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.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;

import org.apache.samoa.instances.Instances;
import org.apache.samoa.instances.InstancesHeader;
import org.apache.samoa.moa.core.InputStreamProgressMonitor;
import org.apache.samoa.moa.core.InstanceExample;
import org.apache.samoa.moa.core.ObjectRepository;
import org.apache.samoa.moa.options.AbstractOptionHandler;
import org.apache.samoa.moa.tasks.TaskMonitor;

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

/**
 * Stream reader of ARFF files.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
public class ArffFileStream extends AbstractOptionHandler implements InstanceStream {

  @Override
  public String getPurposeString() {
    return "A stream read from an ARFF file.";
  }

  private static final long serialVersionUID = 1L;

  public FileOption arffFileOption = new FileOption("arffFile", 'f',
      "ARFF file to load.", null, "arff", 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);

  protected Instances instances;

  transient protected Reader fileReader;

  protected boolean hitEndOfFile;

  protected InstanceExample lastInstanceRead;

  protected int numInstancesRead;

  transient protected InputStreamProgressMonitor fileProgressMonitor;

  protected boolean hasStarted;

  public ArffFileStream() {
  }

  public ArffFileStream(String arffFileName, int classIndex) {
    this.arffFileOption.setValue(arffFileName);
    this.classIndexOption.setValue(classIndex);
    this.hasStarted = false;
    restart();
  }

  @Override
  public void prepareForUseImpl(TaskMonitor monitor,
      ObjectRepository repository) {
    // restart();
    this.hasStarted = false;
    this.lastInstanceRead = null;
  }

  @Override
  public InstancesHeader getHeader() {
    return new InstancesHeader(this.instances);
  }

  @Override
  public long estimatedRemainingInstances() {
    double progressFraction = this.fileProgressMonitor.getProgressFraction();
    if ((progressFraction > 0.0) && (this.numInstancesRead > 0)) {
      return (long) ((this.numInstancesRead / progressFraction) - this.numInstancesRead);
    }
    return -1;
  }

  @Override
  public boolean hasMoreInstances() {
    return !this.hitEndOfFile;
  }

  @Override
  public InstanceExample nextInstance() {
    if (this.lastInstanceRead == null) {
      readNextInstanceFromFile();
    }
    InstanceExample prevInstance = this.lastInstanceRead;
    this.hitEndOfFile = !readNextInstanceFromFile();
    return prevInstance;
  }

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

  @Override
  public void restart() {
    try {
      reset();
      // this.hitEndOfFile = !readNextInstanceFromFile();
    } catch (IOException ioe) {
      throw new RuntimeException("ArffFileStream restart failed.", ioe);
    }
  }

  protected boolean readNextInstanceFromFile() {
    boolean ret;
    if (!this.hasStarted) {
      try {
        reset();
        ret = getNextInstanceFromFile();
        this.hitEndOfFile = !ret;
      } catch (IOException ioe) {
        throw new RuntimeException("ArffFileStream restart failed.", ioe);
      }
      this.hasStarted = true;
    } else {
      ret = getNextInstanceFromFile();
    }
    return ret;
  }

  @Override
  public void getDescription(StringBuilder sb, int indent) {
    // TODO Auto-generated method stub
  }

  private void reset() throws IOException {
    if (this.fileReader != null) {
      this.fileReader.close();
    }
    InputStream fileStream = new FileInputStream(this.arffFileOption.getFile());
    this.fileProgressMonitor = new InputStreamProgressMonitor(
        fileStream);
    this.fileReader = new BufferedReader(new InputStreamReader(
        this.fileProgressMonitor));
    this.instances = new Instances(this.fileReader, 1, this.classIndexOption.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);
    }
    this.numInstancesRead = 0;
    this.lastInstanceRead = null;
  }

  private boolean getNextInstanceFromFile() throws RuntimeException {
    try {
      if (this.instances.readInstance(this.fileReader)) {
        this.lastInstanceRead = new InstanceExample(this.instances.instance(0));
        this.instances.delete(); // keep instances clean
        this.numInstancesRead++;
        return true;
      }
      if (this.fileReader != null) {
        this.fileReader.close();
        this.fileReader = null;
      }
      return false;
    } catch (IOException ioe) {
      throw new RuntimeException(
          "ArffFileStream failed to read instance from stream.", ioe);
    }
  }
}