[ISSUE-011] BaseViewModel 및 샘플 데이터 생성

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

@@ -0,0 +1,51 @@
+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()
+
+    init {
+        subscribeToEvents()
+    }
+
+    private fun subscribeToEvents() {
+        viewModelScope.launch {
+            _event.collect {
+                handleEvents(it)
+            }
+        }
+    }
+
+    protected fun setState(reducer: S.() -> S) {
+        val newState = currentState.reducer()
+        _viewState.value = newState
+    }
+
+    protected fun setEffect(builder: () -> A) {
+        val effectValue = builder()
+        viewModelScope.launch { _effect.send(effectValue) }
+    }
+
+    open fun setEvent(event : E) {
+        viewModelScope.launch { _event.emit(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

@@ -0,0 +1,4 @@
+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 SampleViewSideEffect : ViewSideEffect {
+        object NavigateToAnyScreen : SampleViewSideEffect()
+        data class ShowToast(val msg: String) : SampleViewSideEffect()
+    }
+
+    sealed class SampleViewEvent : ViewEvent {
+        object OnAnyButtonClicked : SampleViewEvent()
+    }
+
+}

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, SampleViewSideEffect, SampleViewEvent>(
+    SampleViewState()
+) {
+
+    fun anyFunction() {
+        // anything do . . .
+        setEffect { SampleViewSideEffect.NavigateToAnyScreen }
+        setState { copy(isLoading = false) }
+    }
+
+    override fun handleEvents(event: SampleViewEvent) {
+        when (event) {
+            is SampleViewEvent.OnAnyButtonClicked -> {
+                setState { copy(isLoading = true) }
+                anyFunction()
+            }
+        }
+    }
+}