homework

app/build.gradle

@@ -60,9 +60,11 @@ dependencies {
     implementation libs.androidx.datastore.preferences
 
     implementation libs.dagger
+    implementation libs.androidx.ui
+    implementation libs.recyclerview
     kapt libs.daggerCompiler
 
     testImplementation libs.junit
     androidTestImplementation libs.androidx.test.ext.junit
     androidTestImplementation libs.espresso.core
-}
+}

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

@@ -11,9 +11,11 @@ import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.repeatOnLifecycle
 import androidx.recyclerview.widget.GridLayoutManager
+import androidx.recyclerview.widget.RecyclerView
 import kotlinx.coroutines.launch
 import ru.otus.cryptosample.CoinsSampleApp
 import ru.otus.cryptosample.coins.feature.adapter.CoinsAdapter
+import ru.otus.cryptosample.coins.feature.adapter.FadeSlideItemAnimator
 import ru.otus.cryptosample.coins.feature.di.DaggerCoinListComponent
 import ru.otus.cryptosample.databinding.FragmentCoinListBinding
 import javax.inject.Inject
@@ -28,7 +30,8 @@ class CoinListFragment : Fragment() {
 
     private val viewModel: CoinListViewModel by viewModels { factory }
 
-    private lateinit var coinsAdapter: CoinsAdapter
+    private var coinsAdapter: CoinsAdapter? = null
+    private var sharedViewPool: RecyclerView.RecycledViewPool? = null
 
     override fun onAttach(context: Context) {
         super.onAttach(context)
@@ -59,22 +62,24 @@ class CoinListFragment : Fragment() {
     }
 
     private fun setupRecyclerView() {
-        coinsAdapter = CoinsAdapter()
+        val viewPool = RecyclerView.RecycledViewPool().apply {
+            setMaxRecycledViews(CoinsAdapter.HORIZONTAL_COIN_VIEW_TYPE, 20)
+        }
+        val adapter = CoinsAdapter(viewPool)
+        sharedViewPool = viewPool
+        coinsAdapter = adapter
 
         val gridLayoutManager = GridLayoutManager(requireContext(), 2)
         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
-                    else -> 1
-                }
+                return if (adapter.isFullSpan(position)) 2 else 1
             }
         }
 
         binding.recyclerView.apply {
             layoutManager = gridLayoutManager
-            adapter = coinsAdapter
+            this.adapter = adapter
+            itemAnimator = FadeSlideItemAnimator()
         }
     }
 
@@ -99,11 +104,21 @@ class CoinListFragment : Fragment() {
     }
 
     private fun renderState(state: CoinsScreenState) {
-        coinsAdapter.setData(state.categories)
+        if (binding.showAllChip.isChecked != state.showAll) {
+            binding.showAllChip.isChecked = state.showAll
+        }
+        if (binding.highlightChip.isChecked != state.highlightMovers) {
+            binding.highlightChip.isChecked = state.highlightMovers
+        }
+        coinsAdapter?.submitData(state.categories, state.showAll)
     }
 
     override fun onDestroyView() {
         super.onDestroyView()
+        binding.recyclerView.adapter = null
+        sharedViewPool?.clear()
+        sharedViewPool = null
+        coinsAdapter = null
         _binding = null
     }
 }

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

@@ -29,11 +29,15 @@ class CoinListViewModel(
     }
 
     fun onHighlightMoversToggled(isChecked: Boolean) {
+        if (highlightMovers == isChecked) return
+
         highlightMovers = isChecked
         updateUiState()
     }
 
     fun onShowAllToggled(isChecked: Boolean) {
+        if (showAll == isChecked) return
+
         showAll = isChecked
         updateUiState()
     }
@@ -54,20 +58,18 @@ class CoinListViewModel(
     }
 
     private fun updateUiState() {
-        var processedCategories = if (showAll) {
-            fullCategories
-        } else {
-            fullCategories.map { category ->
-                category.copy(coins = category.coins.take(4))
-            }
-        }
-
-        processedCategories = processedCategories.map { category ->
+        val processedCategories = fullCategories.map { category ->
             category.copy(coins = category.coins.map { coin ->
                 coin.copy(highlight = highlightMovers && coin.isHotMover)
             })
         }
 
-        _state.update { it.copy(categories = processedCategories) }
+        _state.update {
+            it.copy(
+                categories = processedCategories,
+                showAll = showAll,
+                highlightMovers = highlightMovers,
+            )
+        }
     }
 }

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

@@ -2,6 +2,8 @@ package ru.otus.cryptosample.coins.feature
 
 data class CoinsScreenState(
     val categories: List<CoinCategoryState> = emptyList(),
+    val showAll: Boolean = true,
+    val highlightMovers: Boolean = false,
 )
 
 data class CoinCategoryState(

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

@@ -0,0 +1,30 @@
+package ru.otus.cryptosample.coins.feature.adapter
+
+import androidx.recyclerview.widget.DiffUtil
+import ru.otus.cryptosample.coins.feature.CoinState
+
+data class HighlightPayload(val isHighlighted: Boolean)
+
+data class HorizontalCoinsPayload(val coins: List<CoinState>)
+
+fun coinHighlightPayload(oldItem: CoinState, newItem: CoinState): HighlightPayload? {
+    val onlyHighlightChanged = oldItem.highlight != newItem.highlight &&
+        oldItem.copy(highlight = newItem.highlight) == newItem
+
+    return if (onlyHighlightChanged) {
+        HighlightPayload(newItem.highlight)
+    } else {
+        null
+    }
+}
+
+object CoinDiffCallback : DiffUtil.ItemCallback<CoinState>() {
+    override fun areItemsTheSame(oldItem: CoinState, newItem: CoinState): Boolean =
+        oldItem.id == newItem.id
+
+    override fun areContentsTheSame(oldItem: CoinState, newItem: CoinState): Boolean =
+        oldItem == newItem
+
+    override fun getChangePayload(oldItem: CoinState, newItem: CoinState): Any? =
+        coinHighlightPayload(oldItem, newItem)
+}

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

@@ -1,5 +1,6 @@
 package ru.otus.cryptosample.coins.feature.adapter
 
+import android.view.View
 import androidx.core.content.ContextCompat
 import androidx.core.view.isVisible
 import androidx.recyclerview.widget.RecyclerView
@@ -9,8 +10,9 @@ import ru.otus.cryptosample.coins.feature.CoinState
 import ru.otus.cryptosample.databinding.ItemCoinBinding
 
 class CoinViewHolder(
-    private val binding: ItemCoinBinding
-) : RecyclerView.ViewHolder(binding.root) {
+    private val binding: ItemCoinBinding,
+    root: View = binding.root,
+) : RecyclerView.ViewHolder(root) {
 
     fun bind(coin: CoinState) {
         with(binding) {
@@ -30,7 +32,11 @@ class CoinViewHolder(
                 error(R.drawable.generic)
             }
 
-            fireBadge.isVisible = coin.highlight
+            bindHighlight(coin.highlight)
         }
     }
+
+    fun bindHighlight(isHighlighted: Boolean) {
+        binding.fireBadge.isVisible = isHighlighted
+    }
 }