/*
 * Copyright 2002-2020 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.security.oauth2.client.userinfo;

import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

import org.springframework.core.ParameterizedTypeReference;
import org.springframework.core.convert.converter.Converter;
import org.springframework.http.RequestEntity;
import org.springframework.http.ResponseEntity;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.oauth2.client.http.OAuth2ErrorResponseErrorHandler;
import org.springframework.security.oauth2.client.registration.ClientRegistration;
import org.springframework.security.oauth2.core.OAuth2AccessToken;
import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
import org.springframework.security.oauth2.core.OAuth2AuthorizationException;
import org.springframework.security.oauth2.core.OAuth2Error;
import org.springframework.security.oauth2.core.user.DefaultOAuth2User;
import org.springframework.security.oauth2.core.user.OAuth2User;
import org.springframework.security.oauth2.core.user.OAuth2UserAuthority;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.client.ResponseErrorHandler;
import org.springframework.web.client.RestClientException;
import org.springframework.web.client.RestOperations;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.client.UnknownContentTypeException;

/**
 * An implementation of an {@link OAuth2UserService} that supports standard OAuth 2.0
 * Provider's.
 * <p>
 * For standard OAuth 2.0 Provider's, the attribute name used to access the user's name
 * from the UserInfo response is required and therefore must be available via
 * {@link ClientRegistration.ProviderDetails.UserInfoEndpoint#getUserNameAttributeName()
 * UserInfoEndpoint.getUserNameAttributeName()}.
 * <p>
 * <b>NOTE:</b> Attribute names are <b>not</b> standardized between providers and
 * therefore will vary. Please consult the provider's API documentation for the set of
 * supported user attribute names.
 *
 * @author Joe Grandja
 * @since 5.0
 * @see OAuth2UserService
 * @see OAuth2UserRequest
 * @see OAuth2User
 * @see DefaultOAuth2User
 */
public class DefaultOAuth2UserService implements OAuth2UserService<OAuth2UserRequest, OAuth2User> {

	private static final String MISSING_USER_INFO_URI_ERROR_CODE = "missing_user_info_uri";

	private static final String MISSING_USER_NAME_ATTRIBUTE_ERROR_CODE = "missing_user_name_attribute";

	private static final String INVALID_USER_INFO_RESPONSE_ERROR_CODE = "invalid_user_info_response";

	private static final ParameterizedTypeReference<Map<String, Object>> PARAMETERIZED_RESPONSE_TYPE = new ParameterizedTypeReference<Map<String, Object>>() {
	};

	private Converter<OAuth2UserRequest, RequestEntity<?>> requestEntityConverter = new OAuth2UserRequestEntityConverter();

	private RestOperations restOperations;

	public DefaultOAuth2UserService() {
		RestTemplate restTemplate = new RestTemplate();
		restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());
		this.restOperations = restTemplate;
	}

	@Override
	public OAuth2User loadUser(OAuth2UserRequest userRequest) throws OAuth2AuthenticationException {
		Assert.notNull(userRequest, "userRequest cannot be null");
		if (!StringUtils
				.hasText(userRequest.getClientRegistration().getProviderDetails().getUserInfoEndpoint().getUri())) {
			OAuth2Error oauth2Error = new OAuth2Error(MISSING_USER_INFO_URI_ERROR_CODE,
					"Missing required UserInfo Uri in UserInfoEndpoint for Client Registration: "
							+ userRequest.getClientRegistration().getRegistrationId(),
					null);
			throw new OAuth2AuthenticationException(oauth2Error, oauth2Error.toString());
		}
		String userNameAttributeName = userRequest.getClientRegistration().getProviderDetails().getUserInfoEndpoint()
				.getUserNameAttributeName();
		if (!StringUtils.hasText(userNameAttributeName)) {
			OAuth2Error oauth2Error = new OAuth2Error(MISSING_USER_NAME_ATTRIBUTE_ERROR_CODE,
					"Missing required \"user name\" attribute name in UserInfoEndpoint for Client Registration: "
							+ userRequest.getClientRegistration().getRegistrationId(),
					null);
			throw new OAuth2AuthenticationException(oauth2Error, oauth2Error.toString());
		}
		RequestEntity<?> request = this.requestEntityConverter.convert(userRequest);
		ResponseEntity<Map<String, Object>> response = getResponse(userRequest, request);
		Map<String, Object> userAttributes = response.getBody();
		Set<GrantedAuthority> authorities = new LinkedHashSet<>();
		authorities.add(new OAuth2UserAuthority(userAttributes));
		OAuth2AccessToken token = userRequest.getAccessToken();
		for (String authority : token.getScopes()) {
			authorities.add(new SimpleGrantedAuthority("SCOPE_" + authority));
		}
		return new DefaultOAuth2User(authorities, userAttributes, userNameAttributeName);
	}

	private ResponseEntity<Map<String, Object>> getResponse(OAuth2UserRequest userRequest, RequestEntity<?> request) {
		try {
			return this.restOperations.exchange(request, PARAMETERIZED_RESPONSE_TYPE);
		}
		catch (OAuth2AuthorizationException ex) {
			OAuth2Error oauth2Error = ex.getError();
			StringBuilder errorDetails = new StringBuilder();
			errorDetails.append("Error details: [");
			errorDetails.append("UserInfo Uri: ")
					.append(userRequest.getClientRegistration().getProviderDetails().getUserInfoEndpoint().getUri());
			errorDetails.append(", Error Code: ").append(oauth2Error.getErrorCode());
			if (oauth2Error.getDescription() != null) {
				errorDetails.append(", Error Description: ").append(oauth2Error.getDescription());
			}
			errorDetails.append("]");
			oauth2Error = new OAuth2Error(INVALID_USER_INFO_RESPONSE_ERROR_CODE,
					"An error occurred while attempting to retrieve the UserInfo Resource: " + errorDetails.toString(),
					null);
			throw new OAuth2AuthenticationException(oauth2Error, oauth2Error.toString(), ex);
		}
		catch (UnknownContentTypeException ex) {
			String errorMessage = "An error occurred while attempting to retrieve the UserInfo Resource from '"
					+ userRequest.getClientRegistration().getProviderDetails().getUserInfoEndpoint().getUri()
					+ "': response contains invalid content type '" + ex.getContentType().toString() + "'. "
					+ "The UserInfo Response should return a JSON object (content type 'application/json') "
					+ "that contains a collection of name and value pairs of the claims about the authenticated End-User. "
					+ "Please ensure the UserInfo Uri in UserInfoEndpoint for Client Registration '"
					+ userRequest.getClientRegistration().getRegistrationId() + "' conforms to the UserInfo Endpoint, "
					+ "as defined in OpenID Connect 1.0: 'https://openid.net/specs/openid-connect-core-1_0.html#UserInfo'";
			OAuth2Error oauth2Error = new OAuth2Error(INVALID_USER_INFO_RESPONSE_ERROR_CODE, errorMessage, null);
			throw new OAuth2AuthenticationException(oauth2Error, oauth2Error.toString(), ex);
		}
		catch (RestClientException ex) {
			OAuth2Error oauth2Error = new OAuth2Error(INVALID_USER_INFO_RESPONSE_ERROR_CODE,
					"An error occurred while attempting to retrieve the UserInfo Resource: " + ex.getMessage(), null);
			throw new OAuth2AuthenticationException(oauth2Error, oauth2Error.toString(), ex);
		}
	}

	/**
	 * Sets the {@link Converter} used for converting the {@link OAuth2UserRequest} to a
	 * {@link RequestEntity} representation of the UserInfo Request.
	 * @param requestEntityConverter the {@link Converter} used for converting to a
	 * {@link RequestEntity} representation of the UserInfo Request
	 * @since 5.1
	 */
	public final void setRequestEntityConverter(Converter<OAuth2UserRequest, RequestEntity<?>> requestEntityConverter) {
		Assert.notNull(requestEntityConverter, "requestEntityConverter cannot be null");
		this.requestEntityConverter = requestEntityConverter;
	}

	/**
	 * Sets the {@link RestOperations} used when requesting the UserInfo resource.
	 *
	 * <p>
	 * <b>NOTE:</b> At a minimum, the supplied {@code restOperations} must be configured
	 * with the following:
	 * <ol>
	 * <li>{@link ResponseErrorHandler} - {@link OAuth2ErrorResponseErrorHandler}</li>
	 * </ol>
	 * @param restOperations the {@link RestOperations} used when requesting the UserInfo
	 * resource
	 * @since 5.1
	 */
	public final void setRestOperations(RestOperations restOperations) {
		Assert.notNull(restOperations, "restOperations cannot be null");
		this.restOperations = restOperations;
	}

}
