import { ok, err } from "@tailor-platform/erp-kit/core";
import { uoMCategoryLifecycle } from "../db/uoMCategory.lifecycle.generated";
import type { Transaction } from "../generated/kysely-tailordb";
import { CategoryHasActiveUnitsError, UomCategoryNotFoundError } from "../lib/errors.generated";

export interface DeactivateCategoryInput {
  categoryId: string;
}

/**
 * Function: deactivateCategory
 *
 * Disables a UoM category from being used in new product assignments
 * while preserving historical data. All units must be deactivated first.
 */
export async function run(db: Transaction, input: DeactivateCategoryInput) {
  // 1. Find category by ID
  const uoMCategory = await db
    .selectFrom("UoMCategory")
    .selectAll()
    .where("id", "=", input.categoryId)
    .forUpdate()
    .executeTakeFirst();

  // 2. If not found, throw error
  if (!uoMCategory) {
    return err(new UomCategoryNotFoundError(input.categoryId));
  }

  // Active units must be deactivated before their category
  const activeUnits = await db
    .selectFrom("Unit")
    .selectAll()
    .where("categoryId", "=", input.categoryId)
    .where("status", "=", "ACTIVE")
    .execute();

  if (activeUnits.length > 0) {
    return err(new CategoryHasActiveUnitsError(input.categoryId));
  }

  // 3. If already inactive, return category (idempotent)
  const nextStatus = uoMCategoryLifecycle.tryTransition(uoMCategory.status, "deactivate");
  if (!nextStatus) {
    return ok({ uoMCategory });
  }

  // 4. Update status to INACTIVE
  const updatedCategory = await db
    .updateTable("UoMCategory")
    .set({
      status: nextStatus,
    })
    .where("id", "=", input.categoryId)
    .returningAll()
    .executeTakeFirstOrThrow();

  // 5. Return updated category
  return ok({ uoMCategory: updatedCategory });
}