Add support for downgrading backup.

app/src/main/java/org/thoughtcrime/securesms/backup/v2/ui/subscription/MessageBackupsFlowFragment.kt

@@ -243,6 +243,8 @@ class MessageBackupsFlowFragment : ComposeFragment(), InAppPaymentCheckoutDelega
   }
 
   override fun onSubscriptionCancelled(inAppPaymentType: InAppPaymentType) {
+    viewModel.onCancellationComplete()
+
     if (!findNavController().popBackStack()) {
       requireActivity().finishAfterTransition()
     }

app/src/main/java/org/thoughtcrime/securesms/backup/v2/ui/subscription/MessageBackupsFlowViewModel.kt

@@ -45,6 +45,7 @@ class MessageBackupsFlowViewModel : ViewModel() {
   )
 
   private val internalPinState = mutableStateOf("")
+  private var isDowngrading = false
 
   val stateFlow: StateFlow<MessageBackupsFlowState> = internalStateFlow
   val pinState: State<String> = internalPinState
@@ -129,6 +130,15 @@ class MessageBackupsFlowViewModel : ViewModel() {
     internalStateFlow.update { it.copy(selectedMessageBackupTier = messageBackupTier) }
   }
 
+  fun onCancellationComplete() {
+    if (isDowngrading) {
+      SignalStore.backup.areBackupsEnabled = true
+      SignalStore.backup.backupTier = MessageBackupTier.FREE
+
+      // TODO [message-backups] -- Trigger backup now?
+    }
+  }
+
   private fun validatePinAndUpdateState(pin: String): MessageBackupsScreen {
     val pinHash = SignalStore.svr.localPinHash
 
@@ -141,14 +151,18 @@ class MessageBackupsFlowViewModel : ViewModel() {
   }
 
   private fun validateTypeAndUpdateState(tier: MessageBackupTier): MessageBackupsScreen {
-    // TODO [message-backups] - Does anything need to be kicked off?
-
     return when (tier) {
       MessageBackupTier.FREE -> {
-        SignalStore.backup.areBackupsEnabled = true
+        if (SignalStore.backup.backupTier == MessageBackupTier.PAID) {
-        SignalStore.backup.backupTier = MessageBackupTier.FREE
+          isDowngrading = true
+          MessageBackupsScreen.PROCESS_CANCELLATION
+        } else {
+          SignalStore.backup.areBackupsEnabled = true
+          SignalStore.backup.backupTier = MessageBackupTier.FREE
 
-        MessageBackupsScreen.COMPLETED
+          // TODO [message-backups] -- Trigger backup now?
+          MessageBackupsScreen.COMPLETED
+        }
       }
       MessageBackupTier.PAID -> MessageBackupsScreen.CHECKOUT_SHEET
     }

app/src/main/java/org/thoughtcrime/securesms/backup/v2/ui/subscription/MessageBackupsTypeSelectionScreen.kt

@@ -148,14 +148,14 @@ fun MessageBackupsTypeSelectionScreen(
         }
       }
 
-      val hasSelectedBackupTier = currentBackupTier != null
+      val hasCurrentBackupTier = currentBackupTier != null
 
       Buttons.LargePrimary(
         onClick = onNextClicked,
-        enabled = selectedBackupTier != null,
+        enabled = selectedBackupTier != currentBackupTier && hasCurrentBackupTier,
         modifier = Modifier
           .fillMaxWidth()
-          .padding(vertical = if (hasSelectedBackupTier) 10.dp else 16.dp)
+          .padding(vertical = if (hasCurrentBackupTier) 10.dp else 16.dp)
       ) {
         Text(
           text = stringResource(
@@ -168,7 +168,7 @@ fun MessageBackupsTypeSelectionScreen(
         )
       }
 
-      if (hasSelectedBackupTier) {
+      if (hasCurrentBackupTier) {
         TextButton(
           onClick = onCancelSubscriptionClicked,
           modifier = Modifier

app/src/main/java/org/thoughtcrime/securesms/keyvalue/InAppPaymentValues.kt

@@ -466,7 +466,6 @@ class InAppPaymentValues internal constructor(store: KeyValueStore) : SignalStor
       } else {
         markBackupSubscriptionpManuallyCancelled()
 
-        // TODO [message-backups] -- Handle downgrades?
         SignalStore.backup.areBackupsEnabled = false
         SignalStore.backup.backupTier = null
       }