From de85bb806faaf9b91f54b6a1e302d3c0b93da300 Mon Sep 17 00:00:00 2001
From: Vadim <korobeinikovv@mail.ru>
Date: Thu, 9 Sep 2021 12:35:57 +0300
Subject: [PATCH] #69 : Fix showPage logic fot non infinite case

---
 src/components/Carousel/Carousel.svelte | 35 +++++++++++++++++++++----
 src/utils/page.js                       | 13 +++++++++
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/src/components/Carousel/Carousel.svelte b/src/components/Carousel/Carousel.svelte
index 1b50a77..ad2e6d1 100644
--- a/src/components/Carousel/Carousel.svelte
+++ b/src/components/Carousel/Carousel.svelte
@@ -23,6 +23,7 @@
     getClonesCount,
     getPartialPageSize,
     getScrollsCount,
+    getPageIndexByScrollIndex,
   } from '../../utils/page'
   import { get } from '../../utils/object'
   import { ProgressManager } from '../../utils/ProgressManager'
@@ -60,6 +61,7 @@
    * Page to start on
    */
   export let initialPageIndex = 0
+  $: initialScrollIndex = initialPageIndex
 
   /**
    * Transition duration (ms)
@@ -116,11 +118,19 @@
   export let pagesToScroll = 1
 
   export async function goTo(pageIndex, options) {
+    const scrollIndex = pageIndex
     const animated = get(options, 'animated', true)
-    if (typeof pageIndex !== 'number') {
+    if (typeof scrollIndex !== 'number') {
       throw new Error('pageIndex should be a number')
     }
-    await showPage(pageIndex * pagesToScroll + clonesCount.head, { animated })
+    await showPage(getPageIndexByScrollIndex({
+      infinite,
+      scrollIndex,
+      clonesCountHead: clonesCount.head,
+      pagesToScroll,
+      pagesCount,
+      pagesToShow,
+    }), { animated })
   }
 
   export async function goToPrev(options) {
@@ -269,9 +279,17 @@
         await tick()
         infinite && addClones()
 
-        // TODO: validate initialPageIndex, initialPageIndex is an initialScrollIndex
-        store.init(initialPageIndex * pagesToScroll + clonesCount.head)
         initPageSizes()
+        
+        // TODO: validate initialScrollIndex
+        store.init(getPageIndexByScrollIndex({
+          infinite,
+          scrollIndex: initialScrollIndex,
+          clonesCountHead: clonesCount.head,
+          pagesToScroll,
+          pagesCount,
+          pagesToShow,
+        }))
       }
 
       addResizeEventListener(initPageSizes)
@@ -284,7 +302,14 @@
   })
 
   async function handlePageChange(pageIndex) {
-    await showPage(pageIndex * pagesToScroll + clonesCount.head)
+    await showPage(getPageIndexByScrollIndex({
+      infinite,
+      scrollIndex: pageIndex,
+      clonesCountHead: clonesCount.head,
+      pagesToScroll,
+      pagesCount,
+      pagesToShow,
+    }))
   }
 
   function offsetPage(options) {
diff --git a/src/utils/page.js b/src/utils/page.js
index b8840f9..38aa44f 100644
--- a/src/utils/page.js
+++ b/src/utils/page.js
@@ -219,3 +219,16 @@ export function getScrollsCount({
     ? Math.ceil(pagesCountWithoutClones / pagesToScroll)
     : Math.round(pagesCountWithoutClones / pagesToScroll)
 }
+
+export function getPageIndexByScrollIndex({
+  infinite,
+  scrollIndex,
+  clonesCountHead,
+  pagesToScroll,
+  pagesCount,
+  pagesToShow,
+}) {
+  return infinite
+    ? clonesCountHead + scrollIndex * pagesToScroll
+    : Math.min(scrollIndex * pagesToScroll, pagesCount - pagesToShow)
+}