v1980.toFixed(1), color: "var(--chart-1)" },
            { label: "2015 Ratio", value: d.v2015.toFixed(1), color: "var(--chart-2)" },
            { label: "Net Shift", value: `+${(d.v2015 - d.v1980).toFixed(1)}`, color: "var(--foreground)" },
        ],
    };
}

export function DumbbellChart() {
    const data = useMemo(() => generateDemoData(), []);

    const definition = useMemo(
        () =>
            defineChart(
                {
                    renderer: motionRenderer,
                    marks: [
                        link(data, {
                            id: "dumbbell-connector",
                            x1: "v1980",
                            y1: "city",
                            x2: "v2015",
                            y2: "city",
                            stroke: "var(--border)",
                            strokeWidth: 2,
                        }),
                        dot(data, {
                            id: "dumbbell-1980",
                            x: "v1980",
                            y: "city",
                            fill: "var(--chart-1)",
                            r: 4.5,
                        }),
                        dot(data, {
                            id: "dumbbell-2015",
                            x: "v2015",
                            y: "city",
                            fill: "var(--chart-2)",
                            r: 4.5,
                        }),
                    ],
                    scales: {
                        x: {
                            scale: scaleLinear().domain([2, 10]),
                            grid: true,
                            axis: {
                                line: false,
                                label: "90th/10th Percentile Wage Ratio",
                                ticks: { size: 0 },
                            },
                        },
                        y: {
                            scale: () => scaleBand<string>().padding(0.3),
                            axis: {
                                line: false,
                                ticks: { size: 0 },
                            },
                        },
                    },
                    color: {
                        domain: ["1980", "2015"],
                        range: ["var(--chart-1)", "var(--chart-2)"],
                    },
                    margin: { top: 24, right: 24, bottom: 32, left: 100 },
                    theme: {
                        foreground: "var(--muted-foreground)",
                        grid: "var(--border)",
                        background: "transparent",
                    },
                },
                {
                    focus: "group-y",
                    tooltip: {
                        use: tooltip,
                        className:
                            "font-sans shadow-none rounded-md bg-popover text-popover-foreground border p-2 text-xs",
                        anchor: "group-center",
                        placement: "auto",
                        content: (points) => shadcnTooltipContent(points),
                    },
                },
            ),
        [data],
    );

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Metro Inequality Shift (1980 vs 2015)</CardTitle>
                <CardDescription>Dumbbell plot comparing historical baseline and current wage ratios</CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Metro Inequality Shift Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    San Francisco experienced largest ratio expansion (+4.6){" "}
                    <ArrowLeftRight className="h-4 w-4 text-orange-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    Blue dots mark 1980 baseline; Orange dots denote 2015 measurement
                </div>
            </CardFooter>
        </Card>
    );
}

export default DumbbellChart;