From d907193e4146cb8476de526f85f9a8f5724058b9 Mon Sep 17 00:00:00 2001
From: Kirill Nayduik <kirill.nayduikkn1@gmail.com>
Date: Mon, 28 Feb 2022 13:22:39 +0300
Subject: [PATCH] Add subclass of PagingDataAdapter with implementation of
 updating inner list

---
 recyclerview-adapters/build.gradle            |  7 +++++
 .../adapters/SubmittablePagingAdapter.kt      | 27 +++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 recyclerview-adapters/src/main/java/ru/touchin/roboswag/recyclerview_adapters/adapters/SubmittablePagingAdapter.kt

diff --git a/recyclerview-adapters/build.gradle b/recyclerview-adapters/build.gradle
index 8b8971b..c72248a 100644
--- a/recyclerview-adapters/build.gradle
+++ b/recyclerview-adapters/build.gradle
@@ -7,6 +7,8 @@ dependencies {
 
     implementation "androidx.core:core-ktx"
 
+    implementation "androidx.paging:paging-runtime"
+
     constraints {
         implementation("androidx.recyclerview:recyclerview") {
             version {
@@ -18,5 +20,10 @@ dependencies {
                 require '1.0.0'
             }
         }
+        implementation("androidx.paging:paging-runtime") {
+            version {
+                require '3.0.0-alpha06'
+            }
+        }
     }
 }
diff --git a/recyclerview-adapters/src/main/java/ru/touchin/roboswag/recyclerview_adapters/adapters/SubmittablePagingAdapter.kt b/recyclerview-adapters/src/main/java/ru/touchin/roboswag/recyclerview_adapters/adapters/SubmittablePagingAdapter.kt
new file mode 100644
index 0000000..e2162c6
--- /dev/null
+++ b/recyclerview-adapters/src/main/java/ru/touchin/roboswag/recyclerview_adapters/adapters/SubmittablePagingAdapter.kt
@@ -0,0 +1,27 @@
+package ru.touchin.roboswag.recyclerview_adapters.adapters
+
+import androidx.paging.PagingDataAdapter
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.RecyclerView
+
+abstract class SubmittablePagingAdapter<T : Any, VH : RecyclerView.ViewHolder>(private val diffCallback: DiffUtil.ItemCallback<T>):
+        PagingDataAdapter<T, VH>(diffCallback) {
+    /**
+     * [items] list of updated elements
+     * [transform] callback that keeps logic of transformation item based on newItem.
+     * Should return updated element
+     */
+    fun submitList(items: List<T>, transform: T.(newItem: T, payload: Any?) -> T) {
+        items.forEach { newItem ->
+            snapshot().forEachIndexed { index, oldItem ->
+                if (oldItem != null && diffCallback.areItemsTheSame(oldItem, newItem) && !diffCallback.areContentsTheSame(oldItem, newItem)) {
+                    val payload = diffCallback.getChangePayload(oldItem, newItem)
+
+                    oldItem.transform(newItem, payload)
+
+                    notifyItemChanged(index, payload)
+                }
+            }
+        }
+    }
+}