/*
 * Copyright 2002-2011 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
 *
 *      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 org.springframework.security.oauth2.provider.approval;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.security.core.Authentication;
import org.springframework.security.oauth2.common.OAuth2AccessToken;
import org.springframework.security.oauth2.provider.AuthorizationRequest;
import org.springframework.security.oauth2.provider.OAuth2Authentication;
import org.springframework.security.oauth2.provider.token.AuthorizationServerTokenServices;
import org.springframework.util.Assert;

/**
 * A user approval handler that remembers approval decisions by consulting existing tokens.
 * 
 * @author Dave Syer
 * 
 */
public class TokenServicesUserApprovalHandler implements UserApprovalHandler, InitializingBean {

	private static Log logger = LogFactory.getLog(TokenServicesUserApprovalHandler.class);

	private String approvalParameter = AuthorizationRequest.USER_OAUTH_APPROVAL;
	
	/**
	 * @param approvalParameter the approvalParameter to set
	 */
	public void setApprovalParameter(String approvalParameter) {
		this.approvalParameter = approvalParameter;
	}

	private AuthorizationServerTokenServices tokenServices;

	/**
	 * @param tokenServices the token services to set
	 */
	public void setTokenServices(AuthorizationServerTokenServices tokenServices) {
		this.tokenServices = tokenServices;
	}

	public void afterPropertiesSet() {
		Assert.state(tokenServices != null, "AuthorizationServerTokenServices must be provided");
	}
	
	public AuthorizationRequest updateBeforeApproval(AuthorizationRequest authorizationRequest, Authentication userAuthentication) {
		return authorizationRequest;
	}
	
	/**
	 * Basic implementation just requires the authorization request to be explicitly approved and the user to be
	 * authenticated.
	 * 
	 * @param authorizationRequest The authorization request.
	 * @param userAuthentication the current user authentication
	 * 
	 * @return Whether the specified request has been approved by the current user.
	 */
	public boolean isApproved(AuthorizationRequest authorizationRequest, Authentication userAuthentication) {

		String flag = authorizationRequest.getApprovalParameters().get(approvalParameter);
		boolean approved = flag != null && flag.toLowerCase().equals("true");

		OAuth2Authentication authentication = new OAuth2Authentication(authorizationRequest, userAuthentication);
		if (logger.isDebugEnabled()) {
			StringBuilder builder = new StringBuilder("Looking up existing token for ");
			builder.append("client_id=" + authorizationRequest.getClientId());
			builder.append(", scope=" + authorizationRequest.getScope());
			builder.append(" and username=" + userAuthentication.getName());
			logger.debug(builder.toString());
		}

		OAuth2AccessToken accessToken = tokenServices.getAccessToken(authentication);
		logger.debug("Existing access token=" + accessToken);
		if (accessToken != null && !accessToken.isExpired()) {
			logger.debug("User already approved with token=" + accessToken);
			// A token was already granted and is still valid, so this is already approved
			approved = true;
		}
		else {
			logger.debug("Checking explicit approval");
			approved = userAuthentication.isAuthenticated() && approved;
		}
		
		return approved;

	}
}