import { createCache } from '$lib/cache.server';
import { cacheUpdater, cachedMethod } from './root';

const cache = createCache();

/**
 * @template T
 * @typedef {import('$types/base').Result<T>} Result<T>
 */

/**
 * @typedef {import('$types/base').Category} Category
 */

/**
 * @param {Result<Category>} categories 
 * @returns {Result<Category>}
 */
const updateCategoryCache = cacheUpdater(cache);

/**
 * @param {import('postgres').Sql} sql 
 * @param {number[]} user_ids 
 * @returns {Promise<Result<Category>>}
 */
export const getCategoriesCached = cachedMethod(cache, getCategories);

/**
 * @param {import('postgres').Sql} sql 
 * @param {number[]} category_ids 
 * @returns {Promise<Result<Category>>}
 */
export async function getCategories(sql, category_ids) {
  if (category_ids.length == 0) return {};

  const query = sql`
      SELECT id, name
      FROM doki8902.post_category
      WHERE id IN ${ sql(category_ids) };`;

  let categories = await query;

  /**
   * @type {Result<Category>}
   */
  let result = {};

  categories.forEach(row => {
    result[row['id']] = {
      id: row['id'],
      name: row['name']
    }
  })

  return updateCategoryCache(result);
}

/**
 * 
 * @param {import('postgres').Sql} sql 
 * @param {number} category_id 
 * @returns {Promise<Category | import('$types/error').Error>}
 */
export async function getCategoryCached(sql, category_id) {
  const categories = await getCategoriesCached(sql, [category_id]);

  if (Object.keys(categories).length == 0) {
    return {
      error: true,
      msg: `Could not find Category of ID ${category_id}`
    };
  }

  return categories[category_id];
}