package org.apache.samoa.moa.streams;

/*
 * #%L
 * SAMOA
 * %%
 * Copyright (C) 2014 - 2015 Apache Software Foundation
 * %%
 * 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.
 * #L%
 */

import java.io.IOException;
import java.io.InputStream;

import org.apache.samoa.instances.Instances;
import org.apache.samoa.moa.core.InstanceExample;
import org.apache.samoa.moa.core.ObjectRepository;
import org.apache.samoa.moa.tasks.TaskMonitor;
import org.apache.samoa.streams.FileStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.github.javacliparser.FileOption;
import com.github.javacliparser.IntOption;
import com.github.javacliparser.StringOption;


/**
 *  InstanceStream implementation to handle Apache Avro Files.
 *  Handles both JSON & Binary encoded streams
 *  
 *  @author jayadeepj
 *
 */
public class AvroFileStream extends FileStream {

	private static final long serialVersionUID = 1L;
	private static final Logger logger = LoggerFactory.getLogger(AvroFileStream.class);

	public FileOption avroFileOption = new FileOption("avroFile", 'f',"Avro File(s) to load.", null, null, false);
	public IntOption classIndexOption = new IntOption("classIndex", 'c',"Class index of data. 0 for none or -1 for last attribute in file.",-1, -1, Integer.MAX_VALUE);
	public StringOption encodingFormatOption = new StringOption("encodingFormatOption", 'e', "Encoding format for Avro Files. Can be JSON/AVRO", "BINARY");

	/** Represents the last read Instance **/
	protected InstanceExample lastInstanceRead;

	/** Represents the binary input stream of avro data **/
	protected transient InputStream inputStream = null;

	/** The extension to be considered for the files **/
	private static final String AVRO_FILE_EXTENSION = "avro";

	/* (non-Javadoc)
	 * @see org.apache.samoa.streams.FileStream#reset()
	 * Reset the BINARY encoded Avro Stream & Close the file source
	 */
	@Override
	protected void reset() {

		try {
			if (this.inputStream != null)
				this.inputStream.close();

			fileSource.reset();
		} catch (IOException ioException) {
			logger.error(AVRO_STREAM_FAILED_RESTART_ERROR+" : {}",ioException);
			throw new RuntimeException(AVRO_STREAM_FAILED_RESTART_ERROR, ioException);
		}

		if (!getNextFileStream()) {
			hitEndOfStream = true;
			throw new RuntimeException(AVRO_STREAM_EMPTY_STREAM_ERROR);
		}
	}


	/**
	 * Get next File Stream & set the class index read from the command line option
	 * @return
	 */
	protected boolean getNextFileStream() {
		if (this.inputStream != null)
			try {
				this.inputStream.close();
			} catch (IOException ioException) {
				logger.error(AVRO_STREAM_FAILED_READ_ERROR+" : {}",ioException);
				throw new RuntimeException(AVRO_STREAM_FAILED_READ_ERROR, ioException);
			}

		this.inputStream = this.fileSource.getNextInputStream();

		if (this.inputStream == null)
			return false;

		this.instances = new Instances(this.inputStream, classIndexOption.getValue(),encodingFormatOption.getValue());

		if (this.classIndexOption.getValue() < 0) {
			this.instances.setClassIndex(this.instances.numAttributes() - 1);
		} else if (this.classIndexOption.getValue() > 0) {
			this.instances.setClassIndex(this.classIndexOption.getValue() - 1);
		}
		return true;
	}


	/* (non-Javadoc)
	 * @see org.apache.samoa.streams.FileStream#readNextInstanceFromFile()
	 * Read next Instance from File. Return false if unable to read next Instance
	 */
	@Override
	protected boolean readNextInstanceFromFile() {
		try {
			if (this.instances.readInstance()) {
				this.lastInstanceRead = new InstanceExample(this.instances.instance(0));
				this.instances.delete(); 
				return true;
			}
			if (this.inputStream != null) {
				this.inputStream.close();
				this.inputStream = null;
			}
			return false;
		} catch (IOException ioException) {
			logger.error(AVRO_STREAM_FAILED_READ_ERROR+" : {}",ioException);
			throw new RuntimeException(AVRO_STREAM_FAILED_READ_ERROR, ioException);
		}

	}

	@Override
	public void prepareForUseImpl(TaskMonitor monitor, ObjectRepository repository) {
		super.prepareForUseImpl(monitor, repository);
		String filePath = this.avroFileOption.getFile().getAbsolutePath();
		this.fileSource.init(filePath, AvroFileStream.AVRO_FILE_EXTENSION);
		this.lastInstanceRead = null;
	}


	/* (non-Javadoc)
	 * @see org.apache.samoa.streams.FileStream#getLastInstanceRead()
	 * Return the last read Instance
	 */
	@Override
	protected InstanceExample getLastInstanceRead() {
		return this.lastInstanceRead;
	}


	@Override
	public void getDescription(StringBuilder sb, int indent) {
		throw new UnsupportedOperationException(AVRO_STREAM_UNSUPPORTED_METHOD);
	}

	/** Error Messages to for all types of Avro File Streams */
	protected static final String AVRO_STREAM_FAILED_RESTART_ERROR = "Avro FileStream restart failed."; 
	protected static final String AVRO_STREAM_EMPTY_STREAM_ERROR = "Avro FileStream is empty."; 
	protected static final String AVRO_STREAM_FAILED_READ_ERROR = "Failed to read next instance from Avro File Stream.";
	protected static final String AVRO_STREAM_UNSUPPORTED_METHOD = "This method is not supported for AvroFileStream yet.";	
	
}