Modernize Todo App: Enhanced Data Model and Architectural Improvements

.gitignore

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+<<<<<<< HEAD
+# Gradle files
+.gradle/
+build/
+
+# Local configuration file
+local.properties
+
+# Android Studio generated files
+*.iml
+.idea/
+=======
+# Android Studio
+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+
+# Gradle files
+gradle-app.setting
+!gradle-wrapper.jar
+.gradletasknamecache
+>>>>>>> pr-7-Ralfmal-kotlinTodoApp
+
+# Compiled class files
+*.class
+
+# Log files
+*.log
+
+<<<<<<< HEAD
+# Android generated files
+bin/
+gen/
+out/
+
+# Dependency directories
+/captures
+.externalNativeBuild
+.cxx
+
+# macOS system files
+.DS_Store
+
+# Backup files
+*.bak
+*.swp
+
+# Kotlin build artifacts
+*.jar
+*.war
+*.ear
+=======
+# Package Files
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+>>>>>>> pr-7-Ralfmal-kotlinTodoApp
+
+# Virtual machine crash logs
+hs_err_pid*
+
+<<<<<<< HEAD
+# Android Profiling
+*.hprof
+=======
+# Android specific
+bin/
+gen/
+out/
+release/
+
+# Android Profiling
+*.hprof
+
+# Dependency directories
+/node_modules
+/jspm_packages
+
+# Editor directories and files
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# Environment files
+.env
+
+# Secrets
+*.key
+secrets.json
+
+# Build output
+/build
+/dist
+/target
+>>>>>>> pr-7-Ralfmal-kotlinTodoApp

app/build.gradle.kts

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+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+    id("kotlin-kapt")
+}
+
+android {
+    namespace = "com.todoapp"
+    compileSdk = 33
+
+    defaultConfig {
+        applicationId = "com.todoapp"
+        minSdk = 26  // Updated to support Java 8 time
+        targetSdk = 33
+        versionCode = 1
+        versionName = "1.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+        isCoreLibraryDesugaringEnabled = true  // Enable desugaring for Java 8 features
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
+dependencies {
+    // Room Database
+    val roomVersion = "2.5.1"
+    implementation("androidx.room:room-runtime:$roomVersion")
+    implementation("androidx.room:room-ktx:$roomVersion")
+    kapt("androidx.room:room-compiler:$roomVersion")
+    testImplementation("androidx.room:room-testing:$roomVersion")
+
+    // Java 8 time support
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.0.3")
+
+    // Kotlin standard library
+    implementation("org.jetbrains.kotlin:kotlin-stdlib:1.8.20")
+
+    // Testing
+    testImplementation("junit:junit:4.13.2")
+    testImplementation("org.jetbrains.kotlin:kotlin-test:1.8.20")
+
+    // Android testing
+    androidTestImplementation("androidx.test.ext:junit:1.1.5")
+    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
+}

app/src/main/java/com/example/todoapp/data/dao/TodoItemDao.kt

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+package com.example.todoapp.data.dao
+
+import androidx.room.*
+import com.example.todoapp.data.model.TodoItem
+import kotlinx.coroutines.flow.Flow
+
+@Dao
+interface TodoItemDao {
+    /**
+     * Inserts a new todo item into the database.
+     * @param todoItem The todo item to insert
+     * @return The ID of the newly inserted item
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insert(todoItem: TodoItem): Long
+
+    /**
+     * Inserts multiple todo items into the database.
+     * @param todoItems The list of todo items to insert
+     * @return List of inserted item IDs
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insertAll(todoItems: List<TodoItem>): List<Long>
+
+    /**
+     * Updates an existing todo item.
+     * @param todoItem The todo item with updated information
+     */
+    @Update
+    suspend fun update(todoItem: TodoItem)
+
+    /**
+     * Deletes a specific todo item.
+     * @param todoItem The todo item to delete
+     */
+    @Delete
+    suspend fun delete(todoItem: TodoItem)
+
+    /**
+     * Retrieves a todo item by its ID.
+     * @param id The ID of the todo item
+     * @return The todo item or null if not found
+     */
+    @Query("SELECT * FROM todo_items WHERE id = :id")
+    suspend fun getById(id: Long): TodoItem?
+
+    /**
+     * Retrieves all todo items, sorted by creation date.
+     * @return A Flow of todo items
+     */
+    @Query("SELECT * FROM todo_items ORDER BY createdAt DESC")
+    fun getAllTodoItems(): Flow<List<TodoItem>>
+
+    /**
+     * Retrieves completed todo items.
+     * @return A Flow of completed todo items
+     */
+    @Query("SELECT * FROM todo_items WHERE isCompleted = 1 ORDER BY updatedAt DESC")
+    fun getCompletedTodoItems(): Flow<List<TodoItem>>
+
+    /**
+     * Retrieves active (not completed) todo items.
+     * @return A Flow of active todo items
+     */
+    @Query("SELECT * FROM todo_items WHERE isCompleted = 0 ORDER BY createdAt DESC")
+    fun getActiveTodoItems(): Flow<List<TodoItem>>
+
+    /**
+     * Deletes all todo items from the database.
+     */
+    @Query("DELETE FROM todo_items")
+    suspend fun deleteAll()
+
+    /**
+     * Counts the total number of todo items.
+     * @return The total number of todo items
+     */
+    @Query("SELECT COUNT(*) FROM todo_items")
+    suspend fun count(): Int
+}

app/src/main/java/com/example/todoapp/data/database/TodoDatabase.kt

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+package com.example.todoapp.data.database
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+import androidx.room.TypeConverters
+import com.example.todoapp.data.dao.TodoItemDao
+import com.example.todoapp.data.model.TodoItem
+import java.time.LocalDateTime
+
+@Database(entities = [TodoItem::class], version = 2, exportSchema = false)
+@TypeConverters(Converters::class)
+abstract class TodoDatabase : RoomDatabase() {
+    abstract fun todoItemDao(): TodoItemDao
+
+    companion object {
+        @Volatile
+        private var INSTANCE: TodoDatabase? = null
+
+        fun getDatabase(context: Context): TodoDatabase {
+            return INSTANCE ?: synchronized(this) {
+                val instance = Room.databaseBuilder(
+                    context.applicationContext,
+                    TodoDatabase::class.java,
+                    "todo_database"
+                )
+                .fallbackToDestructiveMigration() // Use with caution in production
+                .build()
+                INSTANCE = instance
+                instance
+            }
+        }
+    }
+}
+
+// Type converters for LocalDateTime
+class Converters {
+    @androidx.room.TypeConverter
+    fun fromTimestamp(value: String?): LocalDateTime? {
+        return value?.let { LocalDateTime.parse(it) }
+    }
+
+    @androidx.room.TypeConverter
+    fun dateToTimestamp(date: LocalDateTime?): String? {
+        return date?.toString()
+    }
+}

app/src/main/java/com/example/todoapp/data/model/TodoItem.kt

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+package com.example.todoapp.data.model
+
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+import java.time.LocalDateTime
+
+/**
+ * Room database entity representing a Todo item.
+ * 
+ * @property id Unique identifier for the Todo item
+ * @property title Title of the Todo item
+ * @property description Detailed description of the Todo item
+ * @property isCompleted Indicates whether the Todo item is completed
+ * @property createdAt Timestamp of when the Todo item was created
+ * @property dueDate Optional due date for the Todo item
+ */
+@Entity(tableName = "todo_items")
+data class TodoItem(
+    @PrimaryKey(autoGenerate = true)
+    val id: Int = 0,
+
+    @ColumnInfo(name = "title")
+    val title: String,
+
+    @ColumnInfo(name = "description")
+    val description: String? = null,
+
+    @ColumnInfo(name = "is_completed")
+    val isCompleted: Boolean = false,
+
+    @ColumnInfo(name = "created_at")
+    val createdAt: LocalDateTime = LocalDateTime.now(),
+
+    @ColumnInfo(name = "due_date")
+    val dueDate: LocalDateTime? = null
+) {
+    /**
+     * Validates the Todo item properties.
+     * 
+     * @throws IllegalArgumentException if validation fails
+     */
+    init {
+        require(title.isNotBlank()) { "Title cannot be blank" }
+        require(title.length <= 100) { "Title cannot exceed 100 characters" }
+        description?.let {
+            require(it.length <= 500) { "Description cannot exceed 500 characters" }
+        }
+    }
+}

app/src/main/java/com/todoapp/data/entity/Todo.kt

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+// Deprecated: Replaced by TodoItem in com.example.todoapp.data.model package
+// This file is kept for historical reference and can be safely removed in future cleanup