package com.yahoo.labs.samoa.streams.fs;

/*
 * #%L
 * SAMOA
 * %%
 * Copyright (C) 2013 - 2014 Yahoo! Inc.
 * %%
 * 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.InputStream;
import java.io.IOException;
import java.io.Serializable;

/**
 * An interface for FileStream's source (Local FS, HDFS,...)
 * 
 * @author Casey
 */
public interface FileStreamSource extends Serializable {

  /**
   * Init the source with file/directory path and file extension
   * 
   * @param path
   *          File or directory path
   * @param ext
   *          File extension to be used to filter files in a directory. If null, all files in the directory are
   *          accepted.
   */
  public void init(String path, String ext);

  /**
   * Reset the source
   */
  public void reset() throws IOException;

  /**
   * Retrieve InputStream for next file. This method will return null if we are at the last file in the list.
   * 
   * @return InputStream for next file in the list
   */
  public InputStream getNextInputStream();

  /**
   * Retrieve InputStream for current file. The "current pointer" is moved forward with getNextInputStream method. So if
   * there was no invocation of getNextInputStream, this method will return null.
   * 
   * @return InputStream for current file in the list
   */
  public InputStream getCurrentInputStream();
}