/*
 * Copyright 2015 Red Hat, Inc.
 *
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  and Apache License v2.0 which accompanies this distribution.
 *
 *  The Eclipse Public License is available at
 *  http://www.eclipse.org/legal/epl-v10.html
 *
 *  The Apache License v2.0 is available at
 *  http://www.opensource.org/licenses/apache2.0.php
 *
 *  You may elect to redistribute this code under either of these licenses.
 */
package io.vertx.ext.auth.oauth2;

import io.vertx.codegen.annotations.VertxGen;

OAuth2 Flows
Author:
Paulo Lopes/**
 * OAuth2 Flows
 *
 * @author Paulo Lopes
 */
@VertxGen
public enum OAuth2FlowType {
  
The authorization code is obtained by using an authorization server
as an intermediary between the client and resource owner.  Instead of
requesting authorization directly from the resource owner, the client
directs the resource owner to an authorization server (via its
user-agent as defined in [RFC2616]), which in turn directs the
resource owner back to the client with the authorization code.

Before directing the resource owner back to the client with the
authorization code, the authorization server authenticates the
resource owner and obtains authorization.  Because the resource owner
only authenticates with the authorization server, the resource
owner's credentials are never shared with the client.

The authorization code provides a few important security benefits,
such as the ability to authenticate the client, as well as the
transmission of the access token directly to the client without
passing it through the resource owner's user-agent and potentially
exposing it to others, including the resource owner.
/**
   * The authorization code is obtained by using an authorization server
   * as an intermediary between the client and resource owner.  Instead of
   * requesting authorization directly from the resource owner, the client
   * directs the resource owner to an authorization server (via its
   * user-agent as defined in [RFC2616]), which in turn directs the
   * resource owner back to the client with the authorization code.
   * <p>
   * Before directing the resource owner back to the client with the
   * authorization code, the authorization server authenticates the
   * resource owner and obtains authorization.  Because the resource owner
   * only authenticates with the authorization server, the resource
   * owner's credentials are never shared with the client.
   * <p>
   * The authorization code provides a few important security benefits,
   * such as the ability to authenticate the client, as well as the
   * transmission of the access token directly to the client without
   * passing it through the resource owner's user-agent and potentially
   * exposing it to others, including the resource owner.
   */
  AUTH_CODE("authorization_code"),

  
The implicit grant is a simplified authorization code flow optimized
for clients implemented in a browser using a scripting language such
as JavaScript.  In the implicit flow, instead of issuing the client
an authorization code, the client is issued an access token directly
(as the result of the resource owner authorization).  The grant type
is implicit, as no intermediate credentials (such as an authorization
code) are issued (and later used to obtain an access token).

When issuing an access token during the implicit grant flow, the
authorization server does not authenticate the client.  In some
cases, the client identity can be verified via the redirection URI
used to deliver the access token to the client.  The access token may
be exposed to the resource owner or other applications with access to
the resource owner's user-agent.

Implicit grants improve the responsiveness and efficiency of some
clients (such as a client implemented as an in-browser application),
since it reduces the number of round trips required to obtain an
access token.  However, this convenience should be weighed against
the security implications of using implicit grants, especially when the
authorization code grant type is available.
/**
   * The implicit grant is a simplified authorization code flow optimized
   * for clients implemented in a browser using a scripting language such
   * as JavaScript.  In the implicit flow, instead of issuing the client
   * an authorization code, the client is issued an access token directly
   * (as the result of the resource owner authorization).  The grant type
   * is implicit, as no intermediate credentials (such as an authorization
   * code) are issued (and later used to obtain an access token).
   * <p>
   * When issuing an access token during the implicit grant flow, the
   * authorization server does not authenticate the client.  In some
   * cases, the client identity can be verified via the redirection URI
   * used to deliver the access token to the client.  The access token may
   * be exposed to the resource owner or other applications with access to
   * the resource owner's user-agent.
   * <p>
   * Implicit grants improve the responsiveness and efficiency of some
   * clients (such as a client implemented as an in-browser application),
   * since it reduces the number of round trips required to obtain an
   * access token.  However, this convenience should be weighed against
   * the security implications of using implicit grants, especially when the
   * authorization code grant type is available.
   */
  IMPLICIT(null),

  
The resource owner password credentials (i.e., username and password)
can be used directly as an authorization grant to obtain an access
token.  The credentials should only be used when there is a high
degree of trust between the resource owner and the client (e.g., the
client is part of the device operating system or a highly privileged
application), and when other authorization grant types are not
available (such as an authorization code).

Even though this grant type requires direct client access to the
resource owner credentials, the resource owner credentials are used
for a single request and are exchanged for an access token.  This
grant type can eliminate the need for the client to store the
resource owner credentials for future use, by exchanging the
credentials with a long-lived access token or refresh token.
/**
   * The resource owner password credentials (i.e., username and password)
   * can be used directly as an authorization grant to obtain an access
   * token.  The credentials should only be used when there is a high
   * degree of trust between the resource owner and the client (e.g., the
   * client is part of the device operating system or a highly privileged
   * application), and when other authorization grant types are not
   * available (such as an authorization code).
   * <p>
   * Even though this grant type requires direct client access to the
   * resource owner credentials, the resource owner credentials are used
   * for a single request and are exchanged for an access token.  This
   * grant type can eliminate the need for the client to store the
   * resource owner credentials for future use, by exchanging the
   * credentials with a long-lived access token or refresh token.
   */
  PASSWORD("password"),

  
The client credentials (or other forms of client authentication) can
be used as an authorization grant when the authorization scope is
limited to the protected resources under the control of the client,
or to protected resources previously arranged with the authorization
server.  Client credentials are used as an authorization grant
typically when the client is acting on its own behalf (the client is
also the resource owner) or is requesting access to protected
resources based on an authorization previously arranged with the
authorization server.
/**
   * The client credentials (or other forms of client authentication) can
   * be used as an authorization grant when the authorization scope is
   * limited to the protected resources under the control of the client,
   * or to protected resources previously arranged with the authorization
   * server.  Client credentials are used as an authorization grant
   * typically when the client is acting on its own behalf (the client is
   * also the resource owner) or is requesting access to protected
   * resources based on an authorization previously arranged with the
   * authorization server.
   */
  CLIENT("client_credentials"),

  
RFC7523
/**
   * RFC7523
   */
  AUTH_JWT("urn:ietf:params:oauth:grant-type:jwt-bearer");

  private final String grantType;

  OAuth2FlowType(String grantType) {
    this.grantType = grantType;
  }

  public String getGrantType() {
    return grantType;
  }
}