Added extension 'unwrapOrError' to main RX classes typed with Optional

rx-extensions/build.gradle

@@ -1,6 +1,18 @@
-apply plugin: 'kotlin'
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+
+android {
+    compileSdkVersion versions.compileSdk
+
+    defaultConfig {
+        minSdkVersion 16
+    }
+}
 
 dependencies {
+    api project(":utils")
+    api project(":logging")
+
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
     implementation "io.reactivex.rxjava2:rxjava:$versions.rxJava"
 }

rx-extensions/src/main/java/ru/touchin/extensions/rx/Flowable.kt

@@ -2,7 +2,18 @@ package ru.touchin.extensions.rx
 
 import io.reactivex.Completable
 import io.reactivex.Flowable
+import ru.touchin.extensions.rx.utils.StringConstants
+import ru.touchin.roboswag.core.utils.Optional
+import ru.touchin.roboswag.core.utils.ShouldNotHappenException
 
 fun <T> Flowable<T>.emitAfter(other: Completable): Flowable<T> = this.flatMap { value ->
     other.andThen(Flowable.just(value))
 }
+
+fun <T> Flowable<Optional<T>>.unwrapOrError(
+        errorMessage: String = StringConstants.OPTIONAL_UNWRAPPING_ERROR_MESSAGE
+): Flowable<T> = this.flatMap { wrapper ->
+    wrapper.get()
+            ?.let { Flowable.just(it) }
+            ?: Flowable.error(ShouldNotHappenException(errorMessage))
+}

rx-extensions/src/main/java/ru/touchin/extensions/rx/Maybe.kt

@@ -2,7 +2,18 @@ package ru.touchin.extensions.rx
 
 import io.reactivex.Completable
 import io.reactivex.Maybe
+import ru.touchin.extensions.rx.utils.StringConstants
+import ru.touchin.roboswag.core.utils.Optional
+import ru.touchin.roboswag.core.utils.ShouldNotHappenException
 
 fun <T> Maybe<T>.emitAfter(other: Completable): Maybe<T> = this.flatMap { value ->
     other.andThen(Maybe.just(value))
 }
+
+fun <T> Maybe<Optional<T>>.unwrapOrError(
+        errorMessage: String = StringConstants.OPTIONAL_UNWRAPPING_ERROR_MESSAGE
+): Maybe<T> = this.flatMap { wrapper ->
+    wrapper.get()
+            ?.let { Maybe.just(it) }
+            ?: Maybe.error(ShouldNotHappenException(errorMessage))
+}

rx-extensions/src/main/java/ru/touchin/extensions/rx/Observable.kt

@@ -2,7 +2,18 @@ package ru.touchin.extensions.rx
 
 import io.reactivex.Completable
 import io.reactivex.Observable
+import ru.touchin.extensions.rx.utils.StringConstants
+import ru.touchin.roboswag.core.utils.Optional
+import ru.touchin.roboswag.core.utils.ShouldNotHappenException
 
 fun <T> Observable<T>.emitAfter(other: Completable): Observable<T> = this.flatMap { value ->
     other.andThen(Observable.just(value))
 }
+
+fun <T> Observable<Optional<T>>.unwrapOrError(
+        errorMessage: String = StringConstants.OPTIONAL_UNWRAPPING_ERROR_MESSAGE
+): Observable<T> = this.flatMap { wrapper ->
+    wrapper.get()
+            ?.let { Observable.just(it) }
+            ?: Observable.error(ShouldNotHappenException(errorMessage))
+}

rx-extensions/src/main/java/ru/touchin/extensions/rx/Single.kt

@@ -2,7 +2,18 @@ package ru.touchin.extensions.rx
 
 import io.reactivex.Completable
 import io.reactivex.Single
+import ru.touchin.extensions.rx.utils.StringConstants
+import ru.touchin.roboswag.core.utils.Optional
+import ru.touchin.roboswag.core.utils.ShouldNotHappenException
 
 fun <T> Single<T>.emitAfter(other: Completable): Single<T> = this.flatMap { value ->
     other.andThen(Single.just(value))
 }
+
+fun <T> Single<Optional<T>>.unwrapOrError(
+        errorMessage: String = StringConstants.OPTIONAL_UNWRAPPING_ERROR_MESSAGE
+): Single<T> = this.flatMap { wrapper ->
+    wrapper.get()
+            ?.let { Single.just(it) }
+            ?: Single.error(ShouldNotHappenException(errorMessage))
+}

rx-extensions/src/main/java/ru/touchin/extensions/rx/utils/Constants.kt

@@ -0,0 +1,5 @@
+package ru.touchin.extensions.rx.utils
+
+object StringConstants {
+    const val OPTIONAL_UNWRAPPING_ERROR_MESSAGE = "Wrapped object must not be null"
+}