ДЗ сделано, есть 2 вопроса

app/build.gradle

@@ -44,6 +44,10 @@ dependencies {
     implementation 'com.squareup.picasso:picasso:2.71828'
     implementation 'androidx.activity:activity-ktx:1.8.2'
     implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.7.0'
+
     implementation "io.reactivex.rxjava2:rxjava:2.2.21"
     implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
+
+    // Для использования RxJava c Retrofit
+    implementation "com.squareup.retrofit2:adapter-rxjava2:2.7.1"
 }

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

@@ -1,10 +1,10 @@
 package otus.homework.reactivecats
 
-import retrofit2.Call
+import io.reactivex.Single
 import retrofit2.http.GET
 
 interface CatsService {
 
     @GET("random?animal_type=cat")
-    fun getCatFact(): Call<Fact>
+    fun getCatFact(): Single<Fact>
 }

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

@@ -5,48 +5,80 @@ import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
-import retrofit2.Call
-import retrofit2.Callback
-import retrofit2.Response
+import io.reactivex.BackpressureStrategy
+import io.reactivex.Flowable
+import io.reactivex.Observable
+import io.reactivex.android.schedulers.AndroidSchedulers
+import io.reactivex.disposables.CompositeDisposable
+import io.reactivex.schedulers.Schedulers
+import java.util.concurrent.TimeUnit
 
 class CatsViewModel(
-    catsService: CatsService,
-    localCatFactsGenerator: LocalCatFactsGenerator,
+    private val catsService: CatsService,
+    private val localCatFactsGenerator: LocalCatFactsGenerator,
     context: Context
 ) : ViewModel() {
 
     private val _catsLiveData = MutableLiveData<Result>()
     val catsLiveData: LiveData<Result> = _catsLiveData
 
+    val compositeDisposable = CompositeDisposable()
+
     init {
-        catsService.getCatFact().enqueue(object : Callback<Fact> {
-            override fun onResponse(call: Call<Fact>, response: Response<Fact>) {
-                if (response.isSuccessful && response.body() != null) {
-                    _catsLiveData.value = Success(response.body()!!)
-                } else {
-                    _catsLiveData.value = Error(
-                        response.errorBody()?.string() ?: context.getString(
-                            R.string.default_error_text
-                        )
-                    )
+        val disposable = getFacts1()
+            .subscribeOn(Schedulers.io())
+            .observeOn(AndroidSchedulers.mainThread())
+            .subscribe(
+                { fact ->
+                    println("mytag: +++ fact received")
+                    _catsLiveData.value = Success(fact)
+                },
+                { throwable ->
+                    _catsLiveData.value = Error(throwable?.message?:context.getString(R.string.default_error_text))
                 }
+            )
+        compositeDisposable.add(disposable)
+    }
+
+    //Вопрос: при медленном интернет соединении посылается первый запрос, потом пауза в 6-10 сек,
+    // а потом выплевывает сразу несколько значений. Как сделать так, чтоб поток ждал ответа от сервера?
+    fun getFacts(): Observable<Fact> {
+        val source = Observable.interval(2, TimeUnit.SECONDS)
+            .flatMap {
+                println("mytag: sending request")
+                catsService.getCatFact().toObservable()
             }
+            .onErrorResumeNext(
+                localCatFactsGenerator.generateCatFactPeriodically()
+            )
 
-            override fun onFailure(call: Call<Fact>, t: Throwable) {
-                _catsLiveData.value = ServerError
+        return source
+    }
+
+    fun getFacts1(): Flowable<Fact> {
+        // Вопрос: почему при создании interval не просить указать BackpressureStrategy?
+        val source = Flowable.interval(2, TimeUnit.SECONDS)
+            .flatMap {
+                println("mytag: sending request")
+                catsService.getCatFact().toFlowable()
             }
-        })
+            .onErrorResumeNext(
+                localCatFactsGenerator.generateCatFactPeriodically().toFlowable(BackpressureStrategy.BUFFER)
+            )
+
+        return source
     }
 
-    fun getFacts() {}
+    fun onStop() {
+        compositeDisposable.dispose()
+    }
 }
 
 class CatsViewModelFactory(
     private val catsRepository: CatsService,
     private val localCatFactsGenerator: LocalCatFactsGenerator,
     private val context: Context
-) :
-    ViewModelProvider.NewInstanceFactory() {
+) : ViewModelProvider.NewInstanceFactory() {
 
     override fun <T : ViewModel> create(modelClass: Class<T>): T =
         CatsViewModel(catsRepository, localCatFactsGenerator, context) as T

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

@@ -2,6 +2,7 @@ package otus.homework.reactivecats
 
 import android.content.Context
 import retrofit2.Retrofit
+import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory
 import retrofit2.converter.gson.GsonConverterFactory
 
 class DiContainer {
@@ -10,6 +11,7 @@ class DiContainer {
         Retrofit.Builder()
             .baseUrl("https://cat-fact.herokuapp.com/facts/")
             .addConverterFactory(GsonConverterFactory.create())
+            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
             .build()
     }
 

app/src/main/java/otus/homework/reactivecats/LocalCatFactsGenerator.kt

@@ -1,8 +1,9 @@
 package otus.homework.reactivecats
 
 import android.content.Context
-import io.reactivex.Flowable
+import io.reactivex.Observable
 import io.reactivex.Single
+import java.util.concurrent.TimeUnit
 import kotlin.random.Random
 
 class LocalCatFactsGenerator(
@@ -15,16 +16,25 @@ class LocalCatFactsGenerator(
      * обернутую в подходящий стрим(Flowable/Single/Observable и т.п)
      */
     fun generateCatFact(): Single<Fact> {
-        return Single.never()
+        return Single.create {
+            val fact = Fact(context.resources.getStringArray(R.array.local_cat_facts)[Random.nextInt(5)])
+            it.onSuccess(fact)
+        }
     }
 
     /**
      * Реализуйте функцию otus.homework.reactivecats.LocalCatFactsGenerator#generateCatFactPeriodically так,
      * чтобы она эмитила Fact со случайной строкой из массива строк R.array.local_cat_facts каждые 2000 миллисекунд.
      * Если вновь заэмиченный Fact совпадает с предыдущим - пропускаем элемент.
      */
-    fun generateCatFactPeriodically(): Flowable<Fact> {
-        val success = Fact(context.resources.getStringArray(R.array.local_cat_facts)[Random.nextInt(5)])
-        return Flowable.empty()
+    fun generateCatFactPeriodically(): Observable<Fact> {
+        val source = Observable.interval(2, TimeUnit.SECONDS)
+            .map {
+                val fact = Fact(context.resources.getStringArray(R.array.local_cat_facts)[Random.nextInt(5)])
+                fact
+            }
+           .distinctUntilChanged()
+
+        return source
     }
 }

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

@@ -1,10 +1,9 @@
 package otus.homework.reactivecats
 
-import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
 import android.widget.Toast
 import androidx.activity.viewModels
-import androidx.lifecycle.lifecycleScope
+import androidx.appcompat.app.AppCompatActivity
 import com.google.android.material.snackbar.Snackbar
 
 class MainActivity : AppCompatActivity() {
@@ -30,4 +29,9 @@ class MainActivity : AppCompatActivity() {
             }
         }
     }
+
+    override fun onStop() {
+        super.onStop()
+        catsViewModel.onStop()
+    }
 }