/*
 * Copyright (C) 2010 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;

import com.android.email.service.MailService;
import com.android.emailcommon.AccountManagerTypes;
import com.android.emailcommon.CalendarProviderStub;
import com.android.emailcommon.Logging;
import com.android.emailcommon.provider.EmailContent;

import android.content.ContentResolver;
import android.content.Context;
import android.database.Cursor;
import android.provider.ContactsContract;
import android.util.Log;

/**
 * Utility functions to support backup and restore of accounts.
 *
 * In the short term, this is used to work around local database failures.  In the long term,
 * this will also support server-side backups, providing support for automatic account restoration
 * when switching or replacing phones.
 */
public class AccountBackupRestore {

    // This reduces the need for expensive checks to just the first time only/
    // synchronize on AccountBackupRestore.class
    private static boolean sBackupsChecked = false;

    /**
     * Backup accounts.  Can be called from UI thread (does work in a new thread)
     */
    public static void backupAccounts(final Context context) {
        if (Email.DEBUG) {
            Log.v(Logging.LOG_TAG, "backupAccounts");
        }
        // Because we typically call this from the UI, let's do the work in a thread
        new Thread() {
            @Override
            public void run() {
                doBackupAccounts(context, Preferences.getPreferences(context));
            }
        }.start();
    }

    /**
     * Restore accounts if needed.  This is blocking, and should only be called in specific
     * startup/entry points.
     */
    public static synchronized void restoreAccountsIfNeeded(final Context context) {
        // Quick exit if possible
        if (sBackupsChecked) return;

        // Don't log here;  This is called often.
        boolean restored = doRestoreAccounts(context, Preferences.getPreferences(context), false);
        if (restored) {
            // after restoring accounts, register services appropriately
            Log.w(Logging.LOG_TAG, "Register services after restoring accounts");
            // update security profile
            SecurityPolicy.getInstance(context).updatePolicies(-1);
            // enable/disable other email services as necessary
            Email.setServicesEnabledSync(context);
            ExchangeUtils.startExchangeService(context);
        }
        sBackupsChecked = true;
    }

    /**
     * Non-UI-Thread worker to backup all accounts
     *
     * @param context used to access the provider
     * @param preferences used to access the backups (provided separately for testability)
     */
    /* package */ synchronized static void doBackupAccounts(Context context,
            Preferences preferences) {
        // 1.  Wipe any existing backup accounts
        Account[] oldBackups = preferences.getAccounts();
        for (Account backup : oldBackups) {
            backup.delete(preferences);
        }

        // 2. Identify the default account (if any).  This is required because setting
        // the default account flag is lazy,and sometimes we don't have any flags set.  We'll
        // use this to make it explicit (see loop, below).
        // This is also the quick check for "no accounts" (the only case in which the returned
        // value is -1) and if so, we can exit immediately.
        long defaultAccountId = EmailContent.Account.getDefaultAccountId(context);
        if (defaultAccountId == -1) {
            return;
        }

        // 3. Create new backup(s), if any
        Cursor c = context.getContentResolver().query(EmailContent.Account.CONTENT_URI,
                EmailContent.Account.CONTENT_PROJECTION, null, null, null);
        try {
            while (c.moveToNext()) {
                EmailContent.Account fromAccount =
                        EmailContent.getContent(c, EmailContent.Account.class);
                if (Email.DEBUG) {
                    Log.v(Logging.LOG_TAG, "Backing up account:" + fromAccount.getDisplayName());
                }
                Account toAccount = LegacyConversions.makeLegacyAccount(context, fromAccount);

                // Determine if contacts are also synced, and if so, record that
                if (fromAccount.isEasAccount(context)) {
                    android.accounts.Account acct = new android.accounts.Account(
                            fromAccount.mEmailAddress, AccountManagerTypes.TYPE_EXCHANGE);
                    boolean syncContacts = ContentResolver.getSyncAutomatically(acct,
                            ContactsContract.AUTHORITY);
                    if (syncContacts) {
                        toAccount.mBackupFlags |= Account.BACKUP_FLAGS_SYNC_CONTACTS;
                    }
                    boolean syncCalendar = ContentResolver.getSyncAutomatically(acct,
                            CalendarProviderStub.AUTHORITY);
                    if (syncCalendar) {
                        toAccount.mBackupFlags |= Account.BACKUP_FLAGS_SYNC_CALENDAR;
                    }
                    boolean syncEmail = ContentResolver.getSyncAutomatically(acct,
                            EmailContent.AUTHORITY);
                    if (!syncEmail) {
                        toAccount.mBackupFlags |= Account.BACKUP_FLAGS_DONT_SYNC_EMAIL;
                    }
                }

                // Attachment downloading
                if ((fromAccount.mFlags & EmailContent.Account.FLAGS_BACKGROUND_ATTACHMENTS) != 0) {
                    toAccount.mBackupFlags |= Account.BACKUP_FLAGS_BACKGROUND_ATTACHMENTS;
                }

                // If this is the default account, mark it as such
                if (fromAccount.mId == defaultAccountId) {
                    toAccount.mBackupFlags |= Account.BACKUP_FLAGS_IS_DEFAULT;
                }

                // Mark this account as a backup of a Provider account, instead of a legacy
                // account to upgrade
                toAccount.mBackupFlags |= Account.BACKUP_FLAGS_IS_BACKUP;

                toAccount.save(preferences);
            }
        } finally {
            c.close();
        }
    }

    /**
     * Restore all accounts.  This is blocking.
     *
     * @param context used to access the provider
     * @param preferences used to access the backups (provided separately for testability)
     * @return true if accounts were restored (meaning services should be restarted, etc.)
     */
    /* package */ synchronized static boolean doRestoreAccounts(Context context,
            Preferences preferences, boolean unitTest) {
        boolean result = false;

        // 1. Quick check - if we have any accounts, get out
        int numAccounts = EmailContent.count(context, EmailContent.Account.CONTENT_URI, null, null);
        if (numAccounts > 0) {
            return result;
        }
        // 2. Quick check - if no backup accounts, get out
        Account[] backups = preferences.getAccounts();
        if (backups.length == 0) {
            return result;
        }

        Log.w(Logging.LOG_TAG, "*** Restoring Email Accounts, found " + backups.length);

        // 3. Possible lost accounts situation - check for any backups, and restore them
        for (Account backupAccount : backups) {
            // don't back up any leftover legacy accounts (these are migrated elsewhere).
            if ((backupAccount.mBackupFlags & Account.BACKUP_FLAGS_IS_BACKUP) == 0) {
                continue;
            }
            // Restore the account
            Log.w(Logging.LOG_TAG, "Restoring account:" + backupAccount.getDescription());
            EmailContent.Account toAccount = LegacyConversions.makeAccount(context, backupAccount);

            // Mark the default account if this is it
            if (0 != (backupAccount.mBackupFlags & Account.BACKUP_FLAGS_IS_DEFAULT)) {
                toAccount.setDefaultAccount(true);
            }

            // Restore attachment flag
            if (0 != (backupAccount.mBackupFlags & Account.BACKUP_FLAGS_BACKGROUND_ATTACHMENTS)) {
                toAccount.mFlags |= EmailContent.Account.FLAGS_BACKGROUND_ATTACHMENTS;
            }

            // Note that the sense of the email flag is opposite that of contacts/calendar flags
            boolean email =
                (backupAccount.mBackupFlags & Account.BACKUP_FLAGS_DONT_SYNC_EMAIL) == 0;
            boolean contacts = false;
            boolean calendar = false;
            // Handle system account first, then save in provider
            if (toAccount.isEasAccount(context)) {
                contacts = (backupAccount.mBackupFlags & Account.BACKUP_FLAGS_SYNC_CONTACTS) != 0;
                calendar = (backupAccount.mBackupFlags & Account.BACKUP_FLAGS_SYNC_CALENDAR) != 0;
            }

            toAccount.save(context);
            // Don't simulate AccountManager in unit tests; this results in an NPE
            // The unit tests only check EmailProvider based functionality
            if (!unitTest) {
                MailService.setupAccountManagerAccount(context, toAccount, email, calendar,
                        contacts, null);
            }
            result = true;
        }
        return result;
    }
}