Fix Paging 3

extensions/android-paging3/build.gradle

@@ -1,9 +1,15 @@
 plugins {
-  alias(deps.plugins.kotlin.jvm)
+  alias(deps.plugins.android.library)
+  alias(deps.plugins.kotlin.android)
   alias(deps.plugins.publish)
   alias(deps.plugins.dokka)
 }
 
+android {
+  namespace 'app.cash.sqldelight.paging3'
+  compileSdkVersion 23
+}
+
 archivesBaseName = 'sqldelight-androidx-paging3'
 
 dependencies {
@@ -12,6 +18,8 @@ dependencies {
   api deps.androidx.paging3.common
 
   testImplementation project(':drivers:sqlite-driver')
+  testImplementation deps.androidx.paging3.runtime
+  testImplementation deps.androidx.recyclerView
   testImplementation deps.truth
   testImplementation deps.kotlin.test.junit
   testImplementation deps.kotlin.coroutines.test

extensions/android-paging3/src/main/java/app/cash/sqldelight/paging3/OffsetQueryPagingSource.kt

@@ -33,33 +33,33 @@ internal class OffsetQueryPagingSource<RowType : Any>(
   override suspend fun load(
     params: LoadParams<Int>,
   ): LoadResult<Int, RowType> = withContext(context) {
-    try {
-      val key = params.key ?: 0
-      transacter.transactionWithResult {
-        val count = countQuery.executeAsOne()
-        if (count != 0 && key >= count) throw IndexOutOfBoundsException()
-
-        val loadSize = if (key < 0) params.loadSize + key else params.loadSize
-
-        val data = queryProvider(loadSize, maxOf(0, key))
-          .also { currentQuery = it }
-          .executeAsList()
-
-        LoadResult.Page(
-          data = data,
-          // allow one, and only one negative prevKey in a paging set. This is done for
-          // misaligned prepend queries to avoid duplicates.
-          prevKey = if (key <= 0L) null else key - params.loadSize,
-          nextKey = if (key + params.loadSize >= count) null else key + params.loadSize,
-          itemsBefore = maxOf(0, key),
-          itemsAfter = maxOf(0, (count - (key + params.loadSize))),
-        )
+    val key = params.key ?: 0
+    val limit = when (params) {
+      is LoadParams.Prepend -> minOf(key, params.loadSize)
+      else -> params.loadSize
+    }
+    val loadResult = transacter.transactionWithResult {
+      val count = countQuery.executeAsOne()
+      val offset = when (params) {
+        is LoadParams.Prepend -> maxOf(0, key - params.loadSize)
+        is LoadParams.Append -> key
+        is LoadParams.Refresh -> if (key >= count) maxOf(0, count - params.loadSize) else key
       }
-    } catch (e: Exception) {
-      if (e is IndexOutOfBoundsException) throw e
-      LoadResult.Error(e)
+      val data = queryProvider(limit, offset)
+        .also { currentQuery = it }
+        .executeAsList()
+      val nextPosToLoad = offset + data.size
+      LoadResult.Page(
+        data = data,
+        prevKey = offset.takeIf { it > 0 && data.isNotEmpty() },
+        nextKey = nextPosToLoad.takeIf { data.isNotEmpty() && data.size >= limit && it < count },
+        itemsBefore = offset,
+        itemsAfter = maxOf(0, count - nextPosToLoad),
+      )
     }
+    if (invalid) LoadResult.Invalid() else loadResult
   }
 
-  override fun getRefreshKey(state: PagingState<Int, RowType>) = state.anchorPosition
+  override fun getRefreshKey(state: PagingState<Int, RowType>) =
+    state.anchorPosition?.let { maxOf(0, it - (state.config.initialLoadSize / 2)) }
 }