// <CartStub> — minimal cart preview at /cart.
//
// Reads from useCart(). Renders a table of line items with thumbnail,
// label, size, option choices, quantity controls, line total, and a
// grand total. The "Proceed to checkout" button shows an inline
// banner with "Checkout coming soon" — checkout is downstream.
//
// Why a stub
// ──────────
// Per locked decision #14: checkout is intentionally out of scope
// for v0.7. The cart is the hand-off point. When a real checkout
// lands (Stripe Checkout session, custom flow, whatever), this
// component is the place to wire it — replace the banner with a
// POST to the order endpoint and a redirect.

import { useState } from 'react';
import { Link } from 'react-router-dom';
import { ShopHeader } from './ShopHeader.jsx';
import { useCart } from '../../hooks/useCart.js';

function formatUSD(cents) {
  return `$${((cents || 0) / 100).toLocaleString('en-US', { minimumFractionDigits: 2, maximumFractionDigits: 2 })}`;
}

function describeOptions(optionChoices) {
  const entries = Object.entries(optionChoices || {});
  if (entries.length === 0) return null;
  return entries
    .map(([groupSlug, valueSlug]) => `${groupSlug}: ${valueSlug}`)
    .join(' · ');
}

export function CartStub() {
  const { items, count, totalCents, updateItem, removeItem, clear } = useCart();
  const [checkoutBanner, setCheckoutBanner] = useState(false);

  const handleCheckout = () => {
    setCheckoutBanner(true);
    // Auto-dismiss after a few seconds so the page doesn't get
    // stuck in the toast state. Re-clicking the button re-arms it.
    setTimeout(() => setCheckoutBanner(false), 4000);
  };

  return (
    <div className="app-shell">
      <ShopHeader />
      <main className="shop-main">
        <section className="shop-cart">
          <header className="shop-cart__head">
            <h1 className="shop-cart__title">Your cart</h1>
            <p className="shop-cart__count">
              {count === 0 ? 'Empty' : count === 1 ? '1 item' : `${count} items`}
            </p>
          </header>

          {items.length === 0 ? (
            <div className="shop-cart__empty">
              <p>Your cart is empty.</p>
              <Link to="/shop" className="shop-cart__continue">Continue shopping →</Link>
            </div>
          ) : (
            <>
              <ul className="shop-cart__items">
                {items.map((line) => (
                  <li key={line.id} className="shop-cart__line">
                    <div className="shop-cart__thumb">
                      {line.imageUrl ? (
                        <img src={line.imageUrl} alt={line.productLabel} loading="lazy" />
                      ) : (
                        <div className="shop-cart__thumb-fallback" aria-hidden="true">🐾</div>
                      )}
                    </div>
                    <div className="shop-cart__details">
                      <h3 className="shop-cart__label">{line.productLabel}</h3>
                      <p className="shop-cart__meta">
                        {line.sizeLabel && <span>{line.sizeLabel}</span>}
                        {describeOptions(line.optionChoices) && (
                          <>
                            <span aria-hidden="true"> · </span>
                            <span>{describeOptions(line.optionChoices)}</span>
                          </>
                        )}
                      </p>
                      <p className="shop-cart__unit">{formatUSD(line.unitPriceCents)} each</p>
                    </div>
                    <div className="shop-cart__qty">
                      <button
                        type="button"
                        onClick={() => updateItem(line.id, { quantity: Math.max(1, line.quantity - 1) })}
                        aria-label="Decrease quantity"
                        className="shop-qty-btn"
                        disabled={line.quantity <= 1}
                      >−</button>
                      <input
                        type="number"
                        min="1"
                        max="99"
                        value={line.quantity}
                        onChange={(e) => {
                          const n = parseInt(e.target.value, 10);
                          if (Number.isFinite(n) && n > 0) {
                            updateItem(line.id, { quantity: Math.min(99, n) });
                          }
                        }}
                        className="shop-qty-input"
                        aria-label="Quantity"
                      />
                      <button
                        type="button"
                        onClick={() => updateItem(line.id, { quantity: Math.min(99, line.quantity + 1) })}
                        aria-label="Increase quantity"
                        className="shop-qty-btn"
                      >+</button>
                    </div>
                    <div className="shop-cart__line-total">
                      {formatUSD(line.unitPriceCents * line.quantity)}
                    </div>
                    <button
                      type="button"
                      onClick={() => removeItem(line.id)}
                      className="shop-cart__remove"
                      aria-label={`Remove ${line.productLabel} from cart`}
                    >
                      ✕
                    </button>
                  </li>
                ))}
              </ul>

              <div className="shop-cart__summary">
                <div className="shop-cart__total">
                  <span>Total</span>
                  <strong className="shop-price-large">{formatUSD(totalCents)}</strong>
                </div>
                <p className="shop-cart__shipping-note">
                  Shipping and taxes calculated at checkout.
                </p>
                {checkoutBanner && (
                  <p className="shop-cart__checkout-banner" role="status">
                    🚧 Checkout coming soon! We're still building this part — your cart will be here when it's ready.
                  </p>
                )}
                <div className="shop-cart__actions">
                  <Link to="/shop" className="shop-cart__continue">
                    ← Continue shopping
                  </Link>
                  <div className="shop-cart__actions-right">
                    <button
                      type="button"
                      onClick={() => {
                        if (window.confirm('Clear all items from your cart?')) clear();
                      }}
                      className="shop-cart__clear"
                    >
                      Clear cart
                    </button>
                    <button
                      type="button"
                      onClick={handleCheckout}
                      className="shop-cart__checkout"
                    >
                      Proceed to checkout →
                    </button>
                  </div>
                </div>
              </div>
            </>
          )}
        </section>
      </main>
    </div>
  );
}