/*
 * 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 android.accounts;

import com.google.android.collect.Sets;

import android.app.Activity;
import android.app.ActivityManager;
import android.content.Intent;
import android.os.Bundle;
import android.os.IBinder;
import android.os.Parcelable;
import android.os.RemoteException;
import android.os.UserHandle;
import android.os.UserManager;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

import com.android.internal.R;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

@hide
/**
 * @hide
 */
public class ChooseTypeAndAccountActivity extends Activity
        implements AccountManagerCallback<Bundle> {
    private static final String TAG = "AccountChooser";

    
A Parcelable ArrayList of Account objects that limits the choosable accounts to those
in this list, if this parameter is supplied.
/**
     * A Parcelable ArrayList of Account objects that limits the choosable accounts to those
     * in this list, if this parameter is supplied.
     */
    public static final String EXTRA_ALLOWABLE_ACCOUNTS_ARRAYLIST = "allowableAccounts";

    
A Parcelable ArrayList of String objects that limits the accounts to choose to those
that match the types in this list, if this parameter is supplied. This list is also
used to filter the allowable account types if add account is selected.
/**
     * A Parcelable ArrayList of String objects that limits the accounts to choose to those
     * that match the types in this list, if this parameter is supplied. This list is also
     * used to filter the allowable account types if add account is selected.
     */
    public static final String EXTRA_ALLOWABLE_ACCOUNT_TYPES_STRING_ARRAY = "allowableAccountTypes";

    
This is passed as the addAccountOptions parameter in AccountManager.addAccount()
if it is called.
/**
     * This is passed as the addAccountOptions parameter in AccountManager.addAccount()
     * if it is called.
     */
    public static final String EXTRA_ADD_ACCOUNT_OPTIONS_BUNDLE = "addAccountOptions";

    
This is passed as the requiredFeatures parameter in AccountManager.addAccount()
if it is called.
/**
     * This is passed as the requiredFeatures parameter in AccountManager.addAccount()
     * if it is called.
     */
    public static final String EXTRA_ADD_ACCOUNT_REQUIRED_FEATURES_STRING_ARRAY =
            "addAccountRequiredFeatures";

    
This is passed as the authTokenType string in AccountManager.addAccount()
if it is called.
/**
     * This is passed as the authTokenType string in AccountManager.addAccount()
     * if it is called.
     */
    public static final String EXTRA_ADD_ACCOUNT_AUTH_TOKEN_TYPE_STRING = "authTokenType";

    
If set then the specified account is already "selected".
/**
     * If set then the specified account is already "selected".
     */
    public static final String EXTRA_SELECTED_ACCOUNT = "selectedAccount";

    
Deprecated. Providing this extra to ChooseTypeAndAccountActivity will have no effect. /**
     * Deprecated. Providing this extra to {@link ChooseTypeAndAccountActivity}
     * will have no effect.
     */
    @Deprecated
    public static final String EXTRA_ALWAYS_PROMPT_FOR_ACCOUNT =
            "alwaysPromptForAccount";

    
If set then this string will be used as the description rather than
the default.
/**
     * If set then this string will be used as the description rather than
     * the default.
     */
    public static final String EXTRA_DESCRIPTION_TEXT_OVERRIDE = "descriptionTextOverride";

    public static final int REQUEST_NULL = 0;
    public static final int REQUEST_CHOOSE_TYPE = 1;
    public static final int REQUEST_ADD_ACCOUNT = 2;

    private static final String KEY_INSTANCE_STATE_PENDING_REQUEST = "pendingRequest";
    private static final String KEY_INSTANCE_STATE_EXISTING_ACCOUNTS = "existingAccounts";
    private static final String KEY_INSTANCE_STATE_SELECTED_ACCOUNT_NAME = "selectedAccountName";
    private static final String KEY_INSTANCE_STATE_SELECTED_ADD_ACCOUNT = "selectedAddAccount";
    private static final String KEY_INSTANCE_STATE_ACCOUNTS_LIST = "accountsList";
    private static final String KEY_INSTANCE_STATE_VISIBILITY_LIST = "visibilityList";

    private static final int SELECTED_ITEM_NONE = -1;

    private Set<Account> mSetOfAllowableAccounts;
    private Set<String> mSetOfRelevantAccountTypes;
    private String mSelectedAccountName = null;
    private boolean mSelectedAddNewAccount = false;
    private String mDescriptionOverride;

    private LinkedHashMap<Account, Integer> mAccounts;
    // TODO Redesign flow to show NOT_VISIBLE accounts
    // and display a warning if they are selected.
    // Currently NOT_VISBILE accounts are not shown at all.
    private ArrayList<Account> mPossiblyVisibleAccounts;
    private int mPendingRequest = REQUEST_NULL;
    private Parcelable[] mExistingAccounts = null;
    private int mSelectedItemIndex;
    private Button mOkButton;
    private int mCallingUid;
    private String mCallingPackage;
    private boolean mDisallowAddAccounts;
    private boolean mDontShowPicker;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "ChooseTypeAndAccountActivity.onCreate(savedInstanceState="
                    + savedInstanceState + ")");
        }

        String message = null;

        try {
            IBinder activityToken = getActivityToken();
            mCallingUid = ActivityManager.getService().getLaunchedFromUid(activityToken);
            mCallingPackage = ActivityManager.getService().getLaunchedFromPackage(
                    activityToken);
            if (mCallingUid != 0 && mCallingPackage != null) {
                Bundle restrictions = UserManager.get(this)
                        .getUserRestrictions(new UserHandle(UserHandle.getUserId(mCallingUid)));
                mDisallowAddAccounts =
                        restrictions.getBoolean(UserManager.DISALLOW_MODIFY_ACCOUNTS, false);
            }
        } catch (RemoteException re) {
            // Couldn't figure out caller details
            Log.w(getClass().getSimpleName(), "Unable to get caller identity \n" + re);
        }

        // save some items we use frequently
        final Intent intent = getIntent();

        mSetOfAllowableAccounts = getAllowableAccountSet(intent);
        mSetOfRelevantAccountTypes = getReleventAccountTypes(intent);
        mDescriptionOverride = intent.getStringExtra(EXTRA_DESCRIPTION_TEXT_OVERRIDE);

        if (savedInstanceState != null) {
            mPendingRequest = savedInstanceState.getInt(KEY_INSTANCE_STATE_PENDING_REQUEST);
            mExistingAccounts =
                    savedInstanceState.getParcelableArray(KEY_INSTANCE_STATE_EXISTING_ACCOUNTS);

            // Makes sure that any user selection is preserved across orientation changes.
            mSelectedAccountName =
                    savedInstanceState.getString(KEY_INSTANCE_STATE_SELECTED_ACCOUNT_NAME);
            mSelectedAddNewAccount =
                    savedInstanceState.getBoolean(KEY_INSTANCE_STATE_SELECTED_ADD_ACCOUNT, false);
            // restore mAccounts
            Parcelable[] accounts =
                savedInstanceState.getParcelableArray(KEY_INSTANCE_STATE_ACCOUNTS_LIST);
            ArrayList<Integer> visibility =
                savedInstanceState.getIntegerArrayList(KEY_INSTANCE_STATE_VISIBILITY_LIST);
            mAccounts = new LinkedHashMap<>();
            for (int i = 0; i < accounts.length; i++) {
                mAccounts.put((Account) accounts[i], visibility.get(i));
            }
        } else {
            mPendingRequest = REQUEST_NULL;
            mExistingAccounts = null;
            // If the selected account as specified in the intent matches one in the list we will
            // show is as pre-selected.
            Account selectedAccount = (Account) intent.getParcelableExtra(EXTRA_SELECTED_ACCOUNT);
            if (selectedAccount != null) {
                mSelectedAccountName = selectedAccount.name;
            }
            mAccounts = getAcceptableAccountChoices(AccountManager.get(this));
        }

        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "selected account name is " + mSelectedAccountName);
        }

        mPossiblyVisibleAccounts = new ArrayList<>(mAccounts.size());
        for (Map.Entry<Account, Integer> entry : mAccounts.entrySet()) {
            if (AccountManager.VISIBILITY_NOT_VISIBLE != entry.getValue()) {
                mPossiblyVisibleAccounts.add(entry.getKey());
            }
        }

        if (mPossiblyVisibleAccounts.isEmpty() && mDisallowAddAccounts) {
            requestWindowFeature(Window.FEATURE_NO_TITLE);
            setContentView(R.layout.app_not_authorized);
            mDontShowPicker = true;
        }

        if (mDontShowPicker) {
            super.onCreate(savedInstanceState);
            return;
        }

        // In cases where the activity does not need to show an account picker, cut the chase
        // and return the result directly. Eg:
        // Single account -> select it directly
        // No account -> launch add account activity directly
        if (mPendingRequest == REQUEST_NULL) {
            // If there are no relevant accounts and only one relevant account type go directly to
            // add account. Otherwise let the user choose.
            if (mPossiblyVisibleAccounts.isEmpty()) {
                setNonLabelThemeAndCallSuperCreate(savedInstanceState);
                if (mSetOfRelevantAccountTypes.size() == 1) {
                    runAddAccountForAuthenticator(mSetOfRelevantAccountTypes.iterator().next());
                } else {
                    startChooseAccountTypeActivity();
                }
            }
        }

        String[] listItems = getListOfDisplayableOptions(mPossiblyVisibleAccounts);
        mSelectedItemIndex = getItemIndexToSelect(mPossiblyVisibleAccounts, mSelectedAccountName,
                mSelectedAddNewAccount);

        super.onCreate(savedInstanceState);
        setContentView(R.layout.choose_type_and_account);
        overrideDescriptionIfSupplied(mDescriptionOverride);
        populateUIAccountList(listItems);

        // Only enable "OK" button if something has been selected.
        mOkButton = findViewById(android.R.id.button2);
        mOkButton.setEnabled(mSelectedItemIndex != SELECTED_ITEM_NONE);
    }

    @Override
    protected void onDestroy() {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "ChooseTypeAndAccountActivity.onDestroy()");
        }
        super.onDestroy();
    }

    @Override
    protected void onSaveInstanceState(final Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(KEY_INSTANCE_STATE_PENDING_REQUEST, mPendingRequest);
        if (mPendingRequest == REQUEST_ADD_ACCOUNT) {
            outState.putParcelableArray(KEY_INSTANCE_STATE_EXISTING_ACCOUNTS, mExistingAccounts);
        }
        if (mSelectedItemIndex != SELECTED_ITEM_NONE) {
            if (mSelectedItemIndex == mPossiblyVisibleAccounts.size()) {
                outState.putBoolean(KEY_INSTANCE_STATE_SELECTED_ADD_ACCOUNT, true);
            } else {
                outState.putBoolean(KEY_INSTANCE_STATE_SELECTED_ADD_ACCOUNT, false);
                outState.putString(KEY_INSTANCE_STATE_SELECTED_ACCOUNT_NAME,
                        mPossiblyVisibleAccounts.get(mSelectedItemIndex).name);
            }
        }
        // save mAccounts
        Parcelable[] accounts = new Parcelable[mAccounts.size()];
        ArrayList<Integer> visibility = new ArrayList<>(mAccounts.size());
        int i = 0;
        for (Map.Entry<Account, Integer> e : mAccounts.entrySet()) {
            accounts[i++] = e.getKey();
            visibility.add(e.getValue());
        }
        outState.putParcelableArray(KEY_INSTANCE_STATE_ACCOUNTS_LIST, accounts);
        outState.putIntegerArrayList(KEY_INSTANCE_STATE_VISIBILITY_LIST, visibility);
    }

    public void onCancelButtonClicked(View view) {
        onBackPressed();
    }

    public void onOkButtonClicked(View view) {
        if (mSelectedItemIndex == mPossiblyVisibleAccounts.size()) {
            // Selected "Add New Account" option
            startChooseAccountTypeActivity();
        } else if (mSelectedItemIndex != SELECTED_ITEM_NONE) {
            onAccountSelected(mPossiblyVisibleAccounts.get(mSelectedItemIndex));
        }
    }

    // Called when the choose account type activity (for adding an account) returns.
    // If it was a success read the account and set it in the result. In all cases
    // return the result and finish this activity.
    @Override
    protected void onActivityResult(final int requestCode, final int resultCode,
            final Intent data) {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            if (data != null && data.getExtras() != null) data.getExtras().keySet();
            Bundle extras = data != null ? data.getExtras() : null;
            Log.v(TAG, "ChooseTypeAndAccountActivity.onActivityResult(reqCode=" + requestCode
                    + ", resCode=" + resultCode + ", extras=" + extras + ")");
        }

        // we got our result, so clear the fact that we had a pending request
        mPendingRequest = REQUEST_NULL;

        if (resultCode == RESULT_CANCELED) {
            // if canceling out of addAccount and the original state caused us to skip this,
            // finish this activity
            if (mPossiblyVisibleAccounts.isEmpty()) {
                setResult(Activity.RESULT_CANCELED);
                finish();
            }
            return;
        }

        if (resultCode == RESULT_OK) {
            if (requestCode == REQUEST_CHOOSE_TYPE) {
                if (data != null) {
                    String accountType = data.getStringExtra(AccountManager.KEY_ACCOUNT_TYPE);
                    if (accountType != null) {
                        runAddAccountForAuthenticator(accountType);
                        return;
                    }
                }
                Log.d(TAG, "ChooseTypeAndAccountActivity.onActivityResult: unable to find account "
                        + "type, pretending the request was canceled");
            } else if (requestCode == REQUEST_ADD_ACCOUNT) {
                String accountName = null;
                String accountType = null;

                if (data != null) {
                    accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
                    accountType = data.getStringExtra(AccountManager.KEY_ACCOUNT_TYPE);
                }

                if (accountName == null || accountType == null) {
                    // new account was added.
                    Account[] currentAccounts = AccountManager.get(this).getAccountsForPackage(
                            mCallingPackage, mCallingUid);
                    Set<Account> preExistingAccounts = new HashSet<Account>();
                    for (Parcelable accountParcel : mExistingAccounts) {
                        preExistingAccounts.add((Account) accountParcel);
                    }
                    for (Account account : currentAccounts) {
                        // New account is visible to the app - return it.
                        if (!preExistingAccounts.contains(account)) {
                            accountName = account.name;
                            accountType = account.type;
                            break;
                        }
                    }
                }

                if (accountName != null || accountType != null) {
                    setResultAndFinish(accountName, accountType);
                    return;
                }
            }
            Log.d(TAG, "ChooseTypeAndAccountActivity.onActivityResult: unable to find added "
                    + "account, pretending the request was canceled");
        }
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "ChooseTypeAndAccountActivity.onActivityResult: canceled");
        }
        setResult(Activity.RESULT_CANCELED);
        finish();
    }

    protected void runAddAccountForAuthenticator(String type) {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "runAddAccountForAuthenticator: " + type);
        }
        final Bundle options = getIntent().getBundleExtra(
                ChooseTypeAndAccountActivity.EXTRA_ADD_ACCOUNT_OPTIONS_BUNDLE);
        final String[] requiredFeatures = getIntent().getStringArrayExtra(
                ChooseTypeAndAccountActivity.EXTRA_ADD_ACCOUNT_REQUIRED_FEATURES_STRING_ARRAY);
        final String authTokenType = getIntent().getStringExtra(
                ChooseTypeAndAccountActivity.EXTRA_ADD_ACCOUNT_AUTH_TOKEN_TYPE_STRING);
        AccountManager.get(this).addAccount(type, authTokenType, requiredFeatures,
                options, null /* activity */, this /* callback */, null /* Handler */);
    }

    @Override
    public void run(final AccountManagerFuture<Bundle> accountManagerFuture) {
        try {
            final Bundle accountManagerResult = accountManagerFuture.getResult();
            final Intent intent = (Intent)accountManagerResult.getParcelable(
                    AccountManager.KEY_INTENT);
            if (intent != null) {
                mPendingRequest = REQUEST_ADD_ACCOUNT;
                mExistingAccounts = AccountManager.get(this).getAccountsForPackage(mCallingPackage,
                        mCallingUid);
                intent.setFlags(intent.getFlags() & ~Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivityForResult(intent, REQUEST_ADD_ACCOUNT);
                return;
            }
        } catch (OperationCanceledException e) {
            setResult(Activity.RESULT_CANCELED);
            finish();
            return;
        } catch (IOException e) {
        } catch (AuthenticatorException e) {
        }
        Bundle bundle = new Bundle();
        bundle.putString(AccountManager.KEY_ERROR_MESSAGE, "error communicating with server");
        setResult(Activity.RESULT_OK, new Intent().putExtras(bundle));
        finish();
    }

    
The default activity theme shows label at the top. Set a theme which does
not show label, which effectively makes the activity invisible. Note that
no content is being set. If something gets set, using this theme may be
useless.
/**
     * The default activity theme shows label at the top. Set a theme which does
     * not show label, which effectively makes the activity invisible. Note that
     * no content is being set. If something gets set, using this theme may be
     * useless.
     */
    private void setNonLabelThemeAndCallSuperCreate(Bundle savedInstanceState) {
        setTheme(R.style.Theme_DeviceDefault_Light_Dialog_NoActionBar);
        super.onCreate(savedInstanceState);
    }

    private void onAccountSelected(Account account) {
      Log.d(TAG, "selected account " + account);
      setResultAndFinish(account.name, account.type);
    }

    private void setResultAndFinish(final String accountName, final String accountType) {
        // Mark account as visible since user chose it.
        Account account = new Account(accountName, accountType);
        Integer oldVisibility =
            AccountManager.get(this).getAccountVisibility(account, mCallingPackage);
        if (oldVisibility != null
                && oldVisibility == AccountManager.VISIBILITY_USER_MANAGED_NOT_VISIBLE) {
            AccountManager.get(this).setAccountVisibility(account, mCallingPackage,
                    AccountManager.VISIBILITY_USER_MANAGED_VISIBLE);
        }

        if (oldVisibility != null && oldVisibility == AccountManager.VISIBILITY_NOT_VISIBLE) {
            // Added account is not visible to caller.
            setResult(Activity.RESULT_CANCELED);
            finish();
            return;
        }
        Bundle bundle = new Bundle();
        bundle.putString(AccountManager.KEY_ACCOUNT_NAME, accountName);
        bundle.putString(AccountManager.KEY_ACCOUNT_TYPE, accountType);
        setResult(Activity.RESULT_OK, new Intent().putExtras(bundle));
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "ChooseTypeAndAccountActivity.setResultAndFinish: selected account "
                    + accountName + ", " + accountType);
        }

        finish();
    }

    private void startChooseAccountTypeActivity() {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.v(TAG, "ChooseAccountTypeActivity.startChooseAccountTypeActivity()");
        }
        final Intent intent = new Intent(this, ChooseAccountTypeActivity.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
        intent.putExtra(EXTRA_ALLOWABLE_ACCOUNT_TYPES_STRING_ARRAY,
                getIntent().getStringArrayExtra(EXTRA_ALLOWABLE_ACCOUNT_TYPES_STRING_ARRAY));
        intent.putExtra(EXTRA_ADD_ACCOUNT_OPTIONS_BUNDLE,
                getIntent().getBundleExtra(EXTRA_ADD_ACCOUNT_OPTIONS_BUNDLE));
        intent.putExtra(EXTRA_ADD_ACCOUNT_REQUIRED_FEATURES_STRING_ARRAY,
                getIntent().getStringArrayExtra(EXTRA_ADD_ACCOUNT_REQUIRED_FEATURES_STRING_ARRAY));
        intent.putExtra(EXTRA_ADD_ACCOUNT_AUTH_TOKEN_TYPE_STRING,
                getIntent().getStringExtra(EXTRA_ADD_ACCOUNT_AUTH_TOKEN_TYPE_STRING));
        startActivityForResult(intent, REQUEST_CHOOSE_TYPE);
        mPendingRequest = REQUEST_CHOOSE_TYPE;
    }

    
Returns:
a value between 0 (inclusive) and accounts.size() (inclusive) or SELECTED_ITEM_NONE.
     An index value of accounts.size() indicates 'Add account' option./**
     * @return a value between 0 (inclusive) and accounts.size() (inclusive) or SELECTED_ITEM_NONE.
     *      An index value of accounts.size() indicates 'Add account' option.
     */
    private int getItemIndexToSelect(ArrayList<Account> accounts, String selectedAccountName,
        boolean selectedAddNewAccount) {
      // If "Add account" option was previously selected by user, preserve it across
      // orientation changes.
      if (selectedAddNewAccount) {
          return accounts.size();
      }
      // search for the selected account name if present
      for (int i = 0; i < accounts.size(); i++) {
        if (accounts.get(i).name.equals(selectedAccountName)) {
          return i;
        }
      }
      // no account selected.
      return SELECTED_ITEM_NONE;
    }

    private String[] getListOfDisplayableOptions(ArrayList<Account> accounts) {
      // List of options includes all accounts found together with "Add new account" as the
      // last item in the list.
      String[] listItems = new String[accounts.size() + (mDisallowAddAccounts ? 0 : 1)];
      for (int i = 0; i < accounts.size(); i++) {
          listItems[i] = accounts.get(i).name;
      }
      if (!mDisallowAddAccounts) {
          listItems[accounts.size()] = getResources().getString(
                  R.string.add_account_button_label);
      }
      return listItems;
    }

    
Create a list of Account objects for each account that is acceptable. Filter out accounts
that don't match the allowable types, if provided, or that don't match the allowable
accounts, if provided.
/**
     * Create a list of Account objects for each account that is acceptable. Filter out accounts
     * that don't match the allowable types, if provided, or that don't match the allowable
     * accounts, if provided.
     */
    private LinkedHashMap<Account, Integer> getAcceptableAccountChoices(AccountManager accountManager) {
        Map<Account, Integer> accountsAndVisibilityForCaller =
                accountManager.getAccountsAndVisibilityForPackage(mCallingPackage, null);
        Account[] allAccounts = accountManager.getAccounts();
        LinkedHashMap<Account, Integer> accountsToPopulate =
                new LinkedHashMap<>(accountsAndVisibilityForCaller.size());
        for (Account account : allAccounts) {
            if (mSetOfAllowableAccounts != null
                    && !mSetOfAllowableAccounts.contains(account)) {
                continue;
            }
            if (mSetOfRelevantAccountTypes != null
                    && !mSetOfRelevantAccountTypes.contains(account.type)) {
                continue;
            }
            if (accountsAndVisibilityForCaller.get(account) != null) {
                accountsToPopulate.put(account, accountsAndVisibilityForCaller.get(account));
            }
        }
        return accountsToPopulate;
    }

    
Return a set of account types specified by the intent as well as supported by the
AccountManager.
/**
     * Return a set of account types specified by the intent as well as supported by the
     * AccountManager.
     */
    private Set<String> getReleventAccountTypes(final Intent intent) {
      // An account type is relevant iff it is allowed by the caller and supported by the account
      // manager.
      Set<String> setOfRelevantAccountTypes = null;
      final String[] allowedAccountTypes =
              intent.getStringArrayExtra(EXTRA_ALLOWABLE_ACCOUNT_TYPES_STRING_ARRAY);
        AuthenticatorDescription[] descs = AccountManager.get(this).getAuthenticatorTypes();
        Set<String> supportedAccountTypes = new HashSet<String>(descs.length);
        for (AuthenticatorDescription desc : descs) {
            supportedAccountTypes.add(desc.type);
        }
        if (allowedAccountTypes != null) {
            setOfRelevantAccountTypes = Sets.newHashSet(allowedAccountTypes);
            setOfRelevantAccountTypes.retainAll(supportedAccountTypes);
        } else {
            setOfRelevantAccountTypes = supportedAccountTypes;
      }
      return setOfRelevantAccountTypes;
    }

    
Returns a set of whitelisted accounts given by the intent or null if none specified by the
intent.
/**
     * Returns a set of whitelisted accounts given by the intent or null if none specified by the
     * intent.
     */
    private Set<Account> getAllowableAccountSet(final Intent intent) {
      Set<Account> setOfAllowableAccounts = null;
      final ArrayList<Parcelable> validAccounts =
              intent.getParcelableArrayListExtra(EXTRA_ALLOWABLE_ACCOUNTS_ARRAYLIST);
      if (validAccounts != null) {
          setOfAllowableAccounts = new HashSet<Account>(validAccounts.size());
          for (Parcelable parcelable : validAccounts) {
              setOfAllowableAccounts.add((Account)parcelable);
          }
      }
      return setOfAllowableAccounts;
    }

    
Overrides the description text view for the picker activity if specified by the intent.
If not specified then makes the description invisible.
/**
     * Overrides the description text view for the picker activity if specified by the intent.
     * If not specified then makes the description invisible.
     */
    private void overrideDescriptionIfSupplied(String descriptionOverride) {
      TextView descriptionView = findViewById(R.id.description);
      if (!TextUtils.isEmpty(descriptionOverride)) {
          descriptionView.setText(descriptionOverride);
      } else {
          descriptionView.setVisibility(View.GONE);
      }
    }

    
Populates the UI ListView with the given list of items and selects an item based on mSelectedItemIndex member variable. /**
     * Populates the UI ListView with the given list of items and selects an item
     * based on {@code mSelectedItemIndex} member variable.
     */
    private final void populateUIAccountList(String[] listItems) {
      ListView list = findViewById(android.R.id.list);
      list.setAdapter(new ArrayAdapter<String>(this,
              android.R.layout.simple_list_item_single_choice, listItems));
      list.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
      list.setItemsCanFocus(false);
      list.setOnItemClickListener(
              new AdapterView.OnItemClickListener() {
                  @Override
                  public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
                      mSelectedItemIndex = position;
                      mOkButton.setEnabled(true);
                  }
              });
      if (mSelectedItemIndex != SELECTED_ITEM_NONE) {
          list.setItemChecked(mSelectedItemIndex, true);
          if (Log.isLoggable(TAG, Log.VERBOSE)) {
              Log.v(TAG, "List item " + mSelectedItemIndex + " should be selected");
          }
      }
    }
}