Inventory App Structure with Efficient Excel Import

inventory-app/app/build.gradle

@@ -21,8 +21,13 @@ android {
         viewBinding true
     }
 
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
     kotlinOptions {
-        jvmTarget = '17'
+        jvmTarget = '1.8'
     }
 }
 
@@ -41,15 +46,23 @@ dependencies {
 
     implementation "com.squareup.okhttp3:okhttp:4.12.0"
     implementation "com.squareup.retrofit2:retrofit:2.11.0"
+    implementation "com.squareup.retrofit2:converter-gson:2.11.0"
 
-    implementation "org.apache.poi:poi-ooxml-lite:5.2.5"
+    // Apache POI for Excel and Streaming Reader
+    implementation "org.apache.poi:poi:5.2.5"
+    implementation "org.apache.poi:poi-ooxml:5.2.5"
+    // Using excel-streaming-reader for memory efficiency (batch processing of large files)
+    implementation "com.github.pjfanning:excel-streaming-reader:4.2.1"
 
     implementation "com.journeyapps:zxing-android-embedded:4.3.0"
+    implementation "com.google.zxing:core:3.5.3"
 
     implementation "com.google.dagger:hilt-android:2.51"
     kapt "com.google.dagger:hilt-compiler:2.51"
 
     implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.7.0"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.7.0"
+    implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.7.0"
     implementation "androidx.activity:activity-ktx:1.9.0"
     implementation "androidx.fragment:fragment-ktx:1.6.2"
 }

inventory-app/app/src/main/AndroidManifest.xml

@@ -1,21 +1,38 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="com.example.inventory">
 
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.CAMERA" />
+
     <application
+        android:name=".InventoryApplication"
         android:allowBackup="true"
-        android:label="@string/app_name"
-        android:supportsRtl="true">
-        <activity
-            android:name="com.example.inventory.ui.settings.SettingsActivity"
-            android:exported="false" />
+        android:label="Inventory App"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.AppCompat.Light.DarkActionBar"
+        tools:replace="android:theme">
+
         <activity
-            android:name="com.example.inventory.ui.MainActivity"
+            android:name=".ui.main.MainActivity"
             android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <activity
+            android:name=".ui.settings.SettingsActivity"
+            android:exported="false"
+            android:parentActivityName=".ui.main.MainActivity"/>
+
+        <activity
+            android:name="com.journeyapps.barcodescanner.CaptureActivity"
+            android:screenOrientation="fullSensor"
+            tools:replace="android:screenOrientation" />
+
     </application>
+
 </manifest>

inventory-app/app/src/main/java/com/example/inventory/InventoryApplication.kt

@@ -0,0 +1,7 @@
+package com.example.inventory
+
+import android.app.Application
+import dagger.hilt.android.HiltAndroidApp
+
+@HiltAndroidApp
+class InventoryApplication : Application()

inventory-app/app/src/main/java/com/example/inventory/data/AppDatabase.kt

@@ -2,9 +2,11 @@ package com.example.inventory.data
 
 import androidx.room.Database
 import androidx.room.RoomDatabase
+import com.example.inventory.data.dao.InventoryDao
+import com.example.inventory.data.entity.Item
+import com.example.inventory.data.entity.WarehouseStock
 
-@Database(entities = [Item::class, WarehouseStock::class], version = 1)
+@Database(entities = [Item::class, WarehouseStock::class], version = 1, exportSchema = false)
 abstract class AppDatabase : RoomDatabase() {
-    abstract fun itemDao(): ItemDao
-    abstract fun warehouseStockDao(): WarehouseStockDao
+    abstract fun inventoryDao(): InventoryDao
 }

inventory-app/app/src/main/java/com/example/inventory/data/api/DownloadService.kt

@@ -0,0 +1,13 @@
+package com.example.inventory.data.api
+
+import okhttp3.ResponseBody
+import retrofit2.Response
+import retrofit2.http.GET
+import retrofit2.http.Streaming
+import retrofit2.http.Url
+
+interface DownloadService {
+    @Streaming
+    @GET
+    suspend fun downloadFile(@Url url: String): Response<ResponseBody>
+}

inventory-app/app/src/main/java/com/example/inventory/data/dao/InventoryDao.kt

@@ -0,0 +1,42 @@
+package com.example.inventory.data.dao
+
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import androidx.room.Transaction
+import com.example.inventory.data.entity.Item
+import com.example.inventory.data.entity.WarehouseStock
+
+@Dao
+interface InventoryDao {
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insertItems(items: List<Item>): List<Long>
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insertStocks(stocks: List<WarehouseStock>)
+
+    @Query("SELECT * FROM items WHERE code = :code LIMIT 1")
+    suspend fun getItemByCode(code: String): Item?
+
+    @Query("SELECT * FROM warehouse_stocks WHERE itemId = :itemId AND quantity > 0")
+    suspend fun getStocksByItemId(itemId: Long): List<WarehouseStock>
+
+    @Query("DELETE FROM items")
+    suspend fun clearAllItems()
+
+    @Query("DELETE FROM warehouse_stocks")
+    suspend fun clearAllStocks()
+
+    @Transaction
+    suspend fun clearAndInsertBatch(items: List<Item>, stocks: Map<String, List<WarehouseStock>>) {
+        // This method is tricky because we need IDs for stocks.
+        // It's better to handle logic in Repository to insert items, get IDs, then insert stocks.
+        // But for batch processing, we might want to do it differently.
+        // Actually, if we use code as a reference in stock it might be easier but requirement says:
+        // "Item (id, code, name, price) and WarehouseStock (itemId, warehouseName, quantity)"
+
+        // So we will just provide basic insert methods and handle logic in repository/usecase.
+    }
+}

inventory-app/app/src/main/java/com/example/inventory/data/entity/Item.kt

@@ -0,0 +1,17 @@
+package com.example.inventory.data.entity
+
+import androidx.room.Entity
+import androidx.room.Index
+import androidx.room.PrimaryKey
+
+@Entity(
+    tableName = "items",
+    indices = [Index(value = ["code"], unique = true)]
+)
+data class Item(
+    @PrimaryKey(autoGenerate = true)
+    val id: Long = 0,
+    val code: String,
+    val name: String,
+    val price: Double
+)

inventory-app/app/src/main/java/com/example/inventory/data/WarehouseStock.kt → inventory-app/app/src/main/java/com/example/inventory/data/entity/WarehouseStock.kt

@@ -1,12 +1,12 @@
-package com.example.inventory.data
+package com.example.inventory.data.entity
 
 import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Index
+import androidx.room.PrimaryKey
 
 @Entity(
-    tableName = "warehouse_stock",
-    primaryKeys = ["itemId", "warehouseName"],
+    tableName = "warehouse_stocks",
     foreignKeys = [
         ForeignKey(
             entity = Item::class,
@@ -15,9 +15,11 @@ import androidx.room.Index
             onDelete = ForeignKey.CASCADE
         )
     ],
-    indices = [Index("itemId"), Index("warehouseName")]
+    indices = [Index(value = ["itemId"])]
 )
 data class WarehouseStock(
+    @PrimaryKey(autoGenerate = true)
+    val id: Long = 0,
     val itemId: Long,
     val warehouseName: String,
     val quantity: Int

inventory-app/app/src/main/java/com/example/inventory/di/DatabaseModule.kt

@@ -0,0 +1,32 @@
+package com.example.inventory.di
+
+import android.content.Context
+import androidx.room.Room
+import com.example.inventory.data.AppDatabase
+import com.example.inventory.data.dao.InventoryDao
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+object DatabaseModule {
+
+    @Provides
+    @Singleton
+    fun provideDatabase(@ApplicationContext context: Context): AppDatabase {
+        return Room.databaseBuilder(
+            context,
+            AppDatabase::class.java,
+            "inventory_db"
+        ).fallbackToDestructiveMigration().build()
+    }
+
+    @Provides
+    fun provideInventoryDao(database: AppDatabase): InventoryDao {
+        return database.inventoryDao()
+    }
+}