app: switch to Hilt for dependency injection

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

app/src/main/java/dev/msfjarvis/todo/Application.kt

@@ -1,11 +1,8 @@
 package dev.msfjarvis.todo
 
 import android.app.Application
-import dev.msfjarvis.todo.di.Graph
+import dagger.hilt.android.HiltAndroidApp
 
+@HiltAndroidApp
 class Application : Application() {
-  override fun onCreate() {
-    super.onCreate()
-    Graph.provide(this)
-  }
 }

app/src/main/java/dev/msfjarvis/todo/MainActivity.kt

@@ -26,20 +26,25 @@ import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.unit.dp
 import androidx.ui.tooling.preview.Preview
+import dagger.hilt.android.AndroidEntryPoint
 import dev.msfjarvis.todo.compose.utils.IconResource
 import dev.msfjarvis.todo.data.model.TodoItem
-import dev.msfjarvis.todo.di.Graph
+import dev.msfjarvis.todo.data.source.TodoDatabase
 import dev.msfjarvis.todo.ui.TodoRowItem
 import dev.msfjarvis.todo.ui.TodoTheme
 import kotlinx.coroutines.launch
+import javax.inject.Inject
 
+@AndroidEntryPoint
 class MainActivity : AppCompatActivity() {
+  @Inject lateinit var database: TodoDatabase
+
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     setContent {
       TodoTheme {
         val coroutineScope = rememberCoroutineScope()
-        val itemsDao = Graph.database.todoItemsDao()
+        val itemsDao = database.todoItemsDao()
         val items by itemsDao.getAllItems().collectAsState(initial = emptyList())
         TodoApp(
           items,

app/src/main/java/dev/msfjarvis/todo/di/Graph.kt

@@ -1,19 +0,0 @@
-package dev.msfjarvis.todo.di
-
-import android.content.Context
-import androidx.room.Room
-import dev.msfjarvis.todo.data.source.TodoDatabase
-
-/**
- * Rudimentary DI container to initialize singletons, will be switched to Hilt when architecture becomes
- * a focus again.
- */
-object Graph {
-
-  lateinit var database: TodoDatabase
-
-  fun provide(context: Context) {
-    database = Room.databaseBuilder(context, TodoDatabase::class.java, "data.db")
-      .fallbackToDestructiveMigration().build()
-  }
-}

app/src/main/java/dev/msfjarvis/todo/di/PersistenceModule.kt

@@ -0,0 +1,20 @@
+package dev.msfjarvis.todo.di
+
+import android.content.Context
+import androidx.room.Room
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import dev.msfjarvis.todo.data.source.TodoDatabase
+
+@InstallIn(SingletonComponent::class)
+@Module
+object PersistenceModule {
+  @Provides
+  fun provideItemsDatabase(@ApplicationContext context: Context): TodoDatabase {
+    return Room.databaseBuilder(context, TodoDatabase::class.java, "data.db")
+      .fallbackToDestructiveMigration().build()
+  }
+}