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 { buildAccountGroups } from "@/lib/cost-centre-groups";
import { formatDeliveryLocation } from "@/lib/delivery-location";
import { getTermsCatalogue, getDefaultPoTerms } from "@/lib/terms-data";
import { buildDuplicatePrefill, type DuplicatePrefill } from "@/lib/duplicate-po";
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; vesselId?: string; duplicate?: 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, vesselId, duplicate } = await searchParams;

  // Duplicate-PO prefill (issue #142): copy a source PO's editable order fields
  // onto a fresh draft. Nothing is written until the user saves/submits — same
  // shape as the cart→new-PO prefill below, just a richer field set.
  let dup: DuplicatePrefill | null = null;
  let initialLineItems: LineItemInput[] | undefined;
  let initialVendorId: string | undefined;
  let initialVesselId: string | undefined = vesselId;

  if (duplicate) {
    const source = await db.purchaseOrder.findUnique({
      where: { id: duplicate },
      include: { lineItems: { orderBy: { sortOrder: "asc" } } },
    });
    if (source) dup = buildDuplicatePrefill(source);
  } else 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
    }
  }

  const [vessels, leafAccounts, vendors, companies, deliveryLocations, projectCodes] = await Promise.all([
    db.vessel.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" } }),
    db.company.findMany({ where: { isActive: true }, orderBy: { name: "asc" }, select: { id: true, name: true, code: true } }),
    db.deliveryLocation.findMany({ where: { isActive: true }, orderBy: { createdAt: "asc" }, include: { company: { select: { name: true } } } }),
    db.projectCode.findMany({ where: { isActive: true }, orderBy: { code: "asc" }, select: { code: true } }),
  ]);

  const accounts = buildAccountGroups(leafAccounts);
  const deliveryOptions = deliveryLocations.map((l) => formatDeliveryLocation(l.company.name, l.address));
  const projectCodeOptions = projectCodes.map((c) => c.code);
  const [termsCatalogue, defaultTerms] = await Promise.all([getTermsCatalogue(), getDefaultPoTerms()]);

  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
        vessels={vessels}
        accounts={accounts}
        vendors={vendors}
        companies={companies}
        deliveryOptions={deliveryOptions}
        projectCodeOptions={projectCodeOptions}
        termsCatalogue={termsCatalogue}
        defaultTerms={defaultTerms}
        initialLineItems={dup?.initialLineItems ?? initialLineItems}
        initialVendorId={dup?.initialVendorId ?? initialVendorId}
        initialVesselId={dup?.initialVesselId ?? initialVesselId}
        initialCompanyId={dup?.initialCompanyId}
        initialTitle={dup?.initialTitle}
        initialAccountId={dup?.initialAccountId}
        initialMultiAccount={dup?.initialMultiAccount}
        initialProjectCode={dup?.initialProjectCode}
        initialPlaceOfDelivery={dup?.initialPlaceOfDelivery}
        initialDateRequired={dup?.initialDateRequired}
        initialPiQuotationNo={dup?.initialPiQuotationNo}
        initialPiQuotationDate={dup?.initialPiQuotationDate}
        initialRequisitionNo={dup?.initialRequisitionNo}
        initialRequisitionDate={dup?.initialRequisitionDate}
        initialTerms={dup?.initialTerms}
      />
    </div>
  );
}