/* Copyright (c) 2009 Matthias Kaeppler
 *
 * 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 com.socialize.oauth.signpost.signature;

import com.socialize.oauth.OAuthSignListener;
import com.socialize.oauth.signpost.OAuth;
import com.socialize.oauth.signpost.exception.OAuthMessageSignerException;
import com.socialize.oauth.signpost.http.HttpParameters;
import com.socialize.oauth.signpost.http.HttpRequest;

import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.GeneralSecurityException;


@SuppressWarnings("serial")
public class HmacSha1MessageSigner extends OAuthMessageSigner {

	private static final String MAC_NAME = "HmacSHA1";

	@Override
	public String getSignatureMethod() {
		return "HMAC-SHA1";
	}
	
	@Override
	public String sign(HttpRequest request, HttpParameters requestParameters) throws OAuthMessageSignerException {
		return sign(request, requestParameters, null);
	}

	@Override
	public String sign(HttpRequest request, HttpParameters requestParams, OAuthSignListener listener) throws OAuthMessageSignerException {
		try {
			String keyString = OAuth.percentEncode(getConsumerSecret()) + '&' + OAuth.percentEncode(getTokenSecret());
			byte[] keyBytes = keyString.getBytes(OAuth.ENCODING);

			SecretKey key = new SecretKeySpec(keyBytes, MAC_NAME);
			Mac mac = Mac.getInstance(MAC_NAME);
			mac.init(key);

			String sbs = new SignatureBaseString(request, requestParams).generate();
			OAuth.debugOut("SBS", sbs);
			
			if(listener != null) {
				listener.onSignature(sbs);
			}
			
			byte[] text = sbs.getBytes(OAuth.ENCODING);

			return base64Encode(mac.doFinal(text)).trim();
		} catch (GeneralSecurityException e) {
			throw new OAuthMessageSignerException(e);
		} catch (UnsupportedEncodingException e) {
			throw new OAuthMessageSignerException(e);
		}
	}
}