Connected Scatter

import { type ChartPoint, arrow, d3Curve, defineChart, dot, lineY, rollingWindow, text } 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 { scaleLinear } from "d3-scale";
import { curveCatmullRom } from "d3-shape";
import { Route } from "lucide-react";

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

interface DrivingDatum {
    year: number;
    miles: number;
    gas: number;
}

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

function generateDemoData(): DrivingDatum[] {
    const results: DrivingDatum[] = [];
    let miles = 4000;
    let gas = 1.2;

    for (let yr = 1980; yr <= 2024; yr += 2) {
        miles += (Math.sin(yr * 0.2) + 1.5) * 200;
        gas += (Math.cos(yr * 0.3) + 0.2) * 0.15;
        results.push({
            year: yr,
            miles: Math.round(miles),
            gas: Number(gas.toFixed(2)),
        });
    }
    return results;
}

function shadcnTooltipContent<TDatum>(points: readonly ChartPoint<TDatum>[]) {
    if (points.length === 0) return { title: "", rows: [] };
    const d = points[0].datum as DrivingDatum;
    if (!d) return { title: "", rows: [] };
    return {
        title: `Year ${d.year}`,
        rows: [
            { label: "Miles Driven / Person", value: `${d.miles.toLocaleString()} mi`, color: "var(--chart-1)" },
            { label: "Gasoline Price", value: `$${d.gas.toFixed(2)}/gal`, color: "var(--foreground)" },
        ],
    };
}

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

    const directionPairs = useMemo(() => {
        return rollingWindow(data, {
            orderBy: "year",
            size: 2,
            partial: false,
            outputs: {},
        }).filter(({ sourceIndexes }) => (sourceIndexes[1] ?? -1) % 4 === 0);
    }, [data]);

    const labels = useMemo(() => data.filter((d) => d.year % 10 === 0), [data]);

    const definition = useMemo(
        () =>
            defineChart(
                {
                    renderer: motionRenderer,
                    marks: [
                        lineY(data, {
                            id: "driving-path",
                            x: "miles",
                            y: "gas",
                            stroke: "var(--chart-1)",
                            strokeWidth: 2.25,
                            curve: d3Curve(curveCatmullRom.alpha(0.5)),
                        }),
                        dot(data, {
                            id: "driving-points",
                            x: "miles",
                            y: "gas",
                            fill: "var(--chart-2)",
                            r: 3.5,
                        }),
                        arrow(directionPairs, {
                            id: "direction-arrows",
                            x1: ({ source }) => source[0]?.miles,
                            y1: ({ source }) => source[0]?.gas,
                            x2: "miles",
                            y2: "gas",
                            stroke: "var(--chart-2)",
                            strokeWidth: 1.5,
                            headLength: 6,
                        }),
                        text(labels, {
                            id: "year-labels",
                            x: "miles",
                            y: "gas",
                            text: (row: DrivingDatum) => `${row.year}`,
                            fill: "var(--foreground)",
                            anchor: "middle",
                            dy: -10,
                            fontSize: 10,
                            fontWeight: 600,
                        }),
                    ],
                    scales: {
                        x: {
                            scale: scaleLinear,
                            grid: true,
                            axis: { label: "Miles Driven per Person" },
                        },
                        y: {
                            scale: scaleLinear,
                            grid: true,
                            axis: { label: "Cost of Gasoline ($/gal)" },
                        },
                    },
                    margin: { top: 24, right: 24, bottom: 32, left: 45 },
                    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, directionPairs, labels],
    );

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Directed Connected Scatterplot</CardTitle>
                <CardDescription>
                    2D path trajectory tracking driving distance vs gas prices across time
                </CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Directed Connected Scatterplot Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    Trajectory arrows illustrate chronological progression over 40 years{" "}
                    <Route className="h-4 w-4 text-emerald-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    Connected scatterplot connects 2D points sequentially to visualize non-monotonic relationship
                    dynamics
                </div>
            </CardFooter>
        </Card>
    );
}

export default ConnectedScatter;