Move getting indexes to utils

src/utils/item-index.js

@@ -0,0 +1,25 @@
+export function getNextItemIndexLimited(currentItemIndex, items) {
+  return Math.min(currentItemIndex + 1, items.length - 1)
+}
+
+export function getNextItemIndexInfinte(currentItemIndex, items) {
+  const newCurrentItemIndex = currentItemIndex + 1
+  return newCurrentItemIndex > items.length - 1 ? 0 : newCurrentItemIndex
+}
+
+export function getNextItemIndexFn(infinite) {
+  return infinite ? getNextItemIndexInfinte : getNextItemIndexLimited
+}
+
+export function getPrevItemIndexLimited(currentItemIndex, items) {
+  return Math.max(currentItemIndex - 1, 0)
+}
+
+export function getPrevItemIndexInfinte(currentItemIndex, items) {
+  const newCurrentItemIndex = currentItemIndex - 1
+  return newCurrentItemIndex >= 0 ? newCurrentItemIndex : items.length - 1
+}
+
+export function getPrevItemIndexFn(infinite) {
+  return infinite ? getPrevItemIndexInfinte : getPrevItemIndexLimited
+}