AccountChangeReceiver.java

package edu.mit.mobile.android.locast.accounts;

/*
 * Copyright (C) 2011  MIT Mobile Experience Lab
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
import java.util.Arrays;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.util.Log;
import edu.mit.mobile.android.locast.Constants;
import edu.mit.mobile.android.locast.ver2.browser.ResetActivity;

public class AccountChangeReceiver extends BroadcastReceiver {
	private static final String TAG = AccountChangeReceiver.class.getSimpleName();

	private static final String PREF_ACCOUNT_NAMES = "accountNames";

	private static final String ACCOUNT_STRING_DELIMITER = ",";


	@Override
	public void onReceive(Context context, Intent intent) {
		final AccountManager am = AccountManager.get(context);

		final SharedPreferences prefs = context.getSharedPreferences("account",
				Context.MODE_PRIVATE);
		final String existingAccountString = prefs.getString(PREF_ACCOUNT_NAMES, "");
		final Account[] currentAccounts = am.getAccountsByType(AuthenticationService.ACCOUNT_TYPE);
		Arrays.sort(currentAccounts);
		final String[] lastKnownAccounts = existingAccountString.length() > 0 ? existingAccountString
				.split(ACCOUNT_STRING_DELIMITER) : new String[0];

		// not very efficient for large numbers, but we only ever expect to have 0 or 1 accounts
		// maybe 2 if we're unlucky.
		for (final String lastKnownAccount : lastKnownAccounts) {

			boolean found = false;
			for (final Account currentAccount : currentAccounts) {
				if (currentAccount.name.equals(lastKnownAccount)) {
					found = true;
					break;
				}
			}

			// account has been deleted
			if (!found) {
				onAccountDeleted(context, new Account(lastKnownAccount,
						AuthenticationService.ACCOUNT_TYPE));
			}
		}

		final StringBuilder accountString = new StringBuilder();
		final boolean first = true;
		for (final Account currentAccount : currentAccounts) {
			boolean found = false;
			for (final String lastKnownAccount : lastKnownAccounts) {
				if (currentAccount.name.equals(lastKnownAccount)) {
					found = true;
					break;
				}
			}

			if (!found) {
				onAccountAdded(context, currentAccount);
			}
			if (!first) {
				accountString.append(ACCOUNT_STRING_DELIMITER);
			}
			accountString.append(currentAccount.name);
		}

		prefs.edit().putString(PREF_ACCOUNT_NAMES, accountString.toString()).commit();
	}

	private void onAccountDeleted(Context context, Account account) {
		if (Constants.DEBUG) {
			Log.d(TAG, "Locast account removed: " + account);
		}

		// only delete the database when it was a real account
		if (!Authenticator.DEMO_ACCOUNT.equals(account.name)) {
			ResetActivity.resetEverything(context, false, false);
		}
	}

	private void onAccountAdded(Context context, Account account) {
		// that's swell! we don't really need to do anything.
		if (Constants.DEBUG) {
			Log.d(TAG, "Locast account added: " + account);
		}
	}

}