Fix Qr Code errors

app/src/main/java/org/thoughtcrime/securesms/conversation/start/newmessage/NewMessage.kt

@@ -44,7 +44,7 @@ private val TITLES = listOf(R.string.enter_account_id, R.string.qrScan)
 @Composable
 internal fun NewMessage(
     state: State,
-    errors: Flow<String> = emptyFlow(),
+    qrErrors: Flow<String> = emptyFlow(),
     callbacks: Callbacks = object: Callbacks {},
     onClose: () -> Unit = {},
     onBack: () -> Unit = {},
@@ -58,7 +58,7 @@ internal fun NewMessage(
         HorizontalPager(pagerState) {
             when (TITLES[it]) {
                 R.string.enter_account_id -> EnterAccountId(state, callbacks, onHelp)
-                R.string.qrScan -> MaybeScanQrCode(errors, onScan = callbacks::onScanQrCode)
+                R.string.qrScan -> MaybeScanQrCode(qrErrors, onScan = callbacks::onScanQrCode)
             }
         }
     }

app/src/main/java/org/thoughtcrime/securesms/conversation/start/newmessage/NewMessageViewModel.kt

@@ -7,6 +7,7 @@ import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.TimeoutCancellationException
+import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asSharedFlow
@@ -34,7 +35,7 @@ internal class NewMessageViewModel @Inject constructor(
     private val _success = MutableSharedFlow<Success>()
     val success get() = _success.asSharedFlow()
 
-    private val _qrErrors = MutableSharedFlow<String>()
+    private val _qrErrors = MutableSharedFlow<String>(extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST)
     val qrErrors = _qrErrors.asSharedFlow()
 
     private var loadOnsJob: Job? = null

app/src/main/java/org/thoughtcrime/securesms/onboarding/loadaccount/LoadAccountViewModel.kt

@@ -4,10 +4,13 @@ import android.app.Application
 import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asSharedFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.mapNotNull
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
@@ -36,7 +39,7 @@ internal class LinkDeviceViewModel @Inject constructor(
     private val _events = MutableSharedFlow<LoadAccountEvent>()
     val events = _events.asSharedFlow()
 
-    private val _qrErrors = MutableSharedFlow<Throwable>()
+    private val _qrErrors = MutableSharedFlow<Throwable>(extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST)
     val qrErrors = _qrErrors.asSharedFlow()
         .mapNotNull { application.getString(R.string.qrNotRecoveryPassword) }
 
@@ -57,7 +60,7 @@ internal class LinkDeviceViewModel @Inject constructor(
             try {
                 decode(string).let(::onSuccess)
             } catch (e: Exception) {
-                onFailure(e)
+                onQrCodeScanFailure(e)
             }
         }
     }

app/src/main/java/org/thoughtcrime/securesms/preferences/QRCodeActivity.kt

@@ -13,6 +13,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.style.TextAlign
+import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.asSharedFlow
@@ -38,7 +39,7 @@ private val TITLES = listOf(R.string.view, R.string.scan)
 
 class QRCodeActivity : PassphraseRequiredActionBarActivity() {
 
-    private val errors = MutableSharedFlow<String>()
+    private val errors = MutableSharedFlow<String>(extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST)
 
     override fun onCreate(savedInstanceState: Bundle?, isReady: Boolean) {
         super.onCreate(savedInstanceState, isReady)

app/src/main/java/org/thoughtcrime/securesms/ui/components/QR.kt

@@ -31,6 +31,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -51,15 +52,13 @@ import com.google.mlkit.vision.barcode.BarcodeScannerOptions
 import com.google.mlkit.vision.barcode.BarcodeScanning
 import com.google.mlkit.vision.barcode.common.Barcode
 import com.google.mlkit.vision.common.InputImage
-import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.buffer
-import kotlinx.coroutines.flow.filter
+import kotlinx.coroutines.launch
 import network.loki.messenger.R
 import org.session.libsignal.utilities.Log
 import org.thoughtcrime.securesms.ui.LocalDimensions
-import org.thoughtcrime.securesms.ui.color.LocalColors
 import org.thoughtcrime.securesms.ui.base
+import org.thoughtcrime.securesms.ui.color.LocalColors
 import org.thoughtcrime.securesms.ui.xl
 import java.util.concurrent.Executors
 
@@ -161,11 +160,24 @@ fun ScanQrCode(errors: Flow<String>, onScan: (String) -> Unit) {
 
     val scaffoldState = rememberScaffoldState()
 
+    val scope = rememberCoroutineScope()
+
     LaunchedEffect(Unit) {
-        errors.filter { scaffoldState.snackbarHostState.currentSnackbarData == null }
-            .buffer(0, BufferOverflow.DROP_OLDEST)
-            .collect { error ->
-                scaffoldState.snackbarHostState.showSnackbar(message = error)
+        errors.collect { error ->
+            scaffoldState.snackbarHostState
+                .takeIf { it.currentSnackbarData == null }
+                ?.run {
+                    scope.launch {
+                        // showSnackbar() suspends until the Snackbar is dismissed.
+                        // Launch in new scope so we drop new QR scan events, to prevent spamming
+                        // snackbars to the user, or worse, queuing a chain of snackbars one after
+                        // another to show and hide for the next minute or 2.
+                        // Don't use debounce() because many QR scans can come through each second,
+                        // and each scan could restart the timer which could mean no scan gets
+                        // through until the user stops scanning; quite perplexing.
+                        showSnackbar(message = error)
+                    }
+                }
         }
     }