src/com/android/email/activity/UIControllerOnePane.java - platform/packages/apps/Email - Git at Google

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.email.activity;

 import android.app.Activity;
 import android.app.Fragment;
 import android.app.FragmentTransaction;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;

 import com.android.email.Email;
 import com.android.email.MessageListContext;
 import com.android.email.R;
 import com.android.emailcommon.Logging;
 import com.android.emailcommon.provider.Account;
 import com.android.emailcommon.provider.EmailContent.Message;
 import com.android.emailcommon.provider.Mailbox;

 import java.util.Set;


 /**
  * UI Controller for non x-large devices.  Supports a single-pane layout.
  *
  * One one-pane, only at most one fragment can be installed at a time.
  *
  * Note: Always use {@link #commitFragmentTransaction} to operate fragment transactions,
  * so that we can easily switch between synchronous and asynchronous transactions.
  *
  * Major TODOs
  * - TODO Implement callbacks
  */
 class UIControllerOnePane extends UIControllerBase {
     private static final String BUNDLE_KEY_PREVIOUS_FRAGMENT
             = "UIControllerOnePane.PREVIOUS_FRAGMENT";

     // Our custom poor-man's back stack which has only one entry at maximum.
     private Fragment mPreviousFragment;

     // MailboxListFragment.Callback
     @Override
     public void onAccountSelected(long accountId) {
         // It's from combined view, so "forceShowInbox" doesn't really matter.
         // (We're always switching accounts.)
         switchAccount(accountId, true);
     }

     // MailboxListFragment.Callback
     @Override
     public void onMailboxSelected(long accountId, long mailboxId, boolean nestedNavigation) {
         if (nestedNavigation) {
             return; // Nothing to do on 1-pane.
         }
         openMailbox(accountId, mailboxId);
     }

     // MailboxListFragment.Callback
     @Override
     public void onParentMailboxChanged() {
         refreshActionBar();
     }

     // MessageListFragment.Callback
     @Override
     public void onAdvancingOpAccepted(Set<Long> affectedMessages) {
         // Nothing to do on 1 pane.
     }

     // MessageListFragment.Callback
     @Override
     public void onMessageOpen(
             long messageId, long messageMailboxId, long listMailboxId, int type) {
         if (type == MessageListFragment.Callback.TYPE_DRAFT) {
             MessageCompose.actionEditDraft(mActivity, messageId);
         } else {
             open(mListContext, messageId);
         }
     }

     // MessageListFragment.Callback
     @Override
     public boolean onDragStarted() {
         // No drag&drop on 1-pane
         return false;
     }

     // MessageListFragment.Callback
     @Override
     public void onDragEnded() {
         // No drag&drop on 1-pane
     }

     // MessageViewFragment.Callback
     @Override
     public void onForward() {
         MessageCompose.actionForward(mActivity, getMessageId());
     }

     // MessageViewFragment.Callback
     @Override
     public void onReply() {
         MessageCompose.actionReply(mActivity, getMessageId(), false);
     }

     // MessageViewFragment.Callback
     @Override
     public void onReplyAll() {
         MessageCompose.actionReply(mActivity, getMessageId(), true);
     }

     // MessageViewFragment.Callback
     @Override
     public void onCalendarLinkClicked(long epochEventStartTime) {
         ActivityHelper.openCalendar(mActivity, epochEventStartTime);
     }

     // MessageViewFragment.Callback
     @Override
     public boolean onUrlInMessageClicked(String url) {
         return ActivityHelper.openUrlInMessage(mActivity, url, getActualAccountId());
     }

     // MessageViewFragment.Callback
     @Override
     public void onLoadMessageError(String errorMessage) {
         // TODO Auto-generated method stub
     }

     // MessageViewFragment.Callback
     @Override
     public void onLoadMessageFinished() {
         // TODO Auto-generated method stub
     }

     // MessageViewFragment.Callback
     @Override
     public void onLoadMessageStarted() {
         // TODO Auto-generated method stub
     }

     private boolean isInboxShown() {
         if (!isMessageListInstalled()) {
             return false;
         }
         return getMessageListFragment().isInboxList();
     }

     // This is all temporary as we'll have a different action bar controller for 1-pane.
     private class ActionBarControllerCallback implements ActionBarController.Callback {
         @Override
         public int getTitleMode() {
             if (isMailboxListInstalled()) {
                 return TITLE_MODE_ACCOUNT_WITH_ALL_FOLDERS_LABEL;
             }
             if (isMessageViewInstalled()) {
                 return TITLE_MODE_MESSAGE_SUBJECT;
             }
             return TITLE_MODE_ACCOUNT_WITH_MAILBOX;
         }

         public String getMessageSubject() {
             if (isMessageViewInstalled() && getMessageViewFragment().isMessageOpen()) {
                 return getMessageViewFragment().getMessage().mSubject;
             } else {
                 return null;
             }
         }

         @Override
         public boolean shouldShowUp() {
             return isMessageViewInstalled()
                     || (isMessageListInstalled() && !isInboxShown())
                     || isMailboxListInstalled();
         }

         @Override
         public long getUIAccountId() {
             return UIControllerOnePane.this.getUIAccountId();
         }

         @Override
         public long getMailboxId() {
             return UIControllerOnePane.this.getMailboxId();
         }

         @Override
         public void onMailboxSelected(long accountId, long mailboxId) {
             if (mailboxId == Mailbox.NO_MAILBOX) {
                 showAllMailboxes();
             } else {
                 openMailbox(accountId, mailboxId);
             }
         }

         @Override
         public boolean isAccountSelected() {
             return UIControllerOnePane.this.isAccountSelected();
         }

         @Override
         public void onAccountSelected(long accountId) {
             switchAccount(accountId, true); // Always go to inbox
         }

         @Override
         public void onNoAccountsFound() {
             Welcome.actionStart(mActivity);
             mActivity.finish();
         }

         @Override
         public String getSearchHint() {
             if (!isMessageListInstalled()) {
                 return null;
             }
             return UIControllerOnePane.this.getSearchHint();
         }

         @Override
         public void onSearchStarted() {
             if (!isMessageListInstalled()) {
                 return;
             }
             UIControllerOnePane.this.onSearchStarted();
         }

         @Override
         public void onSearchSubmit(String queryTerm) {
             if (!isMessageListInstalled()) {
                 return;
             }
             UIControllerOnePane.this.onSearchSubmit(queryTerm);
         }

         @Override
         public void onSearchExit() {
             UIControllerOnePane.this.onSearchExit();
         }
     }

     public UIControllerOnePane(EmailActivity activity) {
         super(activity);
     }

     @Override
     protected ActionBarController createActionBarController(Activity activity) {

         // For now, we just reuse the same action bar controller used for 2-pane.
         // We may change it later.

         return new ActionBarController(activity, activity.getLoaderManager(),
                 activity.getActionBar(), new ActionBarControllerCallback());
     }

     @Override
     public void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
         if (mPreviousFragment != null) {
             mFragmentManager.putFragment(outState,
                     BUNDLE_KEY_PREVIOUS_FRAGMENT, mPreviousFragment);
         }
     }

     @Override
     public void onRestoreInstanceState(Bundle savedInstanceState) {
         super.onRestoreInstanceState(savedInstanceState);
         mPreviousFragment = mFragmentManager.getFragment(savedInstanceState,
                 BUNDLE_KEY_PREVIOUS_FRAGMENT);
     }

     @Override
     public int getLayoutId() {
         return R.layout.email_activity_one_pane;
     }

     @Override
     public long getUIAccountId() {
         if (mListContext != null) {
             return mListContext.mAccountId;
         }
         if (isMailboxListInstalled()) {
             return getMailboxListFragment().getAccountId();
         }
         return Account.NO_ACCOUNT;
     }

     private long getMailboxId() {
         if (mListContext != null) {
             return mListContext.getMailboxId();
         }
         return Mailbox.NO_MAILBOX;
     }

     @Override
     public boolean onBackPressed(boolean isSystemBackKey) {
         if (Email.DEBUG) {
             // This is VERY important -- no check for DEBUG_LIFECYCLE
             Log.d(Logging.LOG_TAG, this + " onBackPressed: " + isSystemBackKey);
         }
         // The action bar controller has precedence.  Must call it first.
         if (mActionBarController.onBackPressed(isSystemBackKey)) {
             return true;
         }
         // If the mailbox list is shown and showing a nested mailbox, let it navigate up first.
         if (isMailboxListInstalled() && getMailboxListFragment().navigateUp()) {
             if (DEBUG_FRAGMENTS) {
                 Log.d(Logging.LOG_TAG, this + " Back: back handled by mailbox list");
             }
             return true;
         }

         // Custom back stack
         if (shouldPopFromBackStack(isSystemBackKey)) {
             if (DEBUG_FRAGMENTS) {
                 Log.d(Logging.LOG_TAG, this + " Back: Popping from back stack");
             }
             popFromBackStack();
             return true;
         }

         // No entry in the back stack.
         if (isMessageViewInstalled()) {
             if (DEBUG_FRAGMENTS) {
                 Log.d(Logging.LOG_TAG, this + " Back: Message view -> Message List");
             }
             // If the message view is shown, show the "parent" message list.
             // This happens when we get a deep link to a message.  (e.g. from a widget)
             openMailbox(mListContext.mAccountId, mListContext.getMailboxId());
             return true;
         } else if (isMailboxListInstalled()) {
             // If the mailbox list is shown, always go back to the inbox.
             switchAccount(getMailboxListFragment().getAccountId(), true /* force show inbox */);
             return true;
         } else if (isMessageListInstalled() && !isInboxShown()) {
             // Non-inbox list. Go to inbox.
             switchAccount(mListContext.mAccountId, true /* force show inbox */);
             return true;
         }
         return false;
     }

     @Override
     public void openInternal(final MessageListContext listContext, final long messageId) {
         if (Email.DEBUG) {
             // This is VERY important -- don't check for DEBUG_LIFECYCLE
             Log.i(Logging.LOG_TAG, this + " open " + listContext + " messageId=" + messageId);
         }

         if (messageId != Message.NO_MESSAGE) {
             openMessage(messageId);
         } else {
             showFragment(MessageListFragment.newInstance(listContext));
         }
     }

     /**
      * @return currently installed {@link Fragment} (1-pane has only one at most), or null if none
      *         exists.
      */
     private Fragment getInstalledFragment() {
         if (isMailboxListInstalled()) {
             return getMailboxListFragment();
         } else if (isMessageListInstalled()) {
             return getMessageListFragment();
         } else if (isMessageViewInstalled()) {
             return getMessageViewFragment();
         }
         return null;
     }

     /**
      * Show the mailbox list.
      *
      * This is the only way to open the mailbox list on 1-pane.
      * {@link #open(MessageListContext, long)} will only open either the message list or the
      * message view.
      */
     private void openMailboxList(long accountId) {
         setListContext(null);
         showFragment(MailboxListFragment.newInstance(accountId, Mailbox.NO_MAILBOX, false));
     }

     private void openMessage(long messageId) {
         showFragment(MessageViewFragment.newInstance(messageId));
     }

     /**
      * Push the installed fragment into our custom back stack (or optionally
      * {@link FragmentTransaction#remove} it) and {@link FragmentTransaction#add} {@code fragment}.
      *
      * @param fragment {@link Fragment} to be added.
      *
      *  TODO Delay-call the whole method and use the synchronous transaction.
      */
     private void showFragment(Fragment fragment) {
         final FragmentTransaction ft = mFragmentManager.beginTransaction();
         final Fragment installed = getInstalledFragment();
         if ((installed instanceof MessageViewFragment)
                 && (fragment instanceof MessageViewFragment)) {
             // Newer/older navigation, auto-advance, etc.
             // In this case we want to keep the backstack untouched, so that after back navigation
             // we can restore the message list, including scroll position and batch selection.
         } else {
             if (DEBUG_FRAGMENTS) {
                 Log.i(Logging.LOG_TAG, this + " backstack: [push] " + getInstalledFragment()
                         + " -> " + fragment);
             }
             if (mPreviousFragment != null) {
                 if (DEBUG_FRAGMENTS) {
                     Log.d(Logging.LOG_TAG, this + " showFragment: destroying previous fragment "
                             + mPreviousFragment);
                 }
                 removeFragment(ft, mPreviousFragment);
                 mPreviousFragment = null;
             }
             // Remove the current fragment or push it into the backstack.
             if (installed != null) {
                 if (installed instanceof MessageViewFragment) {
                     // Message view should never be pushed to the backstack.
                     if (DEBUG_FRAGMENTS) {
                         Log.d(Logging.LOG_TAG, this + " showFragment: removing " + installed);
                     }
                     ft.remove(installed);
                 } else {
                     // Other fragments should be pushed.
                     mPreviousFragment = installed;
                     if (DEBUG_FRAGMENTS) {
                         Log.d(Logging.LOG_TAG, this + " showFragment: detaching "
                                 + mPreviousFragment);
                     }
                     ft.detach(mPreviousFragment);
                 }
             }
         }
         // Show the new one
         if (DEBUG_FRAGMENTS) {
             Log.d(Logging.LOG_TAG, this + " showFragment: replacing with " + fragment);
         }
         ft.replace(R.id.fragment_placeholder, fragment);
         ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
         commitFragmentTransaction(ft);
     }

     /**
      * @param isSystemBackKey <code>true</code> if the system back key was pressed.
      *        <code>false</code> if it's caused by the "home" icon click on the action bar.
      * @return true if we should pop from our custom back stack.
      */
     private boolean shouldPopFromBackStack(boolean isSystemBackKey) {
         if (mPreviousFragment == null) {
             return false; // Nothing in the back stack
         }
         if (mPreviousFragment instanceof MessageViewFragment) {
             throw new IllegalStateException("Message view should never be in backstack");
         }
         final Fragment installed = getInstalledFragment();
         if (installed == null) {
             // If no fragment is installed right now, do nothing.
             return false;
         }

         // Okay now we have 2 fragments; the one in the back stack and the one that's currently
         // installed.
         if (isInboxShown()) {
             // Inbox is the top level list - never go back from here.
             return false;
         }

         // Disallow the MailboxList--> non-inbox MessageList transition as the Mailbox list
         // is always considered "higher" than a non-inbox MessageList
         if ((mPreviousFragment instanceof MessageListFragment)
                 && (!((MessageListFragment) mPreviousFragment).isInboxList())
                 && (installed  instanceof MailboxListFragment)) {
             return false;
         }
         return true;
     }

     /**
      * Pop from our custom back stack.
      *
      * TODO Delay-call the whole method and use the synchronous transaction.
      */
     private void popFromBackStack() {
         if (mPreviousFragment == null) {
             return;
         }
         final FragmentTransaction ft = mFragmentManager.beginTransaction();
         final Fragment installed = getInstalledFragment();
         if (DEBUG_FRAGMENTS) {
             Log.i(Logging.LOG_TAG, this + " backstack: [pop] " + installed + " -> "
                     + mPreviousFragment);
         }
         removeFragment(ft, installed);

         // Restore listContext.
         if (mPreviousFragment instanceof MailboxListFragment) {
             setListContext(null);
         } else if (mPreviousFragment instanceof MessageListFragment) {
             setListContext(((MessageListFragment) mPreviousFragment).getListContext());
         } else {
             throw new IllegalStateException("Message view should never be in backstack");
         }

         ft.attach(mPreviousFragment);
         ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE);
         mPreviousFragment = null;
         commitFragmentTransaction(ft);
         return;
     }

     private void showAllMailboxes() {
         if (!isAccountSelected()) {
             return; // Can happen because of asynchronous fragment transactions.
         }

         openMailboxList(getUIAccountId());
     }

     @Override
     protected void installMailboxListFragment(MailboxListFragment fragment) {
         stopMessageOrderManager();
         super.installMailboxListFragment(fragment);
     }

     @Override
     protected void installMessageListFragment(MessageListFragment fragment) {
         stopMessageOrderManager();
         super.installMessageListFragment(fragment);
     }

     @Override
     protected long getMailboxSettingsMailboxId() {
         return isMessageListInstalled()
                 ? getMessageListFragment().getMailboxId()
                 : Mailbox.NO_MAILBOX;
     }

     /**
      * Handles the {@link android.app.Activity#onCreateOptionsMenu} callback.
      */
     public boolean onCreateOptionsMenu(MenuInflater inflater, Menu menu) {
         if (isMessageListInstalled()) {
             inflater.inflate(R.menu.message_list_fragment_option, menu);
             return true;
         }
         if (isMessageViewInstalled()) {
             inflater.inflate(R.menu.message_view_fragment_option, menu);
             return true;
         }
         return false;
     }

     @Override
     public boolean onPrepareOptionsMenu(MenuInflater inflater, Menu menu) {
         // First, let the base class do what it has to do.
         super.onPrepareOptionsMenu(inflater, menu);

         final boolean messageViewVisible = isMessageViewInstalled();
         if (messageViewVisible) {
             final MessageOrderManager om = getMessageOrderManager();
             menu.findItem(R.id.newer).setVisible(true);
             menu.findItem(R.id.older).setVisible(true);
             // orderManager shouldn't be null when the message view is installed, but just in case..
             menu.findItem(R.id.newer).setEnabled((om != null) && om.canMoveToNewer());
             menu.findItem(R.id.older).setEnabled((om != null) && om.canMoveToOlder());
         }
         return true;
     }

     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
             case R.id.newer:
                 moveToNewer();
                 return true;
             case R.id.older:
                 moveToOlder();
                 return true;
             case R.id.show_all_mailboxes:
                 showAllMailboxes();
                 return true;
         }
         return super.onOptionsItemSelected(item);
     }

     @Override
     protected boolean isRefreshEnabled() {
         // Refreshable only when an actual account is selected, and message view isn't shown.
         // (i.e. only available on the mailbox list or the message view, but not on the combined
         // one)
         if (!isActualAccountSelected() || isMessageViewInstalled()) {
             return false;
         }
         return isMailboxListInstalled() || (mListContext.getMailboxId() > 0);
     }

     @Override
     protected void onRefresh() {
         if (!isRefreshEnabled()) {
             return;
         }
         if (isMessageListInstalled()) {
             mRefreshManager.refreshMessageList(getActualAccountId(), getMailboxId(), true);
         } else {
             mRefreshManager.refreshMailboxList(getActualAccountId());
         }
     }

     @Override
     protected boolean isRefreshInProgress() {
         if (!isRefreshEnabled()) {
             return false;
         }
         if (isMessageListInstalled()) {
             return mRefreshManager.isMessageListRefreshing(getMailboxId());
         } else {
             return mRefreshManager.isMailboxListRefreshing(getActualAccountId());
         }
     }

     @Override protected void navigateToMessage(long messageId) {
         openMessage(messageId);
     }

     @Override protected void updateNavigationArrows() {
         refreshActionBar();
     }
 }
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.email.activity;

	import android.app.Activity;
	import android.app.Fragment;
	import android.app.FragmentTransaction;
	import android.os.Bundle;
	import android.util.Log;
	import android.view.Menu;
	import android.view.MenuInflater;
	import android.view.MenuItem;

	import com.android.email.Email;
	import com.android.email.MessageListContext;
	import com.android.email.R;
	import com.android.emailcommon.Logging;
	import com.android.emailcommon.provider.Account;
	import com.android.emailcommon.provider.EmailContent.Message;
	import com.android.emailcommon.provider.Mailbox;

	import java.util.Set;


	/**
	* UI Controller for non x-large devices. Supports a single-pane layout.
	*
	* One one-pane, only at most one fragment can be installed at a time.
	*
	* Note: Always use {@link #commitFragmentTransaction} to operate fragment transactions,
	* so that we can easily switch between synchronous and asynchronous transactions.
	*
	* Major TODOs
	* - TODO Implement callbacks
	*/
	class UIControllerOnePane extends UIControllerBase {
	private static final String BUNDLE_KEY_PREVIOUS_FRAGMENT
	= "UIControllerOnePane.PREVIOUS_FRAGMENT";

	// Our custom poor-man's back stack which has only one entry at maximum.
	private Fragment mPreviousFragment;

	// MailboxListFragment.Callback
	@Override
	public void onAccountSelected(long accountId) {
	// It's from combined view, so "forceShowInbox" doesn't really matter.
	// (We're always switching accounts.)
	switchAccount(accountId, true);
	}

	// MailboxListFragment.Callback
	@Override
	public void onMailboxSelected(long accountId, long mailboxId, boolean nestedNavigation) {
	if (nestedNavigation) {
	return; // Nothing to do on 1-pane.
	}
	openMailbox(accountId, mailboxId);
	}

	// MailboxListFragment.Callback
	@Override
	public void onParentMailboxChanged() {
	refreshActionBar();
	}

	// MessageListFragment.Callback
	@Override
	public void onAdvancingOpAccepted(Set<Long> affectedMessages) {
	// Nothing to do on 1 pane.
	}

	// MessageListFragment.Callback
	@Override
	public void onMessageOpen(
	long messageId, long messageMailboxId, long listMailboxId, int type) {
	if (type == MessageListFragment.Callback.TYPE_DRAFT) {
	MessageCompose.actionEditDraft(mActivity, messageId);
	} else {
	open(mListContext, messageId);
	}
	}

	// MessageListFragment.Callback
	@Override
	public boolean onDragStarted() {
	// No drag&drop on 1-pane
	return false;
	}

	// MessageListFragment.Callback
	@Override
	public void onDragEnded() {
	// No drag&drop on 1-pane
	}

	// MessageViewFragment.Callback
	@Override
	public void onForward() {
	MessageCompose.actionForward(mActivity, getMessageId());
	}

	// MessageViewFragment.Callback
	@Override
	public void onReply() {
	MessageCompose.actionReply(mActivity, getMessageId(), false);
	}

	// MessageViewFragment.Callback
	@Override
	public void onReplyAll() {
	MessageCompose.actionReply(mActivity, getMessageId(), true);
	}

	// MessageViewFragment.Callback
	@Override
	public void onCalendarLinkClicked(long epochEventStartTime) {
	ActivityHelper.openCalendar(mActivity, epochEventStartTime);
	}

	// MessageViewFragment.Callback
	@Override
	public boolean onUrlInMessageClicked(String url) {
	return ActivityHelper.openUrlInMessage(mActivity, url, getActualAccountId());
	}

	// MessageViewFragment.Callback
	@Override
	public void onLoadMessageError(String errorMessage) {
	// TODO Auto-generated method stub
	}

	// MessageViewFragment.Callback
	@Override
	public void onLoadMessageFinished() {
	// TODO Auto-generated method stub
	}

	// MessageViewFragment.Callback
	@Override
	public void onLoadMessageStarted() {
	// TODO Auto-generated method stub
	}

	private boolean isInboxShown() {
	if (!isMessageListInstalled()) {
	return false;
	}
	return getMessageListFragment().isInboxList();
	}

	// This is all temporary as we'll have a different action bar controller for 1-pane.
	private class ActionBarControllerCallback implements ActionBarController.Callback {
	@Override
	public int getTitleMode() {
	if (isMailboxListInstalled()) {
	return TITLE_MODE_ACCOUNT_WITH_ALL_FOLDERS_LABEL;
	}
	if (isMessageViewInstalled()) {
	return TITLE_MODE_MESSAGE_SUBJECT;
	}
	return TITLE_MODE_ACCOUNT_WITH_MAILBOX;
	}

	public String getMessageSubject() {
	if (isMessageViewInstalled() && getMessageViewFragment().isMessageOpen()) {
	return getMessageViewFragment().getMessage().mSubject;
	} else {
	return null;
	}
	}

	@Override
	public boolean shouldShowUp() {
	return isMessageViewInstalled()
	\|\| (isMessageListInstalled() && !isInboxShown())
	\|\| isMailboxListInstalled();
	}

	@Override
	public long getUIAccountId() {
	return UIControllerOnePane.this.getUIAccountId();
	}

	@Override
	public long getMailboxId() {
	return UIControllerOnePane.this.getMailboxId();
	}

	@Override
	public void onMailboxSelected(long accountId, long mailboxId) {
	if (mailboxId == Mailbox.NO_MAILBOX) {
	showAllMailboxes();
	} else {
	openMailbox(accountId, mailboxId);
	}
	}

	@Override
	public boolean isAccountSelected() {
	return UIControllerOnePane.this.isAccountSelected();
	}

	@Override
	public void onAccountSelected(long accountId) {
	switchAccount(accountId, true); // Always go to inbox
	}

	@Override
	public void onNoAccountsFound() {
	Welcome.actionStart(mActivity);
	mActivity.finish();
	}

	@Override
	public String getSearchHint() {
	if (!isMessageListInstalled()) {
	return null;
	}
	return UIControllerOnePane.this.getSearchHint();
	}

	@Override
	public void onSearchStarted() {
	if (!isMessageListInstalled()) {
	return;
	}
	UIControllerOnePane.this.onSearchStarted();
	}

	@Override
	public void onSearchSubmit(String queryTerm) {
	if (!isMessageListInstalled()) {
	return;
	}
	UIControllerOnePane.this.onSearchSubmit(queryTerm);
	}

	@Override
	public void onSearchExit() {
	UIControllerOnePane.this.onSearchExit();
	}
	}

	public UIControllerOnePane(EmailActivity activity) {
	super(activity);
	}

	@Override
	protected ActionBarController createActionBarController(Activity activity) {

	// For now, we just reuse the same action bar controller used for 2-pane.
	// We may change it later.

	return new ActionBarController(activity, activity.getLoaderManager(),
	activity.getActionBar(), new ActionBarControllerCallback());
	}

	@Override
	public void onSaveInstanceState(Bundle outState) {
	super.onSaveInstanceState(outState);
	if (mPreviousFragment != null) {
	mFragmentManager.putFragment(outState,
	BUNDLE_KEY_PREVIOUS_FRAGMENT, mPreviousFragment);
	}
	}

	@Override
	public void onRestoreInstanceState(Bundle savedInstanceState) {
	super.onRestoreInstanceState(savedInstanceState);
	mPreviousFragment = mFragmentManager.getFragment(savedInstanceState,
	BUNDLE_KEY_PREVIOUS_FRAGMENT);
	}

	@Override
	public int getLayoutId() {
	return R.layout.email_activity_one_pane;
	}

	@Override
	public long getUIAccountId() {
	if (mListContext != null) {
	return mListContext.mAccountId;
	}
	if (isMailboxListInstalled()) {
	return getMailboxListFragment().getAccountId();
	}
	return Account.NO_ACCOUNT;
	}

	private long getMailboxId() {
	if (mListContext != null) {
	return mListContext.getMailboxId();
	}
	return Mailbox.NO_MAILBOX;
	}

	@Override
	public boolean onBackPressed(boolean isSystemBackKey) {
	if (Email.DEBUG) {
	// This is VERY important -- no check for DEBUG_LIFECYCLE
	Log.d(Logging.LOG_TAG, this + " onBackPressed: " + isSystemBackKey);
	}
	// The action bar controller has precedence. Must call it first.
	if (mActionBarController.onBackPressed(isSystemBackKey)) {
	return true;
	}
	// If the mailbox list is shown and showing a nested mailbox, let it navigate up first.
	if (isMailboxListInstalled() && getMailboxListFragment().navigateUp()) {
	if (DEBUG_FRAGMENTS) {
	Log.d(Logging.LOG_TAG, this + " Back: back handled by mailbox list");
	}
	return true;
	}

	// Custom back stack
	if (shouldPopFromBackStack(isSystemBackKey)) {
	if (DEBUG_FRAGMENTS) {
	Log.d(Logging.LOG_TAG, this + " Back: Popping from back stack");
	}
	popFromBackStack();
	return true;
	}

	// No entry in the back stack.
	if (isMessageViewInstalled()) {
	if (DEBUG_FRAGMENTS) {
	Log.d(Logging.LOG_TAG, this + " Back: Message view -> Message List");
	}
	// If the message view is shown, show the "parent" message list.
	// This happens when we get a deep link to a message. (e.g. from a widget)
	openMailbox(mListContext.mAccountId, mListContext.getMailboxId());
	return true;
	} else if (isMailboxListInstalled()) {
	// If the mailbox list is shown, always go back to the inbox.
	switchAccount(getMailboxListFragment().getAccountId(), true /* force show inbox */);
	return true;
	} else if (isMessageListInstalled() && !isInboxShown()) {
	// Non-inbox list. Go to inbox.
	switchAccount(mListContext.mAccountId, true /* force show inbox */);
	return true;
	}
	return false;
	}

	@Override
	public void openInternal(final MessageListContext listContext, final long messageId) {
	if (Email.DEBUG) {
	// This is VERY important -- don't check for DEBUG_LIFECYCLE
	Log.i(Logging.LOG_TAG, this + " open " + listContext + " messageId=" + messageId);
	}

	if (messageId != Message.NO_MESSAGE) {
	openMessage(messageId);
	} else {
	showFragment(MessageListFragment.newInstance(listContext));
	}
	}

	/**
	* @return currently installed {@link Fragment} (1-pane has only one at most), or null if none
	* exists.
	*/
	private Fragment getInstalledFragment() {
	if (isMailboxListInstalled()) {
	return getMailboxListFragment();
	} else if (isMessageListInstalled()) {
	return getMessageListFragment();
	} else if (isMessageViewInstalled()) {
	return getMessageViewFragment();
	}
	return null;
	}

	/**
	* Show the mailbox list.
	*
	* This is the only way to open the mailbox list on 1-pane.
	* {@link #open(MessageListContext, long)} will only open either the message list or the
	* message view.
	*/
	private void openMailboxList(long accountId) {
	setListContext(null);
	showFragment(MailboxListFragment.newInstance(accountId, Mailbox.NO_MAILBOX, false));
	}

	private void openMessage(long messageId) {
	showFragment(MessageViewFragment.newInstance(messageId));
	}

	/**
	* Push the installed fragment into our custom back stack (or optionally
	* {@link FragmentTransaction#remove} it) and {@link FragmentTransaction#add} {@code fragment}.
	*
	* @param fragment {@link Fragment} to be added.
	*
	* TODO Delay-call the whole method and use the synchronous transaction.
	*/
	private void showFragment(Fragment fragment) {
	final FragmentTransaction ft = mFragmentManager.beginTransaction();
	final Fragment installed = getInstalledFragment();
	if ((installed instanceof MessageViewFragment)
	&& (fragment instanceof MessageViewFragment)) {
	// Newer/older navigation, auto-advance, etc.
	// In this case we want to keep the backstack untouched, so that after back navigation
	// we can restore the message list, including scroll position and batch selection.
	} else {
	if (DEBUG_FRAGMENTS) {
	Log.i(Logging.LOG_TAG, this + " backstack: [push] " + getInstalledFragment()
	+ " -> " + fragment);
	}
	if (mPreviousFragment != null) {
	if (DEBUG_FRAGMENTS) {
	Log.d(Logging.LOG_TAG, this + " showFragment: destroying previous fragment "
	+ mPreviousFragment);
	}
	removeFragment(ft, mPreviousFragment);
	mPreviousFragment = null;
	}
	// Remove the current fragment or push it into the backstack.
	if (installed != null) {
	if (installed instanceof MessageViewFragment) {
	// Message view should never be pushed to the backstack.
	if (DEBUG_FRAGMENTS) {
	Log.d(Logging.LOG_TAG, this + " showFragment: removing " + installed);
	}
	ft.remove(installed);
	} else {
	// Other fragments should be pushed.
	mPreviousFragment = installed;
	if (DEBUG_FRAGMENTS) {
	Log.d(Logging.LOG_TAG, this + " showFragment: detaching "
	+ mPreviousFragment);
	}
	ft.detach(mPreviousFragment);
	}
	}
	}
	// Show the new one
	if (DEBUG_FRAGMENTS) {
	Log.d(Logging.LOG_TAG, this + " showFragment: replacing with " + fragment);
	}
	ft.replace(R.id.fragment_placeholder, fragment);
	ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
	commitFragmentTransaction(ft);
	}

	/**
	* @param isSystemBackKey <code>true</code> if the system back key was pressed.
	* <code>false</code> if it's caused by the "home" icon click on the action bar.
	* @return true if we should pop from our custom back stack.
	*/
	private boolean shouldPopFromBackStack(boolean isSystemBackKey) {
	if (mPreviousFragment == null) {
	return false; // Nothing in the back stack
	}
	if (mPreviousFragment instanceof MessageViewFragment) {
	throw new IllegalStateException("Message view should never be in backstack");
	}
	final Fragment installed = getInstalledFragment();
	if (installed == null) {
	// If no fragment is installed right now, do nothing.
	return false;
	}

	// Okay now we have 2 fragments; the one in the back stack and the one that's currently
	// installed.
	if (isInboxShown()) {
	// Inbox is the top level list - never go back from here.
	return false;
	}

	// Disallow the MailboxList--> non-inbox MessageList transition as the Mailbox list
	// is always considered "higher" than a non-inbox MessageList
	if ((mPreviousFragment instanceof MessageListFragment)
	&& (!((MessageListFragment) mPreviousFragment).isInboxList())
	&& (installed instanceof MailboxListFragment)) {
	return false;
	}
	return true;
	}

	/**
	* Pop from our custom back stack.
	*
	* TODO Delay-call the whole method and use the synchronous transaction.
	*/
	private void popFromBackStack() {
	if (mPreviousFragment == null) {
	return;
	}
	final FragmentTransaction ft = mFragmentManager.beginTransaction();
	final Fragment installed = getInstalledFragment();
	if (DEBUG_FRAGMENTS) {
	Log.i(Logging.LOG_TAG, this + " backstack: [pop] " + installed + " -> "
	+ mPreviousFragment);
	}
	removeFragment(ft, installed);

	// Restore listContext.
	if (mPreviousFragment instanceof MailboxListFragment) {
	setListContext(null);
	} else if (mPreviousFragment instanceof MessageListFragment) {
	setListContext(((MessageListFragment) mPreviousFragment).getListContext());
	} else {
	throw new IllegalStateException("Message view should never be in backstack");
	}

	ft.attach(mPreviousFragment);
	ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE);
	mPreviousFragment = null;
	commitFragmentTransaction(ft);
	return;
	}

	private void showAllMailboxes() {
	if (!isAccountSelected()) {
	return; // Can happen because of asynchronous fragment transactions.
	}

	openMailboxList(getUIAccountId());
	}

	@Override
	protected void installMailboxListFragment(MailboxListFragment fragment) {
	stopMessageOrderManager();
	super.installMailboxListFragment(fragment);
	}

	@Override
	protected void installMessageListFragment(MessageListFragment fragment) {
	stopMessageOrderManager();
	super.installMessageListFragment(fragment);
	}

	@Override
	protected long getMailboxSettingsMailboxId() {
	return isMessageListInstalled()
	? getMessageListFragment().getMailboxId()
	: Mailbox.NO_MAILBOX;
	}

	/**
	* Handles the {@link android.app.Activity#onCreateOptionsMenu} callback.
	*/
	public boolean onCreateOptionsMenu(MenuInflater inflater, Menu menu) {
	if (isMessageListInstalled()) {
	inflater.inflate(R.menu.message_list_fragment_option, menu);
	return true;
	}
	if (isMessageViewInstalled()) {
	inflater.inflate(R.menu.message_view_fragment_option, menu);
	return true;
	}
	return false;
	}

	@Override
	public boolean onPrepareOptionsMenu(MenuInflater inflater, Menu menu) {
	// First, let the base class do what it has to do.
	super.onPrepareOptionsMenu(inflater, menu);

	final boolean messageViewVisible = isMessageViewInstalled();
	if (messageViewVisible) {
	final MessageOrderManager om = getMessageOrderManager();
	menu.findItem(R.id.newer).setVisible(true);
	menu.findItem(R.id.older).setVisible(true);
	// orderManager shouldn't be null when the message view is installed, but just in case..
	menu.findItem(R.id.newer).setEnabled((om != null) && om.canMoveToNewer());
	menu.findItem(R.id.older).setEnabled((om != null) && om.canMoveToOlder());
	}
	return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
	switch (item.getItemId()) {
	case R.id.newer:
	moveToNewer();
	return true;
	case R.id.older:
	moveToOlder();
	return true;
	case R.id.show_all_mailboxes:
	showAllMailboxes();
	return true;
	}
	return super.onOptionsItemSelected(item);
	}

	@Override
	protected boolean isRefreshEnabled() {
	// Refreshable only when an actual account is selected, and message view isn't shown.
	// (i.e. only available on the mailbox list or the message view, but not on the combined
	// one)
	if (!isActualAccountSelected() \|\| isMessageViewInstalled()) {
	return false;
	}
	return isMailboxListInstalled() \|\| (mListContext.getMailboxId() > 0);
	}

	@Override
	protected void onRefresh() {
	if (!isRefreshEnabled()) {
	return;
	}
	if (isMessageListInstalled()) {
	mRefreshManager.refreshMessageList(getActualAccountId(), getMailboxId(), true);
	} else {
	mRefreshManager.refreshMailboxList(getActualAccountId());
	}
	}

	@Override
	protected boolean isRefreshInProgress() {
	if (!isRefreshEnabled()) {
	return false;
	}
	if (isMessageListInstalled()) {
	return mRefreshManager.isMessageListRefreshing(getMailboxId());
	} else {
	return mRefreshManager.isMailboxListRefreshing(getActualAccountId());
	}
	}

	@Override protected void navigateToMessage(long messageId) {
	openMessage(messageId);
	}

	@Override protected void updateNavigationArrows() {
	refreshActionBar();
	}
	}