/*
 * Copyright Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags and
 * the COPYRIGHT.txt file distributed with this work.
 *
 * 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.teiid.translator.amazon.s3;

import java.net.URL;
import java.util.Date;
import java.util.Map;

import org.teiid.logging.LogConstants;
import org.teiid.logging.LogManager;

/**
 * Sample AWS4 signer demonstrating how to sign requests to Amazon S3 using an
 * 'Authorization' header.
 * This code was taken from Amazon Example. No copyright found.
 */
public class AWS4SignerForAuthorizationHeader extends AWS4SignerBase {

    public AWS4SignerForAuthorizationHeader(URL endpointUrl, String httpMethod,
            String serviceName, String regionName) {
        super(endpointUrl, httpMethod, serviceName, regionName);
    }
    
    /**
     * Computes an AWS4 signature for a request, ready for inclusion as an
     * 'Authorization' header.
     * 
     * @param headers
     *            The request headers; 'Host' and 'X-Amz-Date' will be added to
     *            this set.
     * @param queryParameters
     *            Any query parameters that will be added to the endpoint. The
     *            parameters should be specified in canonical format.
     * @param bodyHash
     *            Precomputed SHA256 hash of the request body content; this
     *            value should also be set as the header 'X-Amz-Content-SHA256'
     *            for non-streaming uploads.
     * @param awsAccessKey
     *            The user's AWS Access Key.
     * @param awsSecretKey
     *            The user's AWS Secret Key.
     * @return The computed authorization string for the request. This value
     *         needs to be set as the header 'Authorization' on the subsequent
     *         HTTP request.
     */
    public String computeSignature(Map<String, String> headers,
                                   Map<String, String> queryParameters,
                                   String bodyHash,
                                   String awsAccessKey,
                                   String awsSecretKey) {
        // first get the date and time for the subsequent request, and convert
        // to ISO 8601 format for use in signature generation
        Date now = new Date();
        String dateTimeStamp = dateTimeFormat.format(now);

        // update the headers with required 'x-amz-date' and 'host' values
        headers.put("x-amz-date", dateTimeStamp);
        
        String hostHeader = endpointUrl.getHost();
        int port = endpointUrl.getPort();
        if ( port > -1 ) {
            hostHeader.concat(":" + Integer.toString(port));
        }
        headers.put("Host", hostHeader);
        
        // canonicalize the headers; we need the set of header names as well as the
        // names and values to go into the signature process
        String canonicalizedHeaderNames = getCanonicalizeHeaderNames(headers);
        String canonicalizedHeaders = getCanonicalizedHeaderString(headers);
        
        // if any query string parameters have been supplied, canonicalize them
        String canonicalizedQueryParameters = getCanonicalizedQueryString(queryParameters);
        
        // canonicalize the various components of the request
        String canonicalRequest = getCanonicalRequest(endpointUrl, httpMethod,
                canonicalizedQueryParameters, canonicalizedHeaderNames,
                canonicalizedHeaders, bodyHash);
        LogManager.logDetail(LogConstants.CTX_WS, "--------- Canonical request --------");
        LogManager.logDetail(LogConstants.CTX_WS,canonicalRequest);
        LogManager.logDetail(LogConstants.CTX_WS,"------------------------------------");
        
        // construct the string to be signed
        String dateStamp = dateStampFormat.format(now);
        String scope =  dateStamp + "/" + regionName + "/" + serviceName + "/" + TERMINATOR;
        String stringToSign = getStringToSign(SCHEME, ALGORITHM, dateTimeStamp, scope, canonicalRequest);
        LogManager.logDetail(LogConstants.CTX_WS,"--------- String to sign -----------");
        LogManager.logDetail(LogConstants.CTX_WS,stringToSign);
        LogManager.logDetail(LogConstants.CTX_WS,"------------------------------------");
        
        // compute the signing key
        byte[] kSecret = (SCHEME + awsSecretKey).getBytes();
        byte[] kDate = sign(dateStamp, kSecret, "HmacSHA256");
        byte[] kRegion = sign(regionName, kDate, "HmacSHA256");
        byte[] kService = sign(serviceName, kRegion, "HmacSHA256");
        byte[] kSigning = sign(TERMINATOR, kService, "HmacSHA256");
        byte[] signature = sign(stringToSign, kSigning, "HmacSHA256");
        
        String credentialsAuthorizationHeader =
                "Credential=" + awsAccessKey + "/" + scope;
        String signedHeadersAuthorizationHeader =
                "SignedHeaders=" + canonicalizedHeaderNames;
        String signatureAuthorizationHeader =
                "Signature=" + BinaryUtils.toHex(signature);

        String authorizationHeader = SCHEME + "-" + ALGORITHM + " "
                + credentialsAuthorizationHeader + ", "
                + signedHeadersAuthorizationHeader + ", "
                + signatureAuthorizationHeader;

        return authorizationHeader;
    }
}
