import { useState, type FormEvent } from 'react'
import { Navigate, useLocation, type Location } from 'react-router'
import { errorMessage } from '../api'
import { card, inputClass, labelText, primaryButton } from '../ui'
import { useAuth } from './AuthContext'

export function LoginForm() {
  const { user, login, register } = useAuth()
  const location = useLocation()
  const [mode, setMode] = useState<'login' | 'register'>('login')
  const [username, setUsername] = useState('')
  const [password, setPassword] = useState('')
  const [error, setError] = useState<string | null>(null)
  const [busy, setBusy] = useState(false)

  if (user) {
    const from = (location.state as { from?: Location } | null)?.from
    return <Navigate to={from ? from.pathname + from.search : '/books'} replace />
  }

  const isLogin = mode === 'login'

  async function submit(event: FormEvent) {
    event.preventDefault()
    setError(null)
    setBusy(true)
    try {
      await (isLogin ? login : register)(username, password)
    } catch (err) {
      setError(errorMessage(err))
    } finally {
      setBusy(false)
    }
  }

  return (
    <div className="min-h-screen bg-slate-50 px-4 pt-16">
      <main className={`mx-auto max-w-sm ${card}`}>
        <h1 className="mb-4 text-2xl font-semibold">{isLogin ? 'Sign in' : 'Create account'}</h1>
        <form onSubmit={submit} className="space-y-4">
          <label className="block">
            <span className={labelText}>Username</span>
            <input
              className={inputClass}
              value={username}
              onChange={(e) => setUsername(e.target.value)}
              autoComplete="username"
              required
            />
          </label>
          <label className="block">
            <span className={labelText}>Password</span>
            <input
              className={inputClass}
              type="password"
              value={password}
              onChange={(e) => setPassword(e.target.value)}
              autoComplete={isLogin ? 'current-password' : 'new-password'}
              minLength={isLogin ? undefined : 12}
              required
            />
          </label>
          {error && (
            <p role="alert" className="text-sm text-red-700">
              {error}
            </p>
          )}
          <button type="submit" disabled={busy} className={`${primaryButton} w-full`}>
            {isLogin ? 'Sign in' : 'Create account'}
          </button>
        </form>
        <button
          type="button"
          className="mt-4 text-sm text-indigo-700 underline"
          onClick={() => {
            setMode(isLogin ? 'register' : 'login')
            setError(null)
          }}
        >
          {isLogin ? 'Need an account? Register' : 'Have an account? Sign in'}
        </button>
      </main>
    </div>
  )
}