#6 feat/메인화면 : 메인화면의 BottomNavigation 아이템 선택 여부에 따른 Fragment 노출 로직 추가

app/src/main/java/com/ftw/hometerview/di/ui/ActivityViewModelModule.kt

@@ -2,6 +2,7 @@ package com.ftw.hometerview.di.ui
 
 import com.ftw.domain.usecase.login.LoginUseCase
 import com.ftw.hometerview.dispatcher.Dispatcher
+import com.ftw.hometerview.ui.main.MainViewModel
 import com.ftw.hometerview.ui.splash.SplashViewModel
 import dagger.Module
 import dagger.Provides
@@ -20,4 +21,10 @@ class ActivityViewModelModule {
     ): SplashViewModel {
         return SplashViewModel(dispatcher, loginUseCase)
     }
+
+    @Provides
+    @ActivityScoped
+    fun provideMainViewModel(): MainViewModel {
+        return MainViewModel()
+    }
 }

app/src/main/java/com/ftw/hometerview/ui/main/MainActivity.kt

@@ -1,17 +1,65 @@
 package com.ftw.hometerview.ui.main
 
-import androidx.appcompat.app.AppCompatActivity
+import android.content.Context
+import android.content.Intent
 import android.os.Bundle
-import android.util.Log
-import com.ftw.domain.usecase.login.LoginUseCase
-import com.ftw.domain.usecase.login.LoginUseCaseImpl
+import androidx.appcompat.app.AppCompatActivity
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
 import com.ftw.hometerview.R
+import com.ftw.hometerview.databinding.ActivityMainBinding
+import com.ftw.hometerview.ui.main.favorite.FavoriteFragment
+import com.ftw.hometerview.ui.main.home.HomeFragment
+import com.ftw.hometerview.ui.main.map.MapFragment
+import com.ftw.hometerview.ui.main.mypage.MyPageFragment
+import dagger.hilt.android.AndroidEntryPoint
+import javax.inject.Inject
+import kotlinx.coroutines.launch
 
+@AndroidEntryPoint
 class MainActivity : AppCompatActivity() {
+
+    companion object {
+        fun newIntent(context: Context): Intent = Intent(context, MainActivity::class.java)
+    }
+
+    @Inject
+    lateinit var viewModel: MainViewModel
+
+    private val homeFragment by lazy { HomeFragment() }
+    private val mapFragment by lazy { MapFragment() }
+    private val favoriteFragment by lazy { FavoriteFragment() }
+    private val myPageFragment by lazy { MyPageFragment() }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_main)
+        DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
+            .apply {
+                viewModel = this@MainActivity.viewModel
+                lifecycleOwner = this@MainActivity
+            }
 
+        lifecycleScope.launch {
+            repeatOnLifecycle(Lifecycle.State.STARTED) {
+                viewModel.state.collect { state ->
+                    when (state) {
+                        MainViewModel.State.HomeItemSelected -> replaceFragment(homeFragment)
+                        MainViewModel.State.MapItemSelected -> replaceFragment(mapFragment)
+                        MainViewModel.State.FavoriteItemSelected -> replaceFragment(favoriteFragment)
+                        MainViewModel.State.MyPageItemSelected -> replaceFragment(myPageFragment)
+                        MainViewModel.State.None -> throw IllegalArgumentException()
+                    }
+                }
+            }
+        }
+    }
 
+    private fun replaceFragment(fragment: Fragment) {
+        supportFragmentManager.beginTransaction()
+            .replace(R.id.frame_layout, fragment)
+            .commitAllowingStateLoss()
     }
 }

app/src/main/java/com/ftw/hometerview/ui/main/MainViewModel.kt

@@ -0,0 +1,33 @@
+package com.ftw.hometerview.ui.main
+
+import android.view.MenuItem
+import com.ftw.hometerview.R
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+class MainViewModel {
+
+    sealed class State {
+        object HomeItemSelected : State()
+        object MapItemSelected : State()
+        object FavoriteItemSelected : State()
+        object MyPageItemSelected : State()
+        object None : State()
+    }
+
+    private val _state: MutableStateFlow<State> = MutableStateFlow(State.HomeItemSelected)
+    val state: StateFlow<State> get() = _state.asStateFlow()
+
+    fun onNavigationItemSelected(item: MenuItem): Boolean {
+        _state.value = when (item.itemId) {
+            R.id.home -> State.HomeItemSelected
+            R.id.map -> State.MapItemSelected
+            R.id.heart -> State.FavoriteItemSelected
+            R.id.user -> State.MyPageItemSelected
+            else -> State.HomeItemSelected
+        }
+
+        return state.value != State.None
+    }
+}