[ISSUE-011] BaseViewModel 및 샘플 데이터 생성

presentation/src/main/java/com/yapp/growth/base/BaseViewModel.kt

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+package com.yapp.growth.base
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.launch
+
+abstract class BaseViewModel<S : ViewState, A : ViewSideEffect, E : ViewEvent>(
+ initialState: S
+) : ViewModel() {
+
+ abstract fun handleEvents(event: E)
+
+ private val _viewState: MutableStateFlow<S> = MutableStateFlow<S>(initialState)
+ val viewState = _viewState.asStateFlow()
+
+ private val currentState: S
+ get() = _viewState.value
+
+ private val _effect: Channel<A> = Channel()
+ val effect = _effect.receiveAsFlow()
+
+ private val _event: MutableSharedFlow<E> = MutableSharedFlow()
+
+ protected fun updateState(reducer: S.() -> S) {
+ val newState = currentState.reducer()
+ _viewState.value = newState
+ }
+
+ protected fun sendEffect(vararg builder: () -> A) {
+ for (effectValue in builder) {
+ viewModelScope.launch { _effect.send(effectValue()) }
+ }
+ }
+
+ open fun setEvent(event : E) {
+ deliverEvent(event)
+ }
+
+ private fun deliverEvent(event : E) = viewModelScope.launch {
+ handleEvents(event)
+ }
+}

presentation/src/main/java/com/yapp/growth/base/ViewEvent.kt

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+package com.yapp.growth.base
+
+interface ViewEvent {
+}

presentation/src/main/java/com/yapp/growth/base/ViewSideEffect.kt

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+package com.yapp.growth.base
+
+interface ViewSideEffect {
+}

presentation/src/main/java/com/yapp/growth/base/ViewState.kt

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+package com.yapp.growth.base
+
+interface ViewState {
+}

presentation/src/main/java/com/yapp/growth/ui/sample/SampleContract.kt

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+package com.yapp.growth.ui.sample
+
+import com.yapp.growth.base.ViewEvent
+import com.yapp.growth.base.ViewSideEffect
+import com.yapp.growth.base.ViewState
+
+class SampleContract {
+
+ data class SampleViewState(
+ val isLoading: Boolean = false
+ ) : ViewState
+
+ sealed class SampleSideEffect : ViewSideEffect {
+ object NavigateToAnyScreen : SampleSideEffect()
+ data class ShowToast(val msg: String) : SampleSideEffect()
+ }
+
+ sealed class SampleEvent : ViewEvent {
+ object OnAnyButtonClicked : SampleEvent()
+ }
+
+}

presentation/src/main/java/com/yapp/growth/ui/sample/SampleViewModel.kt

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+package com.yapp.growth.ui.sample
+
+import com.yapp.growth.base.BaseViewModel
+import com.yapp.growth.domain.usecase.UseCase
+import com.yapp.growth.ui.sample.SampleContract.*
+
+class SampleViewModel(
+ private val useCase: UseCase
+) : BaseViewModel<SampleViewState, SampleSideEffect, SampleEvent>(
+ SampleViewState()
+) {
+
+ private fun anyFunction() {
+ // anything do . . .
+ sendEffect(
+ { SampleSideEffect.NavigateToAnyScreen },
+ { SampleSideEffect.ShowToast("This is Sample Data") }
+ )
+ updateState { copy(isLoading = false) }
+ }
+
+ override fun handleEvents(event: SampleEvent) {
+ when (event) {
+ is SampleEvent.OnAnyButtonClicked -> {
+ updateState { copy(isLoading = true) }
+ anyFunction()
+ }
+ }
+ }
+}