Cumulative Histogram

import { type ChartPoint, binX, cumulative, defineChart, rect } 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 { thresholdScott } from "d3-array";
import { scaleLinear } from "d3-scale";
import { BarChart2 } from "lucide-react";

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

interface WeightDatum {
    weight: number;
}

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

function generateDemoData(): WeightDatum[] {
    const results: WeightDatum[] = [];
    for (let i = 0; i < 80; i++) {
        // Normal distribution approximation
        const weight = 65 + (Math.sin(i) + Math.cos(i * 1.5) + Math.sin(i * 0.7)) * 12;
        results.push({ weight });
    }
    return results;
}

function shadcnTooltipContent<TDatum>(points: readonly ChartPoint<TDatum>[]) {
    if (points.length === 0) return { title: "", rows: [] };
    const p = points[0];
    const d = p.datum as any;
    if (!d) return { title: "", rows: [] };
    return {
        title: `Weight Range: ${d.x1.toFixed(1)} – ${d.x2.toFixed(1)} kg`,
        rows: [
            {
                label: "Cumulative Total",
                value: `${d.cumulativeCount} subjects`,
                color: "var(--chart-1)",
            },
        ],
    };
}

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

    const cumulativeBins = useMemo(() => {
        const bins = binX(data, {
            value: "weight",
            thresholds: thresholdScott,
            outputs: { count: { reduce: "count" } },
        });
        return cumulative(bins, {
            orderBy: "x1",
            outputs: { cumulativeCount: { value: "count", reduce: "sum" } },
        });
    }, [data]);

    const definition = useMemo(
        () =>
            defineChart(
                {
                    renderer: motionRenderer,
                    marks: [
                        rect(cumulativeBins, {
                            id: "cumulative-rects",
                            x1: "x1",
                            x2: "x2",
                            y1: () => 0,
                            y2: "cumulativeCount",
                            fill: "var(--chart-1)",
                            inset: 1,
                        }),
                    ],
                    scales: {
                        x: {
                            scale: scaleLinear,
                            grid: true,
                            axis: {
                                line: false,
                                label: "Weight (kg)",
                                ticks: { size: 0 },
                            },
                        },
                        y: {
                            scale: scaleLinear,
                            grid: true,
                            axis: {
                                line: false,
                                label: "Cumulative Count",
                                ticks: { size: 0 },
                            },
                        },
                    },
                    margin: { top: 24, right: 24, bottom: 32, left: 45 },
                    theme: {
                        foreground: "var(--muted-foreground)",
                        grid: "var(--border)",
                        background: "transparent",
                    },
                },
                {
                    focus: "group-x",
                    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),
                    },
                },
            ),
        [cumulativeBins],
    );

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Cumulative Population Distribution</CardTitle>
                <CardDescription>Binned cumulative frequency histogram of subject body weights</CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Cumulative Population Distribution Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    80% of cohort falls below 78kg weight threshold <BarChart2 className="h-4 w-4 text-cyan-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    Bar height reflects total cumulative count up to each bin upper bound
                </div>
            </CardFooter>
        </Card>
    );
}

export default CumulativeHistogram;