Indexed Multi Line

import { type ChartPoint, defineChart, lineY, normalize, ruleY, select, 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, scaleUtc } from "d3-scale";
import { TrendingUp } from "lucide-react";

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

interface IndustryDatum {
    industry: string;
    date: Date;
    unemployed: number;
    indexed?: number;
}

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

const industryList = ["Construction", "Finance", "Government", "Manufacturing"];

function generateDemoData(): IndustryDatum[] {
    const results: IndustryDatum[] = [];
    const months = 24;

    industryList.forEach((ind, i) => {
        let baseVal = 100 + i * 20;
        for (let m = 0; m < months; m++) {
            const date = new Date(Date.UTC(2023, m, 1));
            const change = (Math.random() - 0.45) * 8 + m * 1.5 * (i % 2 === 0 ? 1 : -0.5);
            baseVal = Math.max(50, baseVal + change);
            results.push({
                industry: ind,
                date,
                unemployed: baseVal,
            });
        }
    });

    return results;
}

function shadcnTooltipContent<TDatum>(points: readonly ChartPoint<TDatum>[]) {
    if (points.length === 0) return { title: "", rows: [] };
    const d = points[0].datum as IndustryDatum;
    if (!d || !d.date || d.indexed === undefined) return { title: "", rows: [] };
    const dateObj = d.date instanceof Date ? d.date : new Date(d.date);
    const dateStr = isNaN(dateObj.getTime())
        ? ""
        : dateObj.toLocaleDateString("en-US", { month: "short", year: "numeric", timeZone: "UTC" });
    const pctChange = ((d.indexed - 1) * 100).toFixed(1);
    const sign = Number(pctChange) >= 0 ? "+" : "";
    return {
        title: `${d.industry}${dateStr ? ` (${dateStr})` : ""}`,
        rows: [{ label: "Change from Baseline", value: `${sign}${pctChange}%`, color: "var(--chart-1)" }],
    };
}

export function IndexedMultiLine() {
    const rawData = useMemo(() => generateDemoData(), []);

    const rows = useMemo(() => {
        return normalize(
            [...rawData].sort((a, b) => {
                const aTime = a.date ? (a.date instanceof Date ? a.date.getTime() : new Date(a.date).getTime()) : 0;
                const bTime = b.date ? (b.date instanceof Date ? b.date.getTime() : new Date(b.date).getTime()) : 0;
                return aTime - bTime;
            }),
            {
                value: "unemployed",
                by: "industry",
                basis: "first",
                as: "indexed",
            },
        );
    }, [rawData]);

    const labels = useMemo(() => {
        return select(rows, {
            by: "industry",
            value: (datum: IndustryDatum) =>
                datum?.date ? (datum.date instanceof Date ? datum.date.getTime() : new Date(datum.date).getTime()) : 0,
            select: "max",
        });
    }, [rows]);

    const definition = useMemo(
        () =>
            defineChart(
                {
                    renderer: motionRenderer,
                    marks: [
                        ruleY([1], { stroke: "var(--border)", strokeOpacity: 0.8, strokeDasharray: "4 4" }),
                        lineY(rows, {
                            id: "indexed-lines",
                            x: "date",
                            y: "indexed",
                            color: "industry",
                            strokeWidth: 2.25,
                        }),
                        text(labels, {
                            id: "end-labels",
                            x: "date",
                            y: "indexed",
                            text: "industry",
                            color: "industry",
                            anchor: "start",
                            dx: 6,
                            fontSize: 10,
                            fontWeight: 600,
                        }),
                    ],
                    scales: {
                        x: { scale: scaleUtc, axis: { label: "Timeline Month" } },
                        y: {
                            scale: scaleLinear,
                            grid: true,
                            axis: {
                                ticks: { format: (v: number) => `${Math.round((v - 1) * 100)}%` },
                                label: "Percentage Change relative to Baseline",
                            },
                        },
                    },
                    color: {
                        domain: industryList,
                        range: ["var(--chart-1)", "var(--chart-2)", "var(--chart-3)", "var(--chart-4)"],
                    },
                    margin: { top: 24, right: 90, 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),
                    },
                },
            ),
        [rows, labels],
    );

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Indexed Multi-Series Performance Line</CardTitle>
                <CardDescription>Normalized multi-line comparison relative to 100% baseline start</CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Indexed Multi-Series Performance Line Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    Construction shows highest positive divergence from baseline{" "}
                    <TrendingUp className="h-4 w-4 text-emerald-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    Dashed horizontal rule indicates 0% net change initial baseline value
                </div>
            </CardFooter>
        </Card>
    );
}

export default IndexedMultiLine;