/*
 * Copyright 2015 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.social.oauth2;

import java.io.IOException;
import java.nio.charset.Charset;
import java.util.Base64;

import org.springframework.http.HttpRequest;
import org.springframework.http.client.ClientHttpRequestExecution;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.http.client.ClientHttpResponse;

/**
 * Client request interceptor that does preemptive HTTP Basic authentication by ensuring that an Authorization
 * header with HTTP Basic credentials is always included in the request headers.
 * @author Craig Walls
 */
class PreemptiveBasicAuthClientHttpRequestInterceptor implements ClientHttpRequestInterceptor {
	
	private final String username;
	
	private final String password;
	
	private final Charset charset;

	public PreemptiveBasicAuthClientHttpRequestInterceptor(String username, String password) {
		this(username, password, Charset.forName("UTF-8"));
	}
	
	public PreemptiveBasicAuthClientHttpRequestInterceptor(String username, String password, Charset charset) {
		this.username = username;
		this.password = password;	
		this.charset = charset;
	}

	public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
		request.getHeaders().set("Authorization", "Basic " + new String(Base64.getEncoder().encode((username + ":" + password).getBytes(charset)), charset));
		return execution.execute(request, body);
	}

}