Integrate SecretsRepository and ApkImporter with app

Refactor methods out of MainActivity into Controllers for ScanScreen and SettingsScreen

app/src/main/java/com/github/nacabaro/vbhelper/ActivityLifecycleListener.kt

@@ -0,0 +1,16 @@
+package com.github.nacabaro.vbhelper
+
+interface ActivityLifecycleListener {
+    fun onPause()
+    fun onResume()
+
+    companion object {
+        fun noOpInstance(): ActivityLifecycleListener {
+            return object: ActivityLifecycleListener {
+                override fun onPause() {}
+
+                override fun onResume() {}
+            }
+        }
+    }
+}

app/src/main/java/com/github/nacabaro/vbhelper/MainActivity.kt

@@ -1,11 +1,8 @@
 package com.github.nacabaro.vbhelper
 
 import android.content.Intent
-import android.nfc.NfcAdapter
-import android.nfc.Tag
-import android.nfc.tech.NfcA
 import android.os.Bundle
-import android.provider.Settings
+import android.util.Log
 import android.widget.Toast
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
@@ -13,17 +10,10 @@ import androidx.activity.enableEdgeToEdge
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
 import androidx.lifecycle.lifecycleScope
 import com.github.cfogrady.vb.dim.card.DimReader
 import com.github.nacabaro.vbhelper.navigation.AppNavigation
-import com.github.cfogrady.vbnfc.CryptographicTransformer
-import com.github.cfogrady.vbnfc.TagCommunicator
 import com.github.cfogrady.vbnfc.be.BENfcCharacter
-import com.github.cfogrady.vbnfc.data.DeviceType
 import com.github.cfogrady.vbnfc.data.NfcCharacter
 import com.github.nacabaro.vbhelper.di.VBHelper
 import com.github.nacabaro.vbhelper.domain.Dim
@@ -32,39 +22,71 @@ import com.github.nacabaro.vbhelper.domain.Character
 import com.github.nacabaro.vbhelper.domain.device_data.BECharacterData
 import com.github.nacabaro.vbhelper.domain.device_data.TransformationHistory
 import com.github.nacabaro.vbhelper.domain.device_data.UserCharacter
+import com.github.nacabaro.vbhelper.navigation.AppNavigationHandlers
+import com.github.nacabaro.vbhelper.screens.scanScreen.ScanScreenControllerImpl
+import com.github.nacabaro.vbhelper.screens.SettingsScreenController
+import com.github.nacabaro.vbhelper.source.ApkSecretsImporter
 import com.github.nacabaro.vbhelper.ui.theme.VBHelperTheme
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.launch
 
 class MainActivity : ComponentActivity() {
-    private lateinit var nfcAdapter: NfcAdapter
-    private lateinit var deviceToCryptographicTransformers: Map<UShort, CryptographicTransformer>
 
     private var nfcCharacter = MutableStateFlow<NfcCharacter?>(null)
 
     private lateinit var activityResultLauncher: ActivityResultLauncher<Intent>
 
-    // EXTRACTED DIRECTLY FROM EXAMPLE APP
-    override fun onCreate(savedInstanceState: Bundle?) {
-        deviceToCryptographicTransformers = getMapOfCryptographicTransformers()
+    private val onActivityLifecycleListeners = HashMap<String, ActivityLifecycleListener>()
 
+    private fun registerActivityLifecycleListener(key: String, activityLifecycleListener: ActivityLifecycleListener) {
+        if( onActivityLifecycleListeners[key] != null) {
+            throw IllegalStateException("Key is already in use")
+        }
+        onActivityLifecycleListeners[key] = activityLifecycleListener
+    }
+
+    private fun unregisterActivityLifecycleListener(key: String) {
+        onActivityLifecycleListeners.remove(key)
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
         registerFileActivityResult()
 
-        val maybeNfcAdapter = NfcAdapter.getDefaultAdapter(this)
-        if (maybeNfcAdapter == null) {
-            Toast.makeText(this, "No NFC on device!", Toast.LENGTH_SHORT).show()
-            finish()
-            return
-        }
-        nfcAdapter = maybeNfcAdapter
+        val application = applicationContext as VBHelper
+        val settingsScreenController = SettingsScreenController.Factory(this, ApkSecretsImporter(), application.container.dataStoreSecretsRepository)
+            .buildSettingScreenHandlers()
+        val scanScreenController = ScanScreenControllerImpl(
+            application.container.dataStoreSecretsRepository.secretsFlow,
+            this::handleReceivedNfcCharacter,
+            this,
+            this::registerActivityLifecycleListener,
+            this::unregisterActivityLifecycleListener)
+
 
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
         setContent {
             VBHelperTheme {
-                MainApplication()
+                MainApplication(settingsScreenController, scanScreenController)
             }
         }
+        Log.i("MainActivity", "Activity onCreated")
+    }
+
+    override fun onPause() {
+        super.onPause()
+        Log.i("MainActivity", "onPause")
+        for(activityListener in onActivityLifecycleListeners) {
+            activityListener.value.onPause()
+        }
+    }
+
+    override fun onResume() {
+        super.onResume()
+        Log.i("MainActivity", "Resume")
+        for(activityListener in onActivityLifecycleListeners) {
+            activityListener.value.onResume()
+        }
     }
 
     private fun registerFileActivityResult() {
@@ -154,26 +176,10 @@ class MainActivity : ComponentActivity() {
     }
 
     @Composable
-    private fun MainApplication() {
-        var isDoneReadingCharacter by remember { mutableStateOf(false) }
+    private fun MainApplication(settingsScreenController: SettingsScreenController, scanScreenController: ScanScreenControllerImpl) {
 
         AppNavigation(
-            isDoneReadingCharacter = isDoneReadingCharacter,
-            onClickRead = {
-                handleTag {
-                    val character = it.receiveCharacter()
-                    nfcCharacter.value = character
-
-                    val importStatus = addCharacterScannedIntoDatabase()
-
-                    isDoneReadingCharacter = true
-
-                    importStatus
-                }
-            },
-            onClickScan = {
-                isDoneReadingCharacter = false
-            },
+            applicationNavigationHandlers = AppNavigationHandlers(settingsScreenController, scanScreenController),
             onClickImportCard = {
                 val intent = Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
                     addCategory(Intent.CATEGORY_OPENABLE)
@@ -184,73 +190,12 @@ class MainActivity : ComponentActivity() {
         )
     }
 
-    // EXTRACTED DIRECTLY FROM EXAMPLE APP
-    private fun getMapOfCryptographicTransformers(): Map<UShort, CryptographicTransformer> {
-        return mapOf(
-            Pair(DeviceType.VitalBraceletBEDeviceType,
-                CryptographicTransformer(readableHmacKey1 = resources.getString(R.string.password1),
-                    readableHmacKey2 = resources.getString(R.string.password2),
-                    aesKey = resources.getString(R.string.decryptionKey),
-                    substitutionCipher = resources.getIntArray(R.array.substitutionArray))),
-//            Pair(DeviceType.VitalSeriesDeviceType,
-//                CryptographicTransformer(hmacKey1 = resources.getString(R.string.password1),
-//                    hmacKey2 = resources.getString(R.string.password2),
-//                    decryptionKey = resources.getString(R.string.decryptionKey),
-//                    substitutionCipher = resources.getIntArray(R.array.substitutionArray))),
-//            Pair(DeviceType.VitalCharactersDeviceType,
-//                CryptographicTransformer(hmacKey1 = resources.getString(R.string.password1),
-//                    hmacKey2 = resources.getString(R.string.password2),
-//                    decryptionKey = resources.getString(R.string.decryptionKey),
-//                    substitutionCipher = resources.getIntArray(R.array.substitutionArray)))
-        )
-    }
+    private fun handleReceivedNfcCharacter(character: NfcCharacter): String {
+        nfcCharacter.value = character
 
-    // EXTRACTED DIRECTLY FROM EXAMPLE APP
-    private fun showWirelessSettings() {
-        Toast.makeText(this, "NFC must be enabled", Toast.LENGTH_SHORT).show()
-        startActivity(Intent(Settings.ACTION_WIRELESS_SETTINGS))
-    }
+        val importStatus = addCharacterScannedIntoDatabase()
 
-    // EXTRACTED DIRECTLY FROM EXAMPLE APP
-    private fun buildOnReadTag(handlerFunc: (TagCommunicator)->String): (Tag)->Unit {
-        return { tag->
-            val nfcData = NfcA.get(tag)
-            if (nfcData == null) {
-                runOnUiThread {
-                    Toast.makeText(this, "Tag detected is not VB", Toast.LENGTH_SHORT).show()
-                }
-            }
-            nfcData.connect()
-            nfcData.use {
-                val tagCommunicator = TagCommunicator.getInstance(nfcData, deviceToCryptographicTransformers)
-                val successText = handlerFunc(tagCommunicator)
-                runOnUiThread {
-                    Toast.makeText(this, successText, Toast.LENGTH_SHORT).show()
-                }
-            }
-        }
-    }
-
-    // EXTRACTED DIRECTLY FROM EXAMPLE APP
-    private fun handleTag(handlerFunc: (TagCommunicator)->String) {
-        if (!nfcAdapter.isEnabled) {
-            showWirelessSettings()
-        } else {
-            val options = Bundle()
-            // Work around for some broken Nfc firmware implementations that poll the card too fast
-            options.putInt(NfcAdapter.EXTRA_READER_PRESENCE_CHECK_DELAY, 250)
-            nfcAdapter.enableReaderMode(this, buildOnReadTag(handlerFunc), NfcAdapter.FLAG_READER_NFC_A or NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK,
-                options
-            )
-        }
-    }
-
-    // EXTRACTED DIRECTLY FROM EXAMPLE APP
-    override fun onPause() {
-        super.onPause()
-        if (nfcAdapter.isEnabled) {
-            nfcAdapter.disableReaderMode(this)
-        }
+        return importStatus
     }
 
     //

app/src/main/java/com/github/nacabaro/vbhelper/navigation/AppNavigation.kt

@@ -12,17 +12,19 @@ import com.github.nacabaro.vbhelper.screens.BattlesScreen
 import com.github.nacabaro.vbhelper.screens.DexScreen
 import com.github.nacabaro.vbhelper.screens.DiMScreen
 import com.github.nacabaro.vbhelper.screens.HomeScreen
-import com.github.nacabaro.vbhelper.screens.ScanScreen
+import com.github.nacabaro.vbhelper.screens.scanScreen.ScanScreen
+import com.github.nacabaro.vbhelper.screens.scanScreen.ScanScreenControllerImpl
 import com.github.nacabaro.vbhelper.screens.SettingsScreen
+import com.github.nacabaro.vbhelper.screens.SettingsScreenController
 import com.github.nacabaro.vbhelper.screens.SpriteViewer
 import com.github.nacabaro.vbhelper.screens.StorageScreen
 
+data class AppNavigationHandlers(val settingsScreenController: SettingsScreenController, val scanScreenController: ScanScreenControllerImpl)
+
 @Composable
 fun AppNavigation(
-    onClickRead: () -> Unit,
-    onClickScan: () -> Unit,
+    applicationNavigationHandlers: AppNavigationHandlers,
     onClickImportCard: () -> Unit,
-    isDoneReadingCharacter: Boolean
 ) {
     val navController = rememberNavController()
 
@@ -49,11 +51,9 @@ fun AppNavigation(
                 StorageScreen()
             }
             composable(BottomNavItem.Scan.route) {
-                onClickScan()
                 ScanScreen(
                     navController = navController,
-                    onClickRead = onClickRead,
-                    isDoneReadingCharacter = isDoneReadingCharacter
+                    scanScreenController = applicationNavigationHandlers.scanScreenController,
                 )
             }
             composable(BottomNavItem.Dex.route) {
@@ -64,6 +64,7 @@ fun AppNavigation(
             composable(BottomNavItem.Settings.route) {
                 SettingsScreen(
                     navController = navController,
+                    settingsScreenController = applicationNavigationHandlers.settingsScreenController,
                     onClickImportCard = onClickImportCard
                 )
             }

app/src/main/java/com/github/nacabaro/vbhelper/screens/ScanScreen.kt

@@ -1,108 +0,0 @@
-package com.github.nacabaro.vbhelper.screens
-
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
-import androidx.compose.material3.Button
-import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.tooling.preview.Preview
-import androidx.compose.ui.unit.dp
-import androidx.compose.ui.unit.sp
-import androidx.navigation.NavController
-import androidx.navigation.compose.rememberNavController
-import com.github.nacabaro.vbhelper.components.TopBanner
-import com.github.nacabaro.vbhelper.navigation.BottomNavItem
-import com.github.nacabaro.vbhelper.screens.scanScreen.ReadingCharacterScreen
-
-@Composable
-fun ScanScreen(
-    navController: NavController,
-    onClickRead: () -> Unit,
-    isDoneReadingCharacter: Boolean
-) {
-    var readingScreen by remember { mutableStateOf(false) }
-
-    if (isDoneReadingCharacter) {
-        readingScreen = false
-        navController.navigate(BottomNavItem.Home.route)
-    }
-
-    if (readingScreen) {
-        ReadingCharacterScreen { readingScreen = false }
-    } else {
-        ChooseConnectOption(
-            onClickRead = {
-                readingScreen = true
-                onClickRead()
-            },
-        )
-    }
-}
-
-@Composable
-private fun ChooseConnectOption(
-    onClickRead: () -> Unit,
-) {
-    Scaffold(
-        topBar = { TopBanner(text = "Scan a Vital Bracelet") }
-    ) { contentPadding ->
-        Column(
-            verticalArrangement = Arrangement.Center,
-            horizontalAlignment = Alignment.CenterHorizontally,
-            modifier = Modifier
-                .fillMaxSize()
-                .padding(contentPadding)
-        ) {
-            ScanButton(
-                text = "Vital Bracelet to App",
-                onClick = onClickRead
-            )
-            Spacer(modifier = Modifier.height(16.dp))
-            ScanButton(
-                text = "App to Vital Bracelet",
-                onClick = {}
-            )
-        }
-    }
-}
-
-
-@Composable
-fun ScanButton(
-    text: String,
-    onClick: () -> Unit,
-    modifier: Modifier = Modifier
-) {
-    Button(
-        onClick = onClick,
-        modifier = modifier
-    ) {
-        Text(
-            text = text,
-            fontSize = 16.sp,
-            modifier = Modifier
-                .padding(4.dp)
-        )
-    }
-}
-
-@Preview(showBackground = true)
-@Composable
-fun ScanScreenPreview() {
-    ScanScreen(
-        navController = rememberNavController(),
-        onClickRead = {  },
-        isDoneReadingCharacter = false
-    )
-}

app/src/main/java/com/github/nacabaro/vbhelper/screens/SettingsScreen.kt

@@ -1,5 +1,9 @@
 package com.github.nacabaro.vbhelper.screens
 
+import android.net.Uri
+import androidx.activity.ComponentActivity
+import androidx.activity.result.ActivityResultLauncher
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -22,6 +26,7 @@ import com.github.nacabaro.vbhelper.components.TopBanner
 @Composable
 fun SettingsScreen(
     navController: NavController,
+    settingsScreenController: SettingsScreenController,
     onClickImportCard: () -> Unit
 ) {
     Scaffold (
@@ -42,12 +47,10 @@ fun SettingsScreen(
                 .fillMaxSize()
                 .verticalScroll(rememberScrollState())
         ) {
-            SettingsSection("General")
-            SettingsEntry(title = "Import VB key", description = "Import standard vital bracelet keys") { }
-            SettingsEntry(title = "Import VB Characters key", description = "Import standard vital bracelet keys") { }
-            SettingsEntry(title = "Import VB BE key", description = "Import standard vital bracelet keys") { }
-            SettingsEntry(title = "Import transform functions", description = "Import standard vital bracelet keys") { }
-            SettingsEntry(title = "Import decryption key", description = "Import standard vital bracelet keys") { }
+            SettingsSection("NFC Communication")
+            SettingsEntry(title = "Import APK", description = "Import Secrets From Vital Arean 2.1.0 APK") {
+                settingsScreenController.apkFilePickLauncher.launch(arrayOf("*/*"))
+            }
             SettingsSection("DiM/BEm management")
             SettingsEntry(title = "Import DiM card", description = "Import DiM/BEm card file", onClick = onClickImportCard)
             SettingsEntry(title = "Rename DiM/BEm", description = "Set card name") { }
@@ -58,6 +61,12 @@ fun SettingsScreen(
     }
 }
 
+fun buildFilePickLauncher(activity: ComponentActivity, onItemPicked: (Uri?) -> Unit): ActivityResultLauncher<Array<String>> {
+    return activity.registerForActivityResult(ActivityResultContracts.OpenDocument()) {
+        onItemPicked.invoke(it)
+    }
+}
+
 @Composable
 fun SettingsEntry(
     title: String,

app/src/main/java/com/github/nacabaro/vbhelper/screens/SettingsScreenController.kt

@@ -0,0 +1,71 @@
+package com.github.nacabaro.vbhelper.screens
+
+import android.net.Uri
+import android.widget.Toast
+import androidx.activity.ComponentActivity
+import androidx.activity.result.ActivityResultLauncher
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.lifecycle.lifecycleScope
+import com.github.nacabaro.vbhelper.source.SecretsImporter
+import com.github.nacabaro.vbhelper.source.SecretsRepository
+import com.github.nacabaro.vbhelper.source.proto.Secrets
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+
+data class SettingsScreenController(val apkFilePickLauncher: ActivityResultLauncher<Array<String>>) {
+
+    class Factory(private val componentActivity: ComponentActivity, private val secretsImporter: SecretsImporter, private val secretsRepository: SecretsRepository) {
+
+        fun buildSettingScreenHandlers(): SettingsScreenController {
+            return SettingsScreenController(
+                apkFilePickLauncher = buildFilePickerActivityLauncher(this::importApk)
+            )
+        }
+
+        private fun buildFilePickerActivityLauncher(onResult : (Uri?) ->Unit): ActivityResultLauncher<Array<String>> {
+            return componentActivity.registerForActivityResult(ActivityResultContracts.OpenDocument()) {
+                onResult.invoke(it)
+            }
+        }
+
+        private fun importApk(uri: Uri?) {
+            if(uri == null) {
+                componentActivity.runOnUiThread {
+                    Toast.makeText(componentActivity, "APK Import Cancelled", Toast.LENGTH_SHORT)
+                        .show()
+                }
+                return
+            }
+            componentActivity.lifecycleScope.launch(Dispatchers.IO) {
+                componentActivity.contentResolver.openInputStream(uri).use {
+                    if(it == null) {
+                        componentActivity.runOnUiThread {
+                            Toast.makeText(
+                                componentActivity,
+                                "Selected file is empty!",
+                                Toast.LENGTH_SHORT
+                            ).show()
+                        }
+                        return@launch
+                    }
+                    var secrets: Secrets? = null
+                    try {
+                        secrets = secretsImporter.importSecrets(it)
+                    } catch (e: Exception) {
+                        componentActivity.runOnUiThread {
+                            Toast.makeText(componentActivity, "Secrets import failed. Please only select the official Vital Arena App 2.1.0 APK.", Toast.LENGTH_SHORT).show()
+                        }
+                        return@launch
+                    }
+                    componentActivity.lifecycleScope.launch(Dispatchers.IO) {
+                        secretsRepository.updateSecrets(secrets)
+                    }.invokeOnCompletion {
+                        componentActivity.runOnUiThread {
+                            Toast.makeText(componentActivity, "Secrets successfully imported. Connections with devices are now possible.", Toast.LENGTH_SHORT).show()
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

app/src/main/java/com/github/nacabaro/vbhelper/screens/scanScreen/ScanScreen.kt

@@ -0,0 +1,163 @@
+package com.github.nacabaro.vbhelper.screens.scanScreen
+
+import android.widget.Toast
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Button
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.navigation.NavController
+import androidx.navigation.compose.rememberNavController
+import com.github.nacabaro.vbhelper.ActivityLifecycleListener
+import com.github.nacabaro.vbhelper.components.TopBanner
+import com.github.nacabaro.vbhelper.navigation.BottomNavItem
+import com.github.nacabaro.vbhelper.source.isMissingSecrets
+import com.github.nacabaro.vbhelper.source.proto.Secrets
+import kotlinx.coroutines.flow.MutableStateFlow
+
+const val SCAN_SCREEN_ACTIVITY_LIFECYCLE_LISTENER = "SCAN_SCREEN_ACTIVITY_LIFECYCLE_LISTENER"
+
+@Composable
+fun ScanScreen(
+    navController: NavController,
+    scanScreenController: ScanScreenController,
+) {
+    val secrets by scanScreenController.secretsFlow.collectAsState(null)
+    var readingScreen by remember { mutableStateOf(false) }
+    var isDoneReadingCharacter by remember { mutableStateOf(false) }
+
+    DisposableEffect(readingScreen) {
+        if(readingScreen) {
+            scanScreenController.registerActivityLifecycleListener(SCAN_SCREEN_ACTIVITY_LIFECYCLE_LISTENER, object: ActivityLifecycleListener {
+                override fun onPause() {
+                    scanScreenController.cancelRead()
+                }
+
+                override fun onResume() {
+                    scanScreenController.onClickRead(secrets!!) {
+                        isDoneReadingCharacter = true
+                    }
+                }
+
+            })
+            scanScreenController.onClickRead(secrets!!) {
+                isDoneReadingCharacter = true
+            }
+        }
+        onDispose {
+            if(readingScreen) {
+                scanScreenController.unregisterActivityLifecycleListener(SCAN_SCREEN_ACTIVITY_LIFECYCLE_LISTENER)
+                scanScreenController.cancelRead()
+            }
+        }
+    }
+
+    if (isDoneReadingCharacter) {
+        readingScreen = false
+        navController.navigate(BottomNavItem.Home.route)
+    }
+
+    if (readingScreen) {
+        ReadingCharacterScreen {
+            readingScreen = false
+            scanScreenController.cancelRead()
+        }
+    } else {
+        val context = LocalContext.current
+        ChooseConnectOption(
+            onClickRead = {
+                if(secrets == null) {
+                    Toast.makeText(context, "Secrets is not yet initialized. Try again.", Toast.LENGTH_SHORT).show()
+                } else if(secrets?.isMissingSecrets() == true) {
+                    Toast.makeText(context, "Secrets not yet imported. Go to Settings and Import APK", Toast.LENGTH_SHORT).show()
+                } else {
+                    readingScreen = true // kicks off nfc adapter in DisposableEffect
+                }
+            },
+        )
+    }
+}
+
+@Composable
+private fun ChooseConnectOption(
+    onClickRead: () -> Unit,
+) {
+    Scaffold(
+        topBar = { TopBanner(text = "Scan a Vital Bracelet") }
+    ) { contentPadding ->
+        Column(
+            verticalArrangement = Arrangement.Center,
+            horizontalAlignment = Alignment.CenterHorizontally,
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(contentPadding)
+        ) {
+            ScanButton(
+                text = "Vital Bracelet to App",
+                onClick = onClickRead,
+            )
+            Spacer(modifier = Modifier.height(16.dp))
+            ScanButton(
+                text = "App to Vital Bracelet",
+                onClick = {}
+            )
+        }
+    }
+}
+
+
+@Composable
+fun ScanButton(
+    text: String,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Button(
+        onClick = onClick,
+        modifier = modifier
+    ) {
+        Text(
+            text = text,
+            fontSize = 16.sp,
+            modifier = Modifier
+                .padding(4.dp)
+        )
+    }
+}
+
+@Preview(showBackground = true)
+@Composable
+fun ScanScreenPreview() {
+    ScanScreen(
+        navController = rememberNavController(),
+        scanScreenController = object: ScanScreenController {
+            override val secretsFlow = MutableStateFlow<Secrets>(Secrets.getDefaultInstance())
+            override fun unregisterActivityLifecycleListener(key: String) { }
+            override fun registerActivityLifecycleListener(
+                key: String,
+                activityLifecycleListener: ActivityLifecycleListener
+            ) {
+
+            }
+            override fun onClickRead(secrets: Secrets, onComplete: ()->Unit) {}
+            override fun cancelRead() {}
+        }
+    )
+}

app/src/main/java/com/github/nacabaro/vbhelper/screens/scanScreen/ScanScreenController.kt

@@ -0,0 +1,14 @@
+package com.github.nacabaro.vbhelper.screens.scanScreen
+
+import com.github.nacabaro.vbhelper.ActivityLifecycleListener
+import com.github.nacabaro.vbhelper.source.proto.Secrets
+import kotlinx.coroutines.flow.Flow
+
+interface ScanScreenController {
+    val secretsFlow: Flow<Secrets>
+    fun onClickRead(secrets: Secrets, onComplete: ()->Unit)
+    fun cancelRead()
+
+    fun registerActivityLifecycleListener(key: String, activityLifecycleListener: ActivityLifecycleListener)
+    fun unregisterActivityLifecycleListener(key: String)
+}

app/src/main/java/com/github/nacabaro/vbhelper/screens/scanScreen/ScanScreenControllerImpl.kt

@@ -0,0 +1,117 @@
+package com.github.nacabaro.vbhelper.screens.scanScreen
+
+import android.content.Intent
+import android.nfc.NfcAdapter
+import android.nfc.Tag
+import android.nfc.tech.NfcA
+import android.os.Bundle
+import android.provider.Settings
+import android.widget.Toast
+import androidx.activity.ComponentActivity
+import androidx.lifecycle.lifecycleScope
+import com.github.cfogrady.vbnfc.TagCommunicator
+import com.github.cfogrady.vbnfc.data.NfcCharacter
+import com.github.nacabaro.vbhelper.ActivityLifecycleListener
+import com.github.nacabaro.vbhelper.source.getCryptographicTransformerMap
+import com.github.nacabaro.vbhelper.source.isMissingSecrets
+import com.github.nacabaro.vbhelper.source.proto.Secrets
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
+
+class ScanScreenControllerImpl(
+    override val secretsFlow: Flow<Secrets>,
+    private val nfcHandler: (NfcCharacter)->String,
+    private val context: ComponentActivity,
+    private val registerActivityLifecycleListener: (String, ActivityLifecycleListener)->Unit,
+    private val unregisterActivityLifecycleListener: (String)->Unit,
+): ScanScreenController {
+
+    private val nfcAdapter: NfcAdapter
+
+    init {
+        val maybeNfcAdapter = NfcAdapter.getDefaultAdapter(context)
+        if (maybeNfcAdapter == null) {
+            Toast.makeText(context, "No NFC on device!", Toast.LENGTH_SHORT).show()
+        }
+        nfcAdapter = maybeNfcAdapter
+        checkSecrets()
+    }
+
+    override fun onClickRead(secrets: Secrets, onComplete: ()->Unit) {
+        handleTag(secrets) { tagCommunicator ->
+            val character = tagCommunicator.receiveCharacter()
+            val resultMessage = nfcHandler(character)
+            onComplete.invoke()
+            resultMessage
+        }
+    }
+
+    override fun cancelRead() {
+        if(nfcAdapter.isEnabled) {
+            nfcAdapter.disableReaderMode(context)
+        }
+    }
+
+    override fun registerActivityLifecycleListener(
+        key: String,
+        activityLifecycleListener: ActivityLifecycleListener
+    ) {
+        registerActivityLifecycleListener.invoke(key, activityLifecycleListener)
+    }
+
+    override fun unregisterActivityLifecycleListener(key: String) {
+        unregisterActivityLifecycleListener.invoke(key)
+    }
+
+    // EXTRACTED DIRECTLY FROM EXAMPLE APP
+    private fun handleTag(secrets: Secrets, handlerFunc: (TagCommunicator)->String) {
+        if (!nfcAdapter.isEnabled) {
+            showWirelessSettings()
+        } else {
+            val options = Bundle()
+            // Work around for some broken Nfc firmware implementations that poll the card too fast
+            options.putInt(NfcAdapter.EXTRA_READER_PRESENCE_CHECK_DELAY, 250)
+            nfcAdapter.enableReaderMode(context, buildOnReadTag(secrets, handlerFunc), NfcAdapter.FLAG_READER_NFC_A or NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK,
+                options
+            )
+        }
+    }
+
+    // EXTRACTED DIRECTLY FROM EXAMPLE APP
+    private fun buildOnReadTag(secrets: Secrets, handlerFunc: (TagCommunicator)->String): (Tag)->Unit {
+        return { tag->
+            val nfcData = NfcA.get(tag)
+            if (nfcData == null) {
+                context.runOnUiThread {
+                    Toast.makeText(context, "Tag detected is not VB", Toast.LENGTH_SHORT).show()
+                }
+            }
+            nfcData.connect()
+            nfcData.use {
+                val tagCommunicator = TagCommunicator.getInstance(nfcData, secrets.getCryptographicTransformerMap())
+                val successText = handlerFunc(tagCommunicator)
+                context.runOnUiThread {
+                    Toast.makeText(context, successText, Toast.LENGTH_SHORT).show()
+                }
+            }
+        }
+    }
+
+    private fun checkSecrets() {
+        context.lifecycleScope.launch(Dispatchers.IO) {
+            if(secretsFlow.stateIn(context.lifecycleScope).value.isMissingSecrets()) {
+                context.runOnUiThread {
+                    Toast.makeText(context, "Missing Secrets. Go to settings and import Vital Arena APK", Toast.LENGTH_SHORT).show()
+                }
+            }
+        }
+    }
+
+    // EXTRACTED DIRECTLY FROM EXAMPLE APP
+    private fun showWirelessSettings() {
+        Toast.makeText(context, "NFC must be enabled", Toast.LENGTH_SHORT).show()
+        context.startActivity(Intent(Settings.ACTION_WIRELESS_SETTINGS))
+    }
+}

app/src/main/java/com/github/nacabaro/vbhelper/source/DataStoreSecretsRepository.kt

@@ -43,4 +43,17 @@ fun Secrets.getCryptographicTransformerMap(): Map<UShort, CryptographicTransform
         Pair(DeviceType.VitalCharactersDeviceType, CryptographicTransformer(vbcHmacKeys.hmacKey1, vbcHmacKeys.hmacKey2, this.aesKey, cipher)),
         Pair(DeviceType.VitalBraceletBEDeviceType, CryptographicTransformer(beHmacKeys.hmacKey1, beHmacKeys.hmacKey2, this.aesKey, beCipher)),
     )
+}
+
+fun Secrets.isMissingSecrets(): Boolean {
+    return this.aesKey.length != 24 ||
+            this.vbCipherList.size != 16 ||
+            this.beCipherList.size != 16 ||
+            this.vbdmHmacKeys.isMissingKey() ||
+            this.vbcHmacKeys.isMissingKey() ||
+            this.beHmacKeys.isMissingKey()
+}
+
+fun HmacKeys.isMissingKey(): Boolean {
+    return this.hmacKey1.length != 24 || this.hmacKey2.length != 24
 }