/*
 * Copyright 2010 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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.amazonaws.services.s3.internal;

import java.security.SignatureException;
import java.util.Date;

import com.amazonaws.Request;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AbstractAWSSigner;
import com.amazonaws.auth.SigningAlgorithm;

public class S3QueryStringSigner<T> extends AbstractAWSSigner {
    /** AWS Credentials */
    private final AWSCredentials credentials;

    /**
     * The HTTP verb (GET, PUT, HEAD, DELETE) the request to sign
     * is using.
     *
     * TODO: We need to know the HTTP verb in order to
     *       create the authentication signature, but we don't
     *       have easy access to it through the request object.
     *
     *       Maybe it'd be better for the S3 signer (or all signers?)
     *       to work directly off of the HttpRequest instead of
     *       the Request object?
     */
    private final String httpVerb;

    /**
     * The canonical resource path portion of the S3 string to sign.
     * Examples: "/", "/<bucket name>/", or "/<bucket name>/<key>"
     *
     * TODO: We don't want to hold the resource path as member data in the S3
     *       signer, but we need access to it and can't get it through the
     *       request yet.
     */
    private final String resourcePath;

    private final Date expiration;


    public S3QueryStringSigner(AWSCredentials credentials, String httpVerb, String resourcePath, Date expiration) {
        this.credentials = credentials;
        this.httpVerb = httpVerb;
        this.resourcePath = resourcePath;
        this.expiration = expiration;

        if (resourcePath == null)
            throw new IllegalArgumentException("Parameter resourcePath is empty");
    }

    public void sign(Request<T> request) throws SignatureException {
        String expirationInSeconds = Long.toString(expiration.getTime() / 1000L);

        String canonicalString = RestUtils.makeS3CanonicalString(
                httpVerb, resourcePath, request, expirationInSeconds);

        String secretKey;
        String accessKeyId;
        synchronized (credentials) {
            secretKey = credentials.getAWSSecretKey();
            accessKeyId = credentials.getAWSAccessKeyId();
        }

        String signature = super.sign(canonicalString, secretKey, SigningAlgorithm.HmacSHA1);

        request.addParameter("AWSAccessKeyId", accessKeyId);
        request.addParameter("Expires", expirationInSeconds);
        request.addParameter("Signature", signature);
    }
}