/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.util;
  
  import static org.opencastproject.util.PathSupport.path;
  import static org.opencastproject.util.data.Either.left;
  import static org.opencastproject.util.data.Either.right;
  import static org.opencastproject.util.data.functions.Misc.chuck;
  
  import org.opencastproject.security.api.TrustedHttpClient;
  import org.opencastproject.security.api.TrustedHttpClientException;
  import org.opencastproject.util.data.Either;
  
  import com.google.common.io.Resources;
  
  import org.apache.commons.io.IOUtils;
  import org.apache.http.HttpResponse;
  import org.apache.http.client.methods.HttpGet;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.Closeable;
  import java.io.DataInputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.RandomAccessFile;
  import java.io.Serializable;
  import java.net.URISyntaxException;
  import java.net.URL;
  import java.nio.channels.FileLock;
  import java.nio.charset.Charset;
  import java.util.Optional;
  import java.util.Properties;
  import java.util.function.BiFunction;
  import java.util.function.Function;
  import java.util.function.Supplier;
  
  import de.schlichtherle.io.FileWriter;
  
  /**
   * Contains operations concerning IO.
   */
  public final class IoSupport {
  
    /**
     * the logging facility provided by log4j
     */
    private static Logger logger = LoggerFactory.getLogger(IoSupport.class.getName());
  
    public static String getSystemTmpDir() {
      String tmpdir = System.getProperty("java.io.tmpdir");
      if (tmpdir == null) {
        tmpdir = File.separator + "tmp" + File.separator;
      } else {
        if (!tmpdir.endsWith(File.separator)) {
          tmpdir += File.separator;
        }
      }
      return tmpdir;
    }
  
    private IoSupport() {
    }
  
    /**
     * Closes a <code>Closable</code> quietly so that no exceptions are thrown.
     *
     * @param s
     *          maybe null
     */
    public static boolean closeQuietly(final Closeable s) {
      if (s == null) {
        return false;
     }
     try {
       s.close();
       return true;
     } catch (IOException e) {
       return false;
     }
   }
 
   /**
    * Closes the processes input, output and error streams.
    *
    * @param process
    *          the process
    * @return <code>true</code> if the streams were closed
    */
   public static boolean closeQuietly(final Process process) {
     if (process != null) {
       closeQuietly(process.getInputStream());
       closeQuietly(process.getErrorStream());
       closeQuietly(process.getOutputStream());
       return true;
     }
     return false;
   }
 
   /**
    * Writes the contents variable to the {@code URL}. Note that the URL must be a local {@code URL}.
    *
    * @param file
    *          The {@code URL} of the local file you wish to write to.
    * @param contents
    *          The contents of the file you wish to create.
    * @throws IOException
    */
   public static void writeUTF8File(URL file, String contents) throws IOException {
     try {
       writeUTF8File(new File(file.toURI()), contents);
     } catch (URISyntaxException e) {
       throw new IOException("Couldn't parse the URL", e);
     }
   }
 
   /**
    * Writes the contents variable to the {@code File}.
    *
    * @param file
    *          The {@code File} of the local file you wish to write to.
    * @param contents
    *          The contents of the file you wish to create.
    */
   public static void writeUTF8File(File file, String contents) throws IOException {
     writeUTF8File(file.getAbsolutePath(), contents);
   }
 
   /**
    * Writes the contents variable to the {@code File} located at the filename.
    *
    * @param filename
    *          The {@code File} of the local file you wish to write to.
    * @param contents
    *          The contents of the file you wish to create.
    */
   public static void writeUTF8File(String filename, String contents) throws IOException {
     FileWriter out = new FileWriter(filename);
     try {
       out.write(contents);
     } finally {
       closeQuietly(out);
     }
   }
 
   /**
    * Convenience method to read in a file from a local source.
    *
    * @param url
    *          The {@code URL} to read the source data from.
    * @return A String containing the source data or null in the case of an error.
    * @deprecated this method doesn't support UTF8 or handle HTTP response codes
    */
   @Deprecated
   public static String readFileFromURL(URL url) {
     return readFileFromURL(url, null);
   }
 
   /**
    * Convenience method to read in a file from either a remote or local source.
    *
    * @param url
    *          The {@code URL} to read the source data from.
    * @param trustedClient
    *          The {@code TrustedHttpClient} which should be used to communicate with the remote server. This can be null
    *          for local file reads.
    * @return A String containing the source data or null in the case of an error.
    * @deprecated this method doesn't support UTF8 or handle HTTP response codes
    */
   @Deprecated
   public static String readFileFromURL(URL url, TrustedHttpClient trustedClient) {
     StringBuilder sb = new StringBuilder();
     DataInputStream in = null;
     HttpResponse response = null;
     try {
       // Do different things depending on what we're reading...
       if ("file".equals(url.getProtocol())) {
         in = new DataInputStream(url.openStream());
       } else {
         if (trustedClient == null) {
           logger.error("Unable to read from remote source {} because trusted client is null!", url.getFile());
           return null;
         }
         HttpGet get = new HttpGet(url.toURI());
         try {
           response = trustedClient.execute(get);
         } catch (TrustedHttpClientException e) {
           logger.warn("Unable to fetch file from {}.", url, e);
           trustedClient.close(response);
           return null;
         }
         in = new DataInputStream(response.getEntity().getContent());
       }
       int c = 0;
       while ((c = in.read()) != -1) {
         sb.append((char) c);
       }
     } catch (IOException e) {
       logger.warn("IOException attempting to get file from {}.", url);
       return null;
     } catch (URISyntaxException e) {
       logger.warn("URI error attempting to get file from {}.", url);
       return null;
     } catch (NullPointerException e) {
       logger.warn("Nullpointer attempting to get file from {}.", url);
       return null;
     } finally {
       IOUtils.closeQuietly(in);
 
       if (response != null) {
         try {
           trustedClient.close(response);
         } catch (IOException e) {
         }
       }
     }
 
     return sb.toString();
   }
 
   public static Properties loadPropertiesFromUrl(final URL url) {
     try {
       return loadPropertiesFromStream(url.openStream());
     } catch (IOException e) {
       return chuck(e);
     }
   }
 
   /** Load properties from a stream. Close the stream after reading. */
   public static Properties loadPropertiesFromStream(final InputStream stream) {
     return withResource(stream, (InputStream in) -> {
       try {
         Properties p = new Properties();
         p.load(in);
         return p;
       } catch (Exception e) {
         return chuck(e);
       }
     });
   }
 
   /**
    * Handle a closeable resource inside <code>f</code> and ensure it gets closed properly.
    */
   public static <A, B extends Closeable> A withResource(B b, Function<B, A> f) {
     try {
       return f.apply(b);
     } finally {
       IoSupport.closeQuietly(b);
     }
   }
 
   /**
    * Open a classpath resource using the class loader of the given class.
    *
    * @return an input stream to the resource wrapped in a Some or none if the resource cannot be found
    */
   public static Optional<InputStream> openClassPathResource(String resource, Class<?> clazz) {
     return Optional.ofNullable(clazz.getResourceAsStream(resource));
   }
 
   /**
    * Open a classpath resource using the class loader of {@link IoSupport}.
    *
    * @see #openClassPathResource(String, Class)
    */
   public static Optional<InputStream> openClassPathResource(String resource) {
     return openClassPathResource(resource, IoSupport.class);
   }
 
   /** Get a classpath resource as a file using the class loader of {@link IoSupport}. */
   public static Optional<File> classPathResourceAsFile(String resource) {
     try {
       final URL res = IoSupport.class.getResource(resource);
       if (res != null) {
         return Optional.of(new File(res.toURI()));
       } else {
         return Optional.empty();
       }
     } catch (URISyntaxException e) {
       return Optional.empty();
     }
   }
 
   /**
    * Load a classpath resource into a string using UTF-8 encoding and the class loader of the given class.
    *
    * @return the content of the resource wrapped in a Some or none in case of any error
    */
   public static Optional<String> loadFileFromClassPathAsString(String resource, Class<?> clazz) {
     try {
       final URL url = clazz.getResource(resource);
       return url != null ? Optional.of(Resources.toString(clazz.getResource(resource), Charset.forName("UTF-8")))
               : Optional.empty();
     } catch (IOException e) {
       return Optional.empty();
     }
   }
 
   /**
    * Load a classpath resource into a string using the class loader of {@link IoSupport}.
    *
    * @see #loadFileFromClassPathAsString(String, Class)
    */
   public static Optional<String> loadFileFromClassPathAsString(String resource) {
     return loadFileFromClassPathAsString(resource, IoSupport.class);
   }
 
   /**
    * Handle a stream inside <code>f</code> and ensure that <code>s</code> gets closed properly.
    * <p>
    * <strong>Please note:</strong> The outcome of <code>f</code> is wrapped into a some. Therefore <code>f</code> is
    * <em>not</em> allowed to return <code>null</code>. Use an <code>Option</code> instead and flatten the overall
    * result.
    *
    * @return none, if the file does not exist
    */
   public static <A> Optional<A> withFile(File file, BiFunction<InputStream, File, A> f) {
     try (InputStream s = new FileInputStream(file)) {
       return Optional.of(f.apply(s, file));
     } catch (FileNotFoundException e) {
       return Optional.empty();
     } catch (IOException e) {
       return chuck(e);
     }
   }
 
   /**
    * Handle a closeable resource inside <code>f</code> and ensure that <code>r</code> gets closed properly.
    *
    * @param resourceSupplier
    *          resource creation function
    * @param toErr
    *          error handler transforming an exception into something else
    * @param f
    *          resource handler
    */
   public static <A, Err, B extends Closeable> Either<Err, A> withResource(
       Supplier<B> resourceSupplier,
       Function<Exception, Err> toErr,
       Function<B, A> f) {
     B resource = null;
     try {
       resource = resourceSupplier.get();
       return right(f.apply(resource));
     } catch (Exception e) {
       return left(toErr.apply(e));
     } finally {
       IoSupport.closeQuietly(resource);
     }
   }
 
   /** Function that reads an input stream into a string using utf-8 encoding. Stream does not get closed. */
   public static final Function<InputStream, String> readToString = in -> {
     try {
       return IOUtils.toString(in, "utf-8");
     } catch (Exception e) {
       return chuck(e);
     }
   };
 
   /** Create a function that creates a {@link java.io.FileInputStream}. */
   public static InputStream fileInputStream(File file) {
     try {
       return new FileInputStream(file);
     } catch (FileNotFoundException e) {
       return chuck(e);
     }
   }
 
   /** Create a file from the list of path elements. */
   public static File file(String... pathElems) {
     return new File(path(pathElems));
   }
 
   /**
    * Run function <code>f</code> having exclusive read/write access to the given file.
    * <p>
    * Please note that the implementation uses Java NIO {@link java.nio.channels.FileLock} which only guarantees that two
    * Java processes cannot interfere with each other.
    * <p>
    * The implementation blocks until a lock can be acquired.
    *
    * @throws NotFoundException
    *            if the path to the file, to create a lock for, does not exist
    * @throws IOException
    *            if the file lock can not be created due to access limitations
    */
   public static synchronized <A> A locked(File file, Function<File, A> action) throws NotFoundException, IOException {
     Runnable unlock = acquireLock(file);
     try {
       return action.apply(file);
     } finally {
       unlock.run();
     }
   }
 
   /**
    * Acquire a lock on a file. Return a key to release the lock.
    *
    * @return a key to release the lock
    *
    * @throws NotFoundException
    *            if the path to the file, to create a lock for, does not exist
    * @throws IOException
    *            if the file lock can not be created due to access limitations
    */
   private static Runnable acquireLock(File file) throws NotFoundException, IOException {
     final RandomAccessFile raf;
     try {
       raf = new RandomAccessFile(file, "rw");
     } catch (FileNotFoundException e) {
       // this exception is thrown only if the directory path to the file isn't exist
       // make sure to create all parent directories before locking the file
       throw new NotFoundException("Error acquiring lock for " + file.getAbsolutePath(), e);
     }
     final FileLock lock = raf.getChannel().lock();
     return () -> {
       try {
         lock.release();
       } catch (IOException ignore) {
       }
       IoSupport.closeQuietly(raf);
     };
   }
 
   /**
    * Serialize and deserialize an object. To test serializability.
    */
   public static <A extends Serializable> A serializeDeserialize(final A a) {
     final ByteArrayOutputStream out = new ByteArrayOutputStream();
     try {
       withResource(
           new ObjectOutputStream(out),
           new Function<ObjectOutputStream, Void>() {
             @Override
             public Void apply(ObjectOutputStream outStream) {
               try {
                 outStream.writeObject(a);
               } catch (IOException e) {
                 throw new RuntimeException(e);
               }
               return null;
             }
           }
       );
 
       return withResource(
           new ObjectInputStream(new ByteArrayInputStream(out.toByteArray())),
           new Function<ObjectInputStream, A>() {
             @Override
             public A apply(ObjectInputStream inStream) {
               try {
                 @SuppressWarnings("unchecked")
                 A obj = (A) inStream.readObject();
                 return obj;
               } catch (IOException | ClassNotFoundException e) {
                 throw new RuntimeException(e);
               }
             }
           }
       );
 
     } catch (IOException e) {
       throw new RuntimeException(e);
     }
   }
 }