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

export interface ResolveItemValuationPoliciesInput {
  companyId: string;
  itemIds: string[];
}

export interface ItemValuationPolicyResolution {
  itemId: string;
  valuationPolicy: Selectable<"ValuationPolicy">;
}

export async function run(db: ReadonlyDB<DB>, input: ResolveItemValuationPoliciesInput) {
  const itemIds = [...new Set(input.itemIds)];
  if (itemIds.length === 0) {
    return ok({ resolutions: [] as ItemValuationPolicyResolution[] });
  }

  const itemValuations = await db
    .selectFrom("ItemValuation")
    .select(["itemId", "valuationPolicyId"])
    .where("companyId", "=", input.companyId)
    .where("itemId", "in", itemIds)
    .execute();

  // One read covers both the assigned policies and the default.
  const policies = await db
    .selectFrom("ValuationPolicy")
    .selectAll()
    .where("companyId", "=", input.companyId)
    .execute();

  const policyById = new Map(policies.map((policy) => [policy.id, policy]));
  const defaultPolicy =
    policies.find((policy) => policy.defaultCompanyId === input.companyId) ?? null;
  const policyIdByItemId = new Map(
    itemValuations.map((itemValuation) => [itemValuation.itemId, itemValuation.valuationPolicyId]),
  );

  const resolutions = itemIds.flatMap((itemId) => {
    const assignedId = policyIdByItemId.get(itemId);
    const valuationPolicy = (assignedId ? policyById.get(assignedId) : undefined) ?? defaultPolicy;
    return valuationPolicy ? [{ itemId, valuationPolicy }] : [];
  });

  return ok({ resolutions });
}