import { err, ok, type ReadonlyDB } from "@tailor-platform/erp-kit/core";
import type { DB } from "../generated/kysely-tailordb";
import { InvalidPaginationError } from "../lib/errors.generated";

export interface ListBusinessPartnersInput {
  search?: string;
  role?: "ALL" | "CUSTOMER" | "SUPPLIER";
  offset?: number;
  limit?: number;
}

export async function run(db: ReadonlyDB<DB>, input: ListBusinessPartnersInput) {
  const role = input.role ?? "ALL";
  const offset = input.offset ?? 0;
  const limit = input.limit ?? 25;
  if (
    !Number.isSafeInteger(offset) ||
    offset < 0 ||
    !Number.isSafeInteger(limit) ||
    limit < 1 ||
    limit > 100
  ) {
    return err(new InvalidPaginationError(`offset=${offset}, limit=${limit}`));
  }
  let query = db
    .selectFrom("BusinessPartner as partner")
    .leftJoin("CustomerAccount as customer", "customer.partnerId", "partner.id")
    .leftJoin("SupplierAccount as supplier", "supplier.partnerId", "partner.id");
  const search = input.search?.trim();
  if (search) {
    const escaped = search.replace(/[\\%_]/g, "\\$&");
    query = query.where("partner.name", "ilike", `%${escaped}%`);
  }
  // Filter before pagination; DISTINCT keeps multiple company accounts from duplicating partners.
  // Inactive accounts still count as customer/supplier relationships.
  if (role === "CUSTOMER") query = query.where("customer.id", "is not", null);
  if (role === "SUPPLIER") query = query.where("supplier.id", "is not", null);
  const count = await query
    .select((eb) => eb.fn.count<string>("partner.id").distinct().as("total"))
    .executeTakeFirstOrThrow();
  const rows = await query
    .select(["partner.id", "partner.name", "partner.type", "partner.status"])
    .select((eb) => [
      eb.fn.count<string>("customer.id").distinct().as("customerCount"),
      eb.fn.count<string>("supplier.id").distinct().as("supplierCount"),
    ])
    .groupBy(["partner.id", "partner.name", "partner.type", "partner.status"])
    .orderBy("partner.name")
    .orderBy("partner.id")
    .offset(offset)
    .limit(limit)
    .execute();
  return ok({
    items: rows.map(({ customerCount, supplierCount, ...partner }) => ({
      ...partner,
      isCustomer: Number(customerCount) > 0,
      isSupplier: Number(supplierCount) > 0,
    })),
    total: Number(count.total),
  });
}