Exit most activities when accounts are deleted

This resolves cases like this:  You are in the inbox of an Exchange
account.  You click home, settings, accounts & sync, and you delete
the account.  Now re-enter the Email app.  You'll be left in a strangely
empty inbox, for an account that no longer exists.

* Set a flag any time the reconciler deletes an account
* Check that flag in onResume of any activity that depends on the account
    list and could be left in an "empty" state if account(s) are deleted.
* The Activities in which we check it are:
  * AccountFolderList
  * AccountSettings
  * MailboxList
  * MessageCompose
  * MessageList
  * MessageView
* Clear the flag any time we come in through Welcome, which will dispatch
    to other activities properly based on the number of accounts found.

Bug: 2563998
Change-Id: I00fc542581c2bed92d744a4c2e48a88f83737f11

src/com/android/email/Email.java

@@ -143,6 +143,12 @@ public class Email extends Application {
     private static HashMap<Long, Long> sMailboxSyncTimes = new HashMap<Long, Long>();
     private static final long UPDATE_INTERVAL = 5 * DateUtils.MINUTE_IN_MILLIS;
 
+    /**
+     * This is used to force stacked UI to return to the "welcome" screen any time we change
+     * the accounts list (e.g. deleting accounts in the Account Manager preferences.)
+     */
+    private static boolean sAccountsChangedNotification = false;
+
     public static final String EXCHANGE_ACCOUNT_MANAGER_TYPE = "com.android.exchange";
 
     // The color chip resources and the RGB color values in the array below must be kept in sync
@@ -296,4 +302,21 @@ public class Email extends Application {
                         > UPDATE_INTERVAL);
         }
     }
+
+    /**
+     * Called by the accounts reconciler to notify that accounts have changed, or by  "Welcome"
+     * to clear the flag.
+     * @param setFlag true to set the notification flag, false to clear it
+     */
+    public static synchronized void setNotifyUiAccountsChanged(boolean setFlag) {
+        sAccountsChangedNotification = setFlag;
+    }
+
+    /**
+     * Called from activity onResume() functions to check for an accounts-changed condition, at
+     * which point they should finish() and jump to the Welcome activity.
+     */
+    public static synchronized boolean getNotifyUiAccountsChanged() {
+        return sAccountsChangedNotification;
+    }
 }

src/com/android/email/activity/AccountFolderList.java

@@ -197,6 +197,13 @@ public class AccountFolderList extends ListActivity implements OnItemClickListen
 
         Controller.getInstance(getApplication()).addResultCallback(mControllerCallback);
 
+        // Exit immediately if the accounts list has changed (e.g. externally deleted)
+        if (Email.getNotifyUiAccountsChanged()) {
+            Welcome.actionStart(this);
+            finish();
+            return;
+        }
+
         updateAccounts();
         // TODO: What updates do we need to auto-trigger, now that we have mailboxes in view?
     }

src/com/android/email/activity/MailboxList.java

@@ -182,6 +182,14 @@ public class MailboxList extends ListActivity implements OnItemClickListener, On
     public void onResume() {
         super.onResume();
         Controller.getInstance(getApplication()).addResultCallback(mControllerCallback);
+
+        // Exit immediately if the accounts list has changed (e.g. externally deleted)
+        if (Email.getNotifyUiAccountsChanged()) {
+            Welcome.actionStart(this);
+            finish();
+            return;
+        }
+
         updateMessageCount();
 
         // TODO: may need to clear notifications here

src/com/android/email/activity/MessageCompose.java

@@ -368,6 +368,13 @@ public class MessageCompose extends Activity implements OnClickListener, OnFocus
     public void onResume() {
         super.onResume();
         mController.addResultCallback(mListener);
+
+        // Exit immediately if the accounts list has changed (e.g. externally deleted)
+        if (Email.getNotifyUiAccountsChanged()) {
+            Welcome.actionStart(this);
+            finish();
+            return;
+        }
     }
 
     @Override

src/com/android/email/activity/MessageList.java

@@ -317,6 +317,14 @@ public class MessageList extends ListActivity implements OnItemClickListener, On
         NotificationManager notificationManager = (NotificationManager)
                 getSystemService(Context.NOTIFICATION_SERVICE);
         notificationManager.cancel(MailService.NOTIFICATION_ID_NEW_MESSAGES);
+
+        // Exit immediately if the accounts list has changed (e.g. externally deleted)
+        if (Email.getNotifyUiAccountsChanged()) {
+            Welcome.actionStart(this);
+            finish();
+            return;
+        }
+
         restoreListPosition();
         autoRefreshStaleMailbox();
     }

src/com/android/email/activity/MessageView.java

@@ -448,6 +448,14 @@ public class MessageView extends Activity implements OnClickListener {
         super.onResume();
         mWaitForLoadMessageId = -1;
         mController.addResultCallback(mControllerCallback);
+
+        // Exit immediately if the accounts list has changed (e.g. externally deleted)
+        if (Email.getNotifyUiAccountsChanged()) {
+            Welcome.actionStart(this);
+            finish();
+            return;
+        }
+
         if (mMessage != null) {
             startPresenceCheck();
 

src/com/android/email/activity/Welcome.java

@@ -17,6 +17,7 @@
 package com.android.email.activity;
 
 import com.android.email.AccountBackupRestore;
+import com.android.email.Email;
 import com.android.email.ExchangeUtils;
 import com.android.email.activity.setup.AccountSetupBasics;
 import com.android.email.provider.EmailContent;
@@ -48,6 +49,9 @@ public class Welcome extends Activity {
     public void onCreate(Bundle icicle) {
         super.onCreate(icicle);
 
+        // Reset the "accounts changed" notification, now that we're here
+        Email.setNotifyUiAccountsChanged(false);
+
         // Quickly check for bulk upgrades (from older app versions) and switch to the
         // upgrade activity if necessary
         if (UpgradeAccounts.doBulkUpgradeIfNecessary(this)) {

src/com/android/email/activity/setup/AccountSettings.java

@@ -18,6 +18,7 @@ package com.android.email.activity.setup;
 
 import com.android.email.Email;
 import com.android.email.R;
+import com.android.email.activity.Welcome;
 import com.android.email.mail.MessagingException;
 import com.android.email.mail.Sender;
 import com.android.email.mail.Store;
@@ -313,6 +314,14 @@ public class AccountSettings extends PreferenceActivity {
     @Override
     public void onResume() {
         super.onResume();
+
+        // Exit immediately if the accounts list has changed (e.g. externally deleted)
+        if (Email.getNotifyUiAccountsChanged()) {
+            Welcome.actionStart(this);
+            finish();
+            return;
+        }
+
         if (mAccountDirty) {
             // if we are coming back from editing incoming or outgoing settings,
             // we need to refresh them here so we don't accidentally overwrite the

src/com/android/exchange/SyncManager.java

@@ -1551,6 +1551,7 @@ public class SyncManager extends Service implements Runnable {
         if (!blockExternalChanges && accountsDeleted) {
             AccountBackupRestore.backupAccounts(context);
             SecurityPolicy.getInstance(context).reducePolicies();
+            Email.setNotifyUiAccountsChanged(true);
         }
     }