feat: Allow sorting collections in sidebar (#1870)

closes #1759

Co-authored-by: Tom Moor <tom.moor@gmail.com>

server/utils/collectionIndexing.js

@@ -0,0 +1,39 @@
+// @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;
+}

server/utils/removeIndexCollision.js

@@ -0,0 +1,45 @@
+// @flow
+import fractionalIndex from "fractional-index";
+import { Collection } from "../models";
+import { sequelize, Op } from "../sequelize";
+
+/**
+ *
+ * @param teamId The team id whose collections has to be fetched
+ * @param index the index for which collision has to be checked
+ * @returns An index, if there is collision returns a new index otherwise the same index
+ */
+export default async function removeIndexCollision(
+  teamId: string,
+  index: string
+) {
+  const collection = await Collection.findOne({
+    where: { teamId, deletedAt: null, index },
+  });
+
+  if (!collection) {
+    return index;
+  }
+
+  const nextCollection = await Collection.findAll({
+    where: {
+      teamId,
+      deletedAt: null,
+      index: {
+        [Op.gt]: index,
+      },
+    },
+    attributes: ["id", "index"],
+    limit: 1,
+    order: [
+      sequelize.literal('"collection"."index" collate "C"'),
+      ["updatedAt", "DESC"],
+    ],
+  });
+
+  const nextCollectionIndex = nextCollection.length
+    ? nextCollection[0].index
+    : null;
+
+  return fractionalIndex(index, nextCollectionIndex);
+}