done

app/build.gradle

@@ -46,4 +46,5 @@ dependencies {
     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'
+    implementation 'com.squareup.retrofit2:adapter-rxjava2:2.9.0'
 }

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

@@ -1,10 +1,11 @@
 package otus.homework.reactivecats
 
+import io.reactivex.Single
 import retrofit2.Call
 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

@@ -5,40 +5,49 @@ import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
+import io.reactivex.Observable
+import io.reactivex.android.schedulers.AndroidSchedulers
+import io.reactivex.disposables.CompositeDisposable
+import io.reactivex.schedulers.Schedulers
 import retrofit2.Call
 import retrofit2.Callback
 import retrofit2.Response
+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
 
+    private 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
-                        )
-                    )
-                }
-            }
+        getFacts()
+    }
 
-            override fun onFailure(call: Call<Fact>, t: Throwable) {
-                _catsLiveData.value = ServerError
-            }
-        })
+    private fun getFacts() {
+        compositeDisposable.add(
+            Observable.interval(2000, TimeUnit.MILLISECONDS).timeInterval()
+                .flatMap {
+                    catsService.getCatFact().toObservable()
+                        .subscribeOn(Schedulers.io())
+                        .observeOn(AndroidSchedulers.mainThread())
+                        .onErrorResumeNext(localCatFactsGenerator.generateCatFact().toObservable())
+                }
+                .subscribe { result ->
+                    _catsLiveData.value = Success(result)
+                }
+        )
     }
 
-    fun getFacts() {}
+    override fun onCleared() {
+        compositeDisposable.clear()
+        super.onCleared()
+    }
 }
 
 class CatsViewModelFactory(

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

@@ -2,20 +2,24 @@ 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(
     private val context: Context
 ) {
 
+    val array = context.resources.getStringArray(R.array.local_cat_facts)
+
     /**
      * Реализуйте функцию otus.homework.reactivecats.LocalCatFactsGenerator#generateCatFact так,
      * чтобы она возвращала Fact со случайной строкой  из массива строк R.array.local_cat_facts
      * обернутую в подходящий стрим(Flowable/Single/Observable и т.п)
      */
     fun generateCatFact(): Single<Fact> {
-        return Single.never()
+        return Single.just(array[Random.nextInt(array.size)]).map { Fact(it) }
     }
 
     /**
@@ -24,7 +28,9 @@ class LocalCatFactsGenerator(
      * 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()
+        return Flowable
+            .interval(2000, TimeUnit.MILLISECONDS)
+            .map { Fact(array[Random.nextInt(array.size)]) }
+            .distinctUntilChanged()
     }
 }