Area Chart New

import { useId, useState, type KeyboardEvent, type PointerEvent } from 'react';
import { ChartFrame, Legend, SERIES_COLORS, Segmented, Tooltip, fmt, niceMax, scale, smoothPath, useInView, useToggleSet, useWidth } from './chart-utils';

export type AreaSeries = { name: string; color?: string; values: number[] };

export type AreaChartProps = {
  labels: string[];
  series: AreaSeries[];
  mode?: 'stacked' | 'overlay';
  height?: number;
};

const PAD = { t: 12, r: 12, b: 26, l: 40 };

export function AreaChart({ labels, series, mode = 'stacked', height = 260 }: AreaChartProps) {
  const uid = useId().replace(/:/g, '');
  const { ref: wrap, w } = useWidth<HTMLDivElement>();
  const { ref: view, seen } = useInView<HTMLDivElement>();
  const { hidden, toggle } = useToggleSet();
  const [hover, setHover] = useState<number | null>(null);

  const colored = series.map((s, i) => ({ ...s, color: s.color ?? SERIES_COLORS[i % SERIES_COLORS.length] }));
  const visible = colored.filter((s) => !hidden.has(s.name));
  const n = labels.length;

  // Cumulative baselines for stacked mode.
  const bases: number[][] = [];
  const tops: number[][] = [];
  visible.forEach((s, si) => {
    const base = mode === 'stacked' && si > 0 ? tops[si - 1] : new Array(n).fill(0);
    bases.push(base);
    tops.push(s.values.map((v, i) => base[i] + v));
  });
  const max = niceMax(Math.max(1, ...tops.flat()));
  const x = scale(0, n - 1, PAD.l, w - PAD.r);
  const y = scale(0, max, height - PAD.b, PAD.t);
  const labelEvery = Math.ceil(n / Math.max(2, Math.floor(w / 70)));

  const pick = (clientX: number, el: Element) => {
    const r = el.getBoundingClientRect();
    setHover(Math.max(0, Math.min(n - 1, Math.round(((clientX - r.left - PAD.l) / (w - PAD.l - PAD.r)) * (n - 1)))));
  };
  const onKey = (e: KeyboardEvent) => {
    if (e.key === 'ArrowRight') setHover((h) => Math.min(n - 1, (h ?? -1) + 1));
    else if (e.key === 'ArrowLeft') setHover((h) => Math.max(0, (h ?? n) - 1));
    else if (e.key === 'Escape') setHover(null);
  };

  return (
    <div ref={view} className="space-y-3">
      <Legend items={colored} hidden={hidden} onToggle={toggle} />
      <div ref={wrap} className="relative w-full">
        <svg
          width={w}
          height={height}
          className="block touch-pan-y outline-none"
          tabIndex={0}
          role="img"
          aria-label={`${mode === 'stacked' ? 'Stacked' : 'Overlaid'} area chart. Use arrow keys to read values.`}
          onPointerMove={(e: PointerEvent<SVGSVGElement>) => pick(e.clientX, e.currentTarget)}
          onPointerLeave={() => setHover(null)}
          onKeyDown={onKey}
          onBlur={() => setHover(null)}
        >
          <defs>
            {visible.map((s, i) => (
              <linearGradient key={s.name} id={`${uid}-g${i}`} x1="0" y1="0" x2="0" y2="1">
                <stop offset="0%" stopColor={s.color} stopOpacity={mode === 'stacked' ? 0.55 : 0.35} />
                <stop offset="100%" stopColor={s.color} stopOpacity={mode === 'stacked' ? 0.15 : 0.02} />
              </linearGradient>
            ))}
            <clipPath id={`${uid}-reveal`}>
              <rect x={0} y={0} height={height} style={{ width: seen ? w : 0, transition: 'width 1.3s cubic-bezier(0.16,1,0.3,1)' }} />
            </clipPath>
          </defs>
          {[0, 0.25, 0.5, 0.75, 1].map((f) => (
            <g key={f}>
              <line x1={PAD.l} x2={w - PAD.r} y1={y(f * max)} y2={y(f * max)} stroke="rgba(255,255,255,0.06)" strokeDasharray={f ? '3 4' : undefined} />
              <text x={PAD.l - 8} y={y(f * max)} dy="0.32em" textAnchor="end" className="fill-ink-500 font-mono text-[10px]">
                {fmt(f * max)}
              </text>
            </g>
          ))}
          {labels.map((l, i) =>
            i % labelEvery === 0 ? (
              <text key={i} x={x(i)} y={height - 6} textAnchor="middle" className="fill-ink-500 font-mono text-[10px]">
                {l}
              </text>
            ) : null,
          )}
          <g clipPath={`url(#${uid}-reveal)`}>
            {visible.map((s, si) => {
              const top = tops[si].map((v, i) => [x(i), y(v)] as [number, number]);
              const bot = bases[si].map((v, i) => [x(i), y(v)] as [number, number]).reverse();
              const topPath = smoothPath(top);
              const botPath = smoothPath(bot).replace(/^M/, 'L');
              return (
                <g key={s.name}>
                  <path d={`${topPath} ${botPath} Z`} fill={`url(#${uid}-g${si})`} className="transition-all duration-500" />
                  <path d={topPath} fill="none" stroke={s.color} strokeWidth={1.8} />
                </g>
              );
            })}
          </g>
          {hover !== null && (
            <g>
              <line x1={x(hover)} x2={x(hover)} y1={PAD.t} y2={height - PAD.b} stroke="rgba(255,255,255,0.18)" strokeDasharray="3 3" />
              {visible.map((s, si) => (
                <circle key={s.name} cx={x(hover)} cy={y(tops[si][hover])} r={4} fill="#0b0c0e" stroke={s.color} strokeWidth={2} />
              ))}
            </g>
          )}
        </svg>
        {hover !== null && visible.length > 0 && (
          <Tooltip x={x(hover)} y={y(Math.max(...tops.map((t) => t[hover])))} w={w}>
            <p className="mb-1 font-mono text-[10px] text-ink-400">{labels[hover]}</p>
            {[...visible].reverse().map((s) => (
              <p key={s.name} className="flex items-center gap-2 whitespace-nowrap text-ink-100">
                <span className="h-1.5 w-1.5 rounded-full" style={{ background: s.color }} />
                <span className="text-ink-400">{s.name}</span>
                <span className="ml-auto pl-3 font-mono tabular-nums">{s.values[hover].toLocaleString('en-US')}</span>
              </p>
            ))}
            {mode === 'stacked' && (
              <p className="mt-1 flex justify-between border-t border-white/10 pt-1 text-ink-300">
                Total <span className="font-mono tabular-nums text-ink-50">{visible.reduce((a, s) => a + s.values[hover], 0).toLocaleString('en-US')}</span>
              </p>
            )}
          </Tooltip>
        )}
      </div>
    </div>
  );
}

const MONTHS = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
const SERIES: AreaSeries[] = [
  { name: 'Organic', values: [3200, 3600, 3400, 4100, 4600, 4400, 5200, 5600, 5300, 6100, 6600, 7200] },
  { name: 'Paid', values: [1800, 2100, 2600, 2400, 2900, 3300, 3100, 3600, 4000, 3800, 4300, 4700] },
  { name: 'Referral', values: [900, 1100, 1000, 1400, 1300, 1700, 1900, 1800, 2200, 2500, 2400, 2800] },
];

export function AreaChartDemo() {
  const [mode, setMode] = useState<'Stacked' | 'Overlay'>('Stacked');
  return (
    <ChartFrame title="Visitors by channel" sub="Monthly unique visitors, 2026" right={<Segmented value={mode} options={['Stacked', 'Overlay']} onChange={setMode} />}>
      <AreaChart labels={MONTHS} series={SERIES} mode={mode === 'Stacked' ? 'stacked' : 'overlay'} />
    </ChartFrame>
  );
}

import { useEffect, useRef, useState, type ReactNode } from 'react';
import { cn } from '@/lib/cn';

export const SERIES_COLORS = ['#38bdf8', '#a78bfa', '#34d399', '#fbbf24', '#f472b6'];

export const reducedMotion = () => typeof window !== 'undefined' && window.matchMedia('(prefers-reduced-motion: reduce)').matches;

/** Becomes true once the element scrolls into view (or immediately under reduced motion). */
export function useInView<T extends Element>(threshold = 0.25) {
  const ref = useRef<T>(null);
  const [seen, setSeen] = useState(false);
  useEffect(() => {
    if (reducedMotion()) return setSeen(true);
    const el = ref.current;
    if (!el) return;
    const io = new IntersectionObserver(([e]) => e.isIntersecting && (setSeen(true), io.disconnect()), { threshold });
    io.observe(el);
    return () => io.disconnect();
  }, [threshold]);
  return { ref, seen };
}

/** Tracks the rendered width of an element so SVG charts can draw at true pixel size. */
export function useWidth<T extends Element>(fallback = 600) {
  const ref = useRef<T>(null);
  const [w, setW] = useState(fallback);
  useEffect(() => {
    const el = ref.current;
    if (!el) return;
    const ro = new ResizeObserver(([e]) => setW(Math.max(200, Math.round(e.contentRect.width))));
    ro.observe(el);
    return () => ro.disconnect();
  }, []);
  return { ref, w };
}

export const scale = (d0: number, d1: number, r0: number, r1: number) => (v: number) => r0 + ((v - d0) / (d1 - d0 || 1)) * (r1 - r0);

/** Nice upper bound for an axis. */
export function niceMax(v: number) {
  if (v <= 0) return 1;
  const p = Math.pow(10, Math.floor(Math.log10(v)));
  const n = v / p;
  return (n <= 1 ? 1 : n <= 2 ? 2 : n <= 2.5 ? 2.5 : n <= 5 ? 5 : 10) * p;
}

/** Smooth monotone-ish path through points (Catmull-Rom → Bézier, tension 0.5). */
export function smoothPath(pts: [number, number][]) {
  if (pts.length < 2) return '';
  let d = `M${pts[0][0]},${pts[0][1]}`;
  for (let i = 0; i < pts.length - 1; i++) {
    const p0 = pts[i - 1] ?? pts[i];
    const p1 = pts[i];
    const p2 = pts[i + 1];
    const p3 = pts[i + 2] ?? p2;
    const c1x = p1[0] + (p2[0] - p0[0]) / 6;
    const c1y = p1[1] + (p2[1] - p0[1]) / 6;
    const c2x = p2[0] - (p3[0] - p1[0]) / 6;
    const c2y = p2[1] - (p3[1] - p1[1]) / 6;
    d += ` C${c1x},${c1y} ${c2x},${c2y} ${p2[0]},${p2[1]}`;
  }
  return d;
}

export const fmt = (v: number, prefix = '') => prefix + (Math.abs(v) >= 1000 ? (v / 1000).toFixed(v >= 10000 ? 0 : 1) + 'k' : String(Math.round(v)));

export function Legend({ items, hidden, onToggle }: { items: { name: string; color: string }[]; hidden: Set<string>; onToggle: (name: string) => void }) {
  return (
    <div className="flex flex-wrap gap-1.5">
      {items.map((s) => {
        const off = hidden.has(s.name);
        return (
          <button
            key={s.name}
            onClick={() => onToggle(s.name)}
            aria-pressed={!off}
            className={cn('focus-ring flex items-center gap-1.5 rounded-full border px-2.5 py-1 text-xs transition-all', off ? 'border-white/5 text-ink-500' : 'border-white/10 bg-white/[0.03] text-ink-200 hover:bg-white/[0.06]')}
          >
            <span className="h-2 w-2 rounded-full transition-opacity" style={{ background: s.color, opacity: off ? 0.3 : 1 }} />
            {s.name}
          </button>
        );
      })}
    </div>
  );
}

export function useToggleSet() {
  const [hidden, setHidden] = useState<Set<string>>(new Set());
  const toggle = (k: string) =>
    setHidden((h) => {
      const n = new Set(h);
      if (n.has(k)) n.delete(k);
      else n.add(k);
      return n;
    });
  return { hidden, toggle };
}

export function Tooltip({ x, y, w, children }: { x: number; y: number; w: number; children: ReactNode }) {
  const left = Math.min(Math.max(x, 70), w - 70);
  return (
    <div className="pointer-events-none absolute z-10 -translate-x-1/2 -translate-y-full rounded-xl border border-white/10 bg-ink-850/95 px-3 py-2 text-xs shadow-pop backdrop-blur" style={{ left, top: y - 10 }}>
      {children}
    </div>
  );
}

export function Segmented<T extends string>({ value, options, onChange }: { value: T; options: T[]; onChange: (v: T) => void }) {
  return (
    <div className="flex rounded-lg bg-white/[0.04] p-0.5 ring-1 ring-white/5">
      {options.map((o) => (
        <button key={o} onClick={() => onChange(o)} className={cn('focus-ring rounded-md px-2.5 py-1 text-xs font-medium transition-all', value === o ? 'bg-ink-800 text-ink-50 shadow-hairline' : 'text-ink-400 hover:text-ink-200')}>
          {o}
        </button>
      ))}
    </div>
  );
}

export function ChartFrame({ title, sub, right, children, className }: { title: string; sub?: ReactNode; right?: ReactNode; children: ReactNode; className?: string }) {
  return (
    <div className={cn('w-full rounded-2xl bg-ink-900 p-4 shadow-card sm:p-5', className)}>
      <div className="mb-4 flex flex-wrap items-start justify-between gap-3">
        <div className="min-w-0">
          <p className="text-sm font-medium text-ink-100">{title}</p>
          {sub && <div className="mt-0.5 text-xs text-ink-500">{sub}</div>}
        </div>
        {right}
      </div>
      {children}
    </div>
  );
}