Reactive Cats

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-rxjava2:2.7.1"
 }

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

@@ -5,48 +5,72 @@ 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.Observable
+import io.reactivex.android.schedulers.AndroidSchedulers
+import io.reactivex.disposables.CompositeDisposable
+import io.reactivex.schedulers.Schedulers
+import retrofit2.HttpException
+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 onCatsServiceSuccess(fact: Fact) {
+        _catsLiveData.value = Success(fact)
     }
 
-    fun getFacts() {}
+    private fun onCatsServiceError(error: Throwable) {
+        _catsLiveData.value = if (error is HttpException) {
+            ServerError
+        } else {
+            Error((error.message ?: R.string.default_error_text).toString())
+        }
+    }
+
+    private fun getFacts() {
+        compositeDisposable.add(Observable
+            .interval(2, TimeUnit.SECONDS)
+            .map { getLocalFact() }
+            .distinct()
+            .subscribe { })
+    }
+
+    private fun getLocalFact() {
+        compositeDisposable.add(
+            catsService.getCatFact()
+                .subscribeOn(Schedulers.io())
+                .observeOn(AndroidSchedulers.mainThread())
+                .onErrorResumeNext {
+                    localCatFactsGenerator.generateCatFact()
+                }
+                .subscribe(
+                    { fact -> onCatsServiceSuccess(fact) },
+                    { error -> onCatsServiceError(error) })
+        )
+    }
+
+    override fun onCleared() {
+        compositeDisposable.clear()
+        super.onCleared()
+    }
 }
 
 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

@@ -3,6 +3,7 @@ package otus.homework.reactivecats
 import android.content.Context
 import io.reactivex.Flowable
 import io.reactivex.Single
+import java.util.concurrent.TimeUnit
 import kotlin.random.Random
 
 class LocalCatFactsGenerator(
@@ -15,7 +16,8 @@ class LocalCatFactsGenerator(
      * обернутую в подходящий стрим(Flowable/Single/Observable и т.п)
      */
     fun generateCatFact(): Single<Fact> {
-        return Single.never()
+        val fact = getRandomFact()
+        return Single.just(fact)
     }
 
     /**
@@ -24,7 +26,13 @@ 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(2000L, TimeUnit.MILLISECONDS)
+            .map { getRandomFact() }
+            .distinct()
+    }
+
+    private fun getRandomFact(): Fact {
+        return Fact(context.resources.getStringArray(R.array.local_cat_facts)[Random.nextInt(5)])
     }
 }