/**
 * 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.hadoop.fs.viewfs;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileContext;
import org.apache.hadoop.fs.FileContextTestHelper;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FsConstants;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.viewfs.ViewFileSystemOverloadScheme.ChildFsGetter;
import org.apache.hadoop.util.Shell;
import org.eclipse.jetty.util.log.Log;
import org.junit.Assert;


/**
 * This class is for  setup and teardown for viewFs so that
 * it can be tested via the standard FileContext tests.
 * 
 * If tests launched via ant (build.xml) the test root is absolute path
 * If tests launched via eclipse, the test root is 
 * is a test dir below the working directory. (see FileContextTestHelper)
 * 
 * We set a viewfs with 3 mount points: 
 * 1) /<firstComponent>" of testdir  pointing to same in  target fs
 * 2)   /<firstComponent>" of home  pointing to same in  target fs 
 * 3)  /<firstComponent>" of wd  pointing to same in  target fs
 * (note in many cases the link may be the same - viewfs handles this)
 * 
 * We also set the view file system's wd to point to the wd.  
 */

public class ViewFsTestSetup {
  
  static public String ViewFSTestDir = "/testDir";


   /* 
   * return the ViewFS File context to be used for tests
   */
  static public FileContext setupForViewFsLocalFs(FileContextTestHelper helper) throws Exception {
    /**
     * create the test root on local_fs - the  mount table will point here
     */
    FileContext fsTarget = FileContext.getLocalFSFileContext();
    Path targetOfTests = helper.getTestRootPath(fsTarget);
    // In case previous test was killed before cleanup
    fsTarget.delete(targetOfTests, true);
    
    fsTarget.mkdir(targetOfTests, FileContext.DEFAULT_PERM, true);
    Configuration conf = new Configuration();
    
    // Set up viewfs link for test dir as described above
    String testDir = helper.getTestRootPath(fsTarget).toUri()
        .getPath();
    linkUpFirstComponents(conf, testDir, fsTarget, "test dir");
    
    
    // Set up viewfs link for home dir as described above
    setUpHomeDir(conf, fsTarget);
      
    // the test path may be relative to working dir - we need to make that work:
    // Set up viewfs link for wd as described above
    String wdDir = fsTarget.getWorkingDirectory().toUri().getPath();
    linkUpFirstComponents(conf, wdDir, fsTarget, "working dir");
    
    FileContext fc = FileContext.getFileContext(FsConstants.VIEWFS_URI, conf);
    fc.setWorkingDirectory(new Path(wdDir)); // in case testdir relative to wd.
    Log.getLog().info("Working dir is: " + fc.getWorkingDirectory());
    //System.out.println("SRCOfTests = "+ getTestRootPath(fc, "test"));
    //System.out.println("TargetOfTests = "+ targetOfTests.toUri());
    return fc;
  }

  /**
   * 
   * delete the test directory in the target local fs
   */
  static public void tearDownForViewFsLocalFs(FileContextTestHelper helper) throws Exception {
    FileContext fclocal = FileContext.getLocalFSFileContext();
    Path targetOfTests = helper.getTestRootPath(fclocal);
    fclocal.delete(targetOfTests, true);
  }
  
  
  static void setUpHomeDir(Configuration conf, FileContext fsTarget) {
    String homeDir = fsTarget.getHomeDirectory().toUri().getPath();
    int indexOf2ndSlash = homeDir.indexOf('/', 1);
    if (indexOf2ndSlash >0) {
      linkUpFirstComponents(conf, homeDir, fsTarget, "home dir");
    } else { // home dir is at root. Just link the home dir itse
      URI linkTarget = fsTarget.makeQualified(new Path(homeDir)).toUri();
      ConfigUtil.addLink(conf, homeDir, linkTarget);
      Log.getLog().info("Added link for home dir " + homeDir + "->" + linkTarget);
    }
    // Now set the root of the home dir for viewfs
    String homeDirRoot = fsTarget.getHomeDirectory().getParent().toUri().getPath();
    ConfigUtil.setHomeDirConf(conf, homeDirRoot);
    Log.getLog().info("Home dir base for viewfs" + homeDirRoot);
  }
  
  /*
   * Set up link in config for first component of path to the same
   * in the target file system.
   */
  static void linkUpFirstComponents(Configuration conf, String path,
      FileContext fsTarget, String info) {
    int indexOfEnd = path.indexOf('/', 1);
    if (Shell.WINDOWS) {
      indexOfEnd = path.indexOf('/', indexOfEnd + 1);
    }
    String firstComponent = path.substring(0, indexOfEnd);
    URI linkTarget = fsTarget.makeQualified(new Path(firstComponent)).toUri();
    ConfigUtil.addLink(conf, firstComponent, linkTarget);
    Log.getLog().info("Added link for " + info + " "
        + firstComponent + "->" + linkTarget);    
  }

  /**
   * Adds the given mount links to the given Hadoop compatible file system path.
   * Mount link mappings are in sources, targets at their respective index
   * locations.
   */
  static void addMountLinksToFile(String mountTable, String[] sources,
      String[] targets, Path mountTableConfPath, Configuration conf)
      throws IOException, URISyntaxException {
    ChildFsGetter cfs = new ViewFileSystemOverloadScheme.ChildFsGetter(
        mountTableConfPath.toUri().getScheme());
    try (FileSystem fs = cfs.getNewInstance(mountTableConfPath.toUri(),
        conf)) {
      try (FSDataOutputStream out = fs.create(mountTableConfPath)) {
        String prefix =
            new StringBuilder(Constants.CONFIG_VIEWFS_PREFIX).append(".")
                .append((mountTable == null
                    ? Constants.CONFIG_VIEWFS_DEFAULT_MOUNT_TABLE
                    : mountTable))
                .append(".").toString();
        out.writeBytes("<configuration>");
        for (int i = 0; i < sources.length; i++) {
          String src = sources[i];
          String target = targets[i];
          boolean isNfly = src.startsWith(Constants.CONFIG_VIEWFS_LINK_NFLY);
          out.writeBytes("<property><name>");
          if (isNfly) {
            String[] srcParts = src.split("[.]");
            Assert.assertEquals("Invalid NFlyLink format", 3, srcParts.length);
            String actualSrc = srcParts[srcParts.length - 1];
            String params = srcParts[srcParts.length - 2];
            out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK_NFLY + "."
                + params + "." + actualSrc);
          } else if (Constants.CONFIG_VIEWFS_LINK_FALLBACK.equals(src)) {
            out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK_FALLBACK);
          } else if (Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH.equals(src)) {
            out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH);
          } else {
            out.writeBytes(prefix + Constants.CONFIG_VIEWFS_LINK + "." + src);
          }
          out.writeBytes("</name>");
          out.writeBytes("<value>");
          out.writeBytes(target);
          out.writeBytes("</value></property>");
          out.flush();
        }
        out.writeBytes(("</configuration>"));
        out.flush();
      }
    }
  }

  /**
   * Adds the given mount links to the configuration. Mount link mappings are
   * in sources, targets at their respective index locations.
   */
  static void addMountLinksToConf(String mountTable, String[] sources,
      String[] targets, Configuration config) throws URISyntaxException {
    for (int i = 0; i < sources.length; i++) {
      String src = sources[i];
      String target = targets[i];
      String mountTableName = mountTable == null ?
          Constants.CONFIG_VIEWFS_DEFAULT_MOUNT_TABLE : mountTable;
      boolean isNfly = src.startsWith(Constants.CONFIG_VIEWFS_LINK_NFLY);
      if (isNfly) {
        String[] srcParts = src.split("[.]");
        Assert.assertEquals("Invalid NFlyLink format", 3, srcParts.length);
        String actualSrc = srcParts[srcParts.length - 1];
        String params = srcParts[srcParts.length - 2];
        ConfigUtil.addLinkNfly(config, mountTableName, actualSrc, params,
            target);
      } else if (src.equals(Constants.CONFIG_VIEWFS_LINK_FALLBACK)) {
        ConfigUtil.addLinkFallback(config, mountTableName, new URI(target));
      } else if (src.equals(Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH)) {
        ConfigUtil.addLinkMergeSlash(config, mountTableName, new URI(target));
      } else {
        ConfigUtil.addLink(config, mountTableName, src, new URI(target));
      }
    }
  }

}
