"use server";

import { auth } from "@/auth";
import { db } from "@/lib/db";
import { hasPermission } from "@/lib/permissions";
import { revalidatePath } from "next/cache";
import { z } from "zod";

type ActionResult = { ok: true } | { error: string };

const lineItemSchema = z.object({
  name: z.string().min(1),
  description: z.string().optional(),
  quantity: z.coerce.number().positive(),
  unit: z.string().min(1),
  size: z.string().optional(),
  unitPrice: z.coerce.number().nonnegative(),
  gstRate: z.coerce.number().min(0).max(1).default(0.18),
});

export async function managerEditLineItems({
  poId,
  lineItems,
}: {
  poId: string;
  lineItems: Array<{ name: string; description?: string; quantity: number; unit: string; size?: string; unitPrice: number }>;
}): Promise<ActionResult> {
  const session = await auth();
  if (!session?.user || !hasPermission(session.user.role, "approve_po")) {
    return { error: "Forbidden" };
  }

  const parsed = z.array(lineItemSchema).min(1).safeParse(lineItems);
  if (!parsed.success) return { error: parsed.error.errors[0].message };

  const po = await db.purchaseOrder.findUnique({
    where: { id: poId },
    include: { lineItems: { orderBy: { sortOrder: "asc" } } },
  });
  if (!po) return { error: "PO not found" };
  if (po.status !== "MGR_REVIEW") return { error: "Line items can only be edited while the PO is under review." };

  const originalSnapshot = po.lineItems.map((li) => ({
    name: (li as typeof li & { name: string }).name,
    description: li.description ?? undefined,
    quantity: Number(li.quantity),
    unit: li.unit,
    size: li.size ?? undefined,
    unitPrice: Number(li.unitPrice),
  }));

  const newTotal = parsed.data.reduce(
    (sum, item) => sum + item.quantity * item.unitPrice * (1 + item.gstRate),
    0
  );

  await db.purchaseOrder.update({
    where: { id: poId },
    data: {
      totalAmount: newTotal,
      lineItems: {
        deleteMany: {},
        create: parsed.data.map((item, idx) => ({
          name: item.name,
          description: item.description ?? null,
          quantity: item.quantity,
          unit: item.unit,
          size: item.size ?? null,
          unitPrice: item.unitPrice,
          totalPrice: item.quantity * item.unitPrice,
          gstRate: item.gstRate,
          sortOrder: idx,
        })),
      },
      actions: {
        create: {
          actionType: "MANAGER_LINE_EDIT",
          actorId: session.user.id,
          metadata: { original: originalSnapshot },
        },
      },
    },
  });

  revalidatePath(`/approvals/${poId}`);
  return { ok: true };
}