"use client";

import { useEffect, useId, useRef, type ElementType, type PointerEvent, type ReactNode } from "react";
import { animate, motion, useInView, useReducedMotion } from "motion/react";

export type StatsShowcaseStat = {
  label: string;
  value: number;
  /** Goes before the number, such as $. */
  prefix?: string;
  /** Goes after the number, such as %. */
  suffix?: string;
  /** Small line under the number. */
  note?: string;
  /** Small chart under the number, oldest first. Two values or more. */
  trend?: number[];
};

type StatsShowcaseProps = {
  stats: StatsShowcaseStat[];
  title: string;
  /** Small line above the title. */
  eyebrow?: string;
  subtitle?: string;
  /** Goes under the numbers: a link or a button. */
  children?: ReactNode;
  /** Colour of the charts, the notes and the light on the lines. */
  color?: string;
  /** Tile colour. */
  tile?: string;
  /** Size of the light that follows the pointer, in px. */
  reach?: number;
  /** h2 by default. */
  headingAs?: ElementType;
  /** Set padding and colours here. */
  className?: string;
};

const EASE = [0.16, 1, 0.3, 1] as const;

const places = (value: number) => (String(value).split(".")[1] ?? "").length;
const format = (value: number, digits: number) => value.toLocaleString("en-US", { minimumFractionDigits: digits, maximumFractionDigits: digits });

function Count({ stat, start, delay }: { stat: StatsShowcaseStat; start: boolean; delay: number }) {
  const number = useRef<HTMLSpanElement>(null);
  useEffect(() => {
    const el = number.current;
    if (!el || window.matchMedia("(prefers-reduced-motion: reduce)").matches) return;
    const digits = places(stat.value);
    el.textContent = format(0, digits);
    if (!start) return;
    const run = animate(0, stat.value, {
      duration: 1.6,
      delay,
      ease: EASE,
      onUpdate: (now) => {
        el.textContent = format(now, digits);
      },
    });
    return () => run.stop();
  }, [stat.value, start, delay]);
  return (
    <>
      {stat.prefix}
      <span ref={number}>{format(stat.value, places(stat.value))}</span>
      {stat.suffix}
    </>
  );
}

function Trend({ stat, color, start, delay, instant }: { stat: StatsShowcaseStat; color: string; start: boolean; delay: number; instant: boolean }) {
  const trend = stat.trend ?? [];
  const low = Math.min(...trend);
  const span = Math.max(...trend) - low || 1;
  const line = trend.map((value, i) => `${i ? "L" : "M"}${((i / (trend.length - 1)) * 100).toFixed(2)} ${(22 - ((value - low) / span) * 20).toFixed(2)}`).join(" ");
  return (
    <motion.div
      className="mt-4 h-8"
      initial={{ clipPath: "inset(-10% 100% -10% 0%)" }}
      animate={{ clipPath: start ? "inset(-10% 0% -10% 0%)" : "inset(-10% 100% -10% 0%)" }}
      transition={{ duration: instant ? 0 : 1.4, delay: instant ? 0 : delay + 0.2, ease: "easeInOut" }}
    >
      <svg role="img" aria-label={`${stat.label} trend: from ${trend[0]} to ${trend[trend.length - 1]}`} viewBox="0 0 100 24" preserveAspectRatio="none" className="size-full overflow-visible">
        <path d={line} fill="none" stroke={color} strokeWidth="1.5" strokeLinejoin="round" strokeLinecap="round" vectorEffect="non-scaling-stroke" />
      </svg>
    </motion.div>
  );
}

/* StatsShowcase: big proof numbers in a lit grid. Numbers count up when the section scrolls in, small charts draw themselves, and the grid lines glow near the pointer. */
export function StatsShowcase({
  stats,
  title,
  eyebrow,
  subtitle,
  children,
  color = "#a78bfa",
  tile = "#15122a",
  reach = 280,
  headingAs: Heading = "h2",
  className = "bg-[#0b0a14] px-5 py-16 text-white",
}: StatsShowcaseProps) {
  const reduce = useReducedMotion();
  const id = useId();
  const section = useRef<HTMLElement>(null);
  const grid = useRef<HTMLDivElement>(null);
  const inView = useInView(section, { once: true, amount: 0.15 });
  const instant = Boolean(reduce);

  const move = (e: PointerEvent) => {
    const box = grid.current?.getBoundingClientRect();
    if (e.pointerType !== "mouse" || !box) return;
    grid.current?.style.setProperty("--ss-x", `${e.clientX - box.left}px`);
    grid.current?.style.setProperty("--ss-y", `${e.clientY - box.top}px`);
  };

  const rise = (delay: number) => ({
    initial: instant ? { opacity: 0 } : { opacity: 0, y: 20 },
    animate: inView ? { opacity: 1, y: 0 } : undefined,
    transition: { duration: instant ? 0.3 : 0.7, delay: instant ? 0 : delay, ease: EASE },
  });

  return (
    <section ref={section} aria-labelledby={id} className={`@container ${className}`}>
      <div className="mx-auto max-w-6xl">
        <motion.div {...rise(0)} className="max-w-2xl">
          {eyebrow && <p className="mb-3 text-xs font-medium tracking-[0.2em] uppercase opacity-70 @2xl:text-sm">{eyebrow}</p>}
          <Heading id={id} className="text-[clamp(1.6rem,7cqw,2.75rem)] leading-[1.08] font-semibold tracking-tight text-balance">
            {title}
          </Heading>
          {subtitle && <p className="mt-3 text-sm text-pretty opacity-70 @2xl:text-lg">{subtitle}</p>}
        </motion.div>

        <div ref={grid} onPointerMove={move} className="group relative mt-8 overflow-hidden rounded-2xl bg-current/10 @2xl:mt-12">
          <span
            aria-hidden
            className="absolute inset-0 opacity-0 transition-opacity duration-300 pointer-fine:group-hover:opacity-100"
            style={{ backgroundImage: `radial-gradient(${reach}px at var(--ss-x, 50%) var(--ss-y, 50%), ${color}, transparent)` }}
          />
          <dl className="relative flex flex-wrap gap-px p-px">
            {stats.map((stat, i) => {
              const delay = 0.1 + i * 0.1;
              return (
                <div key={stat.label} className="min-w-0 flex-1 basis-52 p-5 @2xl:p-7" style={{ backgroundColor: `color-mix(in srgb, ${tile} 94%, transparent)` }}>
                  <motion.div {...rise(delay)}>
                    <dt className="text-sm opacity-70">{stat.label}</dt>
                    <dd className="mt-2 text-[clamp(2.25rem,7cqw,3.5rem)] leading-none font-semibold tracking-tight tabular-nums">
                      <Count stat={stat} start={inView} delay={delay} />
                    </dd>
                    {stat.note && (
                      <dd className="mt-2 text-sm" style={{ color }}>
                        {stat.note}
                      </dd>
                    )}
                    {stat.trend && stat.trend.length > 1 && (
                      <dd>
                        <Trend stat={stat} color={color} start={inView} delay={delay} instant={instant} />
                      </dd>
                    )}
                  </motion.div>
                </div>
              );
            })}
          </dl>
        </div>

        {children && (
          <motion.div {...rise(0.2 + stats.length * 0.1)} className="mt-8 flex flex-wrap gap-3">
            {children}
          </motion.div>
        )}
      </div>
    </section>
  );
}