"use client";

import { useEffect, useState } from "react";
import { useRouter } from "next/navigation";
import { Trash2, ShoppingCart } from "lucide-react";
import { getCart, saveCart, clearCart, type CartItem } from "@/lib/cart";
import { formatCurrency } from "@/lib/utils";
import Link from "next/link";

export function CartView() {
  const router = useRouter();
  const [items, setItems] = useState<CartItem[]>([]);
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    setItems(getCart());
    setMounted(true);
    const handler = () => setItems(getCart());
    window.addEventListener("cart-updated", handler);
    return () => window.removeEventListener("cart-updated", handler);
  }, []);

  function updateQty(idx: number, qty: number) {
    const next = items.map((item, i) => i === idx ? { ...item, quantity: qty } : item);
    setItems(next); saveCart(next);
  }

  function remove(idx: number) {
    const next = items.filter((_, i) => i !== idx);
    setItems(next); saveCart(next);
  }

  function createPO() {
    const encoded = encodeURIComponent(JSON.stringify(items));
    clearCart();
    setItems([]);
    router.push(`/po/new?cart=${encoded}`);
  }

  if (!mounted) return null;

  if (items.length === 0) {
    return (
      <div className="rounded-lg border border-neutral-200 bg-white p-12 text-center">
        <ShoppingCart className="h-12 w-12 text-neutral-300 mx-auto mb-4" />
        <p className="text-neutral-500 font-medium">Your cart is empty</p>
        <p className="text-sm text-neutral-400 mt-1 mb-6">Browse Items or Vendors to add line items</p>
        <div className="flex gap-3 justify-center">
          <Link href="/inventory/items" className="rounded-lg border border-neutral-300 px-4 py-2 text-sm font-medium text-neutral-700 hover:bg-neutral-50">Browse Items</Link>
          <Link href="/inventory/vendors" className="rounded-lg border border-neutral-300 px-4 py-2 text-sm font-medium text-neutral-700 hover:bg-neutral-50">Browse Vendors</Link>
        </div>
      </div>
    );
  }

  const total = items.reduce((s, i) => s + i.quantity * i.unitPrice, 0);

  return (
    <div className="space-y-4">
      <div className="rounded-lg border border-neutral-200 bg-white overflow-hidden">
        <table className="w-full text-sm">
          <thead className="bg-neutral-50 border-b border-neutral-200">
            <tr>
              <th className="px-4 py-3 text-left font-medium text-neutral-600">Item</th>
              <th className="px-4 py-3 text-left font-medium text-neutral-600">Vendor</th>
              <th className="px-4 py-3 text-right font-medium text-neutral-600">Unit Price</th>
              <th className="px-4 py-3 text-right font-medium text-neutral-600">Qty</th>
              <th className="px-4 py-3 text-right font-medium text-neutral-600">Total</th>
              <th className="px-4 py-3 w-8" />
            </tr>
          </thead>
          <tbody className="divide-y divide-neutral-100">
            {items.map((item, i) => (
              <tr key={i}>
                <td className="px-4 py-3">
                  <p className="font-medium text-neutral-900">{item.name}</p>
                  {item.description && <p className="text-xs text-neutral-500">{item.description}</p>}
                </td>
                <td className="px-4 py-3 text-neutral-600">{item.vendorName ?? <span className="italic text-neutral-400">Not specified</span>}</td>
                <td className="px-4 py-3 text-right text-neutral-700">{item.unitPrice > 0 ? formatCurrency(item.unitPrice) : <span className="italic text-neutral-400">TBD</span>}</td>
                <td className="px-4 py-3 text-right">
                  <input
                    type="number" min="1" step="any"
                    value={item.quantity}
                    onChange={(e) => updateQty(i, parseFloat(e.target.value) || 1)}
                    className="w-20 rounded border border-neutral-200 px-2 py-1 text-sm text-right"
                  />
                </td>
                <td className="px-4 py-3 text-right font-medium text-neutral-900">
                  {item.unitPrice > 0 ? formatCurrency(item.quantity * item.unitPrice) : "—"}
                </td>
                <td className="px-4 py-3">
                  <button onClick={() => remove(i)} className="text-neutral-400 hover:text-danger"><Trash2 className="h-4 w-4" /></button>
                </td>
              </tr>
            ))}
          </tbody>
          <tfoot className="border-t border-neutral-200 bg-neutral-50">
            <tr>
              <td colSpan={4} className="px-4 py-3 text-right text-sm font-semibold text-neutral-900">Estimated Total (excl. GST)</td>
              <td className="px-4 py-3 text-right text-sm font-semibold text-neutral-900">{formatCurrency(total)}</td>
              <td />
            </tr>
          </tfoot>
        </table>
      </div>

      <div className="flex items-center justify-between">
        <button onClick={() => { clearCart(); setItems([]); }} className="text-sm text-danger-600 hover:underline">Clear cart</button>
        <div className="flex gap-3">
          <Link href="/inventory/items" className="rounded-lg border border-neutral-300 px-4 py-2 text-sm font-medium text-neutral-700 hover:bg-neutral-50">
            + Add more items
          </Link>
          <button onClick={createPO} className="rounded-lg bg-primary-600 px-5 py-2 text-sm font-semibold text-white hover:bg-primary-700">
            Create Purchase Order →
          </button>
        </div>
      </div>

      <p className="text-xs text-neutral-400">Prices shown are last known prices. Final amounts are set in the PO form.</p>
    </div>
  );
}