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 type { CostCentreOption } from "./new-po-form";
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,
        }));
        // Pre-fill vendor only when all items share the same vendor
        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 } }),
    db.site.findMany({ where: { isActive: true }, orderBy: { name: "asc" }, select: { id: true, name: true, code: 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" } }),
  ]);

  // Build grouped account list for optgroups: "TOP CAT > Sub Cat" → items
  const accountGroupMap = new Map<string, typeof leafAccounts>();
  for (const a of leafAccounts) {
    const subLabel = a.parent ? `${a.parent.code} — ${a.parent.name}` : "Uncategorised";
    const topLabel = a.parent?.parent ? `${a.parent.parent.name} › ` : "";
    const groupKey = `${topLabel}${subLabel}`;
    if (!accountGroupMap.has(groupKey)) accountGroupMap.set(groupKey, []);
    accountGroupMap.get(groupKey)!.push(a);
  }
  const accounts = Array.from(accountGroupMap.entries()).map(([group, items]) => ({ group, items }));

  const costCentres: CostCentreOption[] = [
    ...vessels.map((v) => ({ ref: `v:${v.id}` as const, label: `${v.code} — ${v.name}`, group: "Vessels" as const })),
    ...sites.map((s) => ({ ref: `s:${s.id}` as const, label: `${s.code} — ${s.name}`, group: "Sites" as const })),
  ];

  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>
  );
}