Free 2D Continuous Crosshair Cursor

import { defineChart, dot, lineY } from "@tanstack/charts";
import { type ContinuousCursorPosition, continuousCursor } from "@tanstack/charts/interaction/cursor";
import { controlledSignal } from "@tanstack/charts/interaction/signal";
import { motion } from "@tanstack/charts/motion";
import { Chart } from "@tanstack/react-charts/core";
import { useMemo, useState } from "react";

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

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

interface FreeCursorDatum {
    hp: number;
    mpg: number;
}

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

function generateDemoData(): FreeCursorDatum[] {
    const results: FreeCursorDatum[] = [];
    for (let hp = 60; hp <= 300; hp += 15) {
        const mpg = 45 - (hp - 60) * 0.12 + (Math.random() - 0.5) * 4;
        results.push({ hp, mpg: Number(Math.max(10, mpg).toFixed(1)) });
    }
    return results;
}

export function EchartsFreeCursor() {
    const data = useMemo(() => generateDemoData(), []);
    const [cursorPos, setCursorPos] = useState<ContinuousCursorPosition<number, number> | null>({
        x: 180,
        y: 28,
    });

    const definition = useMemo(
        () =>
            defineChart(
                {
                    renderer: motionRenderer,
                    marks: [
                        lineY(data, {
                            id: "free-cursor-line",
                            x: "hp",
                            y: "mpg",
                            stroke: "var(--chart-1)",
                            strokeWidth: 2,
                        }),
                        dot(data, {
                            id: "free-cursor-dots",
                            x: "hp",
                            y: "mpg",
                            fill: "var(--chart-1)",
                            r: 3.5,
                            stroke: "var(--background)",
                            strokeWidth: 1,
                        }),
                    ],
                    scales: {
                        x: {
                            scale: scaleLinear().domain([50, 310]),
                            axis: { label: "Horsepower (HP)" },
                        },
                        y: {
                            scale: scaleLinear().domain([5, 50]),
                            grid: true,
                            axis: { label: "Fuel Economy (MPG)" },
                        },
                    },
                    controls: [
                        continuousCursor({
                            position: controlledSignal<ContinuousCursorPosition<number, number> | null, any>(
                                cursorPos,
                                (next) => setCursorPos(next),
                            ),
                            xRule: {
                                stroke: "var(--muted-foreground)",
                                strokeWidth: 1,
                                strokeDasharray: "4 4",
                            },
                            yRule: {
                                stroke: "var(--muted-foreground)",
                                strokeWidth: 1,
                                strokeDasharray: "4 4",
                            },
                            marker: {
                                radius: 5,
                                fill: "var(--background)",
                                stroke: "var(--chart-1)",
                                strokeWidth: 2,
                            },
                            xLabel: {
                                background: "var(--foreground)",
                                color: "var(--background)",
                                fontSize: 11,
                                fontWeight: 600,
                                radius: 4,
                                paddingX: 6,
                                paddingY: 3,
                                format: (v: number) => `${Math.round(v)} HP`,
                            },
                            yLabel: {
                                side: "start",
                                background: "var(--foreground)",
                                color: "var(--background)",
                                fontSize: 11,
                                fontWeight: 600,
                                radius: 4,
                                paddingX: 6,
                                paddingY: 3,
                                format: (v: number) => `${v.toFixed(1)} MPG`,
                            },
                        }),
                    ],
                    margin: { top: 24, right: 24, bottom: 32, left: 45 },
                    theme: {
                        foreground: "var(--muted-foreground)",
                        grid: "var(--border)",
                        background: "transparent",
                    },
                },
                { keyboard: false },
            ),
        [cursorPos, data],
    );

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Free 2D Continuous Crosshair Cursor</CardTitle>
                <CardDescription>
                    Arbitrary XY continuous crosshairs with floating dynamic tick axis coordinate readouts
                </CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Free 2D Continuous Crosshair Cursor Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    {cursorPos
                        ? `Coordinates: ${Math.round(cursorPos.x)} HP · ${cursorPos.y.toFixed(1)} MPG`
                        : "Move mouse over plot area"}{" "}
                    <Crosshair className="h-4 w-4 text-emerald-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    `continuousCursor` evaluates non-discrete 2D coordinates across spatial plane
                </div>
            </CardFooter>
        </Card>
    );
}

export default EchartsFreeCursor;