import { useState, type FormEvent } from 'react';
import { Navigate } from 'react-router-dom';
import { useAuth } from '../context/AuthContext';
import { ApiError } from '../api/client';

function extractErrorMessage(err: unknown): string {
  if (err instanceof ApiError && err.body && typeof err.body === 'object' && 'error' in err.body) {
    const code = String((err.body as { error: unknown }).error);
    if (code === 'username_taken') return 'That username is already taken.';
    if (code === 'setup_already_complete') return 'Setup was already completed. Please log in.';
  }
  return 'Something went wrong. Please try again.';
}

export function SetupPage() {
  const { completeSetup, user, needsSetup } = useAuth();
  const [username, setUsername] = useState('');
  const [password, setPassword] = useState('');
  const [confirmPassword, setConfirmPassword] = useState('');
  const [error, setError] = useState<string | null>(null);
  const [submitting, setSubmitting] = useState(false);

  if (user) return <Navigate to="/" replace />;
  if (!needsSetup) return <Navigate to="/login" replace />;

  async function handleSubmit(e: FormEvent) {
    e.preventDefault();
    setError(null);
    if (password !== confirmPassword) {
      setError('Passwords do not match.');
      return;
    }
    setSubmitting(true);
    try {
      await completeSetup(username, password);
    } catch (err) {
      setError(extractErrorMessage(err));
    } finally {
      setSubmitting(false);
    }
  }

  return (
    <div className="auth-page">
      <form className="auth-form" onSubmit={handleSubmit}>
        <h1>Welcome to CityTracker</h1>
        <p className="auth-hint">Create the first admin account to get started.</p>
        <label>
          Username
          <input
            value={username}
            onChange={(e) => setUsername(e.target.value)}
            autoComplete="username"
            required
            minLength={3}
            autoFocus
          />
        </label>
        <label>
          Password
          <input
            type="password"
            value={password}
            onChange={(e) => setPassword(e.target.value)}
            autoComplete="new-password"
            required
            minLength={8}
          />
        </label>
        <label>
          Confirm password
          <input
            type="password"
            value={confirmPassword}
            onChange={(e) => setConfirmPassword(e.target.value)}
            autoComplete="new-password"
            required
            minLength={8}
          />
        </label>
        {error && <p className="form-error">{error}</p>}
        <button type="submit" className="btn btn-primary" disabled={submitting}>
          {submitting ? 'Creating…' : 'Create admin account'}
        </button>
      </form>
    </div>
  );
}