refactor() coroutines homework #OTUS_Android-prof-2024-12

app/build.gradle

@@ -41,4 +41,5 @@ dependencies {
     implementation 'com.google.android.material:material:1.11.0'
     implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
     implementation 'com.squareup.picasso:picasso:2.71828'
+    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.4.0"
 }

app/src/main/java/otus/homework/coroutines/CatsPresenter.kt

@@ -1,28 +1,45 @@
 package otus.homework.coroutines
 
-import retrofit2.Call
-import retrofit2.Callback
-import retrofit2.Response
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Deferred
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.async
+import kotlinx.coroutines.launch
+import java.net.SocketTimeoutException
 
 class CatsPresenter(
-    private val catsService: CatsService
+    private val catsService: CatsService,
+    private val imageService: ImageService,
+    private val presenterScope: CoroutineScope
 ) {
 
     private var _catsView: ICatsView? = null
+    private var job: Job? = null
 
     fun onInitComplete() {
-        catsService.getCatFact().enqueue(object : Callback<Fact> {
-
-            override fun onResponse(call: Call<Fact>, response: Response<Fact>) {
-                if (response.isSuccessful && response.body() != null) {
-                    _catsView?.populate(response.body()!!)
-                }
+        job = presenterScope.async {
+            val image = async { imageService.getCatImage().first() }
+            val fact = async { catsService.getCatFact() }
+
+            _catsView?.populate(CatsUIState(fact.await(), image.await()))
+        }
+        presenterScope.launch {
+            try {
+                (job as Deferred<*>).await()
+            } catch (e: CancellationException) {
+                throw e
+            } catch (e: SocketTimeoutException) {
+                showToast("Не удалось получить ответ от сервера")
+            } catch (e: Exception) {
+                CrashMonitor.trackWarning(e)
+                e.message?.let(::showToast)
             }
+        }
+    }
 
-            override fun onFailure(call: Call<Fact>, t: Throwable) {
-                CrashMonitor.trackWarning()
-            }
-        })
+    private fun showToast(message: String) {
+        _catsView?.showToast(message)
     }
 
     fun attachView(catsView: ICatsView) {
@@ -32,4 +49,12 @@ class CatsPresenter(
     fun detachView() {
         _catsView = null
     }
+
+    fun cancelCoroutine() {
+        job?.run {
+            if (isActive) {
+                cancel()
+            }
+        }
+    }
 }

app/src/main/java/otus/homework/coroutines/CatsService.kt

@@ -1,10 +1,9 @@
 package otus.homework.coroutines
 
-import retrofit2.Call
 import retrofit2.http.GET
 
 interface CatsService {
 
     @GET("fact")
-    fun getCatFact() : Call<Fact>
+    suspend fun getCatFact() : Fact
 }

app/src/main/java/otus/homework/coroutines/CatsUIState.kt

@@ -0,0 +1,6 @@
+package otus.homework.coroutines
+
+data class CatsUIState(
+    val fact: Fact,
+    val image: Image
+)

app/src/main/java/otus/homework/coroutines/CatsView.kt

@@ -3,11 +3,14 @@ package otus.homework.coroutines
 import android.content.Context
 import android.util.AttributeSet
 import android.widget.Button
+import android.widget.ImageView
 import android.widget.TextView
+import android.widget.Toast
 import androidx.constraintlayout.widget.ConstraintLayout
+import com.squareup.picasso.Picasso
 
 class CatsView @JvmOverloads constructor(
-    context: Context,
+    private val context: Context,
     attrs: AttributeSet? = null,
     defStyleAttr: Int = 0
 ) : ConstraintLayout(context, attrs, defStyleAttr), ICatsView {
@@ -21,12 +24,19 @@ class CatsView @JvmOverloads constructor(
         }
     }
 
-    override fun populate(fact: Fact) {
-        findViewById<TextView>(R.id.fact_textView).text = fact.fact
+    override fun populate(state: CatsUIState) {
+        findViewById<TextView>(R.id.fact_textView).text = state.fact.fact
+        Picasso.get().load(state.image.url).into(findViewById<ImageView>(R.id.catImage))
+    }
+
+    override fun showToast(message: String) {
+        Toast.makeText(context, message, Toast.LENGTH_SHORT).show()
     }
 }
 
 interface ICatsView {
 
-    fun populate(fact: Fact)
+    fun populate(state: CatsUIState)
+
+    fun showToast(message: String)
 }

app/src/main/java/otus/homework/coroutines/CatsViewModel.kt

@@ -0,0 +1,68 @@
+package otus.homework.coroutines
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import kotlinx.coroutines.CoroutineExceptionHandler
+import kotlinx.coroutines.async
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.filterNotNull
+import kotlinx.coroutines.flow.onStart
+import kotlinx.coroutines.flow.shareIn
+import kotlinx.coroutines.launch
+import java.net.SocketTimeoutException
+
+class CatsViewModel(
+    private val catsService: CatsService,
+    private val imageService: ImageService
+) : ViewModel() {
+
+    private val exceptionHandler = CoroutineExceptionHandler { _, throwable ->
+        when(throwable) {
+            is SocketTimeoutException -> _uiState.tryEmit(Result.Error(Throwable("Не удалось получить ответ от сервера")))
+            else -> {
+                CrashMonitor.trackWarning(throwable)
+                _uiState.tryEmit(Result.Error(throwable))
+            }
+        }
+    }
+
+    private val _uiState = MutableStateFlow<Result?>(null)
+    val uiState = _uiState.onStart { load() }
+        .filterNotNull()
+        .shareIn(
+            viewModelScope,
+            SharingStarted.WhileSubscribed(5000),
+            replay = 1
+        )
+
+    fun load() {
+        viewModelScope.launch(exceptionHandler) {
+            val fact = async { catsService.getCatFact() }
+            val image = async { imageService.getCatImage() }
+
+            _uiState.emit(
+                Result.Success(
+                    CatsUIState(
+                        fact = fact.await(),
+                        image = image.await()[0]
+                    )
+                )
+            )
+        }
+    }
+
+    companion object {
+        fun provideFactory(
+            catsService: CatsService,
+            imageService: ImageService
+        ): ViewModelProvider.Factory = viewModelFactory {
+            initializer {
+                CatsViewModel(catsService, imageService)
+            }
+        }
+    }
+}

app/src/main/java/otus/homework/coroutines/CrashMonitor.kt

@@ -5,6 +5,5 @@ object CrashMonitor {
     /**
      * Pretend this is Crashlytics/AppCenter
      */
-    fun trackWarning() {
-    }
+    fun trackWarning(exception: Throwable) {}
 }

app/src/main/java/otus/homework/coroutines/DiContainer.kt

@@ -1,16 +1,30 @@
 package otus.homework.coroutines
 
+import kotlinx.coroutines.CoroutineName
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import retrofit2.Retrofit
 import retrofit2.converter.gson.GsonConverterFactory
 
 class DiContainer {
 
-    private val retrofit by lazy {
-        Retrofit.Builder()
-            .baseUrl("https://catfact.ninja/")
-            .addConverterFactory(GsonConverterFactory.create())
+    private val converter by lazy { GsonConverterFactory.create() }
+
+    private fun buildRetrofit(baseUrl: String) =
+        Retrofit.Builder().baseUrl(baseUrl).addConverterFactory(converter)
             .build()
+
+    val catsService by lazy {
+        buildRetrofit("https://catfact.ninja/").create(
+            CatsService::class.java
+        )
+    }
+
+    val imageService by lazy {
+        buildRetrofit("https://api.thecatapi.com/v1/images/").create(
+            ImageService::class.java
+        )
     }
 
-    val service by lazy { retrofit.create(CatsService::class.java) }
+    val presenterScope get() = CoroutineScope(CoroutineName("CatsCoroutine") + Dispatchers.Main)
 }

app/src/main/java/otus/homework/coroutines/Image.kt

@@ -0,0 +1,10 @@
+package otus.homework.coroutines
+
+import com.google.gson.annotations.SerializedName
+
+data class Image(
+    @field:SerializedName("id")
+    val id: String,
+    @field:SerializedName("url")
+    val url: String
+)

app/src/main/java/otus/homework/coroutines/ImageService.kt

@@ -0,0 +1,8 @@
+package otus.homework.coroutines
+
+import retrofit2.http.GET
+
+interface ImageService {
+    @GET("search")
+    suspend fun getCatImage(): List<Image>
+}

app/src/main/java/otus/homework/coroutines/MainActivity.kt

@@ -1,30 +1,69 @@
 package otus.homework.coroutines
 
-import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
+import android.widget.Button
+import android.widget.ImageView
+import android.widget.TextView
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.lifecycleScope
+import com.squareup.picasso.Picasso
+import kotlinx.coroutines.launch
+import otus.homework.coroutines.Result.*
 
 class MainActivity : AppCompatActivity() {
 
-    lateinit var catsPresenter: CatsPresenter
-
     private val diContainer = DiContainer()
 
+    private lateinit var fact: TextView
+    private lateinit var image: ImageView
+    private lateinit var loadButton: Button
+
+    private val viewModel by lazy {
+        ViewModelProvider(
+            this, CatsViewModel.provideFactory(diContainer.catsService, diContainer.imageService)
+        )[CatsViewModel::class.java]
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-
-        val view = layoutInflater.inflate(R.layout.activity_main, null) as CatsView
+        val view = layoutInflater.inflate(R.layout.activity_main, null)
         setContentView(view)
+        fact = view.findViewById(R.id.fact_textView)
+        image = view.findViewById(R.id.catImage)
+        loadButton = view.findViewById(R.id.button)
+
+        processState()
+        setListeners()
+    }
 
-        catsPresenter = CatsPresenter(diContainer.service)
-        view.presenter = catsPresenter
-        catsPresenter.attachView(view)
-        catsPresenter.onInitComplete()
+    private fun setListeners() {
+        loadButton.setOnClickListener {
+            viewModel.load()
+        }
     }
 
-    override fun onStop() {
-        if (isFinishing) {
-            catsPresenter.detachView()
+    private fun processState() {
+        lifecycleScope.launch {
+            viewModel.uiState.collect { state ->
+                when(state) {
+                    is Success<*> -> {
+                        (state.data as CatsUIState).also {
+                            fact.text = it.fact.fact
+                            Picasso.get().load(it.image.url).into(image)
+                        }
+                    }
+                    is Error -> {
+                        showToast(state.error)
+                        viewModel.load()
+                    }
+                }
+            }
         }
-        super.onStop()
+    }
+
+    private fun showToast(throwable: Throwable, duration: Int = Toast.LENGTH_LONG) {
+        Toast.makeText(this, throwable.message, duration).show()
     }
 }

app/src/main/java/otus/homework/coroutines/Result.kt

@@ -0,0 +1,6 @@
+package otus.homework.coroutines
+
+sealed class Result{
+    data class Success<out T>(val data: T) : Result()
+    data class Error(val error: Throwable) : Result()
+}

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

@@ -7,16 +7,26 @@
     android:layout_height="match_parent"
     tools:context=".MainActivity">
 
+    <ImageView
+        android:id="@+id/catImage"
+        android:layout_width="300dp"
+        android:layout_height="300dp"
+        android:contentDescription="@string/cat_image_description"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/fact_textView"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        />
+
     <TextView
         android:id="@+id/fact_textView"
         android:textColor="@color/black"
         android:textSize="24sp"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintTop_toBottomOf="@id/catImage" />
 
     <Button
         android:id="@+id/button"