Contour Topography

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

import { scaleLinear, scaleThreshold } from "d3-scale";
import { Compass } from "lucide-react";

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

interface GridCell {
    u: number;
    v: number;
    x: number;
    y: number;
    val: number;
}

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

const contourThresholds = [2, 5, 8, 11, 14];

function generateDemoGrid() {
    const width = 20;
    const height = 15;
    const data: GridCell[] = [];

    for (let j = 0; j < height; j++) {
        for (let i = 0; i < width; i++) {
            const u = Math.sin(i * 0.4) * 8 + 6;
            const v = Math.cos(j * 0.5) * 8 + 6;
            const val = Math.hypot(u, v);
            data.push({ u, v, x: i, y: j, val });
        }
    }
    return { width, height, data };
}

function shadcnTooltipContent<TDatum>(points: readonly ChartPoint<TDatum>[]) {
    if (points.length === 0) return { title: "", rows: [] };
    const d = points[0].datum as GridCell;
    if (!d) return { title: "", rows: [] };
    return {
        title: `Grid Location (${d.x}, ${d.y})`,
        rows: [
            {
                label: "Wind Velocity",
                value: `${d.val.toFixed(1)} m/s`,
                color: "var(--chart-1)",
            },
            {
                label: "Vector (U, V)",
                value: `${d.u.toFixed(1)}, ${d.v.toFixed(1)} m/s`,
                color: "var(--muted-foreground)",
            },
        ],
    };
}

export function ContourTopography() {
    const grid = useMemo(() => generateDemoGrid(), []);

    const definition = useMemo(
        () =>
            defineChart(
                {
                    renderer: motionRenderer,
                    marks: [
                        contour(grid.data, {
                            id: "contour-isobands",
                            width: grid.width,
                            height: grid.height,
                            value: (row: GridCell) => Math.hypot(row.u, row.v),
                            thresholds: contourThresholds,
                            stroke: "var(--background)",
                            strokeWidth: 0.75,
                        }),
                        dot(grid.data, {
                            id: "contour-grid-dots",
                            x: "x",
                            y: "y",
                            r: 2,
                            fill: "var(--foreground)",
                            fillOpacity: 0.25,
                            states: [
                                {
                                    when: { focus: "primary" },
                                    style: { r: 5, fill: "var(--chart-1)", fillOpacity: 1 },
                                },
                            ],
                        }),
                    ],
                    scales: {
                        x: {
                            scale: scaleLinear().domain([0, grid.width]),
                            axis: false,
                        },
                        y: {
                            scale: scaleLinear().domain([0, grid.height]),
                            axis: false,
                        },
                    },
                    color: {
                        scale: scaleThreshold<number, string>,
                        domain: contourThresholds.slice(1),
                        range: [
                            "var(--chart-5)",
                            "var(--chart-4)",
                            "var(--chart-3)",
                            "var(--chart-2)",
                            "var(--chart-1)",
                        ],
                    },
                    margin: { top: 20, right: 24, bottom: 24, left: 24 },
                    theme: {
                        foreground: "var(--muted-foreground)",
                        grid: "transparent",
                        background: "transparent",
                    },
                },
                {
                    focus: "nearest",
                    keyboard: true,
                    tooltip: {
                        use: tooltip,
                        className:
                            "font-sans shadow-none rounded-md bg-popover text-popover-foreground border p-2 text-xs pointer-events-none transition-all duration-75",
                        anchor: "pointer",
                        placement: "auto",
                        content: (points) => shadcnTooltipContent(points),
                    },
                },
            ),
        [grid],
    );

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Topographic Wind Velocity Contours</CardTitle>
                <CardDescription>
                    Filled vector field isoline contours indicating spatial wind speed gradients
                </CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Topographic Wind Velocity Contours Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    High velocity core (dark blue) centers over central grid origin{" "}
                    <Compass className="h-4 w-4 text-blue-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    Hover over grid observation points to view localized wind speed vectors
                </div>
            </CardFooter>
        </Card>
    );
}

export default ContourTopography;