/*
 * Copyright 2010-2016 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.mobileconnectors.s3.transfermanager.internal;

import com.amazonaws.services.s3.internal.InputSubstream;
import com.amazonaws.services.s3.model.PutObjectRequest;
import com.amazonaws.services.s3.model.SSECustomerKey;
import com.amazonaws.services.s3.model.UploadPartRequest;

import java.io.File;

/**
 * Factory for creating all the individual UploadPartRequest objects for a
 * multipart upload.
 * <p>
 * This allows us to delay creating each UploadPartRequest until we're ready for
 * it, instead of immediately creating thousands of UploadPartRequest objects
 * for each large upload, when we won't need most of those request objects for a
 * while.
 */
public class UploadPartRequestFactory {
    private final String bucketName;
    private final String key;
    private final String uploadId;
    private final long optimalPartSize;
    private final File file;
    private final PutObjectRequest putObjectRequest;
    private int partNumber = 1;
    private long offset = 0;
    private long remainingBytes;
    private SSECustomerKey sseCustomerKey;

    public UploadPartRequestFactory(PutObjectRequest putObjectRequest, String uploadId,
            long optimalPartSize) {
        this.putObjectRequest = putObjectRequest;
        this.uploadId = uploadId;
        this.optimalPartSize = optimalPartSize;
        this.bucketName = putObjectRequest.getBucketName();
        this.key = putObjectRequest.getKey();
        this.file = TransferManagerUtils.getRequestFile(putObjectRequest);
        this.remainingBytes = TransferManagerUtils.getContentLength(putObjectRequest);
        this.sseCustomerKey = putObjectRequest.getSSECustomerKey();
    }

    public synchronized boolean hasMoreRequests() {
        return (remainingBytes > 0);
    }

    public synchronized UploadPartRequest getNextUploadPartRequest() {
        long partSize = Math.min(optimalPartSize, remainingBytes);
        boolean isLastPart = (remainingBytes - partSize <= 0);

        UploadPartRequest request = null;
        if (putObjectRequest.getInputStream() != null) {
            request = new UploadPartRequest()
                    .withBucketName(bucketName)
                    .withKey(key)
                    .withUploadId(uploadId)
                    .withInputStream(
                            new InputSubstream(putObjectRequest.getInputStream(), 0, partSize,
                                    isLastPart))
                    .withPartNumber(partNumber++)
                    .withPartSize(partSize);
        } else {
            request = new UploadPartRequest()
                    .withBucketName(bucketName)
                    .withKey(key)
                    .withUploadId(uploadId)
                    .withFile(file)
                    .withFileOffset(offset)
                    .withPartNumber(partNumber++)
                    .withPartSize(partSize);
        }

        if (sseCustomerKey != null)
            request.setSSECustomerKey(sseCustomerKey);

        offset += partSize;
        remainingBytes -= partSize;

        request.setLastPart(isLastPart);
        request.setGeneralProgressListener(putObjectRequest.getGeneralProgressListener());

        return request;
    }
}