import React, { useState } from 'react';
import { loadStripe } from '@stripe/stripe-js';
import { Elements, CardElement, useStripe, useElements } from '@stripe/react-stripe-js';
import './UpgradeFlow.css';

const stripePromise = loadStripe(import.meta.env.VITE_STRIPE_PUBLISHABLE_KEY || 'pk_test_51QTaIiRu6l8tVuJxtest_placeholder');

/**
 * Checkout form component
 */
function CheckoutForm({ tier, domain, onSuccess }) {
  const stripe = useStripe();
  const elements = useElements();
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState(null);

  const handleSubmit = async (e) => {
    e.preventDefault();

    if (!stripe || !elements) return;

    setLoading(true);
    setError(null);

    try {
      // Create payment method
      const { error: pmError, paymentMethod } = await stripe.createPaymentMethod({
        type: 'card',
        card: elements.getElement(CardElement)
      });

      if (pmError) {
        throw new Error(pmError.message);
      }

      // Subscribe or register domain
      const endpoint = domain 
        ? '/api/premium/domains/register'
        : '/api/premium/subscribe';

      const body = domain ? {
        domain: domain,
        walletAddress: window.ethereum?.selectedAddress || '0x0000000000000000000000000000000000000000',
        paymentMethodId: paymentMethod.id
      } : {
        tier: tier,
        paymentMethodId: paymentMethod.id,
        billingPeriod: 'yearly'
      };

      const response = await fetch(endpoint, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'Authorization': `Bearer ${localStorage.getItem('token')}`
        },
        body: JSON.stringify(body)
      });

      const data = await response.json();

      if (data.success) {
        onSuccess(data);
      } else {
        throw new Error(data.error || 'Subscription failed');
      }

    } catch (err) {
      setError(err.message);
    } finally {
      setLoading(false);
    }
  };

  const getAmount = () => {
    if (domain) return '$100/year';
    if (tier === 'premium') return '$100/year';
    if (tier === 'enterprise') return '$500/month';
    return '$0';
  };

  return (
    <form onSubmit={handleSubmit} className="checkout-form">
      <div className="card-element-wrapper">
        <CardElement
          options={{
            style: {
              base: {
                fontSize: '16px',
                color: '#fff',
                '::placeholder': {
                  color: '#9ca3af'
                }
              },
              invalid: {
                color: '#ed4245'
              }
            }
          }}
        />
      </div>

      {error && (
        <div className="error-message">{error}</div>
      )}

      <button
        type="submit"
        disabled={!stripe || loading}
        className="btn-submit"
      >
        {loading ? 'Processing...' : `Subscribe - ${getAmount()}`}
      </button>

      <p style={{ textAlign: 'center', marginTop: '16px', fontSize: '12px', color: '#aaa' }}>
        By subscribing, you agree to our Terms of Service and Privacy Policy
      </p>
    </form>
  );
}

/**
 * Main upgrade flow component
 */
export default function UpgradeFlow({ currentTier = 'free' }) {
  const [selectedTier, setSelectedTier] = useState('premium');
  const [domainName, setDomainName] = useState('');
  const [domainAvailable, setDomainAvailable] = useState(null);
  const [checkingDomain, setCheckingDomain] = useState(false);

  const checkDomain = async () => {
    if (!domainName) {
      setError('Please enter a domain name');
      return;
    }

    setCheckingDomain(true);
    setDomainAvailable(null);

    try {
      const response = await fetch('/api/premium/domains/check-availability', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'Authorization': `Bearer ${localStorage.getItem('token')}`
        },
        body: JSON.stringify({
          domain: `${domainName}.aethex`
        })
      });

      const data = await response.json();
      
      if (data.success) {
        setDomainAvailable(data);
      } else {
        throw new Error(data.error);
      }

    } catch (error) {
      console.error('Failed to check domain:', error);
      setDomainAvailable({
        available: false,
        domain: `${domainName}.aethex`,
        error: error.message
      });
    } finally {
      setCheckingDomain(false);
    }
  };

  const handleSuccess = (data) => {
    alert('Subscription successful! Welcome to premium!');
    // Redirect to dashboard or show success modal
    window.location.href = '/dashboard';
  };

  return (
    <div className="upgrade-flow">
      <h1>Upgrade to Premium</h1>

      <div className="tier-selection">
        <div
          className={`tier-card ${selectedTier === 'premium' ? 'selected' : ''}`}
          onClick={() => setSelectedTier('premium')}
        >
          <h3>Premium</h3>
          <div className="price">$100/year</div>
          <ul>
            <li>✓ Custom .aethex domain</li>
            <li>✓ Blockchain NFT ownership</li>
            <li>✓ Unlimited friends</li>
            <li>✓ HD voice/video calls (1080p)</li>
            <li>✓ 10 GB storage</li>
            <li>✓ Custom branding</li>
            <li>✓ Analytics dashboard</li>
            <li>✓ Priority support</li>
            <li>✓ Ad-free experience</li>
          </ul>
        </div>

        <div
          className={`tier-card ${selectedTier === 'enterprise' ? 'selected' : ''}`}
          onClick={() => setSelectedTier('enterprise')}
        >
          <h3>Enterprise</h3>
          <div className="price">$500+/month</div>
          <ul>
            <li>✓ Everything in Premium</li>
            <li>✓ White-label platform</li>
            <li>✓ Custom domain (chat.yoursite.com)</li>
            <li>✓ Unlimited team members</li>
            <li>✓ Dedicated infrastructure</li>
            <li>✓ 4K video quality</li>
            <li>✓ SLA guarantees (99.9% uptime)</li>
            <li>✓ Dedicated account manager</li>
            <li>✓ Custom integrations</li>
          </ul>
        </div>
      </div>

      {selectedTier === 'premium' && (
        <div className="domain-selection">
          <h3>Choose Your .aethex Domain</h3>
          <p style={{ color: '#aaa', marginBottom: '16px' }}>
            Your premium blockchain domain with NFT ownership proof
          </p>
          
          <div className="domain-input-group">
            <input
              type="text"
              value={domainName}
              onChange={(e) => setDomainName(e.target.value.toLowerCase().replace(/[^a-z0-9-]/g, ''))}
              placeholder="yourname"
              className="domain-input"
              maxLength={50}
            />
            <span className="domain-suffix">.aethex</span>
            <button 
              type="button"
              onClick={checkDomain} 
              disabled={checkingDomain || !domainName}
            >
              {checkingDomain ? 'Checking...' : 'Check'}
            </button>
          </div>

          {domainAvailable && (
            <div className={`domain-status ${domainAvailable.available ? 'available' : 'unavailable'}`}>
              {domainAvailable.available ? (
                <>
                  <p><strong>✓ {domainAvailable.domain} is available!</strong></p>
                  <p style={{ fontSize: '14px', marginTop: '8px', opacity: 0.8 }}>
                    Price: ${domainAvailable.price}/year
                  </p>
                </>
              ) : (
                <div>
                  <p><strong>✗ {domainAvailable.domain} is taken</strong></p>
                  {domainAvailable.error && (
                    <p style={{ fontSize: '14px', marginTop: '4px' }}>{domainAvailable.error}</p>
                  )}
                  {domainAvailable.suggestedAlternatives && domainAvailable.suggestedAlternatives.length > 0 && (
                    <>
                      <p style={{ marginTop: '12px' }}>Try these alternatives:</p>
                      <ul>
                        {domainAvailable.suggestedAlternatives.map(alt => (
                          <li 
                            key={alt} 
                            onClick={() => setDomainName(alt.replace('.aethex', ''))}
                          >
                            {alt}
                          </li>
                        ))}
                      </ul>
                    </>
                  )}
                </div>
              )}
            </div>
          )}
        </div>
      )}

      {(selectedTier === 'enterprise' || (selectedTier === 'premium' && domainAvailable?.available)) && (
        <Elements stripe={stripePromise}>
          <CheckoutForm
            tier={selectedTier}
            domain={domainAvailable?.available ? `${domainName}.aethex` : null}
            onSuccess={handleSuccess}
          />
        </Elements>
      )}

      {selectedTier === 'enterprise' && !domainAvailable && (
        <div style={{ textAlign: 'center', padding: '40px', color: '#aaa' }}>
          <p>For Enterprise plans, please contact our sales team:</p>
          <p style={{ marginTop: '16px' }}>
            <a href="mailto:enterprise@aethex.app" style={{ color: '#5865f2' }}>
              enterprise@aethex.app
            </a>
          </p>
        </div>
      )}
    </div>
  );
}