MailboxFinder.java revision 2193962ca2b3157e79f731736afa2a0c972e778a 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.email.activity;
18
19import com.android.email.Controller;
20import com.android.email.ControllerResultUiThreadWrapper;
21import com.android.email.Email;
22import com.android.email.Utility;
23import com.android.email.provider.EmailContent.Account;
24import com.android.email.provider.EmailContent.Mailbox;
25import com.android.emailcommon.mail.MessagingException;
26
27import android.content.Context;
28import android.os.AsyncTask;
29import android.os.Handler;
30import android.util.Log;
31
32/**
33 * A class that finds a mailbox ID by account ID and mailbox type.
34 *
35 * If an account doesn't have a mailbox of a specified type, it refreshes the mailbox list and
36 * try looking for again.
37 *
38 * This is a "one-shot" class.  You create an instance, call {@link #startLookup}, get a result
39 * or call {@link #cancel}, and that's it.  The instance can't be re-used.
40 */
41public class MailboxFinder {
42    private final Context mContext;
43    private final Controller mController;
44
45    // Actual Controller.Result that will wrapped by ControllerResultUiThreadWrapper.
46    // Unit tests directly use it to avoid asynchronicity caused by ControllerResultUiThreadWrapper.
47    private final ControllerResults mInnerControllerResults;
48    private Controller.Result mControllerResults; // Not final, we null it out when done.
49
50    private final long mAccountId;
51    private final int mMailboxType;
52    private final Callback mCallback;
53
54    private FindMailboxTask mTask;
55    private boolean mStarted;
56    private boolean mClosed;
57
58    /**
59     * Callback for results.
60     */
61    public interface Callback {
62        public void onAccountNotFound();
63        public void onMailboxNotFound(long accountId);
64        public void onAccountSecurityHold(long accountId);
65        public void onMailboxFound(long accountId, long mailboxId);
66    }
67
68    /**
69     * Creates an instance for {@code accountId} and {@code mailboxType}.  (But won't start yet)
70     *
71     * Must be called on the UI thread.
72     */
73    public MailboxFinder(Context context, long accountId, int mailboxType, Callback callback) {
74        if (accountId == -1) {
75            throw new UnsupportedOperationException();
76        }
77        mContext = context.getApplicationContext();
78        mController = Controller.getInstance(context);
79        mAccountId = accountId;
80        mMailboxType = mailboxType;
81        mCallback = callback;
82        mInnerControllerResults = new ControllerResults();
83        mControllerResults = new ControllerResultUiThreadWrapper<ControllerResults>(
84                new Handler(), mInnerControllerResults);
85        mController.addResultCallback(mControllerResults);
86    }
87
88    /**
89     * Start looking up.
90     *
91     * Must be called on the UI thread.
92     */
93    public void startLookup() {
94        if (mStarted) {
95            throw new IllegalStateException(); // Can't start twice.
96        }
97        mStarted = true;
98        mTask = new FindMailboxTask(true);
99        mTask.execute();
100    }
101
102    /**
103     * Cancel the operation.  It's safe to call it multiple times, or even if the operation is
104     * already finished.
105     */
106    public void cancel() {
107        if (!mClosed) {
108            close();
109        }
110    }
111
112    /**
113     * Stop the running task, if exists, and clean up internal resources.
114     */
115    private void close() {
116        mClosed = true;
117        if (mControllerResults != null) {
118            mController.removeResultCallback(mControllerResults);
119            mControllerResults = null;
120        }
121        Utility.cancelTaskInterrupt(mTask);
122        mTask = null;
123    }
124
125    private class ControllerResults extends Controller.Result {
126        @Override
127        public void updateMailboxListCallback(MessagingException result, long accountId,
128                int progress) {
129            if (mClosed || (accountId != mAccountId)) {
130                return; // Already closed, or non-target account.
131            }
132            Log.i(Email.LOG_TAG, "MailboxFinder: updateMailboxListCallback");
133            if (result != null) {
134                // Error while updating the mailbox list.  Notify the UI...
135                try {
136                    mCallback.onMailboxNotFound(mAccountId);
137                } finally {
138                    close();
139                }
140            } else if (progress == 100) {
141                // Mailbox list updated, look for mailbox again...
142                mTask = new FindMailboxTask(false);
143                mTask.execute();
144            }
145        }
146    }
147
148    /**
149     * Async task for finding a single mailbox by type.  If a mailbox of a type is not found,
150     * and {@code okToRecurse} is true, we update the mailbox list and try looking again.
151     */
152    private class FindMailboxTask extends AsyncTask<Void, Void, Long> {
153        private final boolean mOkToRecurse;
154
155        private static final int RESULT_MAILBOX_FOUND = 0;
156        private static final int RESULT_ACCOUNT_SECURITY_HOLD = 1;
157        private static final int RESULT_ACCOUNT_NOT_FOUND = 2;
158        private static final int RESULT_MAILBOX_NOT_FOUND = 3;
159        private static final int RESULT_START_NETWORK_LOOK_UP = 4;
160
161        private int mResult = -1;
162
163        /**
164         * Special constructor to cache some local info
165         */
166        public FindMailboxTask(boolean okToRecurse) {
167            mOkToRecurse = okToRecurse;
168        }
169
170        @Override
171        protected Long doInBackground(Void... params) {
172            // Quick check that account is not in security hold
173            if (Account.isSecurityHold(mContext, mAccountId)) {
174                mResult = RESULT_ACCOUNT_SECURITY_HOLD;
175                return Mailbox.NO_MAILBOX;
176            }
177
178            // See if we can find the requested mailbox in the DB.
179            long mailboxId = Mailbox.findMailboxOfType(mContext, mAccountId, mMailboxType);
180            if (mailboxId != Mailbox.NO_MAILBOX) {
181                mResult = RESULT_MAILBOX_FOUND;
182                return mailboxId; // Found
183            }
184
185            // Mailbox not found.  Does the account really exists?
186            final boolean accountExists = Account.isValidId(mContext, mAccountId);
187            if (accountExists) {
188                if (mOkToRecurse) {
189                    // launch network lookup
190                    mResult = RESULT_START_NETWORK_LOOK_UP;
191                } else {
192                    mResult = RESULT_MAILBOX_NOT_FOUND;
193                }
194            } else {
195                mResult = RESULT_ACCOUNT_NOT_FOUND;
196            }
197            return Mailbox.NO_MAILBOX;
198        }
199
200        @Override
201        protected void onPostExecute(Long mailboxId) {
202            if (isCancelled()) {
203                return;
204            }
205            switch (mResult) {
206                case RESULT_ACCOUNT_SECURITY_HOLD:
207                    Log.w(Email.LOG_TAG, "MailboxFinder: Account security hold.");
208                    try {
209                        mCallback.onAccountSecurityHold(mAccountId);
210                    } finally {
211                        close();
212                    }
213                    return;
214                case RESULT_ACCOUNT_NOT_FOUND:
215                    Log.w(Email.LOG_TAG, "MailboxFinder: Account not found.");
216                    try {
217                        mCallback.onAccountNotFound();
218                    } finally {
219                        close();
220                    }
221                    return;
222                case RESULT_MAILBOX_NOT_FOUND:
223                    Log.w(Email.LOG_TAG, "MailboxFinder: Mailbox not found.");
224                    try {
225                        mCallback.onMailboxNotFound(mAccountId);
226                    } finally {
227                        close();
228                    }
229                    return;
230                case RESULT_MAILBOX_FOUND:
231                    if (Email.DEBUG_LIFECYCLE && Email.DEBUG) {
232                        Log.d(Email.LOG_TAG, "MailboxFinder: mailbox found: id=" + mailboxId);
233                    }
234                    try {
235                        mCallback.onMailboxFound(mAccountId, mailboxId);
236                    } finally {
237                        close();
238                    }
239                    return;
240                case RESULT_START_NETWORK_LOOK_UP:
241                    // Not found locally.  Let's sync the mailbox list...
242                    Log.i(Email.LOG_TAG, "MailboxFinder: Starting network lookup.");
243                    mController.updateMailboxList(mAccountId);
244                    return;
245                default:
246                    throw new RuntimeException();
247            }
248        }
249    }
250
251    /* package */ boolean isStartedForTest() {
252        return mStarted;
253    }
254
255    /**
256     * Called by unit test.  Return true if all the internal resources are really released.
257     */
258    /* package */ boolean isReallyClosedForTest() {
259        return mClosed && (mTask == null) && (mControllerResults == null);
260    }
261
262    /* package */ Controller.Result getControllerResultsForTest() {
263        return mInnerControllerResults;
264    }
265}
266