libs/utils/WordPressUtils/src/main/java/org/wordpress/android/util/UserEmailUtils.java

package org.wordpress.android.util;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.content.Context;
import android.util.Patterns;

import org.wordpress.android.util.AppLog.T;

import java.util.regex.Pattern;

public class UserEmailUtils {
    /**
     * Get primary account and return its name if it matches the email address pattern.
     *
     * @return primary account email address if it can be found or empty string else.
     */
    public static String getPrimaryEmail(Context context) {
        try {
            AccountManager accountManager = AccountManager.get(context);
            if (accountManager == null)
                return "";
            Account[] accounts = accountManager.getAccounts();
            Pattern emailPattern = Patterns.EMAIL_ADDRESS;
            for (Account account : accounts) {
                // make sure account.name is an email address before adding to the list
                if (emailPattern.matcher(account.name).matches()) {
                    return account.name;
                }
            }
            return "";
        } catch (SecurityException e) {
            // exception will occur if app doesn't have GET_ACCOUNTS permission
            AppLog.e(T.UTILS, "SecurityException - missing GET_ACCOUNTS permission");
            return "";
        }
    }
}