feat: Allow sorting collections in sidebar (#1870)

closes #1759

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

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);
+}