import { useEffect, useState } from 'react'
import { Link, useParams } from 'react-router-dom'
import { api } from '../../api/client.js'
import PlayerShell from './PlayerShell.jsx'

// Public, token-gated confirmation page (/account/verify-email/:token).
//
// Unauthenticated on purpose: the link arrives in a mailbox and is routinely
// opened on a device with no session. That is safe because the token IS the
// proof — opening it installs an address on the account it was minted for and
// does nothing else. No session is issued here, deliberately: proving control of
// a mailbox is not proving control of an account.
//
// Every failure the server can have — expired, already used, superseded by a
// later request, or an address another account confirmed first — comes back as
// the same 404. That is not laziness on the server's part; distinguishing them
// would let anyone test which addresses have accounts. So this page says the same
// thing for all of them, and must keep doing so.
export default function VerifyEmail() {
  const { token } = useParams()

  const [link, setLink] = useState(null) // { username, email } once validated
  const [loadErr, setLoadErr] = useState('')
  const [error, setError] = useState('')
  const [busy, setBusy] = useState(false)
  const [done, setDone] = useState(false)

  useEffect(() => {
    let active = true
    api
      .lookupEmailVerification(token)
      .then((r) => active && setLink(r || {}))
      .catch(
        (err) =>
          active &&
          setLoadErr(
            err.status === 404
              ? 'This confirmation link is invalid or has expired.'
              : 'Could not load this confirmation link.',
          ),
      )
    return () => {
      active = false
    }
  }, [token])

  async function onConfirm() {
    setError('')
    setBusy(true)
    try {
      await api.confirmEmailVerification(token)
      setDone(true)
    } catch (err) {
      if (err.status === 404) setError('This confirmation link is no longer usable. Request a new one from your account page.')
      else if (err.status === 429) setError('Too many attempts. Please try again in a little while.')
      else setError('Could not confirm your address right now. Please try again later.')
      setBusy(false)
    }
  }

  // ── Invalid link ───────────────────────────────────────────────────────────
  if (loadErr) {
    return (
      <PlayerShell subtitle="Confirm your email">
        <p className="sans" style={{ margin: 0, color: 'var(--muted)', textAlign: 'center', lineHeight: 1.6 }}>
          {loadErr}
        </p>
        <p className="sans" style={{ textAlign: 'center', margin: '16px 0 0' }}>
          <Link to="/account" style={{ color: 'var(--accent)', textDecoration: 'none' }}>
            Go to your account
          </Link>
        </p>
      </PlayerShell>
    )
  }
  if (link === null) {
    return (
      <PlayerShell subtitle="Confirm your email">
        <div style={{ display: 'grid', placeItems: 'center', padding: 20 }}>
          <span className="spin" />
        </div>
      </PlayerShell>
    )
  }

  // ── Done ───────────────────────────────────────────────────────────────────
  if (done) {
    return (
      <PlayerShell subtitle="Email confirmed">
        <p className="sans" style={{ margin: 0, color: 'var(--muted)', textAlign: 'center', lineHeight: 1.6 }}>
          {link.email ? (
            <>
              <strong style={{ color: 'var(--head)' }}>{link.email}</strong> is now the address for
              {link.username ? (
                <>
                  {' '}
                  <strong style={{ color: 'var(--head)' }}>{link.username}</strong>
                </>
              ) : (
                ' your account'
              )}
              .
            </>
          ) : (
            'Your email address has been confirmed.'
          )}
        </p>
        <p className="sans" style={{ textAlign: 'center', margin: '16px 0 0', fontSize: '0.85rem', color: 'var(--dim)' }}>
          You have not been signed in — confirming an address does not sign you in.
        </p>
        <p className="sans" style={{ textAlign: 'center', margin: '16px 0 0' }}>
          <Link to="/account/login" style={{ color: 'var(--accent)', textDecoration: 'none' }}>
            Sign in
          </Link>
        </p>
      </PlayerShell>
    )
  }

  // ── Confirm ────────────────────────────────────────────────────────────────
  //
  // A button rather than confirming on load. A mail client or scanner that
  // pre-fetches links would otherwise spend the token before the person ever saw
  // it, and this token is single-use.
  return (
    <PlayerShell subtitle="Confirm your email">
      <p
        className="sans"
        style={{ marginTop: 0, marginBottom: 20, color: 'var(--muted)', fontSize: '0.88rem', lineHeight: 1.6 }}
      >
        Confirm that{' '}
        {link.email ? <strong style={{ color: 'var(--head)' }}>{link.email}</strong> : 'this address'} should be
        the contact and account-recovery address for
        {link.username ? (
          <>
            {' '}
            <strong style={{ color: 'var(--head)' }}>{link.username}</strong>
          </>
        ) : (
          ' this account'
        )}
        .
      </p>

      {error && (
        <p className="sans" style={{ margin: '0 0 14px', color: '#d98b84', fontSize: '0.85rem', textAlign: 'center' }}>
          {error}
        </p>
      )}

      <button
        type="button"
        onClick={onConfirm}
        disabled={busy}
        className="btn btn-primary"
        style={{ display: 'block', width: '100%', borderRadius: 8, padding: 12, textAlign: 'center' }}
      >
        {busy ? 'Confirming…' : 'Confirm this address'}
      </button>

      <p className="sans" style={{ textAlign: 'center', margin: '16px 0 0', fontSize: '0.82rem', color: 'var(--dim)' }}>
        If you did not ask for this, close this page. Nothing changes and no account of yours is affected.
      </p>
    </PlayerShell>
  )
}