Migration to Paging 3

app/src/main/java/com/android/tvmaze/network/TvMazeApi.kt

@@ -1,7 +1,9 @@
 package com.android.tvmaze.network
 
+import androidx.paging.PagingData
 import com.android.tvmaze.network.home.Episode
 import com.android.tvmaze.network.home.Show
+import kotlinx.coroutines.flow.Flow
 import retrofit2.http.GET
 import retrofit2.http.Query
 

app/src/main/java/com/android/tvmaze/shows/AllShowsActivity.kt

@@ -3,74 +3,83 @@ package com.android.tvmaze.shows
 import android.content.Context
 import android.content.Intent
 import android.os.Bundle
+import android.view.LayoutInflater
 import android.view.MenuItem
-import android.view.View
 import android.widget.Toast
 import androidx.activity.viewModels
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
-import androidx.lifecycle.Observer
-import androidx.paging.PagedList
-import androidx.recyclerview.widget.LinearLayoutManager
-import androidx.recyclerview.widget.RecyclerView
+import androidx.core.view.isVisible
+import androidx.lifecycle.lifecycleScope
+import androidx.paging.LoadState
 import com.android.tvmaze.R
-import com.android.tvmaze.network.home.Show
+import com.android.tvmaze.databinding.ActivityAllShowsBinding
 import dagger.hilt.android.AndroidEntryPoint
-import kotlinx.android.synthetic.main.activity_all_shows.*
-import kotlinx.android.synthetic.main.toolbar.view.*
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.launch
 
 @AndroidEntryPoint
-class AllShowsActivity : AppCompatActivity(), ShowsPagedAdaptor.Callback {
+class AllShowsActivity : AppCompatActivity() {
     private val showsViewModel: ShowsViewModel by viewModels()
-    private lateinit var showsPagedAdaptor: ShowsPagedAdaptor
-
+    private lateinit var adapter: ShowsPagedAdapter
+    private lateinit var showsBinding: ActivityAllShowsBinding
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_all_shows)
+        showsBinding = ActivityAllShowsBinding.inflate(LayoutInflater.from(this))
+        setContentView(showsBinding.root)
         setToolbar()
-        showsViewModel.onScreenCreated()
         initAdapter()
-        showsViewModel.initialLoadState().observe(this, Observer { setProgress(it) })
+        getShows()
+        showsBinding.retry.setOnClickListener { adapter.retry() }
     }
 
-    private fun initAdapter() {
-        val layoutManager = LinearLayoutManager(this, RecyclerView.VERTICAL, false)
-        showsPagedAdaptor = ShowsPagedAdaptor(ShowDiffUtilItemCallback(), this)
-        shows.layoutManager = layoutManager
-        shows.adapter = showsPagedAdaptor
-        showsViewModel.getShows().observe(this, Observer { showAllShows(it) })
-        showsViewModel.paginatedLoadState().observe(this, Observer { setAdapterState(it) })
+    private fun getShows() {
+        lifecycleScope.launch { showsViewModel.shows().collectLatest { adapter.submitData(it) } }
     }
 
-    private fun setAdapterState(networkState: NetworkState) {
-        showsPagedAdaptor.setNetworkState(networkState)
+    private fun initAdapter() {
+        adapter = ShowsPagedAdapter(ShowDiffUtilItemCallback())
+        showsBinding.shows.adapter = adapter.withLoadStateFooter(
+            footer = ShowsLoadStateAdapter { adapter.retry() }
+        )
+
+        adapter.addLoadStateListener { combinedLoadStates ->
+            // Handle the initial load state
+            when (val loadState = combinedLoadStates.source.refresh) {
+                is LoadState.NotLoading -> {
+                    showsBinding.progress.isVisible = false
+                    showsBinding.shows.isVisible = true
+                    showsBinding.errorGroup.isVisible = false
+                }
+                is LoadState.Loading -> {
+                    showsBinding.progress.isVisible = true
+                    showsBinding.errorGroup.isVisible = false
+                }
+                is LoadState.Error -> {
+                    showsBinding.progress.isVisible = false
+                    showsBinding.errorGroup.isVisible = true
+                    showsBinding.errorMsg.text = loadState.error.localizedMessage
+                }
+            }
+
+            // Show message to the user when an error comes while loading the next page
+            val errorState = combinedLoadStates.source.append as? LoadState.Error
+                ?: combinedLoadStates.append as? LoadState.Error
+            errorState?.let {
+                Toast.makeText(this, errorState.error.localizedMessage, Toast.LENGTH_SHORT).show()
+            }
+        }
     }
 
     private fun setToolbar() {
-        val toolbar = toolbar.toolbar
+        val toolbar = showsBinding.toolbar.toolbar
         setSupportActionBar(toolbar)
         toolbar.setTitleTextColor(ContextCompat.getColor(this, android.R.color.white))
         toolbar.setSubtitleTextColor(ContextCompat.getColor(this, android.R.color.white))
         supportActionBar!!.setDisplayHomeAsUpEnabled(true)
         setTitle(R.string.shows)
     }
 
-    private fun setProgress(loadState: NetworkState) {
-        when (loadState) {
-            is Success -> progress.visibility = View.GONE
-            is NetworkError -> {
-                progress.visibility = View.GONE
-                Toast.makeText(this, loadState.message, Toast.LENGTH_SHORT).show()
-            }
-            is Loading -> progress.visibility = View.VISIBLE
-        }
-    }
-
-    private fun showAllShows(showsList: PagedList<Show>) {
-        showsPagedAdaptor.submitList(showsList)
-        shows.visibility = View.VISIBLE
-    }
-
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
         return if (item.itemId == android.R.id.home) {
             finish()
@@ -80,10 +89,6 @@ class AllShowsActivity : AppCompatActivity(), ShowsPagedAdaptor.Callback {
         }
     }
 
-    override fun onRetryClicked() {
-        showsViewModel.retry()
-    }
-
     companion object {
         fun start(context: Context) {
             val starter = Intent(context, AllShowsActivity::class.java)

app/src/main/java/com/android/tvmaze/shows/ShowsLoadStateAdapter.kt

@@ -0,0 +1,16 @@
+package com.android.tvmaze.shows
+
+import android.view.ViewGroup
+import androidx.paging.LoadState
+import androidx.paging.LoadStateAdapter
+
+class ShowsLoadStateAdapter(private val retry: () -> Unit) :
+    LoadStateAdapter<ShowsStateViewHolder>() {
+    override fun onBindViewHolder(holder: ShowsStateViewHolder, loadState: LoadState) {
+        holder.bind(loadState)
+    }
+
+    override fun onCreateViewHolder(parent: ViewGroup, loadState: LoadState): ShowsStateViewHolder {
+        return ShowsStateViewHolder.create(parent, retry)
+    }
+}

app/src/main/java/com/android/tvmaze/shows/ShowsPagedAdapter.kt

@@ -0,0 +1,50 @@
+package com.android.tvmaze.shows
+
+import android.content.Context
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.paging.PagingDataAdapter
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.RecyclerView
+import com.android.tvmaze.R
+import com.android.tvmaze.databinding.AllShowListItemBinding
+import com.android.tvmaze.network.home.Show
+import com.bumptech.glide.Glide
+import com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions
+import com.bumptech.glide.request.RequestOptions
+
+class ShowsPagedAdapter constructor(
+    diffCallback: DiffUtil.ItemCallback<Show>
+) : PagingDataAdapter<Show, RecyclerView.ViewHolder>(diffCallback) {
+    private lateinit var context: Context
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
+        context = parent.context
+        val layoutInflater = LayoutInflater.from(context)
+        val showListItemBinding = AllShowListItemBinding.inflate(layoutInflater, parent, false)
+        return ShowHolder(showListItemBinding)
+    }
+
+    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
+        if (holder is ShowHolder) {
+            val show = getItem(position)
+            holder.binding.show = show
+            if (show!!.rating != null) {
+                holder.binding.rating = show.rating!!["average"]
+            }
+            configureImage(holder, show)
+        }
+    }
+
+    private fun configureImage(holder: ShowHolder, show: Show) {
+        if (show.image != null) {
+            Glide.with(context).load(show.image["original"])
+                .apply(RequestOptions.placeholderOf(R.color.grey))
+                .centerCrop()
+                .transition(DrawableTransitionOptions.withCrossFade())
+                .into(holder.binding.showImage)
+        }
+    }
+
+    class ShowHolder(val binding: AllShowListItemBinding) : RecyclerView.ViewHolder(binding.root)
+}