Sign in

"use client";

import { useCallback, useEffect, useLayoutEffect, useId, useRef, useState, type FormEvent } from "react";
import { AnimatePresence, LayoutGroup, animate, motion, useMotionValue, useReducedMotion, type Transition, type Variants } from "motion/react";
import { Check, KeyRound } from "lucide-react";
import { Avatar } from "../../avatar/avatar";
import { Button } from "../../button/button";
import { Input } from "../../input/input";
import { OtpInput } from "../../otp-input/otp-input";
import { avatar } from "../../lib/media";
import { motionTokens } from "../../lib/motion-tokens";
import styles from "./sign-in.module.css";

type Step = "email" | "code" | "done";
type Provider = "Google" | "Apple" | "GitHub";
export type SignInMethod = "Email code" | "Passkey" | Provider;
export interface SignInAccount { name: string; email: string; photo?: string }
export interface SignInProps {
  /** The code the simulated email contains. */
  demoCode?: string;
  /** Called once the simulated sign in succeeds. */
  onSignIn?: (account: SignInAccount, method: SignInMethod) => void;
}
type StepCustom = { direction: number; reduce: boolean; still?: boolean };

const RESEND_SECONDS = 30;
const providers: Provider[] = ["Google", "Apple", "GitHub"];
/** The official four-colour Google "G"; Apple and GitHub ship monochrome marks, drawn in currentColor below. */
function GoogleLogo() {
  return <svg className={styles.providerMark} width="16" height="16" viewBox="0 0 24 24" aria-hidden="true">
    <path fill="#4285F4" d="M22.56 12.25c0-.78-.07-1.53-.2-2.25H12v4.26h5.92c-.26 1.37-1.04 2.53-2.21 3.31v2.77h3.57c2.08-1.92 3.28-4.74 3.28-8.09z" />
    <path fill="#34A853" d="M12 23c2.97 0 5.46-.98 7.28-2.66l-3.57-2.77c-.98.66-2.23 1.06-3.71 1.06-2.86 0-5.29-1.93-6.16-4.53H2.18v2.84C3.99 20.53 7.7 23 12 23z" />
    <path fill="#FBBC05" d="M5.84 14.09c-.22-.66-.35-1.36-.35-2.09s.13-1.43.35-2.09V7.07H2.18C1.43 8.55 1 10.22 1 12s.43 3.45 1.18 4.93l2.85-2.22.81-.62z" />
    <path fill="#EA4335" d="M12 5.38c1.62 0 3.06.56 4.21 1.64l3.15-3.15C17.45 2.09 14.97 1 12 1 7.7 1 3.99 3.47 2.18 7.07l3.66 2.84c.87-2.6 3.3-4.53 6.16-4.53z" />
  </svg>;
}
const providerMarks: Record<Provider, string> = {
  Google: "M12.48 10.92v3.28h7.84c-.24 1.84-.853 3.187-1.787 4.133-1.147 1.147-2.933 2.4-6.053 2.4-4.827 0-8.6-3.893-8.6-8.72s3.773-8.72 8.6-8.72c2.6 0 4.507 1.027 5.907 2.347l2.307-2.307C18.747 1.44 16.133 0 12.48 0 5.867 0 .307 5.387.307 12s5.56 12 12.173 12c3.573 0 6.267-1.173 8.373-3.36 2.16-2.16 2.84-5.213 2.84-7.667 0-.76-.053-1.467-.173-2.053H12.48z",
  Apple: "M12.152 6.896c-.948 0-2.415-1.078-3.96-1.04-2.04.027-3.91 1.183-4.961 3.014-2.117 3.675-.546 9.103 1.519 12.09 1.013 1.454 2.208 3.09 3.792 3.039 1.52-.065 2.09-.987 3.935-.987 1.831 0 2.35.987 3.96.948 1.637-.026 2.676-1.48 3.676-2.948 1.156-1.688 1.636-3.325 1.662-3.415-.039-.013-3.182-1.221-3.22-4.857-.026-3.04 2.48-4.494 2.597-4.559-1.429-2.09-3.623-2.324-4.39-2.376-2-.156-3.675 1.09-4.61 1.09zM15.53 3.83c.843-1.012 1.4-2.427 1.245-3.83-1.207.052-2.662.805-3.532 1.818-.78.896-1.454 2.338-1.273 3.714 1.338.104 2.715-.688 3.559-1.701",
  GitHub: "M12 .297c-6.63 0-12 5.373-12 12 0 5.303 3.438 9.8 8.205 11.385.6.113.82-.258.82-.577 0-.285-.01-1.04-.015-2.04-3.338.724-4.042-1.61-4.042-1.61C4.422 18.07 3.633 17.7 3.633 17.7c-1.087-.744.084-.729.084-.729 1.205.084 1.838 1.236 1.838 1.236 1.07 1.835 2.809 1.305 3.495.998.108-.776.417-1.305.76-1.605-2.665-.3-5.466-1.332-5.466-5.93 0-1.31.465-2.38 1.235-3.22-.135-.303-.54-1.523.105-3.176 0 0 1.005-.322 3.3 1.23.96-.267 1.98-.399 3-.405 1.02.006 2.04.138 3 .405 2.28-1.552 3.285-1.23 3.285-1.23.645 1.653.24 2.873.12 3.176.765.84 1.23 1.91 1.23 3.22 0 4.61-2.805 5.625-5.475 5.92.42.36.81 1.096.81 2.22 0 1.606-.015 2.896-.015 3.286 0 .315.21.69.825.57C20.565 22.092 24 17.592 24 12.297c0-6.627-5.373-12-12-12",
};
const people: SignInAccount[] = [
  { name: "Emma Collins", email: "emma@northwind.studio", photo: avatar("emma-collins") },
  { name: "Marcus Johnson", email: "marcus@northwind.studio", photo: avatar("marcus-johnson") },
  { name: "Ava Mitchell", email: "ava@northwind.studio", photo: avatar("ava-mitchell") },
  { name: "Jasmine Brooks", email: "jasmine@northwind.studio", photo: avatar("jasmine-brooks") },
  { name: "Sofia Ramirez", email: "sofia@northwind.studio", photo: avatar("sofia-ramirez") },
];
const domainFixes: Record<string, string> = { "gmial.com": "gmail.com", "gamil.com": "gmail.com", "gmai.com": "gmail.com", "gnail.com": "gmail.com", "gmail.co": "gmail.com", "hotmial.com": "hotmail.com", "outlok.com": "outlook.com", "outlook.co": "outlook.com", "iclod.com": "icloud.com", "icoud.com": "icloud.com", "yaho.com": "yahoo.com" };

const isEmail = (value: string) => /^[^\s@]+@[^\s@]+\.[^\s@]{2,}$/.test(value.trim());
function suggestionFor(value: string) {
  const [local, domain, extra] = value.trim().toLowerCase().split("@");
  return local && domain && extra === undefined && domainFixes[domain] ? `${local}@${domainFixes[domain]}` : "";
}
/** Known teammates keep their photo; anyone else gets a name from their address and an initials avatar. */
function accountFor(value: string): SignInAccount {
  const email = value.trim().toLowerCase();
  const parts = email.split("@")[0]!.split(/[._+-]+/).filter(Boolean);
  const known = people.find(person => person.name.toLowerCase().split(" ")[0] === parts[0]);
  if (known) return { ...known, email };
  return { name: parts.slice(0, 2).map(part => part[0]!.toUpperCase() + part.slice(1)).join(" ") || "Arc member", email };
}

const stepMotion: Variants = {
  enter: ({ direction, reduce, still }: StepCustom) => still ? { opacity: 1, x: 0, filter: "blur(0px)" } : reduce ? { opacity: 0 } : { opacity: 0, x: direction * 28, filter: `blur(${motionTokens.blur.soft}px)` },
  center: ({ reduce }: StepCustom) => ({ opacity: 1, x: 0, filter: "blur(0px)", transition: reduce ? { duration: motionTokens.duration.instant } : { x: motionTokens.spring.smooth, opacity: { duration: motionTokens.duration.standard, ease: motionTokens.ease.enter, delay: .05 }, filter: { duration: motionTokens.duration.standard, ease: motionTokens.ease.enter } } }),
  exit: ({ direction, reduce }: StepCustom) => reduce ? { opacity: 0, transition: { duration: 0 } } : { opacity: 0, x: direction * -20, filter: `blur(${motionTokens.blur.soft}px)`, transition: { x: motionTokens.spring.smooth, opacity: { duration: motionTokens.duration.exit, ease: motionTokens.ease.standard }, filter: { duration: motionTokens.duration.exit } } },
};
/** Seconds roll down while the timer runs and back up when a new code restarts it. */
const roll: Variants = {
  enter: (direction: number) => ({ opacity: 0, y: `${-0.7 * direction}em`, filter: `blur(${motionTokens.blur.subtle}px)` }),
  center: { opacity: 1, y: 0, filter: "blur(0px)" },
  exit: (direction: number) => ({ opacity: 0, y: `${0.7 * direction}em`, filter: `blur(${motionTokens.blur.subtle}px)` }),
};

function RollingTime({ seconds, reduce }: { seconds: number; reduce: boolean }) {
  const [shown, setShown] = useState({ seconds, direction: 1 });
  if (shown.seconds !== seconds) setShown({ seconds, direction: seconds < shown.seconds ? 1 : -1 });
  const text = `${Math.floor(seconds / 60)}:${String(seconds % 60).padStart(2, "0")}`;
  const transition: Transition = reduce ? { duration: 0 } : { y: motionTokens.spring.snappy, opacity: { duration: motionTokens.duration.fast }, filter: { duration: motionTokens.duration.fast } };
  return <span className={styles.time}>{text.split("").map((character, index) => <span key={index} className={styles.timeColumn}>
    <AnimatePresence initial={false} mode="popLayout" custom={shown.direction}><motion.span key={character} custom={shown.direction} variants={roll} initial="enter" animate="center" exit="exit" transition={transition}>{character}</motion.span></AnimatePresence>
  </span>)}</span>;
}

/** The card follows its content on a spring only while the step changes; otherwise it stays auto, so field messages open without lag. */
function useStepHeight(step: Step, reduce: boolean) {
  const track = useRef<HTMLDivElement>(null);
  const height = useMotionValue<number | "auto">("auto");
  const measured = useRef(0);
  const gliding = useRef(false);
  const lastStep = useRef(step);
  const glide = useCallback((to: number) => {
    gliding.current = true;
    animate(height, to, { ...motionTokens.spring.smooth, onComplete: () => { gliding.current = false; height.jump("auto"); } });
  }, [height]);
  useEffect(() => {
    const node = track.current;
    if (!node || typeof ResizeObserver === "undefined") return;
    const observer = new ResizeObserver(([entry]) => {
      if (!entry) return;
      measured.current = entry.borderBoxSize?.[0]?.blockSize ?? node.offsetHeight;
      if (gliding.current) glide(measured.current);
    });
    observer.observe(node);
    return () => observer.disconnect();
  }, [glide]);
  useLayoutEffect(() => {
    if (lastStep.current === step) return;
    lastStep.current = step;
    const current = height.get();
    const from = typeof current === "number" ? current : measured.current;
    const to = track.current?.offsetHeight ?? 0;
    if (reduce || !from || !to) { gliding.current = false; height.jump("auto"); return; }
    if (current === "auto") height.jump(from);
    glide(to);
  }, [step, reduce, height, glide]);
  return { track, height };
}

export function SignIn({ demoCode = "123456", onSignIn }: SignInProps) {
  const id = useId();
  const reduce = !!useReducedMotion();
  const [step, setStep] = useState<Step>("email");
  const [direction, setDirection] = useState(1);
  const [email, setEmail] = useState("");
  const [touched, setTouched] = useState(false);
  const [attempted, setAttempted] = useState(false);
  const [code, setCode] = useState("");
  const [codeError, setCodeError] = useState("");
  const [resendIn, setResendIn] = useState(RESEND_SECONDS);
  const [busy, setBusy] = useState<null | "email" | "code" | "passkey" | Provider>(null);
  const [account, setAccount] = useState<SignInAccount>(people[0]!);
  const [method, setMethod] = useState<SignInMethod>("Email code");
  const [status, setStatus] = useState("");
  const emailRef = useRef<HTMLInputElement>(null);
  const codeRef = useRef<HTMLDivElement>(null);
  const doneRef = useRef<HTMLHeadingElement>(null);
  const focusNext = useRef<"email" | "done" | null>(null);
  const timers = useRef<number[]>([]);
  const { track, height } = useStepHeight(step, reduce);

  const emailError = (touched || attempted) && !isEmail(email) ? (email.trim() ? "Enter a full address, like name@example.com." : "Enter your email address.") : "";
  const suggestion = touched || attempted ? suggestionFor(email) : "";
  const custom: StepCustom = { direction, reduce };
  const avatarTransition: Transition = reduce ? { duration: 0 } : motionTokens.spring.morph;
  const rise = (index: number) => ({
    initial: reduce ? { opacity: 0 } : { opacity: 0, y: 10, filter: `blur(${motionTokens.blur.soft}px)` },
    animate: { opacity: 1, y: 0, filter: "blur(0px)" },
    transition: (reduce ? { duration: motionTokens.duration.instant } : { y: { ...motionTokens.spring.smooth, delay: .14 + index * motionTokens.stagger.line }, opacity: { duration: motionTokens.duration.standard, ease: motionTokens.ease.enter, delay: .14 + index * motionTokens.stagger.line }, filter: { duration: motionTokens.duration.standard, delay: .14 + index * motionTokens.stagger.line } }) as Transition,
  });

  useEffect(() => { const pending = timers.current; return () => pending.forEach(window.clearTimeout); }, []);
  useEffect(() => {
    if (step !== "code" || resendIn <= 0) return;
    const timer = window.setTimeout(() => setResendIn(seconds => Math.max(0, seconds - 1)), 1000);
    return () => window.clearTimeout(timer);
  }, [step, resendIn]);
  useEffect(() => {
    const target = focusNext.current;
    focusNext.current = null;
    if (target === "email") { emailRef.current?.focus(); emailRef.current?.select(); }
    if (target === "done") doneRef.current?.focus();
  }, [step]);

  function later(run: () => void, ms: number) { timers.current.push(window.setTimeout(run, ms)); }
  function go(next: Step, towards: number, focus: "email" | "done" | null = null) { focusNext.current = focus; setDirection(towards); setStep(next); }
  const focusCode = () => codeRef.current?.querySelector("input")?.focus();

  function complete(next: SignInAccount, how: SignInMethod) {
    setBusy(null);
    setAccount(next);
    setMethod(how);
    go("done", 1, "done");
    setStatus(`Signed in with ${how === "Email code" ? "an email code" : how}`);
    onSignIn?.(next, how);
  }

  function submitEmail(event: FormEvent<HTMLFormElement>) {
    event.preventDefault();
    if (busy) return;
    setAttempted(true);
    if (!isEmail(email)) { emailRef.current?.focus(); return; }
    setBusy("email");
    setStatus("Sending a code");
    later(() => {
      setBusy(null);
      setAccount(accountFor(email));
      setCode("");
      setCodeError("");
      setResendIn(RESEND_SECONDS);
      go("code", 1);
      setStatus("Code sent");
    }, 800);
  }

  function applySuggestion() {
    setEmail(suggestion);
    setStatus(`Email changed to ${suggestion}`);
    emailRef.current?.focus();
  }

  function verify(value: string) {
    if (busy) return;
    if (value.length < 6) { setCodeError("Enter all 6 digits."); focusCode(); return; }
    setBusy("code");
    setStatus("Checking code");
    later(() => {
      if (value === demoCode) { complete(account, "Email code"); return; }
      setBusy(null);
      setCode("");
      setCodeError("That code didn't match. Check the latest email and try again.");
      setStatus("Code didn't match");
      focusCode();
    }, 700);
  }

  function changeCode(value: string) {
    if (busy) return;
    setCode(value);
    if (codeError && value) setCodeError("");
    if (value.length === 6) verify(value);
  }

  function resend() {
    if (busy || resendIn > 0) return;
    setResendIn(RESEND_SECONDS);
    setCode("");
    setCodeError("");
    setStatus("New code sent");
    focusCode();
  }

  function changeEmail() {
    if (busy) return;
    setAttempted(false);
    go("email", -1, "email");
    setStatus("Edit your email");
  }

  function signInWith(how: "passkey" | Provider) {
    if (busy) return;
    setBusy(how);
    setStatus(how === "passkey" ? "Waiting for your passkey" : `Opening ${how}`);
    later(() => complete(people[0]!, how === "passkey" ? "Passkey" : how), how === "passkey" ? 1100 : 900);
  }

  function signOut() {
    setEmail(account.email);
    setTouched(false);
    setAttempted(false);
    setCode("");
    go("email", -1, "email");
    setStatus("Signed out");
  }

  return (
    <section className={styles.signIn} aria-label="Sign in">
      <LayoutGroup id={id}>
        <motion.div className={styles.viewport} style={{ height }}>
          <div ref={track} className={styles.track}>
            <AnimatePresence mode="popLayout" initial={false} custom={custom}>
              {step === "email" && <motion.div key="email" className={styles.step} custom={custom} variants={stepMotion} initial="enter" animate="center" exit="exit">
                <div className={styles.heading}><h2>Sign in to Arc</h2><p>Enter your email and we will send you a 6 digit code.</p></div>
                <form className={styles.form} onSubmit={submitEmail} noValidate>
                  <div className={styles.fieldGroup}>
                    <Input ref={emailRef} label="Email" type="email" inputMode="email" autoComplete="email" autoCapitalize="none" spellCheck={false} placeholder="name@example.com" value={email} readOnly={busy === "email"} error={emailError} onChange={event => setEmail(event.target.value)} onBlur={() => { if (email.trim()) setTouched(true); }} />
                    <AnimatePresence initial={false}>
                      {suggestion && <motion.div key="suggestion" className={styles.suggestion} initial={{ height: 0, opacity: 0 }} animate={{ height: "auto", opacity: 1 }} exit={{ height: 0, opacity: 0 }} transition={reduce ? { duration: 0 } : { height: motionTokens.spring.smooth, opacity: { duration: motionTokens.duration.fast } }}>
                        <p>Did you mean <button type="button" className={styles.textButton} aria-label={`Use ${suggestion}`} onClick={applySuggestion}>{suggestion}</button>?</p>
                      </motion.div>}
                    </AnimatePresence>
                  </div>
                  <Button type="submit" className={styles.wide} loading={busy === "email"}>Continue</Button>
                </form>
                <div className={styles.divider}>or</div>
                <div className={styles.alternatives}>
                  <Button type="button" variant="secondary" className={styles.wide} loading={busy === "passkey"} onClick={() => signInWith("passkey")}><KeyRound size={16} strokeWidth={1.75} aria-hidden="true" />Sign in with a passkey</Button>
                  <div className={styles.sso} role="group" aria-label="Single sign-on">
                    {providers.map(provider => <Button key={provider} type="button" variant="secondary" className={styles.ssoButton} aria-label={`Continue with ${provider}`} loading={busy === provider} onClick={() => signInWith(provider)}>{provider === "Google" ? <GoogleLogo /> : <svg className={styles.providerMark} width="16" height="16" viewBox="0 0 24 24" fill="currentColor" aria-hidden="true"><path d={providerMarks[provider]} /></svg>}{provider}</Button>)}
                  </div>
                </div>
              </motion.div>}

              {step === "code" && <motion.div key="code" className={styles.step} custom={custom} variants={stepMotion} initial="enter" animate="center" exit="exit">
                <div className={styles.heading}><h2>Check your email</h2><p>Enter the 6 digit code we sent. It expires in 10 minutes.</p></div>
                <div className={styles.identity}>
                  <motion.span layoutId="account-avatar" className={`${styles.avatarMover} ${styles.avatarSmall}`} transition={avatarTransition}><Avatar name={account.name} src={account.photo} size="xl" className={styles.avatarFill} /></motion.span>
                  <span className={styles.identityEmail}>{account.email}</span>
                  <Button type="button" variant="ghost" size="sm" aria-label="Change email" onClick={changeEmail}>Change</Button>
                </div>
                <form className={styles.form} onSubmit={event => { event.preventDefault(); verify(code); }} noValidate>
                  <div ref={codeRef}><OtpInput label="Verification code" description={`For this demo, the code is ${demoCode}.`} value={code} onChange={changeCode} error={codeError} autoFocus /></div>
                  <Button type="submit" className={styles.wide} loading={busy === "code"}>Verify</Button>
                </form>
                <button type="button" className={styles.resend} aria-disabled={resendIn > 0 || undefined} aria-label={resendIn > 0 ? `Resend code, available in ${resendIn} seconds` : "Resend code"} onClick={resend}>
                  <AnimatePresence mode="popLayout" initial={false}>
                    <motion.span key={resendIn > 0 ? "wait" : "ready"} className={styles.resendLabel} initial={reduce ? { opacity: 0 } : { opacity: 0, y: 6, filter: `blur(${motionTokens.blur.soft}px)` }} animate={{ opacity: 1, y: 0, filter: "blur(0px)" }} exit={reduce ? { opacity: 0, transition: { duration: 0 } } : { opacity: 0, y: -4, filter: `blur(${motionTokens.blur.subtle}px)`, transition: { duration: motionTokens.duration.fast } }} transition={reduce ? { duration: motionTokens.duration.instant } : { duration: motionTokens.duration.standard, ease: motionTokens.ease.enter }}>
                      {resendIn > 0 ? <>Resend code in <RollingTime seconds={resendIn} reduce={reduce} /></> : "Resend code"}
                    </motion.span>
                  </AnimatePresence>
                </button>
              </motion.div>}

              {step === "done" && <motion.div key="done" className={styles.step} custom={{ ...custom, still: true }} variants={stepMotion} initial="enter" animate="center" exit="exit">
                <div className={styles.avatarStage}>
                  <svg className={styles.ring} viewBox="0 0 96 96" aria-hidden="true"><motion.circle cx="48" cy="48" r="47" fill="none" stroke="currentColor" strokeWidth="1.5" initial={reduce ? false : { pathLength: 0, opacity: 0 }} animate={{ pathLength: 1, opacity: 1 }} transition={{ pathLength: { duration: motionTokens.duration.considered * 1.25, ease: motionTokens.ease.inOut, delay: .22 }, opacity: { duration: motionTokens.duration.instant, delay: .22 } }} /></svg>
                  <motion.span layoutId="account-avatar" className={`${styles.avatarMover} ${styles.avatarLarge}`} initial={method === "Email code" || reduce ? false : { opacity: 0, scale: .7 }} animate={{ opacity: 1, scale: 1 }} transition={avatarTransition}><Avatar name={account.name} src={account.photo} size="xl" className={styles.avatarFill} /></motion.span>
                  <motion.span className={styles.badge} aria-hidden="true" initial={reduce ? false : { opacity: 0, scale: .4 }} animate={{ opacity: 1, scale: 1 }} transition={{ ...motionTokens.spring.snappy, delay: .78 }}><Check size={14} strokeWidth={2.25} /></motion.span>
                </div>
                <motion.div className={styles.heading} {...rise(0)}><h2 ref={doneRef} tabIndex={-1}>Welcome back, {account.name.split(" ")[0]}</h2><p className={styles.email}>{account.email}</p></motion.div>
                <motion.dl className={styles.details} {...rise(1)}>
                  <div><dt>Signed in with</dt><dd>{method}</dd></div>
                  <div><dt>This browser</dt><dd>Remembered for 30 days</dd></div>
                </motion.dl>
                <motion.div {...rise(2)}><Button type="button" variant="secondary" className={styles.wide} onClick={signOut}>Sign out</Button></motion.div>
              </motion.div>}
            </AnimatePresence>
          </div>
        </motion.div>
      </LayoutGroup>

      <footer className={styles.footer}>
        <p className={styles.srOnly} role="status" aria-live="polite">{status}</p>
        <span className={styles.status} aria-hidden="true">
          <AnimatePresence mode="popLayout" initial={false}>
            <motion.span key={status} initial={reduce ? { opacity: 0 } : { opacity: 0, y: 6, filter: `blur(${motionTokens.blur.soft}px)` }} animate={{ opacity: 1, y: 0, filter: "blur(0px)" }} exit={reduce ? { opacity: 0, transition: { duration: 0 } } : { opacity: 0, y: -4, filter: `blur(${motionTokens.blur.subtle}px)`, transition: { duration: motionTokens.duration.fast } }} transition={reduce ? { duration: motionTokens.duration.instant } : { duration: motionTokens.duration.standard, ease: motionTokens.ease.enter }}>{status}</motion.span>
          </AnimatePresence>
        </span>
        <span className={styles.switch}>No account? <button type="button" className={styles.textButton} onClick={() => setStatus("Sign up opens in your app")}>Sign up</button></span>
      </footer>
    </section>
  );
}

export default SignIn;