/*
 * 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.samoa.streams.fs;

import static org.junit.Assert.*;

import java.io.BufferedReader;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class HDFSFileStreamSourceTest {

  private static final String[] HOSTS = { "localhost" };
  private static final String BASE_DIR = "/minidfsTest";
  private static final int NUM_FILES_IN_DIR = 4;
  private static final int NUM_NOISE_FILES_IN_DIR = 2;

  private HDFSFileStreamSource streamSource;

  private Configuration config;
  private MiniDFSCluster hdfsCluster;
  private String hdfsURI;

  @Before
  public void setUp() throws Exception {
    // Start MiniDFSCluster
    config = new Configuration();
    config.set("hdfs.minidfs.basedir", "target/build/test/data/dfs");
    MiniDFSCluster.Builder builder = new MiniDFSCluster.Builder(config).hosts(HOSTS).numDataNodes(1)
        .format(true);
    hdfsCluster = builder.build();
    hdfsCluster.waitActive();
    hdfsURI = "hdfs://localhost:" + hdfsCluster.getNameNodePort();

    // Construct stream source
    streamSource = new HDFSFileStreamSource();

    // General config
    config.set("fs.defaultFS", hdfsURI);
  }

  @After
  public void tearDown() throws Exception {
    hdfsCluster.shutdown();
  }

  /*
   * Init tests
   */
  @Test
  public void testInitWithSingleFileAndExtension() {
    // write input file
    writeSimpleFiles(BASE_DIR, "txt", 1);

    // init with path to input file
    streamSource.init(config, BASE_DIR + "/1.txt", "txt");

    // assertions
    assertEquals("Size of filePaths is not correct.", 1, streamSource.getFilePathListSize(), 0);
    String fn = streamSource.getFilePathAt(0);
    assertTrue("Incorrect file in filePaths.",
        fn.equals(BASE_DIR + "/1.txt") || fn.equals(hdfsURI + BASE_DIR + "1.txt"));
  }

  @Test
  public void testInitWithSingleFileAndNullExtension() {
    // write input file
    writeSimpleFiles(BASE_DIR, "txt", 1);

    // init with path to input file
    streamSource.init(config, BASE_DIR + "/1.txt", null);

    // assertions
    assertEquals("Size of filePaths is not correct.", 1, streamSource.getFilePathListSize(), 0);
    String fn = streamSource.getFilePathAt(0);
    assertTrue("Incorrect file in filePaths.",
        fn.equals(BASE_DIR + "/1.txt") || fn.equals(hdfsURI + BASE_DIR + "1.txt"));
  }

  @Test
  public void testInitWithFolderAndExtension() {
    // write input files & noise files
    writeSimpleFiles(BASE_DIR, "txt", NUM_FILES_IN_DIR);
    writeSimpleFiles(BASE_DIR, null, NUM_NOISE_FILES_IN_DIR);

    // init with path to input dir
    streamSource.init(config, BASE_DIR, "txt");

    // assertions
    assertEquals("Size of filePaths is not correct.", NUM_FILES_IN_DIR, streamSource.getFilePathListSize(), 0);
    Set<String> filenames = new HashSet<String>();
    for (int i = 1; i <= NUM_FILES_IN_DIR; i++) {
      String targetFn = BASE_DIR + "/" + Integer.toString(i) + ".txt";
      filenames.add(targetFn);
      filenames.add(hdfsURI + targetFn);
    }
    for (int i = 0; i < NUM_FILES_IN_DIR; i++) {
      String fn = streamSource.getFilePathAt(i);
      assertTrue("Incorrect file in filePaths:" + fn, filenames.contains(fn));
    }
  }

  @Test
  public void testInitWithFolderAndNullExtension() {
    // write input file
    writeSimpleFiles(BASE_DIR, null, NUM_FILES_IN_DIR);

    // init with path to input dir
    streamSource.init(config, BASE_DIR, null);

    // assertions
    assertEquals("Size of filePaths is not correct.", NUM_FILES_IN_DIR, streamSource.getFilePathListSize(), 0);
    Set<String> filenames = new HashSet<String>();
    for (int i = 1; i <= NUM_FILES_IN_DIR; i++) {
      String targetFn = BASE_DIR + "/" + Integer.toString(i);
      filenames.add(targetFn);
      filenames.add(hdfsURI + targetFn);
    }
    for (int i = 0; i < NUM_FILES_IN_DIR; i++) {
      String fn = streamSource.getFilePathAt(i);
      assertTrue("Incorrect file in filePaths:" + fn, filenames.contains(fn));
    }
  }

  /*
   * getNextInputStream tests
   */
  @Test
  public void testGetNextInputStream() {
    // write input files & noise files
    writeSimpleFiles(BASE_DIR, "txt", NUM_FILES_IN_DIR);

    // init with path to input dir
    streamSource.init(config, BASE_DIR, "txt");

    // call getNextInputStream & assertions
    Set<String> contents = new HashSet<String>();
    for (int i = 1; i <= NUM_FILES_IN_DIR; i++) {
      contents.add(Integer.toString(i));
    }
    for (int i = 0; i < NUM_FILES_IN_DIR; i++) {
      InputStream inStream = streamSource.getNextInputStream();
      assertNotNull("Unexpected end of input stream list.", inStream);

      BufferedReader rd = new BufferedReader(new InputStreamReader(inStream));
      String inputRead = null;
      try {
        inputRead = rd.readLine();
      } catch (IOException ioe) {
        fail("Fail reading from stream at index:" + i + ioe.getMessage());
      }
      assertTrue("File content is incorrect.", contents.contains(inputRead));
      Iterator<String> it = contents.iterator();
      while (it.hasNext()) {
        if (it.next().equals(inputRead)) {
          it.remove();
          break;
        }
      }
    }

    // assert that another call to getNextInputStream will return null
    assertNull("Call getNextInputStream after the last file did not return null.", streamSource.getNextInputStream());
  }

  /*
   * getCurrentInputStream tests
   */
  public void testGetCurrentInputStream() {
    // write input files & noise files
    writeSimpleFiles(BASE_DIR, "txt", NUM_FILES_IN_DIR);

    // init with path to input dir
    streamSource.init(config, BASE_DIR, "txt");

    // call getNextInputStream, getCurrentInputStream & assertions
    for (int i = 0; i <= NUM_FILES_IN_DIR; i++) { // test also after-end-of-list
      InputStream inStream1 = streamSource.getNextInputStream();
      InputStream inStream2 = streamSource.getCurrentInputStream();
      assertSame("Incorrect current input stream.", inStream1, inStream2);
    }
  }

  /*
   * reset tests
   */
  public void testReset() {
    // write input files & noise files
    writeSimpleFiles(BASE_DIR, "txt", NUM_FILES_IN_DIR);

    // init with path to input dir
    streamSource.init(config, BASE_DIR, "txt");

    // Get the first input string
    InputStream firstInStream = streamSource.getNextInputStream();
    String firstInput = null;
    assertNotNull("Unexpected end of input stream list.", firstInStream);

    BufferedReader rd1 = new BufferedReader(new InputStreamReader(firstInStream));
    try {
      firstInput = rd1.readLine();
    } catch (IOException ioe) {
      fail("Fail reading from stream at index:0" + ioe.getMessage());
    }

    // call getNextInputStream a few times
    streamSource.getNextInputStream();

    // call reset, call next, assert that output is 1 (the first file)
    try {
      streamSource.reset();
    } catch (IOException ioe) {
      fail("Fail resetting stream source." + ioe.getMessage());
    }

    InputStream inStream = streamSource.getNextInputStream();
    assertNotNull("Unexpected end of input stream list.", inStream);

    BufferedReader rd2 = new BufferedReader(new InputStreamReader(inStream));
    String inputRead = null;
    try {
      inputRead = rd2.readLine();
    } catch (IOException ioe) {
      fail("Fail reading from stream at index:0" + ioe.getMessage());
    }
    assertEquals("File content is incorrect.", firstInput, inputRead);
  }

  private void writeSimpleFiles(String path, String ext, int numOfFiles) {
    // get filesystem
    FileSystem dfs;
    try {
      dfs = hdfsCluster.getFileSystem();
    } catch (IOException ioe) {
      fail("Could not access MiniDFSCluster" + ioe.getMessage());
      return;
    }

    // create basedir
    Path basedir = new Path(path);
    try {
      dfs.mkdirs(basedir);
    } catch (IOException ioe) {
      fail("Could not create DIR:" + path + "\n" + ioe.getMessage());
      return;
    }

    // write files
    for (int i = 1; i <= numOfFiles; i++) {
      String fn = null;
      if (ext != null) {
        fn = Integer.toString(i) + "." + ext;
      } else {
        fn = Integer.toString(i);
      }

      try {
        OutputStream fin = dfs.create(new Path(path, fn));
        BufferedWriter wr = new BufferedWriter(new OutputStreamWriter(fin));
        wr.write(Integer.toString(i));
        wr.close();
        fin.close();
      } catch (IOException ioe) {
        fail("Fail writing to input file: " + fn + " in directory: " + path + ioe.getMessage());
      }
    }
  }

}