email/widget/EmailWidget.java

/*
 * 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.widget;

import com.android.email.Email;
import com.android.email.UiUtilities;
import com.android.email.R;
import com.android.email.ResourceHelper;
import com.android.email.activity.MessageCompose;
import com.android.email.activity.Welcome;
import com.android.email.data.ThrottlingCursorLoader;
import com.android.email.provider.WidgetProvider.WidgetService;
import com.android.emailcommon.provider.EmailContent;
import com.android.emailcommon.provider.EmailContent.Account;
import com.android.emailcommon.provider.EmailContent.AccountColumns;
import com.android.emailcommon.provider.EmailContent.Mailbox;
import com.android.emailcommon.provider.EmailContent.Message;
import com.android.emailcommon.provider.EmailContent.MessageColumns;
import com.android.emailcommon.utility.Utility;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.Context;
import android.content.Intent;
import android.content.Loader;
import android.content.res.Resources;
import android.database.Cursor;
import android.graphics.Typeface;
import android.net.Uri;
import android.net.Uri.Builder;
import android.os.AsyncTask;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.SpannableStringBuilder;
import android.text.TextUtils;
import android.text.format.DateUtils;
import android.text.style.AbsoluteSizeSpan;
import android.text.style.ForegroundColorSpan;
import android.text.style.StyleSpan;
import android.util.Log;
import android.view.View;
import android.widget.RemoteViews;
import android.widget.RemoteViewsService;

import java.util.List;
import java.util.concurrent.ExecutionException;

import junit.framework.Assert;

public class EmailWidget implements RemoteViewsService.RemoteViewsFactory {
    public static final String TAG = "EmailWidget";

    /**
     * When handling clicks in a widget ListView, a single PendingIntent template is provided to
     * RemoteViews, and the individual "on click" actions are distinguished via a "fillInIntent"
     * on each list element; when a click is received, this "fillInIntent" is merged with the
     * PendingIntent using Intent.fillIn().  Since this mechanism does NOT preserve the Extras
     * Bundle, we instead encode information about the action (e.g. view, reply, etc.) and its
     * arguments (e.g. messageId, mailboxId, etc.) in an Uri which is added to the Intent via
     * Intent.setDataAndType()
     *
     * The mime type MUST be set in the Intent, even though we do not use it; therefore, it's value
     * is entirely arbitrary.
     *
     * Our "command" Uri is NOT used by the system in any manner, and is therefore constrained only
     * in the requirement that it be syntactically valid.
     *
     * We use the following convention for our commands:
     *     widget://command/<command>/<arg1>[/<arg2>]
     */
    private static final String WIDGET_DATA_MIME_TYPE = "com.android.email/widget_data";

    private static final Uri COMMAND_URI = Uri.parse("widget://command");

    // Command names and Uri's built upon COMMAND_URI
    private static final String COMMAND_NAME_SWITCH_LIST_VIEW = "switch_list_view";
    private static final Uri COMMAND_URI_SWITCH_LIST_VIEW =
            COMMAND_URI.buildUpon().appendPath(COMMAND_NAME_SWITCH_LIST_VIEW).build();
    private static final String COMMAND_NAME_VIEW_MESSAGE = "view_message";
    private static final Uri COMMAND_URI_VIEW_MESSAGE =
            COMMAND_URI.buildUpon().appendPath(COMMAND_NAME_VIEW_MESSAGE).build();


    private static final int TOTAL_COUNT_UNKNOWN = -1;
    private static final int MAX_MESSAGE_LIST_COUNT = 25;

    private static final String SORT_TIMESTAMP_DESCENDING = MessageColumns.TIMESTAMP + " DESC";
    private static final String SORT_ID_ASCENDING = AccountColumns.ID + " ASC";
    private static final String[] ID_NAME_PROJECTION = {Account.RECORD_ID, Account.DISPLAY_NAME};
    private static final int ID_NAME_COLUMN_ID = 0;
    private static final int ID_NAME_COLUMN_NAME = 1;

    private static String sSubjectSnippetDivider;
    private static String sConfigureText;
    private static int sSenderFontSize;
    private static int sSubjectFontSize;
    private static int sDateFontSize;
    private static int sDefaultTextColor;
    private static int sLightTextColor;

    private final Context mContext;
    private final ContentResolver mResolver;
    private final AppWidgetManager mWidgetManager;

    // The widget identifier
    private final int mWidgetId;

    // The cursor underlying the message list for this widget; this must only be modified while
    // holding mCursorLock
    private volatile Cursor mCursor;
    // A lock on our cursor, which is used in the UI thread while inflating views, and by
    // our Loader in the background
    private final Object mCursorLock = new Object();
    // Number of records in the cursor
    private int mCursorCount = TOTAL_COUNT_UNKNOWN;
    // The widget's loader (derived from ThrottlingCursorLoader)
    private ViewCursorLoader mLoader;
    private final ResourceHelper mResourceHelper;
    // Number of defined accounts
    private int mAccountCount = TOTAL_COUNT_UNKNOWN;

    // The current view type (all mail, unread, or starred for now)
    /*package*/ ViewType mViewType = ViewType.STARRED;

    // The projection to be used by the WidgetLoader
    private static final String[] WIDGET_PROJECTION = new String[] {
            EmailContent.RECORD_ID, MessageColumns.DISPLAY_NAME, MessageColumns.TIMESTAMP,
            MessageColumns.SUBJECT, MessageColumns.FLAG_READ, MessageColumns.FLAG_FAVORITE,
            MessageColumns.FLAG_ATTACHMENT, MessageColumns.MAILBOX_KEY, MessageColumns.SNIPPET,
            MessageColumns.ACCOUNT_KEY, MessageColumns.FLAGS
            };
    private static final int WIDGET_COLUMN_ID = 0;
    private static final int WIDGET_COLUMN_DISPLAY_NAME = 1;
    private static final int WIDGET_COLUMN_TIMESTAMP = 2;
    private static final int WIDGET_COLUMN_SUBJECT = 3;
    private static final int WIDGET_COLUMN_FLAG_READ = 4;
    @SuppressWarnings("unused")
    private static final int WIDGET_COLUMN_FLAG_FAVORITE = 5;
    private static final int WIDGET_COLUMN_FLAG_ATTACHMENT = 6;
    private static final int WIDGET_COLUMN_MAILBOX_KEY = 7;
    private static final int WIDGET_COLUMN_SNIPPET = 8;
    private static final int WIDGET_COLUMN_ACCOUNT_KEY = 9;
    private static final int WIDGET_COLUMN_FLAGS = 10;

    public EmailWidget(Context context, int _widgetId) {
        super();
        if (Email.DEBUG) {
            Log.d(TAG, "Creating EmailWidget with id = " + _widgetId);
        }
        mContext = context.getApplicationContext();
        mResolver = mContext.getContentResolver();
        mWidgetManager = AppWidgetManager.getInstance(mContext);

        mWidgetId = _widgetId;
        mLoader = new ViewCursorLoader();
        if (sSubjectSnippetDivider == null) {
            // Initialize string, color, dimension resources
            Resources res = mContext.getResources();
            sSubjectSnippetDivider =
                res.getString(R.string.message_list_subject_snippet_divider);
            sSenderFontSize = res.getDimensionPixelSize(R.dimen.widget_senders_font_size);
            sSubjectFontSize = res.getDimensionPixelSize(R.dimen.widget_subject_font_size);
            sDateFontSize = res.getDimensionPixelSize(R.dimen.widget_date_font_size);
            sDefaultTextColor = res.getColor(R.color.widget_default_text_color);
            sDefaultTextColor = res.getColor(R.color.widget_default_text_color);
            sLightTextColor = res.getColor(R.color.widget_light_text_color);
            sConfigureText =  res.getString(R.string.widget_other_views);
        }
        mResourceHelper = ResourceHelper.getInstance(mContext);
    }

    public void updateWidget(boolean validateView) {
        new WidgetUpdateTask().execute(validateView);
    }

    /**
     *  Task for updating widget data (eg: the header, view list items, etc...)
     *  If parameter to {@link #execute(Boolean...)} is <code>true</code>, the current
     *  view is validated against the current set of accounts. And if the current view
     *  is determined to be invalid, the view will automatically progress to the next
     *  valid view.
     */
    private final class WidgetUpdateTask extends AsyncTask<Boolean, Void, Boolean> {
        @Override
        protected Boolean doInBackground(Boolean... validateView) {
            mAccountCount = EmailContent.count(mContext, EmailContent.Account.CONTENT_URI);
            // If displaying invalid view, switch to the next view
            return !validateView[0] || isViewValid();
        }

        @Override
        protected void onPostExecute(Boolean isValidView) {
            updateHeader();
            if (!isValidView) {
                switchView();
            }
        }
    }

    /**
     * The ThrottlingCursorLoader does all of the heavy lifting in managing the data loading
     * task; all we need is to register a listener so that we're notified when the load is
     * complete.
     */
    private final class ViewCursorLoader extends ThrottlingCursorLoader {
        protected ViewCursorLoader() {
            super(mContext, Message.CONTENT_URI, WIDGET_PROJECTION, mViewType.selection,
                    mViewType.selectionArgs, SORT_TIMESTAMP_DESCENDING);
            registerListener(0, new OnLoadCompleteListener<Cursor>() {
                @Override
                public void onLoadComplete(Loader<Cursor> loader, Cursor cursor) {
                    synchronized (mCursorLock) {
                        // Save away the cursor
                        mCursor = cursor;
                        // Reset the notification Uri to our Message table notifier URI
                        mCursor.setNotificationUri(mResolver, Message.NOTIFIER_URI);
                        // Save away the count (for display)
                        mCursorCount = mCursor.getCount();
                        if (Email.DEBUG) {
                            Log.d(TAG, "onLoadComplete, count = " + cursor.getCount());
                        }
                    }
                    RemoteViews views =
                        new RemoteViews(mContext.getPackageName(), R.layout.widget);
                    setupTitleAndCount(views);
                    mWidgetManager.partiallyUpdateAppWidget(mWidgetId, views);
                    mWidgetManager.notifyAppWidgetViewDataChanged(mWidgetId, R.id.message_list);
                }
            });
        }

        /**
         * Stop any pending load, reset selection parameters, and start loading
         * Must be called from the UI thread
         * @param viewType the current ViewType
         */
        private void load(ViewType viewType) {
            reset();
            setSelection(viewType.selection);
            setSelectionArgs(viewType.selectionArgs);
            startLoading();
        }
    }

    /**
     * Initialize to first appropriate view (depending on the number of accounts)
     */
    public void init() {
        // Just update the account count & header; no need to validate the view
        updateWidget(false);
        switchView(); // TODO Do we really need this??
    }

    /**
     * Reset cursor and cursor count, notify widget that list data is invalid, and start loading
     * with our current ViewType
     */
    private void loadView() {
        synchronized(mCursorLock) {
            mCursorCount = TOTAL_COUNT_UNKNOWN;
            mCursor = null;
            mWidgetManager.notifyAppWidgetViewDataChanged(mWidgetId, R.id.message_list);
            mLoader.load(mViewType);
        }
    }

    /**
     * Switch to the next widget view (all -> account1 -> ... -> account n -> unread -> starred)
     *
     * This must be called on a background thread.  Use {@link #switchView} on the UI thread.
     */
    private synchronized void switchToNextView() {
        switch(mViewType) {
            // If we're in starred and there is more than one account, go to "all mail"
            // Otherwise, fall through to the accounts themselves
            case STARRED:
                if (EmailContent.count(mContext, Account.CONTENT_URI) > 1) {
                    mViewType = ViewType.ALL_INBOX;
                    break;
                }
                //$FALL-THROUGH$
            case ALL_INBOX:
                ViewType.ACCOUNT.selectionArgs[0] = "0";
                //$FALL-THROUGH$
            case ACCOUNT:
                // Find the next account (or, if none, default to UNREAD)
                String idString = ViewType.ACCOUNT.selectionArgs[0];
                Cursor c = mResolver.query(Account.CONTENT_URI, ID_NAME_PROJECTION, "_id>?",
                        new String[] {idString}, SORT_ID_ASCENDING);
                try {
                    if (c.moveToFirst()) {
                        mViewType = ViewType.ACCOUNT;
                        mViewType.selectionArgs[0] = c.getString(ID_NAME_COLUMN_ID);
                        mViewType.setTitle(c.getString(ID_NAME_COLUMN_NAME));
                    } else {
                        mViewType = ViewType.UNREAD;
                    }
                } finally {
                    c.close();
                }
                break;
            case UNREAD:
                mViewType = ViewType.STARRED;
                break;
        }
    }

    /**
     * Returns whether the current view is valid. The following rules determine if a view is
     * considered valid:
     * 1. If the view is either {@link ViewType#STARRED} or {@link ViewType#UNREAD}, always
     * returns <code>true</code>.
     * 2. If the view is {@link ViewType#ALL_INBOX}, returns <code>true</code> if more than
     * one account is defined. Otherwise, returns <code>false</code>.
     * 3. If the view is {@link ViewType#ACCOUNT}, returns <code>true</code> if the account
     * is defined. Otherwise, returns <code>false</code>.
     */
    private boolean isViewValid() {
        switch(mViewType) {
            case ALL_INBOX:
                // "all inbox" is valid only if there is more than one account
                return (EmailContent.count(mContext, Account.CONTENT_URI) > 1);
            case ACCOUNT:
                // Ensure current account still exists
                String idString = ViewType.ACCOUNT.selectionArgs[0];
                Cursor c = mResolver.query(Account.CONTENT_URI, ID_NAME_PROJECTION, "_id=?",
                        new String[] {idString}, SORT_ID_ASCENDING);
                try {
                    return c.moveToFirst();
                } finally {
                    c.close();
                }
        }
        return true;
    }

    /**
     * Convenience method for creating an onClickPendingIntent that executes a command via
     * our command Uri.  Used for the "next view" command; appends the widget id to the command
     * Uri.
     *
     * @param views The RemoteViews we're inflating
     * @param buttonId the id of the button view
     * @param data the command Uri
     */
    private void setCommandIntent(RemoteViews views, int buttonId, Uri data) {
        Intent intent = new Intent(mContext, WidgetService.class);
        intent.setDataAndType(ContentUris.withAppendedId(data, mWidgetId), WIDGET_DATA_MIME_TYPE);
        PendingIntent pendingIntent = PendingIntent.getService(mContext, 0, intent,
                PendingIntent.FLAG_UPDATE_CURRENT);
        views.setOnClickPendingIntent(buttonId, pendingIntent);
    }

    /**
     * Convenience method for creating an onClickPendingIntent that launches another activity
     * directly.
     *
     * @param views The RemoteViews we're inflating
     * @param buttonId the id of the button view
     * @param intent The intent to be used when launching the activity
     */
    private void setActivityIntent(RemoteViews views, int buttonId, Intent intent) {
        PendingIntent pendingIntent =
                PendingIntent.getActivity(mContext, 0, intent, 0);
        views.setOnClickPendingIntent(buttonId, pendingIntent);
    }

    /**
     * Convenience method for constructing a fillInIntent for a given list view element.
     * Appends the command and any arguments to a base Uri.
     *
     * @param views the RemoteViews we are inflating
     * @param viewId the id of the view
     * @param baseUri the base uri for the command
     * @param args any arguments to the command
     */
    private void setFillInIntent(RemoteViews views, int viewId, Uri baseUri, String ... args) {
        Intent intent = new Intent();
        Builder builder = baseUri.buildUpon();
        for (String arg: args) {
            builder.appendPath(arg);
        }
        intent.setDataAndType(builder.build(), WIDGET_DATA_MIME_TYPE);
        views.setOnClickFillInIntent(viewId, intent);
    }

    /**
     * Called back by {@link com.android.email.provider.WidgetProvider.WidgetService} to
     * handle intents created by remote views.
     */
    public static boolean processIntent(Context context, Intent intent) {
        final Uri data = intent.getData();
        if (data == null) {
            return false;
        }
        List<String> pathSegments = data.getPathSegments();
        // Our path segments are <command>, <arg1> [, <arg2>]
        // First, a quick check of Uri validity
        if (pathSegments.size() < 2) {
            throw new IllegalArgumentException();
        }
        String command = pathSegments.get(0);
        // Ignore unknown action names
        try {
            final long arg1 = Long.parseLong(pathSegments.get(1));
            if (EmailWidget.COMMAND_NAME_VIEW_MESSAGE.equals(command)) {
                // "view", <message id>, <mailbox id>
                openMessage(context, Long.parseLong(pathSegments.get(2)), arg1);
            } else if (EmailWidget.COMMAND_NAME_SWITCH_LIST_VIEW.equals(command)) {
                // "next_view", <widget id>
                EmailWidget widget = WidgetManager.getInstance().get((int)arg1);
                if (widget != null) {
                    widget.switchView();
                }
            }
        } catch (NumberFormatException e) {
            // Shouldn't happen as we construct all of the Uri's
            return false;
        }
        return true;
    }

    private static void openMessage(final Context context, final long mailboxId,
            final long messageId) {
        Utility.runAsync(new Runnable() {
            @Override
            public void run() {
                Mailbox mailbox = Mailbox.restoreMailboxWithId(context, mailboxId);
                if (mailbox == null) return;
                context.startActivity(Welcome.createOpenMessageIntent(context, mailbox.mAccountKey,
                        mailboxId, messageId));
            }
        });
    }

    private void setupTitleAndCount(RemoteViews views) {
        // Set up the title (view type + count of messages)
        views.setTextViewText(R.id.widget_title, mViewType.getTitle(mContext));
        views.setTextViewText(R.id.widget_tap, sConfigureText);
        String count = "";
        if (mCursorCount != TOTAL_COUNT_UNKNOWN) {
            count = UiUtilities.getMessageCountForUi(mContext, mCursor.getCount(), false);
        }
        views.setTextViewText(R.id.widget_count, count);
    }
    /**
     * Update the "header" of the widget (i.e. everything that doesn't include the scrolling
     * message list)
     */
    public void updateHeader() {
        if (Email.DEBUG) {
            Log.d(TAG, "updateWidget " + mWidgetId);
        }

        // Get the widget layout
        RemoteViews views =
                new RemoteViews(mContext.getPackageName(), R.layout.widget);

        // Set up the list with an adapter
        Intent intent = new Intent(mContext, WidgetService.class);
        intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mWidgetId);
        intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME)));
        views.setRemoteAdapter(mWidgetId, R.id.message_list, intent);

        setupTitleAndCount(views);

        if (mAccountCount == 0) {
            // Hide compose icon & show "touch to configure" text
            views.setViewVisibility(R.id.widget_compose, View.INVISIBLE);
            views.setViewVisibility(R.id.message_list, View.GONE);
            views.setViewVisibility(R.id.tap_to_configure, View.VISIBLE);
            // Create click intent for "touch to configure" target
            intent = Welcome.createOpenAccountInboxIntent(mContext, -1);
            setActivityIntent(views, R.id.tap_to_configure, intent);
        } else {
            // Show compose icon & message list
            views.setViewVisibility(R.id.widget_compose, View.VISIBLE);
            views.setViewVisibility(R.id.message_list, View.VISIBLE);
            views.setViewVisibility(R.id.tap_to_configure, View.GONE);
            // Create click intent for "compose email" target
            intent = MessageCompose.getMessageComposeIntent(mContext, -1);
            setActivityIntent(views, R.id.widget_compose, intent);
        }
        // Create click intent for "view rotation" target
        setCommandIntent(views, R.id.widget_logo, COMMAND_URI_SWITCH_LIST_VIEW);

        // Use a bare intent for our template; we need to fill everything in
        intent = new Intent(mContext, WidgetService.class);
        PendingIntent pendingIntent = PendingIntent.getService(mContext, 0, intent,
                PendingIntent.FLAG_UPDATE_CURRENT);
        views.setPendingIntentTemplate(R.id.message_list, pendingIntent);

        // And finally update the widget
        mWidgetManager.updateAppWidget(mWidgetId, views);
    }

    /**
     * Add size and color styling to text
     *
     * @param text the text to style
     * @param size the font size for this text
     * @param color the color for this text
     * @return a CharSequence quitable for use in RemoteViews.setTextViewText()
     */
    private CharSequence addStyle(CharSequence text, int size, int color) {
        SpannableStringBuilder builder = new SpannableStringBuilder(text);
        builder.setSpan(
                new AbsoluteSizeSpan(size), 0, text.length(),
                Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        if (color != 0) {
            builder.setSpan(new ForegroundColorSpan(color), 0, text.length(),
                    Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        }
        return builder;
    }

    /**
     * Create styled text for our combination subject and snippet
     *
     * @param subject the message's subject (or null)
     * @param snippet the message's snippet (or null)
     * @param read whether or not the message is read
     * @return a CharSequence suitable for use in RemoteViews.setTextViewText()
     */
    private CharSequence getStyledSubjectSnippet (String subject, String snippet,
            boolean read) {
        SpannableStringBuilder ssb = new SpannableStringBuilder();
        boolean hasSubject = false;
        if (!TextUtils.isEmpty(subject)) {
            SpannableString ss = new SpannableString(subject);
            ss.setSpan(new StyleSpan(read ? Typeface.NORMAL : Typeface.BOLD), 0, ss.length(),
                    Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            ss.setSpan(new ForegroundColorSpan(sDefaultTextColor), 0, ss.length(),
                    Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            ssb.append(ss);
            hasSubject = true;
        }
        if (!TextUtils.isEmpty(snippet)) {
            if (hasSubject) {
                ssb.append(sSubjectSnippetDivider);
            }
            SpannableString ss = new SpannableString(snippet);
            ss.setSpan(new ForegroundColorSpan(sLightTextColor), 0, snippet.length(),
                    Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            ssb.append(ss);
        }
        return addStyle(ssb, sSubjectFontSize, 0);
    }

    @Override
    public RemoteViews getViewAt(int position) {
        // Use the cursor to set up the widget
        synchronized (mCursorLock) {
            if (mCursor == null || mCursor.isClosed() || !mCursor.moveToPosition(position)) {
                return getLoadingView();
            }
            RemoteViews views =
                new RemoteViews(mContext.getPackageName(), R.layout.widget_list_item);
            boolean isUnread = mCursor.getInt(WIDGET_COLUMN_FLAG_READ) != 1;
            int drawableId = R.drawable.widget_read_conversation_selector;
            if (isUnread) {
                drawableId = R.drawable.widget_unread_conversation_selector;
            }
            views.setInt(R.id.widget_message, "setBackgroundResource", drawableId);

            // Add style to sender
            SpannableStringBuilder from =
                new SpannableStringBuilder(mCursor.getString(WIDGET_COLUMN_DISPLAY_NAME));
            from.setSpan(
                    isUnread ? new StyleSpan(Typeface.BOLD) : new StyleSpan(Typeface.NORMAL), 0,
                    from.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            CharSequence styledFrom = addStyle(from, sSenderFontSize, sDefaultTextColor);
            views.setTextViewText(R.id.widget_from, styledFrom);

            long timestamp = mCursor.getLong(WIDGET_COLUMN_TIMESTAMP);
            // Get a nicely formatted date string (relative to today)
            String date = DateUtils.getRelativeTimeSpanString(mContext, timestamp).toString();
            // Add style to date
            CharSequence styledDate = addStyle(date, sDateFontSize, sDefaultTextColor);
            views.setTextViewText(R.id.widget_date, styledDate);

            // Add style to subject/snippet
            String subject = mCursor.getString(WIDGET_COLUMN_SUBJECT);
            String snippet = mCursor.getString(WIDGET_COLUMN_SNIPPET);
            CharSequence subjectAndSnippet =
                getStyledSubjectSnippet(subject, snippet, !isUnread);
            views.setTextViewText(R.id.widget_subject, subjectAndSnippet);

            int messageFlags = mCursor.getInt(WIDGET_COLUMN_FLAGS);
            boolean hasInvite = (messageFlags & Message.FLAG_INCOMING_MEETING_INVITE) != 0;
            views.setViewVisibility(R.id.widget_invite, hasInvite ? View.VISIBLE : View.GONE);

            boolean hasAttachment = mCursor.getInt(WIDGET_COLUMN_FLAG_ATTACHMENT) != 0;
            views.setViewVisibility(R.id.widget_attachment,
                    hasAttachment ? View.VISIBLE : View.GONE);

            if (mViewType == ViewType.ACCOUNT) {
                views.setViewVisibility(R.id.color_chip, View.INVISIBLE);
            } else {
                long accountId = mCursor.getLong(WIDGET_COLUMN_ACCOUNT_KEY);
                int colorId = mResourceHelper.getAccountColorId(accountId);
                if (colorId != ResourceHelper.UNDEFINED_RESOURCE_ID) {
                    // Color defined by resource ID, so, use it
                    views.setViewVisibility(R.id.color_chip, View.VISIBLE);
                    views.setImageViewResource(R.id.color_chip, colorId);
                } else {
                    // Color not defined by resource ID, nothing we can do, so, hide the chip
                    views.setViewVisibility(R.id.color_chip, View.INVISIBLE);
                }
            }

            // Set button intents for view, reply, and delete
            String messageId = mCursor.getString(WIDGET_COLUMN_ID);
            String mailboxId = mCursor.getString(WIDGET_COLUMN_MAILBOX_KEY);
            setFillInIntent(views, R.id.widget_message, COMMAND_URI_VIEW_MESSAGE,
                    messageId, mailboxId);

            return views;
        }
    }

    @Override
    public int getCount() {
        if (mCursor == null) return 0;
        return Math.min(mCursor.getCount(), MAX_MESSAGE_LIST_COUNT);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public RemoteViews getLoadingView() {
        RemoteViews view = new RemoteViews(mContext.getPackageName(), R.layout.widget_loading);
        view.setTextViewText(R.id.loading_text, mContext.getString(R.string.widget_loading));
        return view;
    }

    @Override
    public int getViewTypeCount() {
        // Regular list view and the "loading" view
        return 2;
    }

    @Override
    public boolean hasStableIds() {
        return true;
    }

    @Override
    public void onDataSetChanged() {
    }

    public void onDeleted() {
        if (mLoader != null) {
            mLoader.stopLoading();
        }
        WidgetManager.getInstance().remove(mWidgetId);
    }

    @Override
    public void onDestroy() {
        if (mLoader != null) {
            mLoader.stopLoading();
        }
        WidgetManager.getInstance().remove(mWidgetId);
    }

    @Override
    public void onCreate() {
    }

    /**
     * Switch to the next view.
     */
    /* package */ void switchView() {
        switchView(false);
    }

    private WidgetViewSwitcher switchView(boolean disableLoadAfterSwitchForTest) {
        WidgetViewSwitcher switcher = new WidgetViewSwitcher(this, disableLoadAfterSwitchForTest);
        switcher.execute();
        return switcher;
    }

    /**
     * Switch views synchronously without loading
     */
    /* package */ void switchViewSyncForTest() {
        WidgetViewSwitcher switcher = switchView(true);
        try {
            switcher.get();
        } catch (InterruptedException e) {
            Assert.fail();
        } catch (ExecutionException e) {
            Assert.fail();
        }
    }

    /**
     * Utility class to handle switching widget views; in the background, we access the database
     * to determine account status, etc.  In the foreground, we start up the Loader with new
     * parameters
     */
    private static class WidgetViewSwitcher extends AsyncTask<Void, Void, Void> {
        private final EmailWidget mWidget;
        private final boolean mDisableLoadAfterSwitchForTest;

        public WidgetViewSwitcher(EmailWidget widget, boolean disableLoadAfterSwitchForTest) {
            mWidget = widget;
            mDisableLoadAfterSwitchForTest = disableLoadAfterSwitchForTest;
        }

        @Override
        protected Void doInBackground(Void... params) {
            mWidget.switchToNextView();
            return null;
        }

        @Override
        protected void onPostExecute(Void param) {
            if (isCancelled()) {
                return;
            }
            if (!mDisableLoadAfterSwitchForTest) {
                mWidget.loadView();
            }
        }
    }
}