// @flow
import fractionalIndex from "fractional-index";
import naturalSort from "../../shared/utils/naturalSort";
import { Collection } from "../models";

export default async function collectionIndexing(teamId: string) {
  const collections = await Collection.findAll({
    where: { teamId, deletedAt: null }, //no point in maintaining index of deleted collections.
    attributes: ["id", "index", "name"],
  });

  let sortableCollections = collections.map((collection) => {
    return [collection, collection.index];
  });

  sortableCollections = naturalSort(
    sortableCollections,
    (collection) => collection[0].name
  );

  //for each collection with null index, use previous collection index to create new index
  let previousCollectionIndex = null;

  for (const collection of sortableCollections) {
    if (collection[1] === null) {
      const index = fractionalIndex(previousCollectionIndex, collection[1]);
      collection[0].index = index;
      await collection[0].save();
    }
    previousCollectionIndex = collection[0].index;
  }

  const indexedCollections = {};
  sortableCollections.forEach((collection) => {
    indexedCollections[collection[0].id] = collection[0].index;
  });

  return indexedCollections;
}