/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.airavata.mft.transport.local;


import org.apache.airavata.mft.admin.TransportProperties;
import org.apache.airavata.mft.core.api.ConnectorConfig;
import org.apache.airavata.mft.core.api.IncomingChunkedConnector;

import java.io.*;
import java.nio.file.Files;
import java.nio.file.Path;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LocalIncomingChunkedConnector implements IncomingChunkedConnector {

    private String resourcePath;
    private long resourceSize;
    private boolean dmaFlag;

    private int buffLen;

    private static final Logger logger = LoggerFactory.getLogger(LocalIncomingChunkedConnector.class);
    private static final TransportProperties transportProperties = new TransportProperties();

    @Override
    public void init(ConnectorConfig connectorConfig) throws Exception {
        this.resourcePath = connectorConfig.getResourcePath();
        this.resourceSize = connectorConfig.getMetadata().getFile().getResourceSize();
        this.dmaFlag = connectorConfig.getTransportConfig().getOrDefault("local.dma", transportProperties.getDma()).toString().equals("true");
        this.buffLen = Integer.valueOf(connectorConfig.getTransportConfig().getOrDefault("local.buffLen",transportProperties.getBuffLen()).toString());
    }

    @Override
    public void complete() throws Exception {
        logger.info("File {} successfully received", this.resourcePath);
    }

    @Override
    public void failed() throws Exception {
        logger.error("Failed while receiving file {}", this.resourcePath);

    }

    @Override
    public void downloadChunk(int chunkId, long startByte, long endByte, String downloadFile) throws Exception {

        logger.info("Downloading chunk {} with start byte {} and end byte {} to file {} from resource path {}",
                chunkId, startByte, endByte, downloadFile, this.resourcePath);

        if (dmaFlag) {
            if (resourceSize <= endByte - startByte) {
                Files.copy(Path.of(this.resourcePath), Path.of(downloadFile));
            } else {
                try (FileInputStream from = new FileInputStream(this.resourcePath);
                     FileOutputStream to = new FileOutputStream(downloadFile)) {
                    from.getChannel().transferTo(startByte, endByte - startByte, to.getChannel());
                } catch (Exception e) {
                    logger.error("Unexpected error occurred while downloading chunk {} to file {} from resource path {}",
                            chunkId, downloadFile, this.resourcePath, e);
                    throw e;
                }
            }
        }   else {
            try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream(this.resourcePath), buffLen);
                 BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(downloadFile))) {
                byte[] buffer = new byte[buffLen];
                int read = 0;
                long totalRead = bis.skip(startByte);
                while ((read = bis.read(buffer, 0, Math.min(buffLen, (int) (endByte - totalRead)))) > 0) {
                    bos.write(buffer, 0, read);
                    totalRead += read;
                }
                bis.close();
                bos.close();
            } catch (Exception e) {
                logger.error("Unexpected error occurred while downloading chunk {} to file {} from resource path {}",
                        chunkId, downloadFile, this.resourcePath, e);
                throw e;
            }
        }
    }

    @Override
    public InputStream downloadChunk(int chunkId, long startByte, long endByte) throws Exception {

        FileInputStream from = new FileInputStream(new File(this.resourcePath));

        from.skip(startByte);

        return new BufferedInputStream(from, Math.min(16 * 1024 * 1024,(int) (endByte - startByte)));
    }
}