/*
 * Copyright (c) 2015-present, Parse, LLC.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */
package com.parse;

import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

import bolts.Continuation;
import bolts.Task;

/**
 * Provides utility functions for working with Anonymously logged-in users. Anonymous users have
 * some unique characteristics:
 * <ul>
 * <li>Anonymous users don't need a user name or password.</li>
 * <li>Once logged out, an anonymous user cannot be recovered.</li>
 * <li>When the current user is anonymous, the following methods can be used to switch to a
 * different user or convert the anonymous user into a regular one:
 * <ul>
 * <li>signUp converts an anonymous user to a standard user with the given username and password.
 * Data associated with the anonymous user is retained.</li>
 * <li>logIn switches users without converting the anonymous user. Data associated with the
 * anonymous user will be lost.</li>
 * <li>Service logIn (e.g. Facebook, Twitter) will attempt to convert the anonymous user into a
 * standard user by linking it to the service. If a user already exists that is linked to the
 * service, it will instead switch to the existing user.</li>
 * <li>Service linking (e.g. Facebook, Twitter) will convert the anonymous user into a standard user
 * by linking it to the service.</li>
 * </ul>
 * </ul>
 */
public final class ParseAnonymousUtils {
  /* package */ static final String AUTH_TYPE = "anonymous";

  /**
   * Whether the user is logged in anonymously.
   * 
   * @param user
   *          User to check for anonymity. The user must be logged in on this device.
   * @return True if the user is anonymous. False if the user is not the current user or is not
   *         anonymous.
   */
  public static boolean isLinked(ParseUser user) {
    return user.isLinked(AUTH_TYPE);
  }

  /**
   * Creates an anonymous user in the background.
   *
   * @return A Task that will be resolved when logging in is completed.
   */
  public static Task<ParseUser> logInInBackground() {
    return ParseUser.logInWithInBackground(AUTH_TYPE, getAuthData());
  }

  /**
   * Creates an anonymous user in the background.
   * 
   * @param callback
   *          The callback to execute when anonymous user creation is complete.
   */
  public static void logIn(LogInCallback callback) {
    ParseTaskUtils.callbackOnMainThreadAsync(logInInBackground(), callback);
  }

  /* package */ static Map<String, String> getAuthData() {
    Map<String, String> authData = new HashMap<>();
    authData.put("id", UUID.randomUUID().toString());
    return authData;
  }

  private ParseAnonymousUtils() {
    // do nothing
  }
}