org.megam.api.APIContentBuilder.java Source code

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Here is the source code for org.megam.api.APIContentBuilder.java

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/* 
 ** Copyright [2012-2013] [Megam Systems]
 **
 ** 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.megam.api;

import java.io.*;
import java.net.URL;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.InvalidKeyException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.net.MalformedURLException;
import org.apache.http.entity.ContentType;
import org.apache.commons.codec.binary.Base64;
import org.apache.http.entity.ContentType;
import org.megam.api.exception.APIContentException;

import java.security.NoSuchAlgorithmException;
import java.net.MalformedURLException;
import java.security.InvalidKeyException;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

/**
 * @author rajthilak
 * 
 */
public class APIContentBuilder {

    public static final String DATE = "X-Megam-DATE";
    public static final String CONTENT_TYPE = "Content-Type";
    public static final String EMAIL = "X-Megam-EMAIL";
    public static final String APIKEY = "X-Megam-APIKEY";
    public static final String ACCEPT = "Accept";
    public static final String HMAC = "X-Megam-HMAC";
    public static final String VND_MEGAM_JSON = "application/vnd.megam+json";
    private final static String HMAC_SHA1_ALGORITHM = "HmacSHA1";
    private final static String API_GATEWAY = "https://api.megam.co";
    private final static String API_GATEWAY_VERSION = "/v1";
    final protected static char[] hexArray = "0123456789abcdef".toCharArray();
    private String email;
    private String api_key;
    private String contentString;
    private Map<String, String> headersAndBody = new HashMap<String, String>();

    private static String urlSuffix = "";

    public APIContentBuilder(String email, String api_key) {
        this.email = email;
        this.api_key = api_key;
    }

    public void buildHeadersAndBody(String jsonBody, String tmpurlSuffix) throws APIContentException {
        urlSuffix = tmpurlSuffix;
        try {
            String DATE_FORMAT = "EEE, d MMM yyyy HH:mm:ss z";
            String currentDate = new SimpleDateFormat(DATE_FORMAT).format(new Date());

            String timeStampedPath = currentDate + "\n" + API_GATEWAY_VERSION + urlSuffix;
            String signedWithHMAC = null;
            if (jsonBody != null) {
                String md5Body = calculateMD5(jsonBody);
                String toSign = timeStampedPath + "\n" + md5Body;
                signedWithHMAC = calculateHMAC(api_key, toSign);
                contentString = jsonBody;
            }
            if (signedWithHMAC != null) {
                stickHeaderMap(currentDate, getFullHMAC(signedWithHMAC));
            } else {
                throw new IllegalArgumentException("No arguments found to sign.");
            }
        } catch (NoSuchAlgorithmException nsae) {
            throw new APIContentException(nsae);
        } catch (InvalidKeyException inke) {
            throw new APIContentException(inke);
        }
    }

    public String getPath() {
        return API_GATEWAY + API_GATEWAY_VERSION + urlSuffix;
    }

    private String getFullHMAC(String tmpSignedWithHMAC) {
        return email + ":" + tmpSignedWithHMAC;
    }

    private void stickHeaderMap(String date, String fullHMAC) {
        headersAndBody.put(DATE, date);
        headersAndBody.put(EMAIL, email);
        headersAndBody.put(APIKEY, api_key);
        headersAndBody.put(ACCEPT, VND_MEGAM_JSON);
        headersAndBody.put(HMAC, fullHMAC);
    }

    private String calculateHMAC(String secret, String data) throws NoSuchAlgorithmException, InvalidKeyException {
        SecretKeySpec signingKey = new SecretKeySpec(secret.getBytes(), "RAW");
        Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
        mac.init(signingKey);
        byte[] rawHmac = mac.doFinal(data.getBytes());
        //String result = new String(Base64.encodeBase64(rawHmac));
        String result = bytesToHex(rawHmac);
        return result;
    }

    public static String bytesToHex(byte[] bytes) {
        char[] hexChars = new char[bytes.length * 2];
        for (int j = 0; j < bytes.length; j++) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = hexArray[v >>> 4];
            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
        }
        return new String(hexChars);
    }

    private String calculateMD5(String contentToEncode) throws NoSuchAlgorithmException {
        MessageDigest digest = MessageDigest.getInstance("MD5");
        digest.update(contentToEncode.getBytes());
        String result = new String(Base64.encodeBase64(digest.digest()));
        return result;
    }

    public Map<String, String> getSignedHeadersAndBody() {
        return headersAndBody;
    }

    public String getContent() {
        return contentString;
    }

    public String toString() {
        return null;
    }

}