import { useState } from 'react'
import { api } from '../api.js'

// Sign in, or join with an invitation.
//
// Both live on this screen because they answer the same question — "let me in"
// — and the person arriving with a code has no account yet, so they cannot be
// asked to sign in first. That is the same reason the endpoint behind it is
// unauthenticated, and the same reason a shop PC claims itself before anybody
// signs in on it.
export default function Login({ onSignedIn }) {
  const [joining, setJoining] = useState(false)
  return joining
    ? <Join onSignedIn={onSignedIn} onCancel={() => setJoining(false)} />
    : <SignIn onSignedIn={onSignedIn} onJoin={() => setJoining(true)} />
}

function SignIn({ onSignedIn, onJoin }) {
  const [email, setEmail] = useState('')
  const [password, setPassword] = useState('')
  const [error, setError] = useState('')
  const [busy, setBusy] = useState(false)

  const submit = async (e) => {
    e.preventDefault()
    setBusy(true)
    setError('')
    try {
      await api.login(email.trim(), password)
      onSignedIn(await api.me())
    } catch (err) {
      // The server's own wording. It says the same thing for an unknown address
      // and a wrong password on purpose - telling them apart turns this form
      // into a way to find out who works at a customer.
      setError(err.message)
      setBusy(false)
    }
  }

  return (
    <div className="signin">
      <form className="card" onSubmit={submit}>
        <span className="mark big" aria-hidden="true" />
        <h1>Behavision</h1>
        <p className="sub">Sign in to your company account.</p>

        <label>
          Email
          <input
            type="email" value={email} autoComplete="username" autoFocus required
            onChange={e => setEmail(e.target.value)} placeholder="you@company.com"
          />
        </label>
        <label>
          Password
          <input
            type="password" value={password} autoComplete="current-password" required
            onChange={e => setPassword(e.target.value)}
          />
        </label>

        {error && <p className="error" role="alert">{error}</p>}

        <button className="primary" disabled={busy || !email || !password}>
          {busy ? 'Signing in…' : 'Sign in'}
        </button>
        <p className="foot">
          Been invited? <button type="button" className="linkish" onClick={onJoin}>
            Use your invitation code
          </button>
        </p>
      </form>
    </div>
  )
}

// Redeeming an invitation.
//
// Two steps deliberately. The code is checked FIRST, so somebody who has
// mistyped it finds out before choosing a password — and so the screen can say
// which company they are joining, which is the only thing that makes "is this
// the right code" answerable by the person holding it.
function Join({ onSignedIn, onCancel }) {
  const [code, setCode] = useState('')
  const [invite, setInvite] = useState(null)
  const [fullName, setFullName] = useState('')
  const [password, setPassword] = useState('')
  const [confirm, setConfirm] = useState('')
  const [error, setError] = useState('')
  const [busy, setBusy] = useState(false)

  const check = async (e) => {
    e.preventDefault()
    setBusy(true); setError('')
    try {
      const prev = await api.previewInvitation(code.trim())
      setInvite(prev)
      setFullName(prev.full_name || '')
    } catch (err) {
      // Unknown, expired, spent and withdrawn are one message from the server.
      // The difference only helps somebody guessing codes, and the next step is
      // the same in all four cases: ask for a new one.
      setError(err.message)
    } finally {
      setBusy(false)
    }
  }

  const join = async (e) => {
    e.preventDefault()
    if (password !== confirm) {
      setError('Those two passwords are not the same.')
      return
    }
    setBusy(true); setError('')
    try {
      // The address and the role are not sent. They belong to the invitation.
      const user = await api.register({ code: code.trim(), full_name: fullName, password })
      onSignedIn(user)
    } catch (err) {
      setError(err.message)
      setBusy(false)
    }
  }

  return (
    <div className="signin">
      <form className="card" onSubmit={invite ? join : check}>
        <span className="mark big" aria-hidden="true" />
        <h1>{invite ? `Join ${invite.client_name}` : 'Behavision'}</h1>

        {!invite ? (
          <>
            <p className="sub">Enter the invitation code you were given.</p>
            <label>
              Invitation code
              <input
                value={code} onChange={e => setCode(e.target.value)}
                autoFocus required autoComplete="off" spellCheck="false"
                placeholder="ABCDEF-123456-GHIJKL-789012" className="codefield"
              />
              <span className="hint">Dashes and capitals do not matter.</span>
            </label>
            {error && <p className="error" role="alert">{error}</p>}
            <button className="primary" disabled={busy || !code.trim()}>
              {busy ? 'Checking…' : 'Continue'}
            </button>
          </>
        ) : (
          <>
            <p className="sub">
              You are joining as <b>{invite.role}</b>, signing in with{' '}
              <code>{invite.email}</code>. Choose a password only you know.
            </p>
            <label>
              Your name
              <input value={fullName} onChange={e => setFullName(e.target.value)}
                     autoFocus autoComplete="name" />
            </label>
            <label>
              Password
              <input type="password" value={password} required minLength={8}
                     autoComplete="new-password"
                     onChange={e => setPassword(e.target.value)} />
              <span className="hint">At least 8 characters. Longer is the only thing that helps.</span>
            </label>
            <label>
              Password again
              <input type="password" value={confirm} required
                     autoComplete="new-password"
                     onChange={e => setConfirm(e.target.value)} />
            </label>
            {error && <p className="error" role="alert">{error}</p>}
            <button className="primary" disabled={busy || !password || !confirm}>
              {busy ? 'Creating your account…' : 'Create account and sign in'}
            </button>
          </>
        )}

        <p className="foot">
          <button type="button" className="linkish" onClick={onCancel}>
            Back to sign in
          </button>
        </p>
      </form>
    </div>
  )
}