From 9c13e34fb10a77e947aaf4e715dfc58f2e3711ad Mon Sep 17 00:00:00 2001
From: HoomanHq <hoomandigital377@gmail.com>
Date: Sun, 10 Nov 2024 21:59:34 +0700
Subject: [PATCH] feat: only same tree next prev (#1239)

Co-authored-by: dharamveergit <dharamveersingh.em@gmail.com>
---
 src/lib/nextPrevPages.ts | 85 ++++++++++++++++++++++++++--------------
 1 file changed, 56 insertions(+), 29 deletions(-)

diff --git a/src/lib/nextPrevPages.ts b/src/lib/nextPrevPages.ts
index 836382ff..0d6b8ab2 100644
--- a/src/lib/nextPrevPages.ts
+++ b/src/lib/nextPrevPages.ts
@@ -2,31 +2,40 @@ import { getNavigation } from "@/layouts/navigation";
 
 export function findPrevAndNextPages(pathname: string) {
   const initialUrl = pathname?.match(/\/([^\/]*)\//)?.[1];
-  const nav = getNavigation(initialUrl);
-  let allItems: any = [];
-
-  function flattenNav(nav) {
-    nav.forEach((item) => {
-      allItems.push(item);
-      if (item.children && item.children.length > 0) {
-        flattenNav(item.children);
-      }
-    });
-  }
+  const nav = getNavigation(initialUrl)?.map((item) => {
+    return item?.children?.length
+      ? { ...item, children: item?.children?.filter((child) => !child.href) }
+      : item;
+  });
 
-  flattenNav(nav);
+  const currentItem = findItemByHref(nav, pathname);
+  if (!currentItem) return { prevPage: null, nextPage: null };
 
-  const currentIndex = allItems.findIndex((item) => item.href === pathname);
+  const parentItem = findParentItem(nav, currentItem);
+  if (!parentItem) return { prevPage: null, nextPage: null };
 
-  const prevIndex = currentIndex - 1;
-  const nextIndex = currentIndex + 1;
+  const currentIndex = parentItem.children.findIndex(
+    (item) => item.href === pathname,
+  );
 
-  let prevPage = prevIndex >= 0 ? allItems[prevIndex] : null;
+  let prevPage =
+    currentIndex > 0 ? parentItem.children[currentIndex - 1] : null;
   let nextPage =
-    nextIndex < allItems.length ? findFirstSubitem(allItems[nextIndex]) : null;
+    currentIndex < parentItem.children.length - 1
+      ? parentItem.children[currentIndex + 1]
+      : null;
+
+  if (prevPage === null && hasSubItems(currentItem)) {
+    prevPage = currentItem.children[0];
+  }
 
-  if (currentIndex > 0 && hasSubItems(allItems[currentIndex - 1])) {
-    prevPage = findLevelBackItem(allItems, currentIndex - 2);
+  if (nextPage === null && hasSubItems(currentItem)) {
+    nextPage = currentItem.children[0];
+  }
+
+  if (!hasSubItems(currentItem)) {
+    prevPage = findPrevSibling(parentItem, currentItem);
+    nextPage = findNextSibling(parentItem, currentItem);
   }
 
   return { prevPage, nextPage };
@@ -36,20 +45,38 @@ function hasSubItems(item) {
   return item.children && item.children.length > 0;
 }
 
-function findFirstSubitem(item) {
-  if (hasSubItems(item) && item?.children && item?.children?.length > 0) {
-    return findFirstSubitem(item?.children[0]);
+function findItemByHref(nav, href) {
+  for (let item of nav) {
+    if (item.href === href) {
+      return item;
+    } else if (item.children && item.children.length > 0) {
+      const childItem = findItemByHref(item.children, href);
+      if (childItem) return childItem;
+    }
   }
-  return item;
+  return null;
 }
 
-function findLevelBackItem(allItems, index: number) {
-  if (index >= 0) {
-    const currentItem = allItems[index];
-    if (hasSubItems(currentItem)) {
-      return findLevelBackItem(allItems, index - 1);
+function findParentItem(nav, currentItem) {
+  for (let item of nav) {
+    if (item.children && item.children.includes(currentItem)) {
+      return item;
+    } else if (item.children && item.children.length > 0) {
+      const parentItem = findParentItem(item.children, currentItem);
+      if (parentItem) return parentItem;
     }
-    return currentItem;
   }
   return null;
 }
+
+function findPrevSibling(parentItem, currentItem) {
+  const index = parentItem.children.findIndex((item) => item === currentItem);
+  return index > 0 ? parentItem.children[index - 1] : null;
+}
+
+function findNextSibling(parentItem, currentItem) {
+  const index = parentItem.children.findIndex((item) => item === currentItem);
+  return index < parentItem.children.length - 1
+    ? parentItem.children[index + 1]
+    : null;
+}