Load more horizontal

Author: hoc081098

app/src/main/java/com/hoc/pagination_mvi/ui/main/MainContract.kt

@@ -24,6 +24,22 @@ interface MainContract {
         ?.state is PlaceholderState.Error
     }
 
+    fun canLoadNextPageHorizontal(): Boolean {
+      val horizontalList =
+        items.singleOrNull { it is Item.HorizontalList } as? Item.HorizontalList ?: return false
+      return !horizontalList.isLoading &&
+          horizontalList.error == null &&
+          horizontalList.postItems.isNotEmpty() &&
+          (horizontalList.items.singleOrNull { it is HorizontalItem.Placeholder } as? HorizontalItem.Placeholder)
+            ?.state == PlaceholderState.Idle
+    }
+
+    fun getHorizontalListCount(): Int {
+      val horizontalList =
+        items.singleOrNull { it is Item.HorizontalList } as? Item.HorizontalList ?: return 0
+      return horizontalList.postItems.size
+    }
+
     companion object Factory {
       @JvmStatic
       fun initial() = ViewState(
@@ -110,8 +126,8 @@ interface MainContract {
     object LoadNextPage : ViewIntent()
     object RetryLoadPage : ViewIntent()
 
-    object LoadNextPageHorizontal: ViewIntent()
-    object RetryLoadPageHorizontal: ViewIntent()
+    object LoadNextPageHorizontal : ViewIntent()
+    object RetryLoadPageHorizontal : ViewIntent()
   }
 
   sealed class PartialStateChange {
@@ -239,6 +255,63 @@ interface MainContract {
         }
       }
     }
+
+    sealed class PostNextPage : PartialStateChange() {
+      data class Data(val posts: List<PostVS>) : PostNextPage()
+      data class Error(val error: Throwable) : PostNextPage()
+      object Loading : PostNextPage()
+
+      override fun reduce(vs: ViewState): ViewState {
+        return when (this) {
+          is Data -> {
+            vs.copy(
+              items = vs.items.map { item ->
+                if (item is Item.HorizontalList) {
+                  val postItems = item.items.filterIsInstance<HorizontalItem.Post>() +
+                      this.posts.map { HorizontalItem.Post(it) }
+                  item.copy(
+                    items = postItems + HorizontalItem.Placeholder(PlaceholderState.Idle),
+                    postItems = postItems
+                  )
+                } else {
+                  item
+                }
+              }
+            )
+          }
+          is Error -> {
+            vs.copy(
+              items = vs.items.map { item ->
+                if (item is Item.HorizontalList) {
+                  val postItems = item.items.filterIsInstance<HorizontalItem.Post>()
+                  item.copy(
+                    items = postItems + HorizontalItem.Placeholder(PlaceholderState.Error(error)),
+                    postItems = postItems
+                  )
+                } else {
+                  item
+                }
+              }
+            )
+          }
+          Loading -> {
+            vs.copy(
+              items = vs.items.map { item ->
+                if (item is Item.HorizontalList) {
+                  val postItems = item.items.filterIsInstance<HorizontalItem.Post>()
+                  item.copy(
+                    items = postItems + HorizontalItem.Placeholder(PlaceholderState.Loading),
+                    postItems = postItems
+                  )
+                } else {
+                  item
+                }
+              }
+            )
+          }
+        }
+      }
+    }
   }
 
   sealed class SingleEvent {
@@ -250,5 +323,6 @@ interface MainContract {
     fun photoFirstPageChanges(limit: Int): Observable<PartialStateChange.PhotoFirstPage>
 
     fun postFirstPageChanges(limit: Int): Observable<PartialStateChange.PostFirstPage>
+    fun postNextPageChanges(start: Int, limit: Int): Observable<PartialStateChange.PostNextPage>
   }
 }

app/src/main/java/com/hoc/pagination_mvi/ui/main/MainInteractorImpl.kt

@@ -66,4 +66,22 @@ class MainInteractorImpl @Inject constructor(
       }
     }
   }
+
+  override fun postNextPageChanges(
+    start: Int,
+    limit: Int
+  ): Observable<MainContract.PartialStateChange.PostNextPage> {
+    return rxObservable(dispatchers.main) {
+      send(MainContract.PartialStateChange.PostNextPage.Loading)
+      try {
+        getPostsUseCase(start = start, limit = limit)
+          .map(::PostVS)
+          .let { MainContract.PartialStateChange.PostNextPage.Data(it) }
+          .let { send(it) }
+      } catch (e: Exception) {
+        delay(500)
+        send(MainContract.PartialStateChange.PostNextPage.Error(e))
+      }
+    }
+  }
 }

app/src/main/java/com/hoc/pagination_mvi/ui/main/MainVM.kt

@@ -67,13 +67,23 @@ class MainVM @Inject constructor(
         .exhaustMap { interactor.photoNextPageChanges(start = it, limit = PHOTO_PAGE_SIZE) }
     }
 
+  private val loadNextPageHorizontalProcessor =
+    ObservableTransformer<ViewIntent.LoadNextPageHorizontal, PartialStateChange> { intents ->
+      intents
+        .withLatestFrom(stateObservable)
+        .filter { (_, vs) -> vs.canLoadNextPageHorizontal() }
+        .map { (_, vs) -> vs.getHorizontalListCount() }
+        .exhaustMap { interactor.postNextPageChanges(start = it, limit = POST_PAGE_SIZE) }
+    }
+
   private val toPartialStateChange =
     ObservableTransformer<ViewIntent, PartialStateChange> { intents ->
       intents.publish { shared ->
         Observable.mergeArray(
           shared.ofType<ViewIntent.Initial>().compose(initialProcessor),
           shared.ofType<ViewIntent.LoadNextPage>().compose(nextPageProcessor),
-          shared.ofType<ViewIntent.RetryLoadPage>().compose(retryLoadPageProcessor)
+          shared.ofType<ViewIntent.RetryLoadPage>().compose(retryLoadPageProcessor),
+          shared.ofType<ViewIntent.LoadNextPageHorizontal>().compose(loadNextPageHorizontalProcessor)
         )
       }
     }

app/src/main/res/layout/recycler_item_horizontal_placeholder.xml

@@ -2,7 +2,7 @@
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="0dp"
+    android:layout_width="wrap_content"
     android:layout_height="match_parent"
     tools:layout_height="200dp">