'use client';

import { useCallback, useEffect, useState } from 'react';
import { loadStripe } from '@stripe/stripe-js';
import { Elements } from '@stripe/react-stripe-js';
import { useOrderStore, orderStore, type CheckoutStep } from '@/store/useOrderStore';
import { ShippingStep } from './checkout/ShippingStep';
import { PaymentStep } from './checkout/PaymentStep';
import { ReviewStep } from './checkout/ReviewStep';
import { ConfirmationStep } from './checkout/ConfirmationStep';

// Without a publishable key (local builds), loadStripe throws on every page that
// imports this module. Elements accepts null and the payment step stays empty.
const publishableKey = process.env.NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY;
const stripePromise = publishableKey ? loadStripe(publishableKey) : null;

const STEPS: { id: CheckoutStep; label: string }[] = [
  { id: 'shipping', label: 'Shipping' },
  { id: 'payment', label: 'Payment' },
  { id: 'review', label: 'Review' },
];

function getStepIndex(step: CheckoutStep): number {
  return STEPS.findIndex((s) => s.id === step);
}

export function CheckoutOverlay() {
  const step = useOrderStore((s) => s.step);
  const clientSecret = useOrderStore((s) => s.payment.clientSecret);
  const paymentStatus = useOrderStore((s) => s.payment.status);
  const paymentError = useOrderStore((s) => s.payment.errorMessage);
  const [isCreatingIntent, setIsCreatingIntent] = useState(false);

  const handleClose = useCallback(() => {
    orderStore.getState().resetOrder();
  }, []);

  const handleBack = useCallback(() => {
    const currentIndex = getStepIndex(step);
    if (currentIndex > 0) {
      orderStore.getState().setStep(STEPS[currentIndex - 1].id);
    } else {
      orderStore.getState().setStep('config');
    }
  }, [step]);

  // Create payment intent when entering the payment step (only once)
  useEffect(() => {
    if (step === 'payment' && !clientSecret && !isCreatingIntent && paymentStatus !== 'failed') {
      setIsCreatingIntent(true);
      orderStore.getState().createPaymentIntent().finally(() => {
        setIsCreatingIntent(false);
      });
    }
  }, [step, clientSecret, isCreatingIntent, paymentStatus]);

  // Close on Escape key
  useEffect(() => {
    if (step === 'config') return;
    const handleKeyDown = (e: KeyboardEvent) => {
      if (e.key === 'Escape') {
        handleClose();
      }
    };
    window.addEventListener('keydown', handleKeyDown);
    return () => window.removeEventListener('keydown', handleKeyDown);
  }, [step, handleClose]);

  if (step === 'config') return null;

  return (
    <div
      role="dialog"
      aria-modal="true"
      aria-label="Checkout"
      style={{
        position: 'fixed',
        inset: 0,
        zIndex: 100,
        display: 'flex',
        alignItems: 'center',
        justifyContent: 'center',
        background: 'rgba(255, 255, 255, 0.92)',
        backdropFilter: 'blur(12px)',
      }}
    >
      <div style={{
        width: '100%',
        maxWidth: '560px',
        maxHeight: '90vh',
        overflowY: 'auto',
        margin: '1rem',
        background: 'rgba(255, 255, 255, 0.95)',
        border: '1px solid rgba(153, 153, 153, 0.08)',
        borderRadius: '1rem',
        boxShadow: '0 24px 80px rgba(0, 0, 0, 0.5), 0 0 40px rgba(153, 153, 153, 0.1)',
      }}>
        {/* Header with progress */}
        {step !== 'confirmed' && (
          <div style={{ padding: '1.25rem 1.5rem', borderBottom: '1px solid rgba(153, 153, 153, 0.1)' }}>
            <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: '1rem' }}>
              <button
                onClick={handleBack}
                style={{
                  padding: '0.35rem 0.75rem',
                  borderRadius: '0.375rem',
                  border: '1px solid rgba(0, 0, 0, 0.08)',
                  background: 'transparent',
                  color: '#a8a8a8',
                  cursor: 'pointer',
                  fontSize: '0.75rem',
                  transition: 'all 0.2s ease',
                }}
              >
                Back
              </button>
              <h2 style={{ fontSize: '0.9rem', fontWeight: 600, color: '#0b0b0b', margin: 0 }}>
                Checkout
              </h2>
              <button
                onClick={handleClose}
                style={{
                  width: '28px',
                  height: '28px',
                  borderRadius: '50%',
                  border: '1px solid rgba(0, 0, 0, 0.08)',
                  background: 'transparent',
                  color: '#a8a8a8',
                  cursor: 'pointer',
                  fontSize: '0.9rem',
                  display: 'flex',
                  alignItems: 'center',
                  justifyContent: 'center',
                }}
                aria-label="Close checkout"
              >
                x
              </button>
            </div>

            {/* Progress bar */}
            <div style={{ display: 'flex', gap: '0.5rem', alignItems: 'center' }}>
              {STEPS.map((s, i) => {
                const currentIdx = getStepIndex(step);
                const isActive = i === currentIdx;
                const isComplete = i < currentIdx;
                return (
                  <div key={s.id} style={{ flex: 1, display: 'flex', flexDirection: 'column', gap: '0.35rem' }}>
                    <div style={{
                      height: '3px',
                      borderRadius: '2px',
                      background: isComplete
                        ? '#999999'
                        : isActive
                          ? 'linear-gradient(90deg, #999999, rgba(153, 153, 153, 0.2))'
                          : 'rgba(0, 0, 0, 0.06)',
                      transition: 'all 0.3s ease',
                    }} />
                    <span style={{
                      fontSize: '0.65rem',
                      color: isActive ? '#888888' : isComplete ? '#999999' : '#888888',
                      fontWeight: isActive ? 600 : 400,
                      textAlign: 'center',
                    }}>
                      {s.label}
                    </span>
                  </div>
                );
              })}
            </div>
          </div>
        )}

        {/* Step Content */}
        <div style={{ padding: '1.5rem' }}>
          {step === 'shipping' && <ShippingStep />}
          {(step === 'payment' || step === 'review') && clientSecret ? (
            <Elements
              stripe={stripePromise}
              options={{
                clientSecret,
                appearance: {
                  theme: 'stripe',
                  variables: {
                    colorPrimary: '#888888',
                    borderRadius: '0.375rem',
                    fontFamily: 'inherit',
                  },
                },
              }}
            >
              {/* Keep PaymentElement mounted (hidden) during review so confirmPayment works */}
              <div style={{ display: step === 'payment' ? 'block' : 'none' }}>
                <PaymentStep />
              </div>
              {step === 'review' && <ReviewStep />}
            </Elements>
          ) : (step === 'payment' || step === 'review') && !clientSecret ? (
            <div style={{ textAlign: 'center', padding: '2rem', fontSize: '0.85rem' }}>
              {paymentStatus === 'failed' ? (
                <div style={{ display: 'flex', flexDirection: 'column', gap: '0.75rem', alignItems: 'center' }}>
                  <div style={{ color: '#dc2626' }}>{paymentError || 'Failed to initialize payment'}</div>
                  <button
                    onClick={() => {
                      orderStore.getState().setPayment({ status: 'idle', errorMessage: '' });
                    }}
                    style={{
                      padding: '0.5rem 1rem',
                      borderRadius: '0.375rem',
                      border: '1px solid rgba(153, 153, 153, 0.5)',
                      background: 'rgba(153, 153, 153, 0.08)',
                      color: '#888888',
                      cursor: 'pointer',
                      fontSize: '0.8rem',
                      fontWeight: 600,
                    }}
                  >
                    Retry
                  </button>
                </div>
              ) : (
                <span style={{ color: '#a8a8a8' }}>Initializing secure payment...</span>
              )}
            </div>
          ) : null}
          {step === 'confirmed' && <ConfirmationStep />}
        </div>
      </div>
    </div>
  );
}