"use client";

/**
 * VerifyFlow, from https://motion-brew.com/components/verify-flow
 *
 * One self contained file: the component, its animated icons and the cn()
 * helper. Needs React 18 or 19 and Tailwind CSS v4.
 *
 * The animated icons are adapted from lucide-animated (https://lucide-animated.com),
 * MIT License, Copyright (c) 2024-2026 pqoqubbw. Icon shapes from Lucide
 * (https://lucide.dev), ISC License. Permission is hereby granted, free of
 * charge, to any person obtaining a copy of this software, to deal in it
 * without restriction, provided the above copyright notice and this
 * permission notice are included in all copies or substantial portions.
 */

import * as React from "react";
import { forwardRef, useCallback, useEffect, useImperativeHandle, useRef, useState } from "react";
import { useGSAP } from "@gsap/react";
import { type ClassValue, clsx } from "clsx";
import gsap from "gsap";
import { ArrowRight } from "lucide-react";
import { AnimatePresence, motion, useAnimation, useReducedMotion, type Variants } from "motion/react";
import { twMerge } from "tailwind-merge";

// cn(): merges Tailwind classes, later ones win.
/** Merge Tailwind classes, letting later classes win conflicts. */
function cn(...inputs: ClassValue[]): string {
  return twMerge(clsx(inputs));
}

// Animated icon: github
const GithubIcon = (() => {
interface GithubIconHandle {
  startAnimation: () => void;
  stopAnimation: () => void;
}

interface GithubIconProps extends React.HTMLAttributes<HTMLSpanElement> {
  /** Size in px; by default it follows className, like a lucide icon. */
  size?: number;
  /** Play while true; when set, hover no longer drives it. */
  active?: boolean;
  /** Line weight, like a lucide icon's. Default `2`. */
  strokeWidth?: number | string;
}

const BODY_VARIANTS: Variants = {
  normal: {
    opacity: 1,
    pathLength: 1,
    scale: 1,
    transition: {
      duration: 0.3,
    },
  },
  animate: {
    opacity: [0, 1],
    pathLength: [0, 1],
    scale: [0.9, 1],
    transition: {
      duration: 0.4,
    },
  },
};

const TAIL_VARIANTS: Variants = {
  normal: {
    pathLength: 1,
    rotate: 0,
    transition: {
      duration: 0.3,
    },
  },
  draw: {
    pathLength: [0, 1],
    rotate: 0,
    transition: {
      duration: 0.5,
    },
  },
  wag: {
    pathLength: 1,
    rotate: [0, -15, 15, -10, 10, -5, 5],
    transition: {
      duration: 2.5,
      ease: "easeInOut",
      repeat: Number.POSITIVE_INFINITY,
    },
  },
};

const GithubIcon = forwardRef<GithubIconHandle, GithubIconProps>(
  ({ onMouseEnter, onMouseLeave, className, size, active, style, strokeWidth, ...props }, ref) => {
    const bodyControls = useAnimation();
    const tailControls = useAnimation();
    const isControlledRef = useRef(false);

    useImperativeHandle(ref, () => {
      isControlledRef.current = true;

      return {
        startAnimation: async () => {
          bodyControls.start("animate");
          await tailControls.start("draw");
          tailControls.start("wag");
        },
        stopAnimation: () => {
          bodyControls.start("normal");
          tailControls.start("normal");
        },
      };
    });

    const handleMouseEnter = useCallback(
      async (e: React.MouseEvent<HTMLSpanElement>) => {
        if (isControlledRef.current) {
          onMouseEnter?.(e);
        } else {
          bodyControls.start("animate");
          await tailControls.start("draw");
          tailControls.start("wag");
        }
      },
      [bodyControls, onMouseEnter, tailControls]
    );

    const handleMouseLeave = useCallback(
      (e: React.MouseEvent<HTMLSpanElement>) => {
        if (isControlledRef.current) {
          onMouseLeave?.(e);
        } else {
          bodyControls.start("normal");
          tailControls.start("normal");
        }
      },
      [bodyControls, tailControls, onMouseLeave]
    );
    // Play with the nearest interactive parent, or whenever `active` is set.
    // Reduced motion keeps the icon still.
    const wrap = useRef<HTMLSpanElement>(null);
    const reduced = useReducedMotion();
    const [hosted, setHosted] = useState(false);
    useEffect(() => {
      const fake = {} as React.MouseEvent<HTMLSpanElement>;
      if (reduced) {
        setHosted(true);
        return;
      }
      if (active !== undefined) {
        setHosted(true);
        (active ? handleMouseEnter : handleMouseLeave)(fake);
        return;
      }
      const host = wrap.current?.parentElement?.closest<HTMLElement>("button, a, [role=button], [role=menuitem], [role=tab], [role=switch], [role=radio], label");
      setHosted(!!host);
      if (!host) return;
      const on = () => handleMouseEnter(fake);
      const off = () => handleMouseLeave(fake);
      host.addEventListener("pointerenter", on);
      host.addEventListener("pointerleave", off);
      return () => {
        host.removeEventListener("pointerenter", on);
        host.removeEventListener("pointerleave", off);
      };
    }, [active, reduced, handleMouseEnter, handleMouseLeave]);

    return (
      <span
        ref={wrap}
        className={cn("inline-grid size-6 shrink-0 place-items-center align-middle [&>svg]:size-full", className)}
        style={size ? { width: size, height: size, ...style } : style}
        onMouseEnter={hosted ? undefined : handleMouseEnter}
        onMouseLeave={hosted ? undefined : handleMouseLeave}
        {...props}
      >
        <svg
          fill="none"
          height={size}
          stroke="currentColor"
          strokeLinecap="round"
          strokeLinejoin="round"
          strokeWidth={strokeWidth ?? 2}
          viewBox="0 0 24 24"
          width={size}
          xmlns="http://www.w3.org/2000/svg"
        >
          <motion.path
            animate={bodyControls}
            d="M15 22v-4a4.8 4.8 0 0 0-1-3.5c3 0 6-2 6-5.5.08-1.25-.27-2.48-1-3.5.28-1.15.28-2.35 0-3.5 0 0-1 0-3 1.5-2.64-.5-5.36-.5-8 0C6 2 5 2 5 2c-.3 1.15-.3 2.35 0 3.5A5.403 5.403 0 0 0 4 9c0 3.5 3 5.5 6 5.5-.39.49-.68 1.05-.85 1.65-.17.6-.22 1.23-.15 1.85v4"
            initial="normal"
            variants={BODY_VARIANTS}
          />
          <motion.path
            animate={tailControls}
            d="M9 18c-4.51 2-5-2-7-2"
            initial="normal"
            variants={TAIL_VARIANTS}
          />
        </svg>
      </span>
    );
  }
);

GithubIcon.displayName = "GithubIcon";
  return GithubIcon;
})();

// Animated icon: lock-keyhole
const LockKeyholeIcon = (() => {
interface LockKeyholeIconHandle {
  startAnimation: () => void;
  stopAnimation: () => void;
}

interface LockKeyholeIconProps extends React.HTMLAttributes<HTMLSpanElement> {
  /** Size in px; by default it follows className, like a lucide icon. */
  size?: number;
  /** Play while true; when set, hover no longer drives it. */
  active?: boolean;
  /** Line weight, like a lucide icon's. Default `2`. */
  strokeWidth?: number | string;
}

const LockKeyholeIcon = forwardRef<LockKeyholeIconHandle, LockKeyholeIconProps>(
  ({ onMouseEnter, onMouseLeave, className, size, active, style, strokeWidth, ...props }, ref) => {
    const controls = useAnimation();
    const isControlledRef = useRef(false);

    useImperativeHandle(ref, () => {
      isControlledRef.current = true;

      return {
        startAnimation: () => controls.start("animate"),
        stopAnimation: () => controls.start("normal"),
      };
    });

    const handleMouseEnter = useCallback(
      (e: React.MouseEvent<HTMLSpanElement>) => {
        if (isControlledRef.current) {
          onMouseEnter?.(e);
        } else {
          controls.start("animate");
        }
      },
      [controls, onMouseEnter]
    );

    const handleMouseLeave = useCallback(
      (e: React.MouseEvent<HTMLSpanElement>) => {
        if (isControlledRef.current) {
          onMouseLeave?.(e);
        } else {
          controls.start("normal");
        }
      },
      [controls, onMouseLeave]
    );
    // Play with the nearest interactive parent, or whenever `active` is set.
    // Reduced motion keeps the icon still.
    const wrap = useRef<HTMLSpanElement>(null);
    const reduced = useReducedMotion();
    const [hosted, setHosted] = useState(false);
    useEffect(() => {
      const fake = {} as React.MouseEvent<HTMLSpanElement>;
      if (reduced) {
        setHosted(true);
        return;
      }
      if (active !== undefined) {
        setHosted(true);
        (active ? handleMouseEnter : handleMouseLeave)(fake);
        return;
      }
      const host = wrap.current?.parentElement?.closest<HTMLElement>("button, a, [role=button], [role=menuitem], [role=tab], [role=switch], [role=radio], label");
      setHosted(!!host);
      if (!host) return;
      const on = () => handleMouseEnter(fake);
      const off = () => handleMouseLeave(fake);
      host.addEventListener("pointerenter", on);
      host.addEventListener("pointerleave", off);
      return () => {
        host.removeEventListener("pointerenter", on);
        host.removeEventListener("pointerleave", off);
      };
    }, [active, reduced, handleMouseEnter, handleMouseLeave]);

    return (
      <span
        ref={wrap}
        className={cn("inline-grid size-6 shrink-0 place-items-center align-middle [&>svg]:size-full", className)}
        style={size ? { width: size, height: size, ...style } : style}
        onMouseEnter={hosted ? undefined : handleMouseEnter}
        onMouseLeave={hosted ? undefined : handleMouseLeave}
        {...props}
      >
        <motion.svg
          animate={controls}
          fill="none"
          height={size}
          initial="normal"
          stroke="currentColor"
          strokeLinecap="round"
          strokeLinejoin="round"
          strokeWidth={strokeWidth ?? 2}
          transition={{
            duration: 1,
            ease: [0.4, 0, 0.2, 1],
          }}
          variants={{
            normal: {
              rotate: 0,
              scale: 1,
            },
            animate: {
              rotate: [-3, 1, -2, 0],
              scale: [0.95, 1.05, 0.98, 1],
            },
          }}
          viewBox="0 0 24 24"
          width={size}
          xmlns="http://www.w3.org/2000/svg"
        >
          <circle cx="12" cy="16" r="1" />
          <rect height="12" rx="2" width="18" x="3" y="10" />
          <motion.path
            animate={controls}
            d="M7 10V7a5 5 0 0 1 10 0v3"
            initial="normal"
            transition={{
              duration: 0.3,
              ease: [0.4, 0, 0.2, 1],
            }}
            variants={{
              normal: {
                pathLength: 1,
              },
              animate: {
                pathLength: 0.7,
              },
            }}
          />
        </motion.svg>
      </span>
    );
  }
);

LockKeyholeIcon.displayName = "LockKeyholeIcon";
  return LockKeyholeIcon;
})();

// VerifyFlow

/**
 * VerifyFlow
 *
 * Trigger: timeline. A verification card in three stages: connect, check,
 * verified. A segmented progress bar fills as it goes, with a rolling timer
 * underneath. First a provider row waits for sign-in; its button shimmers until
 * pressed. Then the checks run in a soft list: a white highlight slides down to
 * whichever check is running, each row's status rolls from Queued to Checking to
 * Passed, and the header icon spins. Finally the header icon turns into a check
 * with a ring pulse, a green seal spins in with a burst of sparks to show the
 * account connected, and the Continue button counts down
 * with a ring that drains inside it. The card's height glides between stages.
 * Runs as a self-playing demo, or drive it with `stage` and `completed`. Status
 * changes are announced politely. Reduced motion swaps states without travel.
 *
 * Engine: motion/react + gsap (Motion for the height glide, sliding highlight,
 * bar fills, rolling text and press feedback; GSAP via @gsap/react for the
 * button shimmer, spinners, check draws, ring pulse and the countdown ring).
 */

gsap.registerPlugin(useGSAP);

export type VerifyStage = "waiting" | "checking" | "done";

export interface VerifyFlowProps {
  /** Current stage. Leave unset to run the self-playing demo. */
  stage?: VerifyStage;
  /** How many checks have passed (the next one is running). Used with `stage="checking"`. */
  completed?: number;
  /** Checks to run. Default three. */
  checks?: string[];
  /** Card title. Default `"Verify your account"`. */
  title?: string;
  /** Provider shown on the sign-in row. Default `"GitHub"`. */
  provider?: string;
  /** Provider icon. Default the GitHub mark. */
  providerIcon?: React.ReactNode;
  /** Called when the sign-in button is pressed. */
  onSignIn?: () => void;
  /** Where Continue goes, named on the button. Default `"Acme"`. */
  destination?: string;
  /** Seconds before `onContinue` fires on its own. Default `5`. */
  redirectSeconds?: number;
  /** Called from Continue, or when the countdown runs out. */
  onContinue?: () => void;
  /** Demo only: start over after finishing. Default `false`. */
  loop?: boolean;
  /** Color for progress and passed checks. Default a calm green. */
  accent?: string;
  className?: string;
}

const GLIDE = [0.22, 1, 0.36, 1] as const;
const FILL = [0.5, 1, 0.89, 1] as const;
const DEFAULT_CHECKS = ["Account age", "Two-factor enabled", "Public activity"];
const SUBTITLES: Record<VerifyStage, string> = {
  waiting: "Connect an account to start",
  checking: "Running a few quick checks",
  done: "Everything checks out",
};

const fmt = (s: number) =>
  `${String(Math.floor(s / 60)).padStart(2, "0")}:${String(s % 60).padStart(2, "0")}`;

/** Text that rolls up and out of a soft blur whenever it changes. */
function Roll({
  children,
  still,
  className,
}: {
  children: string;
  still: boolean;
  className?: string;
}) {
  return (
    <span className={cn("relative inline-grid overflow-hidden", className)}>
      <AnimatePresence mode="popLayout" initial={false}>
        <motion.span
          key={children}
          initial={
            still
              ? { opacity: 0 }
              : { y: "100%", opacity: 0, filter: "blur(3px)" }
          }
          animate={{ y: 0, opacity: 1, filter: "blur(0px)" }}
          exit={
            still
              ? { opacity: 0 }
              : { y: "-100%", opacity: 0, filter: "blur(3px)" }
          }
          transition={{ duration: still ? 0 : 0.35, ease: GLIDE }}
          className="col-start-1 row-start-1 whitespace-nowrap"
        >
          {children}
        </motion.span>
      </AnimatePresence>
    </span>
  );
}

/** A small arc that spins (GSAP). */
function Spinner({ className, still }: { className?: string; still: boolean }) {
  const ref = React.useRef<SVGSVGElement>(null);
  useGSAP(
    () => {
      if (!still)
        gsap.to(ref.current, {
          rotation: 360,
          duration: 0.8,
          ease: "none",
          repeat: -1,
          transformOrigin: "50% 50%",
        });
    },
    { scope: ref },
  );
  return (
    <svg ref={ref} viewBox="0 0 16 16" className={className} aria-hidden>
      <circle
        cx="8"
        cy="8"
        r="6"
        fill="none"
        stroke="currentColor"
        strokeOpacity="0.18"
        strokeWidth="2"
      />
      <circle
        cx="8"
        cy="8"
        r="6"
        fill="none"
        stroke="currentColor"
        strokeWidth="2"
        strokeLinecap="round"
        pathLength={100}
        strokeDasharray="28 100"
      />
    </svg>
  );
}

/** Header status: lock, then a spinner, then an accent check with a ring pulse. */
function HeaderStatus({
  stage,
  accent,
  still,
}: {
  stage: VerifyStage;
  accent: string;
  still: boolean;
}) {
  const ref = React.useRef<HTMLSpanElement>(null);
  useGSAP(
    () => {
      if (stage !== "done" || still) return;
      gsap.fromTo(
        ref.current!.querySelector(".pulse"),
        { scale: 1, autoAlpha: 0.5 },
        {
          scale: 1.9,
          autoAlpha: 0,
          duration: 0.9,
          ease: "power2.out",
          delay: 0.15,
        },
      );
      gsap.fromTo(
        ref.current!.querySelector(".tick"),
        { strokeDashoffset: 1 },
        {
          strokeDashoffset: 0,
          duration: 0.35,
          ease: "power2.out",
          delay: 0.12,
        },
      );
    },
    { dependencies: [stage], scope: ref },
  );
  return (
    <span
      ref={ref}
      className="relative grid size-9 shrink-0 place-items-center rounded-full text-[#242423] transition-colors duration-500 dark:text-zinc-100"
      style={{ background: stage === "done" ? accent : "rgb(36 36 35 / 0.06)" }}
      aria-hidden
    >
      <span
        className="pulse absolute inset-0 rounded-full opacity-0"
        style={{ background: accent }}
      />
      <AnimatePresence mode="popLayout" initial={false}>
        <motion.span
          key={stage}
          initial={{ opacity: 0, scale: 0.6 }}
          animate={{ opacity: 1, scale: 1 }}
          exit={{ opacity: 0, scale: 0.6 }}
          transition={{ duration: still ? 0 : 0.3, ease: GLIDE }}
          className="relative grid place-items-center"
        >
          {stage === "waiting" && (
            <LockKeyholeIcon className="size-4" strokeWidth={2.25} />
          )}
          {stage === "checking" && <Spinner className="size-4" still={still} />}
          {stage === "done" && (
            <svg viewBox="0 0 16 16" className="size-4">
              <path
                className="tick"
                d="M3.5 8.4l2.8 2.8 6.2-6.4"
                fill="none"
                stroke="#fff"
                strokeWidth="2.2"
                strokeLinecap="round"
                strokeLinejoin="round"
                pathLength={1}
                strokeDasharray="1"
                strokeDashoffset={still ? 0 : 1}
              />
            </svg>
          )}
        </motion.span>
      </AnimatePresence>
    </span>
  );
}

/** Dark pill button with a light shimmer sweeping across it every couple of seconds (GSAP). */
function ShimmerButton({
  children,
  onClick,
  pressed,
  still,
}: {
  children: React.ReactNode;
  onClick?: () => void;
  pressed: boolean;
  still: boolean;
}) {
  const ref = React.useRef<HTMLButtonElement>(null);
  useGSAP(
    () => {
      if (still) return;
      gsap.fromTo(
        ref.current!.querySelector(".sheen"),
        { xPercent: -160 },
        {
          xPercent: 260,
          duration: 1.1,
          ease: "power2.inOut",
          repeat: -1,
          repeatDelay: 1.3,
        },
      );
    },
    { scope: ref },
  );
  return (
    <motion.button
      ref={ref}
      type="button"
      onClick={onClick}
      animate={pressed && !still ? { scale: [1, 0.94, 1] } : { scale: 1 }}
      whileTap={still ? undefined : { scale: 0.94 }}
      transition={{ duration: 0.3, ease: GLIDE }}
      className="relative h-8 shrink-0 cursor-pointer overflow-hidden rounded-full bg-[#242423] px-3.5 text-[12px] font-medium text-white outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 dark:bg-white dark:text-zinc-900"
    >
      <span
        aria-hidden
        className="sheen absolute inset-y-0 left-0 w-1/2 -skew-x-12 bg-gradient-to-r from-transparent via-white/25 to-transparent"
      />
      <span className="relative">{children}</span>
    </motion.button>
  );
}

/** Continue button whose countdown ring drains (GSAP) while the number rolls. */
function ContinueButton({
  label,
  seconds,
  total,
  onClick,
  still,
}: {
  label: string;
  seconds: number;
  total: number;
  onClick?: () => void;
  still: boolean;
}) {
  const ref = React.useRef<HTMLButtonElement>(null);
  useGSAP(
    () => {
      gsap.fromTo(
        ref.current!.querySelector(".ring"),
        { strokeDashoffset: 0 },
        { strokeDashoffset: 1, duration: still ? 0 : total, ease: "none" },
      );
    },
    { scope: ref },
  );
  return (
    <motion.button
      ref={ref}
      type="button"
      onClick={onClick}
      initial="rest"
      whileHover="hover"
      whileTap={still ? undefined : { scale: 0.97 }}
      className="group flex h-12 w-full cursor-pointer items-center justify-between rounded-full bg-[#242423] pl-5 pr-2 text-[14px] font-medium text-white outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 dark:bg-white dark:text-zinc-900"
    >
      <span className="flex items-center gap-2">
        {label}
        <motion.span
          variants={{ rest: { x: 0 }, hover: { x: still ? 0 : 3 } }}
          transition={{ duration: 0.3, ease: GLIDE }}
          className="flex"
        >
          <ArrowRight className="size-4" strokeWidth={2.25} />
        </motion.span>
      </span>
      <span
        className="relative grid size-8 place-items-center text-[12px] tabular-nums"
        aria-label={`${seconds} seconds left`}
      >
        <svg
          viewBox="0 0 32 32"
          className="absolute inset-0 size-full -rotate-90"
          aria-hidden
        >
          <circle
            cx="16"
            cy="16"
            r="13"
            fill="none"
            stroke="currentColor"
            strokeOpacity="0.2"
            strokeWidth="2.5"
          />
          <circle
            className="ring"
            cx="16"
            cy="16"
            r="13"
            fill="none"
            stroke="currentColor"
            strokeWidth="2.5"
            strokeLinecap="round"
            pathLength={1}
            strokeDasharray="1"
          />
        </svg>
        <Roll still={still} className="h-[1.2em] leading-[1.2em]">
          {String(seconds)}
        </Roll>
      </span>
    </motion.button>
  );
}

/** Scalloped seal outline, centred in a 100 by 100 box. */
function sealPath(bumps = 9, depth = 0.085, r = 42) {
  const pts: string[] = [];
  for (let i = 0; i <= 180; i++) {
    const t = (i / 180) * Math.PI * 2;
    const rr = r * (1 + depth * Math.cos(bumps * t));
    pts.push(
      `${(50 + Math.cos(t) * rr).toFixed(2)} ${(50 + Math.sin(t) * rr).toFixed(2)}`,
    );
  }
  return `M${pts.join(" L")}Z`;
}
const SEAL = sealPath();

/** Green seal that spins in, draws its check and bursts sparks, then floats. One GSAP timeline on mount. */
function SuccessSeal({ accent, still }: { accent: string; still: boolean }) {
  const ref = React.useRef<SVGSVGElement>(null);
  useGSAP(
    () => {
      const q = (sel: string) => ref.current!.querySelectorAll(sel);
      if (still) {
        gsap.set(q(".seal-tick"), { strokeDashoffset: 0 });
        return;
      }
      gsap
        .timeline({ delay: 0.15 })
        .from(q(".seal"), {
          scale: 0,
          rotation: -60,
          svgOrigin: "60 60",
          duration: 0.7,
          ease: "back.out(1.9)",
        })
        .to(
          q(".seal-tick"),
          { strokeDashoffset: 0, duration: 0.35, ease: "power2.out" },
          0.32,
        )
        .fromTo(
          q(".spark"),
          {
            autoAlpha: 1,
            attr: { "stroke-dashoffset": 1 },
            scale: 0.6,
            svgOrigin: "60 60",
          },
          {
            attr: { "stroke-dashoffset": 0 },
            scale: 1,
            duration: 0.35,
            ease: "power3.out",
            stagger: 0.02,
          },
          0.28,
        )
        .to(
          q(".spark"),
          {
            autoAlpha: 0,
            scale: 1.18,
            svgOrigin: "60 60",
            duration: 0.45,
            ease: "power2.in",
            stagger: 0.02,
          },
          0.62,
        )
        .fromTo(
          q(".dot"),
          { autoAlpha: 1, scale: 0.3, svgOrigin: "60 60" },
          {
            scale: 1.35,
            autoAlpha: 0,
            duration: 0.9,
            ease: "power2.out",
            stagger: 0.03,
          },
          0.3,
        )
        .to(
          q(".seal-wrap"),
          { y: -3, duration: 1.6, ease: "sine.inOut", repeat: -1, yoyo: true },
          1.1,
        );
    },
    { scope: ref },
  );
  const sparks = Array.from({ length: 8 }, (_, i) => {
    const a = (i / 8) * Math.PI * 2 - Math.PI / 2 + 0.2;
    return {
      x1: 60 + Math.cos(a) * 48,
      y1: 60 + Math.sin(a) * 48,
      x2: 60 + Math.cos(a) * 58,
      y2: 60 + Math.sin(a) * 58,
    };
  });
  const dots = Array.from({ length: 6 }, (_, i) => {
    const a = (i / 6) * Math.PI * 2 + 0.5;
    return { cx: 60 + Math.cos(a) * 54, cy: 60 + Math.sin(a) * 54 };
  });
  return (
    <svg
      ref={ref}
      viewBox="0 0 120 120"
      className="size-[104px] overflow-visible"
      aria-hidden
    >
      {sparks.map((p, i) => (
        <line
          key={i}
          className="spark"
          {...p}
          stroke={accent}
          strokeWidth="3"
          strokeLinecap="round"
          pathLength={1}
          strokeDasharray="1"
          style={{ visibility: "hidden" }}
        />
      ))}
      {dots.map((p, i) => (
        <circle
          key={i}
          className="dot"
          {...p}
          r="2.4"
          fill={i % 2 ? "#f5c542" : accent}
          style={{ visibility: "hidden" }}
        />
      ))}
      <g className="seal-wrap">
        <g className="seal">
          <path d={SEAL} transform="translate(10 10)" fill={accent} />
          <path
            className="seal-tick"
            d="M44 61l11 11 22-23"
            fill="none"
            stroke="#fff"
            strokeWidth="7"
            strokeLinecap="round"
            strokeLinejoin="round"
            pathLength={1}
            strokeDasharray="1"
            strokeDashoffset="1"
          />
        </g>
      </g>
    </svg>
  );
}

/** Animates its height to fit whatever is inside. */
function AutoHeight({
  children,
  still,
}: {
  children: React.ReactNode;
  still: boolean;
}) {
  const inner = React.useRef<HTMLDivElement>(null);
  const [h, setH] = React.useState<number | "auto">("auto");
  React.useLayoutEffect(() => {
    const el = inner.current;
    if (!el) return;
    const ro = new ResizeObserver(() => setH(el.offsetHeight));
    ro.observe(el);
    return () => ro.disconnect();
  }, []);
  return (
    <motion.div
      animate={{ height: h }}
      initial={false}
      transition={{ duration: still ? 0 : 0.55, ease: GLIDE }}
      className="relative -mx-2 overflow-hidden px-2"
    >
      <div ref={inner}>{children}</div>
    </motion.div>
  );
}

// ---------------------------------------------------------------------------

export const VerifyFlow = React.forwardRef<HTMLDivElement, VerifyFlowProps>(
  function VerifyFlow(
    {
      stage: stageProp,
      completed: completedProp,
      checks = DEFAULT_CHECKS,
      title = "Verify your account",
      provider = "GitHub",
      providerIcon,
      onSignIn,
      destination = "Acme",
      redirectSeconds = 5,
      onContinue,
      loop = false,
      accent = "#269a5a",
      className,
    },
    ref,
  ) {
    const still = !!useReducedMotion();
    const uid = React.useId();
    const demo = stageProp === undefined;
    const [demoStage, setDemoStage] = React.useState<VerifyStage>("waiting");
    const [demoDone, setDemoDone] = React.useState(0);
    const [demoPress, setDemoPress] = React.useState(false);
    const [run, setRun] = React.useState(0);
    const stage = stageProp ?? demoStage;
    const completed = Math.min(
      checks.length,
      stage === "done"
        ? checks.length
        : stage === "waiting"
          ? 0
          : (completedProp ?? demoDone),
    );
    const [elapsed, setElapsed] = React.useState(0);
    const [seconds, setSeconds] = React.useState(redirectSeconds);

    // Self-playing demo: the sign-in button gets pressed, the checks pass one by one, then it finishes.
    React.useEffect(() => {
      if (!demo) return;
      setDemoStage("waiting");
      setDemoDone(0);
      setDemoPress(false);
      const timers: number[] = [];
      let at = 2400;
      timers.push(window.setTimeout(() => setDemoPress(true), at));
      at += 450;
      timers.push(window.setTimeout(() => setDemoStage("checking"), at));
      checks.forEach((_, i) => {
        at += i === 0 ? 1500 : 1300;
        timers.push(window.setTimeout(() => setDemoDone(i + 1), at));
      });
      at += 600;
      timers.push(window.setTimeout(() => setDemoStage("done"), at));
      return () => timers.forEach((t) => window.clearTimeout(t));
    }, [demo, run, checks]);

    // Elapsed timer while checking; it freezes once verified.
    React.useEffect(() => {
      if (stage === "waiting") setElapsed(0);
      if (stage !== "checking") return;
      const id = window.setInterval(() => setElapsed((s) => s + 1), 1000);
      return () => window.clearInterval(id);
    }, [stage]);

    // Countdown once verified.
    React.useEffect(() => {
      if (stage !== "done") return;
      setSeconds(redirectSeconds);
      let left = redirectSeconds;
      const id = window.setInterval(() => {
        left -= 1;
        setSeconds(Math.max(0, left));
        if (left <= 0) {
          window.clearInterval(id);
          onContinue?.();
          if (demo && loop) window.setTimeout(() => setRun((r) => r + 1), 1200);
        }
      }, 1000);
      return () => window.clearInterval(id);
      // eslint-disable-next-line react-hooks/exhaustive-deps
    }, [stage, redirectSeconds]);

    const step = stage === "waiting" ? 1 : stage === "checking" ? 2 : 3;
    // Three bar segments: connect, checks (fills per passed check), verified.
    const fills = [
      stage === "waiting" ? 0 : 1,
      stage === "done"
        ? 1
        : stage === "checking"
          ? completed / checks.length
          : 0,
      stage === "done" ? 1 : 0,
    ];
    const tr = { duration: still ? 0 : 0.45, ease: GLIDE };
    const swap = {
      initial: still
        ? { opacity: 0 }
        : { opacity: 0, y: 10, filter: "blur(6px)" },
      animate: { opacity: 1, y: 0, filter: "blur(0px)" },
      exit: still ? { opacity: 0 } : { opacity: 0, y: -6, filter: "blur(4px)" },
      transition: { ...tr, delay: still ? 0 : 0.06 },
    };
    const live =
      stage === "waiting"
        ? `Waiting for ${provider} sign-in`
        : stage === "checking"
          ? `Checking: ${checks[completed] ?? ""}`
          : "Verified";

    return (
      <div
        ref={ref}
        className={cn(
          "w-[400px] max-w-full rounded-3xl bg-white px-5 pb-5 pt-6 text-zinc-900 shadow-[0_1px_2px_rgba(0,0,0,0.04),0_12px_32px_-16px_rgba(0,0,0,0.18)] dark:bg-zinc-900 dark:text-zinc-100",
          className,
        )}
      >
        <span className="sr-only" role="status" aria-live="polite">
          {live}
        </span>

        <header className="flex items-start justify-between gap-4 px-1">
          <div className="min-w-0">
            <h3 className="text-lg font-semibold tracking-tight">{title}</h3>
            <p className="mt-0.5 text-sm text-zinc-500 dark:text-zinc-400">
              <Roll still={still}>{SUBTITLES[stage]}</Roll>
            </p>
          </div>
          <HeaderStatus stage={stage} accent={accent} still={still} />
        </header>

        {/* Progress: three pill segments with a caption and a rolling timer. */}
        <div className="mt-6 px-1">
          <div className="flex gap-1.5" aria-hidden>
            {fills.map((f, i) => (
              <span
                key={i}
                className="relative h-2.5 flex-1 overflow-hidden rounded-full bg-zinc-100 dark:bg-zinc-800/60"
              >
                <motion.span
                  className="absolute inset-0 origin-left rounded-full"
                  style={{ background: i === 2 ? accent : "#242423" }}
                  initial={false}
                  animate={{ scaleX: f }}
                  transition={{ duration: still ? 0 : 0.8, ease: FILL }}
                />
              </span>
            ))}
          </div>
          <div className="mt-3 flex items-center justify-between text-[12px] text-zinc-500 dark:text-zinc-400">
            <span className="inline-flex items-center gap-1.5">
              <span
                className="size-2 rounded-full transition-colors duration-500"
                style={{ background: stage === "done" ? accent : "#242423" }}
              />
              <span>
                Step{" "}
                <Roll still={still} className="align-bottom">
                  {String(step)}
                </Roll>{" "}
                of 3
              </span>
            </span>
            <span className="tabular-nums">
              {stage === "done" ? "Done in " : ""}
              {fmt(elapsed)
                .split("")
                .map((ch, i) => (
                  <Roll key={i} still={still}>
                    {ch}
                  </Roll>
                ))}
            </span>
          </div>
        </div>

        {/* Stage body */}
        <div className="mt-5">
          <AutoHeight still={still}>
            <AnimatePresence mode="popLayout" initial={false}>
              {stage === "waiting" && (
                <motion.div
                  key="waiting"
                  {...swap}
                  className="flex items-center gap-3 rounded-[22px] bg-[#242423]/[0.035] p-3 dark:bg-white/5"
                >
                  <span className="grid size-10 shrink-0 place-items-center rounded-full bg-white text-[#242423] ring-1 ring-black/[0.06] dark:bg-zinc-800 dark:text-zinc-100 dark:ring-white/10">
                    {providerIcon ?? (
                      <GithubIcon className="size-[18px]" strokeWidth={2} />
                    )}
                  </span>
                  <span className="min-w-0 flex-1">
                    <span className="block text-[14px] font-medium">
                      {provider}
                    </span>
                    <span className="flex items-center gap-1.5 text-[12px] text-zinc-500 dark:text-zinc-400">
                      <motion.span
                        className="size-1.5 rounded-full bg-zinc-400"
                        animate={still ? undefined : { opacity: [1, 0.25, 1] }}
                        transition={{
                          duration: 1.6,
                          repeat: Infinity,
                          ease: "easeInOut",
                        }}
                      />
                      Not connected yet
                    </span>
                  </span>
                  <ShimmerButton
                    onClick={onSignIn}
                    pressed={demoPress}
                    still={still}
                  >
                    Sign in
                  </ShimmerButton>
                </motion.div>
              )}

              {stage === "checking" && (
                <motion.ul
                  key="checking"
                  {...swap}
                  className="relative rounded-[22px] bg-[#242423]/[0.035] p-1.5 dark:bg-white/5"
                >
                  {checks.map((label, i) => {
                    const state =
                      i < completed
                        ? "passed"
                        : i === completed
                          ? "running"
                          : "queued";
                    return (
                      <li
                        key={label}
                        className="relative flex h-11 items-center justify-between px-3.5"
                      >
                        {state === "running" && (
                          <motion.span
                            layoutId={`${uid}-running`}
                            transition={{
                              type: "spring",
                              stiffness: 420,
                              damping: 36,
                            }}
                            className="absolute inset-0 rounded-2xl bg-white shadow-[0_1px_2px_rgba(0,0,0,0.05)] dark:bg-zinc-800"
                          />
                        )}
                        <span
                          className={cn(
                            "relative text-[14px] transition-colors duration-500",
                            state === "queued"
                              ? "text-zinc-400"
                              : "text-zinc-900 dark:text-zinc-100",
                          )}
                        >
                          {label}
                        </span>
                        <span
                          className={cn(
                            "relative inline-flex items-center gap-1.5 text-[12px]",
                            state === "queued"
                              ? "text-zinc-400"
                              : "text-zinc-500 dark:text-zinc-400",
                          )}
                        >
                          {state === "running" && (
                            <Spinner
                              className="size-3.5 text-[#242423] dark:text-zinc-100"
                              still={still}
                            />
                          )}
                          {state === "passed" && (
                            <motion.span
                              initial={still ? false : { scale: 0 }}
                              animate={{ scale: 1 }}
                              transition={{
                                type: "spring",
                                stiffness: 600,
                                damping: 20,
                              }}
                              className="size-2 rounded-full"
                              style={{ background: accent }}
                            />
                          )}
                          <Roll still={still}>
                            {state === "passed"
                              ? "Passed"
                              : state === "running"
                                ? "Checking"
                                : "Queued"}
                          </Roll>
                        </span>
                      </li>
                    );
                  })}
                </motion.ul>
              )}

              {stage === "done" && (
                <motion.div key="done" {...swap} className="space-y-4">
                  <div className="flex flex-col items-center rounded-[22px] bg-[#242423]/[0.035] px-4 pb-5 pt-6 text-center dark:bg-white/5">
                    <SuccessSeal accent={accent} still={still} />
                    <p className="mt-3 text-[18px] font-semibold tracking-tight">
                      {provider} connected
                    </p>
                    <p className="mt-0.5 text-[12px] text-zinc-500 dark:text-zinc-400">
                      {checks.length} of {checks.length} checks passed
                    </p>
                  </div>
                  <ContinueButton
                    label={`Continue to ${destination}`}
                    seconds={seconds}
                    total={redirectSeconds}
                    onClick={onContinue}
                    still={still}
                  />
                </motion.div>
              )}
            </AnimatePresence>
          </AutoHeight>
        </div>
      </div>
    );
  },
);