import React, { useState } from 'react';
import {
  IonButton,
  IonContent,
  IonHeader,
  IonInput,
  IonItem,
  IonLabel,
  IonPage,
  IonText,
  IonTitle,
  IonToolbar,
  useIonViewWillEnter,
} from '@ionic/react';
import { useHistory } from 'react-router-dom';
import { supabase } from '../supabase';
import { setStatusBarStyle, Style } from '../utils/statusBar';

const Auth: React.FC = () => {
  const history = useHistory();
  const [mode, setMode] = useState<'login' | 'signup'>('login');
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [message, setMessage] = useState('');
  const [errorMessage, setErrorMessage] = useState('');
  const [isSubmitting, setIsSubmitting] = useState(false);

  useIonViewWillEnter(() => {
    setStatusBarStyle(Style.Light);
  });

  const showError = (msg: string) => {
    setErrorMessage(msg);
    window.setTimeout(() => setErrorMessage(''), 4000);
  };

  const showMessage = (msg: string) => {
    setMessage(msg);
    window.setTimeout(() => setMessage(''), 4000);
  };

  const normaliseAuthError = (msg: string) => {
    const lowered = msg.toLowerCase();

    if (lowered.includes('email not confirmed')) {
      return 'Please confirm your email before signing in. Check your inbox for the verification email.';
    }

    if (lowered.includes('invalid login credentials')) {
      return 'Incorrect email or password. Please try again.';
    }

    if (lowered.includes('user already registered')) {
      return 'An account with this email already exists. Please sign in instead.';
    }

    return msg;
  };

  const handleResendConfirmation = async () => {
    if (!email.trim()) {
      showError(
        'Enter your email address first so we can resend the confirmation email.'
      );
      return;
    }

    setIsSubmitting(true);
    const { error } = await supabase.auth.resend({
      type: 'signup',
      email: email.trim(),
    });
    setIsSubmitting(false);

    if (error) {
      showError(normaliseAuthError(error.message));
      return;
    }

    showMessage('Confirmation email sent. Please check your inbox.');
  };

  const handleSubmit = async () => {
    if (!email.trim() || password.trim().length < 6) {
      showError('Enter a valid email and password with at least 6 characters.');
      return;
    }

    setIsSubmitting(true);
    if (mode === 'login') {
      const { error } = await supabase.auth.signInWithPassword({
        email: email.trim(),
        password,
      });
      setIsSubmitting(false);
      if (error) {
        showError(normaliseAuthError(error.message));
        return;
      }
      history.replace('/home');
      return;
    }

    const { data, error } = await supabase.auth.signUp({
      email: email.trim(),
      password,
    });
    setIsSubmitting(false);
    if (error) {
      showError(normaliseAuthError(error.message));
      return;
    }

    if (data.session) {
      history.replace('/home');
      return;
    }

    showMessage('Account created! Check your email for a verification link.');
  };

  return (
    <IonPage>
      <IonHeader className="ion-no-border">
        <IonToolbar>
          <IonTitle>
            {mode === 'login' ? 'Welcome back' : 'Create account'}
          </IonTitle>
        </IonToolbar>
      </IonHeader>
      <IonContent className="ion-padding auth-page">
        <div className="auth-card">
          <h1>
            {mode === 'login'
              ? 'Sign in to continue'
              : 'Create your shopping account'}
          </h1>
          <p className="muted-text">
            Save your orders, addresses, and track deliveries securely.
          </p>

          {errorMessage && (
            <IonText color="danger">
              <p>{errorMessage}</p>
            </IonText>
          )}
          {message && (
            <IonText color="success">
              <p>{message}</p>
            </IonText>
          )}

          <div className="auth-form">
            <IonItem lines="none" className="auth-input-item">
              <IonLabel position="stacked">Email</IonLabel>
              <IonInput
                value={email}
                type="email"
                onIonInput={(e) => setEmail(e.detail.value ?? '')}
              />
            </IonItem>
            <IonItem lines="none" className="auth-input-item">
              <IonLabel position="stacked">Password</IonLabel>
              <IonInput
                value={password}
                type="password"
                onIonInput={(e) => setPassword(e.detail.value ?? '')}
              />
            </IonItem>
            <IonButton
              expand="block"
              onClick={handleSubmit}
              disabled={isSubmitting}
            >
              {mode === 'login' ? 'Sign in' : 'Create account'}
            </IonButton>
            {mode === 'login' && (
              <IonButton
                fill="clear"
                expand="block"
                onClick={handleResendConfirmation}
                disabled={isSubmitting}
              >
                Resend confirmation email
              </IonButton>
            )}
            <IonButton
              fill="clear"
              expand="block"
              onClick={() => setMode(mode === 'login' ? 'signup' : 'login')}
            >
              {mode === 'login'
                ? 'Need an account? Sign up'
                : 'Already have an account? Sign in'}
            </IonButton>
          </div>
        </div>
      </IonContent>
    </IonPage>
  );
};

export default Auth;