/*
 * 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 com.epam.dlab.module.aws;

import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.model.GetObjectRequest;
import com.amazonaws.services.s3.model.S3Object;
import com.epam.dlab.core.AdapterBase;
import com.epam.dlab.exceptions.AdapterException;
import com.epam.dlab.model.aws.ReportLine;
import com.epam.dlab.module.ModuleName;
import com.fasterxml.jackson.annotation.JsonClassDescription;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonTypeName;
import com.google.common.base.MoreObjects.ToStringHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.validation.constraints.NotNull;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Date;
import java.util.List;

/**
 * The adapter for S3 file system of Amazon.
 */
@JsonTypeName(ModuleName.ADAPTER_S3_FILE)
@JsonClassDescription(
		"Amazon S3 file system adapter.\n" +
				"Read source or write converted data to the file in Amazon S3 bucket.\n" +
				"  - type: " + ModuleName.ADAPTER_S3_FILE + "\n" +
				"    [writeHeader: <true | false>]   - write header of data to the adapterOut.\n" +
				"    bucket: <bucketname>            - the name of S3 bucket.\n" +
				"    path: <path>                    - the path to the report or empty if used the root folder.\n" +
				"    accountId: <AWS account number> - the account number, see for details\n" +
				"                                      \"Detailed billing report with resources and tags\"\n" +
				"                                      http://docs.aws.amazon" +
				".com/awsaccountbilling/latest/aboutv2/billing-reports.html#detailed-report-with-resources-tags\n" +
				"    [accessKeyId: <string>]         - Amazon access key ID.\n" +
				"    [secretAccessKey: <string>]     - Amazon secret access key."
)
public class AdapterS3File extends AdapterBase {
	private static final Logger LOGGER = LoggerFactory.getLogger(AdapterS3File.class);

	/**
	 * Name of key for the last loaded file.
	 */
	public static final String DATA_KEY_LAST_LOADED_FILE = "AdapterS3File_lastLoadedFile";

	/**
	 * Name of key for the modification date of loaded file.
	 */
	public static final String DATA_KEY_LAST_MODIFICATION_DATE = "AdapterS3File_lastModifyDate";
	private static final String CANNOT_READ_FILE_FORMAT = "Cannot read file %s. %s";
	private static final String DELIMITER = "/";

	/**
	 * The name of bucket.
	 */
	@NotNull
	@JsonProperty
	private String bucket;

	/**
	 * The path to report.
	 */
	@JsonProperty
	private String path;

	/**
	 * AWS account number.
	 */
	@NotNull
	@JsonProperty
	private String accountId;

	/**
	 * Access key ID for Amazon Web Services.
	 */
	@JsonProperty
	private String accessKeyId;

	/**
	 * Secret key for Amazon Web Services.
	 */
	@JsonProperty
	private String secretAccessKey;

	@JsonProperty
	private boolean awsJobEnabled;

	/**
	 * Return the name of bucket.
	 */
	public String getBucket() {
		return bucket;
	}

	/**
	 * Set the name of bucket.
	 */
	public void setBucket(String bucket) {
		this.bucket = bucket;
	}

	/**
	 * Return the path to report.
	 */
	public String getPath() {
		return path;
	}

	/**
	 * Set the path to report.
	 */
	public void setPath(String path) {
		this.path = path;
	}

	/**
	 * Return the AWS account number.
	 */
	public String getAccountId() {
		return accountId;
	}

	/**
	 * Set the AWS account number.
	 */
	public void setAccountId(String accountId) {
		this.accountId = accountId;
	}

	/**
	 * Return the access key ID for Amazon Web Services.
	 */
	public String getAccessKeyId() {
		return this.accessKeyId;
	}

	/**
	 * Set the access key ID for Amazon Web Services.
	 */
	public void setAccessKeyId(String accessKeyId) {
		this.accessKeyId = accessKeyId;
	}

	/**
	 * Return the secret key for Amazon Web Services.
	 */
	public String getSecretAccessKey() {
		return this.secretAccessKey;
	}

	/**
	 * Set the secret key for Amazon Web Services.
	 */
	public void setSecretAccessKey(String secretAccessKey) {
		this.secretAccessKey = secretAccessKey;
	}


	/**
	 * List of report files for loading.
	 */
	@JsonIgnore
	private List<String> filelist = null;

	/**
	 * Index of current report file.
	 */
	@JsonIgnore
	private int currentFileIndex = -1;

	/**
	 * Index of current report file.
	 */
	@JsonIgnore
	private String entryName = null;

	/**
	 * Amazon S3 client.
	 */
	@JsonIgnore
	private AmazonS3 clientS3 = null;

	/**
	 * Amazon S3 client.
	 */
	@JsonIgnore
	private Date lastModificationDate = null;

	/**
	 * File input stream.
	 */
	@JsonIgnore
	private InputStream fileInputStream = null;

	/**
	 * Reader for adapter.
	 */
	@JsonIgnore
	private BufferedReader reader = null;

	@Override
	public void open() throws AdapterException {
		LOGGER.debug("Adapter S3 will be opened for {}", getMode());
		if (getMode() == Mode.READ) {
			setLastModificationDate();
			clientS3 = getAmazonClient();
			S3FileList s3files = new S3FileList(awsJobEnabled, bucket, getModuleData());
			filelist = s3files.getFiles(clientS3);
			currentFileIndex = (filelist.isEmpty() ? -1 : 0);
			fileInputStream = null;
			reader = null;
			entryName = null;
			openNextEntry();
			LOGGER.debug("Adapter S3 has been opened");
		} else if (getMode() == Mode.WRITE) {
			throw new AdapterException("Unsupported mode " + Mode.WRITE + ".");
		} else {
			throw new AdapterException("Mode of adapter unknown or not defined. Set mode to " + Mode.READ + ".");
		}
	}

	@Override
	public boolean hasMultyEntry() {
		return true;
	}

	@Override
	public boolean openNextEntry() throws AdapterException {
		String filename = getCurrentFileName();
		if (filename == null) {
			if (filelist.isEmpty()) {
				final String reportPath = path == null ? bucket : bucket + DELIMITER + path;
				LOGGER.debug("New report files in bucket folder {} not found", reportPath);
			}
			return false;
		}
		entryName = filename;
		LOGGER.debug("Open a next entry in file {}", filename);
		reader = new BufferedReader(new InputStreamReader(getFileStream()));
		try {
			getModuleData().setId(filename);
			getModuleData().setModificationDate(lastModificationDate);
			getModuleData().set(DATA_KEY_LAST_LOADED_FILE, filename);
			getModuleData().set(DATA_KEY_LAST_MODIFICATION_DATE, lastModificationDate);
			getModuleData().store();
		} catch (Exception e) {
			throw new AdapterException(e.getLocalizedMessage(), e);
		}
		currentFileIndex++;
		return false;
	}

	@Override
	public boolean hasEntryData() {
		return (reader != null);
	}

	@Override
	public void close() throws AdapterException {
		closeFile(getCurrentFileName());
	}

	@Override
	public String getEntryName() {
		return entryName;
	}

	@Override
	public String readLine() throws AdapterException {
		try {
			return reader.readLine();
		} catch (IOException e) {
			throw new AdapterException(String.format(CANNOT_READ_FILE_FORMAT, getCurrentFileName(), e
					.getLocalizedMessage()), e);
		}
	}

	@Override
	public void writeHeader(List<String> header) throws AdapterException {
		throw new AdapterException("Unimplemented method.");
	}

	@Override
	public void writeRow(ReportLine row) throws AdapterException {
		throw new AdapterException("Unimplemented method.");
	}


	/**
	 * Return the current file name.
	 */
	public String getCurrentFileName() {
		return (filelist == null || currentFileIndex < 0 || currentFileIndex >= filelist.size() ? null : filelist.get
				(currentFileIndex));
	}

	/**
	 * Creates and returns the Amazon client, as well as checks bucket existence.
	 *
	 * @throws AdapterException
	 */
	private AmazonS3 getAmazonClient() throws AdapterException {
		AmazonS3 s3 = (accessKeyId == null ?
				new AmazonS3Client() :
				new AmazonS3Client(new BasicAWSCredentials(accessKeyId, secretAccessKey)));

		if (!s3.doesBucketExist(bucket)) {
			throw new AdapterException("Bucket \"" + bucket + "\" does not exist.");
		}

		return s3;
	}

	/**
	 * Open the source file and return reader.
	 *
	 * @throws AdapterException
	 */
	private InputStream getFileStream() throws AdapterException {
		try {
			GetObjectRequest request = new GetObjectRequest(bucket, getCurrentFileName());
			S3Object object = clientS3.getObject(request);
			lastModificationDate = object.getObjectMetadata().getLastModified();
			return object.getObjectContent();
		} catch (Exception e) {
			throw new AdapterException("Cannot open file " + bucket + DELIMITER + getCurrentFileName() + ". " + e
					.getLocalizedMessage(), e);
		}
	}

	/**
	 * Return the modification date of loaded file.
	 *
	 * @throws AdapterException
	 */
	private void setLastModificationDate() throws AdapterException {
		try {
			lastModificationDate = getModuleData().getDate(DATA_KEY_LAST_MODIFICATION_DATE);
		} catch (Exception e) {
			throw new AdapterException("Cannot get the last modification date for report. " + e.getLocalizedMessage(),
					e);
		}
	}

	/**
	 * Close a zip file.
	 *
	 * @param filename file name.
	 * @throws AdapterException
	 */
	private void closeFile(String filename) throws AdapterException {
		if (fileInputStream != null) {
			try {
				fileInputStream.close();
			} catch (IOException e) {
				throw new AdapterException("Cannot close file " + filename + ". " + e.getLocalizedMessage(), e);
			}
			fileInputStream = null;
		}
	}


	@Override
	public ToStringHelper toStringHelper(Object self) {
		return super.toStringHelper(self)
				.add("bucket", bucket)
				.add("path", path)
				.add("accountId", accountId)
				.add("accessKeyId", "***")
				.add("secretAccessKey", "***");
	}
}