HW

app/src/main/java/ru/otus/cryptosample/coins/feature/CoinListFragment.kt

@@ -14,6 +14,7 @@ import androidx.recyclerview.widget.GridLayoutManager
 import kotlinx.coroutines.launch
 import ru.otus.cryptosample.CoinsSampleApp
 import ru.otus.cryptosample.coins.feature.adapter.CoinsAdapter
+import ru.otus.cryptosample.coins.feature.adapter.ItemAnimator
 import ru.otus.cryptosample.coins.feature.di.DaggerCoinListComponent
 import ru.otus.cryptosample.databinding.FragmentCoinListBinding
 import javax.inject.Inject
@@ -65,8 +66,9 @@ class CoinListFragment : Fragment() {
         gridLayoutManager.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
             override fun getSpanSize(position: Int): Int {
                 return when (coinsAdapter.getItemViewType(position)) {
-                    0 -> 2 // Category header spans full width
-                    1 -> 1 // Coin item spans half width
+                    CoinsAdapter.VIEW_TYPE_CATEGORY -> 2 // Category header spans full width
+                    CoinsAdapter.VIEW_TYPE_COIN -> 1 // Coin item spans half width
+                    CoinsAdapter.VIEW_TYPE_CAROUSEL -> 2
                     else -> 1
                 }
             }
@@ -75,6 +77,8 @@ class CoinListFragment : Fragment() {
         binding.recyclerView.apply {
             layoutManager = gridLayoutManager
             adapter = coinsAdapter
+            itemAnimator = ItemAnimator()
+            setRecycledViewPool(CoinsAdapter.sharedPool)
         }
     }
 

app/src/main/java/ru/otus/cryptosample/coins/feature/adapter/CarouselAdapter.kt

@@ -0,0 +1,61 @@
+package ru.otus.cryptosample.coins.feature.adapter
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.ListAdapter
+import androidx.recyclerview.widget.RecyclerView
+import ru.otus.cryptosample.coins.feature.CoinState
+import ru.otus.cryptosample.databinding.ItemCoinBinding
+
+class CarouselAdapter: ListAdapter<CoinState, CoinViewHolder>(CarouselDiff) {
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CoinViewHolder {
+        val binding = ItemCoinBinding.inflate(LayoutInflater.from(parent.context), parent, false)
+        val params = binding.root.layoutParams
+            ?: RecyclerView.LayoutParams(
+                RecyclerView.LayoutParams.WRAP_CONTENT,
+                RecyclerView.LayoutParams.WRAP_CONTENT
+            )
+        val screenWidth = parent.resources.displayMetrics.widthPixels
+        params.width = screenWidth / 2 - 16
+
+        binding.root.layoutParams = params
+
+        return CoinViewHolder(binding)
+    }
+
+    override fun getItemViewType(position: Int): Int = CoinsAdapter.VIEW_TYPE_COIN
+
+    override fun onBindViewHolder(
+        holder: CoinViewHolder,
+        position: Int
+    ) {
+        holder.bind(getItem(position))
+    }
+
+    override fun onBindViewHolder(
+        holder: CoinViewHolder,
+        position: Int,
+        payloads: List<Any>
+    ) {
+        holder.bind(getItem(position), payloads)
+    }
+}
+
+object CarouselDiff : DiffUtil.ItemCallback<CoinState>() {
+
+    override fun areItemsTheSame(old: CoinState, new: CoinState) = old.id == new.id
+
+    override fun areContentsTheSame(old: CoinState, new: CoinState) = old == new
+
+    override fun getChangePayload(oldItem: CoinState, newItem: CoinState): Any? =
+        if (oldItem.highlight != newItem.highlight) {
+            Payload.HOT_MOVER_CHANGED
+        } else null
+
+    object Payload {
+        const val HOT_MOVER_CHANGED = "HOT_MOVER_CHANGED"
+    }
+}
+

app/src/main/java/ru/otus/cryptosample/coins/feature/adapter/CarouselViewHolder.kt

@@ -0,0 +1,30 @@
+package ru.otus.cryptosample.coins.feature.adapter
+
+import androidx.recyclerview.widget.DefaultItemAnimator
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import ru.otus.cryptosample.coins.feature.CoinState
+import ru.otus.cryptosample.databinding.ItemCarouselBinding
+
+class CarouselViewHolder(
+    binding: ItemCarouselBinding,
+    sharedPool: RecyclerView.RecycledViewPool
+): RecyclerView.ViewHolder(binding.root) {
+
+    private val carouselAdapter = CarouselAdapter()
+
+    init {
+        binding.recyclerView.apply {
+            layoutManager = LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false)
+            adapter = carouselAdapter
+            setRecycledViewPool(sharedPool)
+            isNestedScrollingEnabled = false
+            setHasFixedSize(true)
+            itemAnimator = ItemAnimator()
+        }
+    }
+
+    fun bind(coins: List<CoinState>) {
+        carouselAdapter.submitList(coins)
+    }
+}

app/src/main/java/ru/otus/cryptosample/coins/feature/adapter/CoinViewHolder.kt

@@ -33,4 +33,12 @@ class CoinViewHolder(
             fireBadge.isVisible = coin.highlight
         }
     }
+
+    fun bind(coin: CoinState, payloads: List<Any>) {
+        if (CoinDiff.Payload.HOT_MOVER_CHANGED in payloads) {
+            binding.fireBadge.isVisible = coin.highlight
+        } else {
+            bind(coin)
+        }
+    }
 }

app/src/main/java/ru/otus/cryptosample/coins/feature/adapter/CoinsAdapter.kt

@@ -2,43 +2,50 @@ package ru.otus.cryptosample.coins.feature.adapter
 
 import android.view.LayoutInflater
 import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.ListAdapter
 import androidx.recyclerview.widget.RecyclerView
 import ru.otus.cryptosample.coins.feature.CoinCategoryState
+import ru.otus.cryptosample.databinding.ItemCarouselBinding
 import ru.otus.cryptosample.databinding.ItemCategoryHeaderBinding
 import ru.otus.cryptosample.databinding.ItemCoinBinding
 
-class CoinsAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
-    
+class CoinsAdapter : ListAdapter<CoinsAdapterItem, RecyclerView.ViewHolder>(CoinDiff) {
+
     companion object {
-        private const val VIEW_TYPE_CATEGORY = 0
-        private const val VIEW_TYPE_COIN = 1
+        const val VIEW_TYPE_CATEGORY = 0
+        const val VIEW_TYPE_COIN = 1
+        const val VIEW_TYPE_CAROUSEL = 2
+
+        val sharedPool = RecyclerView.RecycledViewPool()
     }
-
-    private var items = listOf<CoinsAdapterItem>()
-
+
     fun setData(categories: List<CoinCategoryState>) {
         val adapterItems = mutableListOf<CoinsAdapterItem>()
-        
+
         categories.forEach { category ->
             adapterItems.add(CoinsAdapterItem.CategoryHeader(category.name))
-            category.coins.forEach { coin ->
-                adapterItems.add(CoinsAdapterItem.CoinItem(coin))
+            if (category.coins.size <= 10) {
+                category.coins.forEach { coin ->
+                    adapterItems.add(CoinsAdapterItem.CoinItem(coin))
+                }
+            } else {
+                adapterItems.add(CoinsAdapterItem.Carousel(category.coins))
             }
         }
-
-        items = adapterItems
-        notifyDataSetChanged()
+        submitList(adapterItems)
     }
-    
-    override fun getItemCount(): Int = items.size
-    
+
+    override fun getItemCount(): Int = currentList.size
+
     override fun getItemViewType(position: Int): Int {
-        return when (items[position]) {
+        return when (getItem(position)) {
             is CoinsAdapterItem.CategoryHeader -> VIEW_TYPE_CATEGORY
             is CoinsAdapterItem.CoinItem -> VIEW_TYPE_COIN
+            is CoinsAdapterItem.Carousel -> VIEW_TYPE_CAROUSEL
         }
     }
-    
+
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
         return when (viewType) {
             VIEW_TYPE_CATEGORY -> CategoryHeaderViewHolder(
@@ -48,25 +55,105 @@ class CoinsAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
                     false
                 )
             )
-            VIEW_TYPE_COIN -> CoinViewHolder(
-                ItemCoinBinding.inflate(
-                    LayoutInflater.from(parent.context),
-                    parent,
-                    false
+            VIEW_TYPE_COIN -> {
+                val binding = ItemCoinBinding.inflate(LayoutInflater.from(parent.context), parent, false)
+                val params = binding.root.layoutParams
+                    ?: RecyclerView.LayoutParams(
+                        RecyclerView.LayoutParams.WRAP_CONTENT,
+                        RecyclerView.LayoutParams.WRAP_CONTENT
+                    )
+                val screenWidth = parent.resources.displayMetrics.widthPixels
+                params.width = screenWidth / 2 - 16
+
+                binding.root.layoutParams = params
+                CoinViewHolder(binding)
+            }
+            VIEW_TYPE_CAROUSEL -> {
+                CarouselViewHolder(
+                    ItemCarouselBinding.inflate(
+                        LayoutInflater.from(parent.context),
+                        parent,
+                        false
+                    ),
+                    sharedPool
                 )
-            )
+            }
             else -> throw IllegalArgumentException("Unknown view type: $viewType")
         }
     }
-    
+
     override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
-        when (val item = items[position]) {
+        when (val item = getItem(position)) {
             is CoinsAdapterItem.CategoryHeader -> {
                 (holder as CategoryHeaderViewHolder).bind(item.categoryName)
             }
             is CoinsAdapterItem.CoinItem -> {
                 (holder as CoinViewHolder).bind(item.coin)
             }
+            is CoinsAdapterItem.Carousel -> {
+                (holder as CarouselViewHolder).bind(item.coins)
+            }
+        }
+    }
+
+    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int, payloads: List<Any>) {
+        when (val item = getItem(position)) {
+            is CoinsAdapterItem.CategoryHeader -> {
+                (holder as CategoryHeaderViewHolder).bind(item.categoryName)
+            }
+            is CoinsAdapterItem.CoinItem -> {
+                if (payloads.isEmpty()) {
+                    (holder as CoinViewHolder).bind(item.coin)
+                } else {
+                    (holder as CoinViewHolder).bind(item.coin, payloads)
+                }
+
+            }
+            is CoinsAdapterItem.Carousel -> {
+                (holder as CarouselViewHolder).bind(item.coins)
+            }
+        }
+    }
+}
+
+object CoinDiff : DiffUtil.ItemCallback<CoinsAdapterItem>() {
+
+    override fun areItemsTheSame(oldItem: CoinsAdapterItem, newItem: CoinsAdapterItem): Boolean =
+        when {
+            oldItem is CoinsAdapterItem.CategoryHeader &&
+                    newItem is CoinsAdapterItem.CategoryHeader ->
+                oldItem.categoryName == newItem.categoryName
+
+            oldItem is CoinsAdapterItem.CoinItem &&
+                    newItem is CoinsAdapterItem.CoinItem ->
+                oldItem.coin.id == newItem.coin.id
+
+            oldItem is CoinsAdapterItem.Carousel &&
+                    newItem is CoinsAdapterItem.Carousel ->
+                // каждая карусель привязана к своей категории и стоит на том же месте
+                oldItem.coins.firstOrNull()?.id == newItem.coins.firstOrNull()?.id
+
+            else -> false
+        }
+
+    override fun areContentsTheSame(oldItem: CoinsAdapterItem, newItem: CoinsAdapterItem): Boolean = oldItem == newItem
+
+    override fun getChangePayload(oldItem: CoinsAdapterItem, newItem: CoinsAdapterItem): Any? {
+        return when (oldItem) {
+            is CoinsAdapterItem.CoinItem -> {
+                val oldCoin = oldItem.coin
+                val newCoin = (newItem as CoinsAdapterItem.CoinItem).coin
+                if (oldCoin.highlight != newCoin.highlight) {
+                    Payload.HOT_MOVER_CHANGED
+                } else {
+                    null
+                }
+            }
+            else -> null
         }
     }
-}
+
+    object Payload {
+        const val HOT_MOVER_CHANGED = "HOT_MOVER_CHANGED"
+    }
+}

app/src/main/java/ru/otus/cryptosample/coins/feature/adapter/CoinsAdapterItem.kt

@@ -5,4 +5,5 @@ import ru.otus.cryptosample.coins.feature.CoinState
 sealed class CoinsAdapterItem {
     data class CategoryHeader(val categoryName: String) : CoinsAdapterItem()
     data class CoinItem(val coin: CoinState) : CoinsAdapterItem()
-}
+    data class Carousel(val coins: List<CoinState>) : CoinsAdapterItem()
+}

app/src/main/java/ru/otus/cryptosample/coins/feature/adapter/ItemAnimator.kt

@@ -0,0 +1,59 @@
+package ru.otus.cryptosample.coins.feature.adapter
+
+import android.view.View
+import androidx.recyclerview.widget.DefaultItemAnimator
+import androidx.recyclerview.widget.RecyclerView
+
+class ItemAnimator : DefaultItemAnimator() {
+
+    override fun animateAdd(holder: RecyclerView.ViewHolder): Boolean {
+        val view: View = holder.itemView
+        addDuration = when (holder) {
+            is CoinViewHolder -> 400L
+            is CategoryHeaderViewHolder -> 50L
+            else -> 200L
+        }
+
+        view.alpha = 0f
+        view.translationX = view.width * -1f
+        view.scaleX = 0.9f
+        view.scaleY = 0.9f
+
+        val animator = view.animate()
+            .alpha(1f)
+            .translationX(0f)
+            .scaleX(1f)
+            .scaleY(1f)
+            .setDuration(addDuration)
+            .setListener(null)
+
+        animator.withStartAction {
+            dispatchAddStarting(holder)
+        }
+
+        animator.withEndAction {
+            view.alpha = 1f
+            view.translationX = 0f
+            view.scaleX = 1f
+            view.scaleY = 1f
+            dispatchAddFinished(holder)
+            view.animate().setListener(null)
+        }
+
+        animator.start()
+        return true
+    }
+
+    override fun runPendingAnimations() {
+        super.runPendingAnimations()
+    }
+
+    override fun endAnimation(item: RecyclerView.ViewHolder) {
+        item.itemView.animate().cancel()
+        super.endAnimation(item)
+    }
+
+    override fun endAnimations() {
+        super.endAnimations()
+    }
+}

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

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.recyclerview.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/recyclerView"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="horizontal" />