From b29c970865c72e08abfa9a471a6674003b8aacc8 Mon Sep 17 00:00:00 2001
From: Christine Coenen <code.coenen@gmail.com>
Date: Sun, 14 Apr 2024 11:48:20 +0200
Subject: [PATCH] Removed duplicate entries when scrolling the mediathek list
 #279

---
 .../mediathek/api/MediathekPagingSource.kt    | 21 +++++--------------
 app/src/main/res/raw/changelog.md             |  3 +++
 2 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/app/src/main/java/de/christinecoenen/code/zapp/app/mediathek/api/MediathekPagingSource.kt b/app/src/main/java/de/christinecoenen/code/zapp/app/mediathek/api/MediathekPagingSource.kt
index 7ef2a8a5..e066ca21 100644
--- a/app/src/main/java/de/christinecoenen/code/zapp/app/mediathek/api/MediathekPagingSource.kt
+++ b/app/src/main/java/de/christinecoenen/code/zapp/app/mediathek/api/MediathekPagingSource.kt
@@ -17,17 +17,8 @@ class MediathekPagingSource(
 ) : PagingSource<Int, MediathekShow>() {
 
 	override fun getRefreshKey(state: PagingState<Int, MediathekShow>): Int? {
-		// Try to find the page key of the closest page to anchorPosition, from
-		// either the prevKey or the nextKey, but you need to handle nullability
-		// here:
-		//  * prevKey == null -> anchorPage is the first page.
-		//  * nextKey == null -> anchorPage is the last page.
-		//  * both prevKey and nextKey null -> anchorPage is the initial page, so
-		//    just return null.
-		return state.anchorPosition?.let { anchorPosition ->
-			val anchorPage = state.closestPageToPosition(anchorPosition)
-			anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
-		}
+		return ((state.anchorPosition ?: 0) - state.config.initialLoadSize / 2)
+			.coerceAtLeast(0)
 	}
 
 	override suspend fun load(params: LoadParams<Int>): LoadResult<Int, MediathekShow> {
@@ -35,22 +26,20 @@ class MediathekPagingSource(
 		queryInfoResultPublisher.emit(null)
 
 		return try {
-			// Start refresh at page 1 if undefined.
-			val nextPageNumber = params.key ?: 1
 			query.size = params.loadSize
-			query.offset = nextPageNumber.minus(1) * params.loadSize
+			query.offset = params.key ?: 0
 
 			val response = mediathekApi.listShows(query)
 
 			val showList = response.result?.results ?: throw Error(response.err)
-			val nextKey = if (showList.isEmpty()) null else nextPageNumber.plus(1)
+			val nextOffset = if (showList.size < query.size) null else query.offset + query.size
 
 			queryInfoResultPublisher.emit(response.result.queryInfo)
 
 			LoadResult.Page(
 				data = showList,
 				prevKey = null, // Only paging forward.
-				nextKey = nextKey
+				nextKey = nextOffset
 			)
 		} catch (e: IOException) {
 			// IOException for network failures.
diff --git a/app/src/main/res/raw/changelog.md b/app/src/main/res/raw/changelog.md
index a275528d..85828ea7 100644
--- a/app/src/main/res/raw/changelog.md
+++ b/app/src/main/res/raw/changelog.md
@@ -1,3 +1,6 @@
+# v-next
+* Duplikate beim Scrollen in der Mediathek-Liste entfernt
+
 # 8.5.1
 * Dynamische Farben wurden auf manchen Geräten nicht übernommen