import {
  ok,
  err,
  buildPaginatedResult,
  DEFAULT_PAGE_SIZE,
  type ReadonlyDB,
  UnauthenticatedError,
  type CallerContext,
  type PaginationInput,
} from "@tailor-platform/erp-kit/core";
import type { DB } from "../generated/kysely-tailordb";
import { ForbiddenError } from "../lib/errors.generated";

type PreferenceOrderByField = "createdAt" | "categoryId" | "channelId";

export interface ListNotificationPreferencesInput extends PaginationInput<PreferenceOrderByField> {
  userId?: string;
}

/**
 * Returns the caller's persisted NotificationPreference rows as a paginated result. Self-service only.
 */
export async function run(
  db: ReadonlyDB<DB>,
  input: ListNotificationPreferencesInput,
  ctx: CallerContext,
) {
  // Every result here is scoped to the caller, so there is nothing to return when
  // there is no caller. Queries carry no permission gate of their own.
  const { actorId } = ctx;
  if (actorId === null) return err(new UnauthenticatedError());
  // Default to caller when userId is omitted; otherwise enforce self-only access.
  const userId = input.userId ?? actorId;
  if (userId !== actorId) {
    return err(new ForbiddenError(userId));
  }

  const limit = input.limit ?? DEFAULT_PAGE_SIZE;
  const offset = input.offset ?? 0;
  const orderBy = input.orderBy ?? "createdAt";
  const orderDirection = input.orderDirection ?? "desc";

  const rows = await db
    .selectFrom("NotificationPreference")
    .selectAll()
    .where("userId", "=", userId)
    .orderBy(orderBy, orderDirection)
    .limit(limit + 1)
    .offset(offset)
    .execute();

  return ok(buildPaginatedResult(rows, limit));
}