Implement ResultHandler

core/core-presentation/src/main/kotlin/com/maximillianleonov/cinemax/core/presentation/common/ResultHandler.kt

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2022 Maximillian Leonov
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.maximillianleonov.cinemax.core.presentation.common
+
+import com.maximillianleonov.cinemax.core.domain.result.Result
+import com.maximillianleonov.cinemax.core.domain.result.isFailure
+import com.maximillianleonov.cinemax.core.domain.result.isLoading
+import com.maximillianleonov.cinemax.core.domain.result.isSuccess
+import com.maximillianleonov.cinemax.core.presentation.util.Constants
+import com.maximillianleonov.cinemax.core.presentation.util.MapperFactory
+
+interface ResultHandler {
+    fun <T, R, S : State> Result<T>.handleResult(
+        onLoading: (S, R?) -> S,
+        onSuccess: (S, R) -> S,
+        onFailure: (S, Throwable) -> S,
+        updateUiState: ((S) -> S) -> Unit
+    )
+
+    fun <T, R, S : State> Result<List<T>>.handleResultList(
+        onLoading: (S, List<R>) -> S,
+        onSuccess: (S, List<R>) -> S,
+        onFailure: (S, Throwable) -> S,
+        updateUiState: ((S) -> S) -> Unit
+    )
+}
+
+fun ResultHandler(): ResultHandler = ResultHandlerImpl()
+
+private class ResultHandlerImpl : ResultHandler {
+    override fun <T, R, S : State> Result<T>.handleResult(
+        onLoading: (S, R?) -> S,
+        onSuccess: (S, R) -> S,
+        onFailure: (S, Throwable) -> S,
+        updateUiState: ((S) -> S) -> Unit,
+    ) = updateUiState { currentState ->
+        handleResult(
+            currentState = currentState,
+            onLoading = onLoading,
+            onSuccess = onSuccess,
+            onFailure = onFailure
+        )
+    }
+
+    override fun <T, R, S : State> Result<List<T>>.handleResultList(
+        onLoading: (S, List<R>) -> S,
+        onSuccess: (S, List<R>) -> S,
+        onFailure: (S, Throwable) -> S,
+        updateUiState: ((S) -> S) -> Unit
+    ) {
+        updateUiState { currentState ->
+            handleResultList(
+                currentState = currentState,
+                onLoading = onLoading,
+                onSuccess = onSuccess,
+                onFailure = onFailure
+            )
+        }
+    }
+}
+
+private fun <T, R, S : State> Result<T>.handleResult(
+    currentState: S,
+    onLoading: (S, R?) -> S,
+    onSuccess: (S, R) -> S,
+    onFailure: (S, Throwable) -> S
+): S {
+    val transform: (T) -> R = MapperFactory.domainMapper()
+    return when {
+        isLoading() -> onLoading(currentState, value?.let(transform))
+        isSuccess() -> onSuccess(currentState, value.let(transform))
+        isFailure() -> onFailure(currentState, error)
+        else -> error("{${Constants.Messages.UNHANDLED_STATE} $this}")
+    }
+}
+
+private fun <T, R, S : State> Result<List<T>>.handleResultList(
+    currentState: S,
+    onLoading: (S, List<R>) -> S,
+    onSuccess: (S, List<R>) -> S,
+    onFailure: (S, Throwable) -> S
+): S {
+    val transform: (T) -> R = MapperFactory.domainMapper()
+    return when {
+        isLoading() -> onLoading(currentState, value?.map(transform).orEmpty())
+        isSuccess() -> onSuccess(currentState, value.map(transform))
+        isFailure() -> onFailure(currentState, error)
+        else -> error("{${Constants.Messages.UNHANDLED_STATE} $this}")
+    }
+}