import { auth } from "@/auth";
import { db } from "@/lib/db";
import { hasPermission } from "@/lib/permissions";
import { redirect } from "next/navigation";
import { NewPoForm } from "./new-po-form";
import { buildCostCentreGroups, buildAccountGroups } from "@/lib/cost-centre-groups";
import type { Metadata } from "next";
import type { LineItemInput } from "@/lib/validations/po";
import type { CartItem } from "@/lib/cart";

export const metadata: Metadata = { title: "New Purchase Order" };

interface Props {
  searchParams: Promise<{ cart?: string; costCentreRef?: string }>;
}

export default async function NewPoPage({ searchParams }: Props) {
  const session = await auth();
  if (!session?.user) redirect("/login");

  if (!hasPermission(session.user.role, "create_po")) {
    redirect("/dashboard");
  }

  const { cart, costCentreRef: initialCostCentreRef } = await searchParams;

  let initialLineItems: LineItemInput[] | undefined;
  let initialVendorId: string | undefined;
  if (cart) {
    try {
      const cartItems: CartItem[] = JSON.parse(decodeURIComponent(cart));
      if (Array.isArray(cartItems) && cartItems.length > 0) {
        initialLineItems = cartItems.map((item) => ({
          name: item.name,
          description: item.description ?? "",
          quantity: item.quantity,
          unit: item.unit,
          size: "",
          unitPrice: item.unitPrice,
          gstRate: 0.18,
          productId: item.productId,
        }));
        const vendorIds = [...new Set(cartItems.map((i) => i.vendorId).filter(Boolean))];
        if (vendorIds.length === 1) initialVendorId = vendorIds[0];
      }
    } catch {
      // malformed cart param — ignore and start empty
    }
  }

  const [vessels, sites, leafAccounts, vendors] = await Promise.all([
    db.vessel.findMany({ where: { isActive: true }, orderBy: { name: "asc" }, select: { id: true, name: true, code: true, siteId: true } }),
    db.site.findMany({ where: { isActive: true }, orderBy: { name: "asc" }, select: { id: true, name: true } }),
    db.account.findMany({
      where: { isActive: true, children: { none: {} } },
      orderBy: { code: "asc" },
      select: { id: true, code: true, name: true, parent: { select: { name: true, code: true, parent: { select: { name: true, code: true } } } } },
    }),
    db.vendor.findMany({ where: { isActive: true }, orderBy: { name: "asc" } }),
  ]);

  const costCentres = buildCostCentreGroups(vessels, sites);
  const accounts = buildAccountGroups(leafAccounts);

  return (
    <div className="max-w-6xl">
      <div className="mb-6">
        <h1 className="text-2xl font-semibold text-neutral-900">New Purchase Order</h1>
        <p className="mt-1 text-sm text-neutral-500">
          Fill in the details below. You can save as draft or submit directly for approval.
        </p>
      </div>
      <NewPoForm
        costCentres={costCentres}
        accounts={accounts}
        vendors={vendors}
        initialLineItems={initialLineItems}
        initialVendorId={initialVendorId}
        initialCostCentreRef={initialCostCentreRef}
      />
    </div>
  );
}
