Adil Ziganshin HW Flow

flowcats/build.gradle

@@ -4,7 +4,7 @@ plugins {
 }
 
 android {
-    compileSdkVersion 30
+    compileSdk 34
     buildToolsVersion "30.0.3"
 
     namespace = "otus.homework.flowcats"
@@ -46,6 +46,7 @@ dependencies {
     implementation 'com.squareup.picasso:picasso:2.71828'
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.3'
     implementation 'androidx.activity:activity-ktx:1.2.3'
+    implementation 'androidx.lifecycle:lifecycle-viewmodel-android:2.8.7'
     testImplementation 'org.jetbrains.kotlinx:kotlinx-coroutines-test:1.4.3'
     implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
 }

flowcats/src/main/java/otus/homework/flowcats/CatsRepository.kt

@@ -3,16 +3,25 @@ package otus.homework.flowcats
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.flow
 
+sealed class Result {
+    class Success(val fact: Fact): Result()
+    class Error(val exception: Throwable): Result()
+}
+
 class CatsRepository(
     private val catsService: CatsService,
     private val refreshIntervalMs: Long = 5000
 ) {
 
     fun listenForCatFacts() = flow {
         while (true) {
-            val latestNews = catsService.getCatFact()
-            emit(latestNews)
+            try {
+                val latestFact = catsService.getCatFact()
+                emit(Result.Success(latestFact))
+            } catch (exception: Throwable) {
+                emit(Result.Error(exception))
+            }
             delay(refreshIntervalMs)
         }
     }
-}
+}

flowcats/src/main/java/otus/homework/flowcats/CatsService.kt

@@ -4,6 +4,6 @@ import retrofit2.http.GET
 
 interface CatsService {
 
-    @GET("random?animal_type=cat")
+    @GET("fact")
     suspend fun getCatFact(): Fact
 }

flowcats/src/main/java/otus/homework/flowcats/CatsViewModel.kt

@@ -1,31 +1,47 @@
 package otus.homework.flowcats
 
+import android.util.Log
 import androidx.lifecycle.*
+import androidx.lifecycle.viewmodel.CreationExtras
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 class CatsViewModel(
     private val catsRepository: CatsRepository
 ) : ViewModel() {
 
-    private val _catsLiveData = MutableLiveData<Fact>()
-    val catsLiveData: LiveData<Fact> = _catsLiveData
+    private val _catsFlow: MutableStateFlow<Fact?> = MutableStateFlow(null)
+    val catsFlow: StateFlow<Fact?> = _catsFlow
 
     init {
-        viewModelScope.launch {
+        val handler = CoroutineExceptionHandler { _, exception ->
+            Log.d("init", "Exception = '$exception'")
+        }
+        viewModelScope.launch(handler) {
             withContext(Dispatchers.IO) {
-                catsRepository.listenForCatFacts().collect {
-                    _catsLiveData.value = it
+                catsRepository.listenForCatFacts().collect { result ->
+                    when (result) {
+                        is Result.Success -> _catsFlow.value = result.fact
+                        is Result.Error -> _catsFlow.value = null
+                    }
                 }
             }
         }
     }
-}
 
-class CatsViewModelFactory(private val catsRepository: CatsRepository) :
-    ViewModelProvider.NewInstanceFactory() {
-    override fun <T : ViewModel?> create(modelClass: Class<T>): T =
-        CatsViewModel(catsRepository) as T
-}
+    companion object {
+        val REPOSITORY_KEY = object : CreationExtras.Key<CatsRepository> {  }
+        val Factory: ViewModelProvider.Factory = viewModelFactory {
+            initializer {
+                val repository = this[REPOSITORY_KEY] as CatsRepository
+                CatsViewModel(repository)
+            }
+        }
+    }
+}

flowcats/src/main/java/otus/homework/flowcats/DiContainer.kt

@@ -7,12 +7,12 @@ class DiContainer {
 
     private val retrofit by lazy {
         Retrofit.Builder()
-            .baseUrl("https://cat-fact.herokuapp.com/facts/")
+            .baseUrl("https://catfact.ninja/")
             .addConverterFactory(GsonConverterFactory.create())
             .build()
     }
 
     val service by lazy { retrofit.create(CatsService::class.java) }
 
     val repository by lazy { CatsRepository(service) }
-}
+}

flowcats/src/main/java/otus/homework/flowcats/Fact.kt

@@ -3,22 +3,7 @@ package otus.homework.flowcats
 import com.google.gson.annotations.SerializedName
 
 data class Fact(
-	@field:SerializedName("createdAt")
-	val createdAt: String,
-	@field:SerializedName("deleted")
-	val deleted: Boolean,
-	@field:SerializedName("_id")
-	val id: String,
-	@field:SerializedName("text")
+	@field:SerializedName("fact")
 	val text: String,
-	@field:SerializedName("source")
-	val source: String,
-	@field:SerializedName("used")
-	val used: Boolean,
-	@field:SerializedName("type")
-	val type: String,
-	@field:SerializedName("user")
-	val user: String,
-	@field:SerializedName("updatedAt")
-	val updatedAt: String
+	val length: Int
 )

flowcats/src/main/java/otus/homework/flowcats/MainActivity.kt

@@ -2,20 +2,42 @@ package otus.homework.flowcats
 
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
-import androidx.activity.viewModels
+import android.widget.Toast
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.viewmodel.MutableCreationExtras
+import kotlinx.coroutines.launch
 
 class MainActivity : AppCompatActivity() {
 
     private val diContainer = DiContainer()
-    private val catsViewModel by viewModels<CatsViewModel> { CatsViewModelFactory(diContainer.repository) }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         val view = layoutInflater.inflate(R.layout.activity_main, null) as CatsView
         setContentView(view)
-
-        catsViewModel.catsLiveData.observe(this){
-            view.populate(it)
+        val catsViewModel: CatsViewModel = ViewModelProvider.create(this,
+            factory = CatsViewModel.Factory,
+            extras = MutableCreationExtras().apply {
+                set(CatsViewModel.REPOSITORY_KEY, diContainer.repository)
+            }
+        ) [CatsViewModel::class]
+        lifecycleScope.launch {
+            catsViewModel.catsFlow.collect {
+                if (it != null) {
+                    view.populate(it)
+                } else {
+                    showError()
+                }
+            }
         }
     }
-}
+
+    private fun showError() {
+        Toast.makeText(
+            this@MainActivity,
+            getString(R.string.could_not_get_response_from_server),
+            Toast.LENGTH_SHORT)
+            .show()
+    }
+}

flowcats/src/main/res/values/strings.xml

@@ -1,3 +1,4 @@
 <resources>
     <string name="app_name">Flow cats</string>
+    <string name="could_not_get_response_from_server">Не удалось получить ответ от сервера</string>
 </resources>

operators/src/main/java/otus/homework/flow/SampleInteractor.kt

@@ -1,7 +1,15 @@
 package otus.homework.flow
 
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.filter
+import kotlinx.coroutines.flow.flatMapConcat
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onCompletion
+import kotlinx.coroutines.flow.take
+import kotlinx.coroutines.flow.zip
 
 @ExperimentalCoroutinesApi
 class SampleInteractor(
@@ -18,7 +26,12 @@ class SampleInteractor(
      * 6) возвращает результат
      */
     fun task1(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .map { it * 5 }
+            .filter { it > 20 }
+            .filter { it.rem(2) == 1 }
+            .map { "$it won" }
+            .take(3)
     }
 
     /**
@@ -29,7 +42,14 @@ class SampleInteractor(
      * Если число не делится на 3,5,15 - эмитим само число
      */
     fun task2(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers().flatMapConcat {
+            when {
+                it.rem(15) == 0 -> flowOf(it.toString(), "FizzBuzz")
+                it.rem(3) == 0 -> flowOf(it.toString(), "Fizz")
+                it.rem(5) == 0 -> flowOf(it.toString(), "Buzz")
+                else -> flowOf(it.toString())
+            }
+        }
     }
 
     /**
@@ -38,7 +58,11 @@ class SampleInteractor(
      * Если айтемы в одно из флоу кончились то результирующий флоу также должен закончится
      */
     fun task3(): Flow<Pair<String, String>> {
-        return flowOf()
+        return with (sampleRepository) {
+            produceColors().zip(produceForms()) { color, form ->
+                Pair(color, form)
+            }
+        }
     }
 
     /**
@@ -48,6 +72,12 @@ class SampleInteractor(
      * При любом исходе, будь то выброс исключения или успешная отработка функции вызовите метод dotsRepository.completed()
      */
     fun task4(): Flow<Int> {
-        return flowOf()
+        return sampleRepository.produceNumbers().catch {
+            if (it is IllegalArgumentException) {
+                emit(-1)
+            } else {
+                throw it
+            }
+        }.onCompletion { sampleRepository.completed() }
     }
 }