/*
    * 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.commons.io.output;
  
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.OutputStreamWriter;
  import java.io.UnsupportedEncodingException;
  import java.io.Writer;
  import java.nio.charset.Charset;
  import java.util.Objects;
  
  import org.apache.commons.io.Charsets;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.io.build.AbstractOrigin;
  import org.apache.commons.io.build.AbstractStreamBuilder;
  
  /**
   * FileWriter that will create and honor lock files to allow simple cross thread file lock handling.
   * <p>
   * This class provides a simple alternative to {@link FileWriter} that will use a lock file to prevent duplicate writes.
   * </p>
   * <p>
   * <strong>Note:</strong> The lock file is deleted when {@link #close()} is called - or if the main file cannot be opened initially. In the (unlikely) event
   * that the lock file cannot be deleted, an exception is thrown.
   * </p>
   * <p>
   * By default, the file will be overwritten, but this may be changed to append. The lock directory may be specified, but defaults to the system property
   * {@code java.io.tmpdir}. The encoding may also be specified, and defaults to the platform default.
   * </p>
   * <p>
   * To build an instance, use {@link Builder}.
   * </p>
   *
   * @see Builder
   */
  public class LockableFileWriter extends Writer {
  
      // @formatter:off
      /**
       * Builds a new {@link LockableFileWriter}.
       *
       * <p>
       * Using a CharsetEncoder:
       * </p>
       * <pre>{@code
       * LockableFileWriter w = LockableFileWriter.builder()
       *   .setPath(path)
       *   .setAppend(false)
       *   .setLockDirectory("Some/Directory")
       *   .get();}
       * </pre>
       *
       * @see #get()
       * @since 2.12.0
       */
      // @formatter:on
      public static class Builder extends AbstractStreamBuilder<LockableFileWriter, Builder> {
  
          private boolean append;
          private AbstractOrigin<?, ?> lockDirectory = newFileOrigin(FileUtils.getTempDirectoryPath());
  
          /**
           * Constructs a new builder of {@link LockableFileWriter}.
           */
          public Builder() {
              setBufferSizeDefault(AbstractByteArrayOutputStream.DEFAULT_SIZE);
              setBufferSize(AbstractByteArrayOutputStream.DEFAULT_SIZE);
          }
  
          /**
           * Constructs a new instance.
           * <p>
           * You must set an aspect that supports {@link File} on this builder, otherwise, this method throws an exception.
           * </p>
           * <p>
           * This builder uses the following aspects:
           * </p>
           * <ul>
           * <li>{@link File} is the target aspect.</li>
           * <li>{@link #getCharset()}</li>
           * <li>append</li>
           * <li>lockDirectory</li>
          * </ul>
          *
          * @return a new instance.
          * @throws UnsupportedOperationException if the origin cannot provide a File.
          * @throws IllegalStateException         if the {@code origin} is {@code null}.
          * @throws IOException                   if an I/O error occurs converting to an {@link File} using {@link #getFile()}.
          * @see AbstractOrigin#getFile()
          * @see #getUnchecked()
          */
         @Override
         public LockableFileWriter get() throws IOException {
             return new LockableFileWriter(checkOrigin().getFile(), getCharset(), append, lockDirectory.getFile().toString());
         }
 
         /**
          * Sets whether to append (true) or overwrite (false).
          *
          * @param append whether to append (true) or overwrite (false).
          * @return {@code this} instance.
          */
         public Builder setAppend(final boolean append) {
             this.append = append;
             return this;
         }
 
         /**
          * Sets the directory in which the lock file should be held.
          *
          * @param lockDirectory the directory in which the lock file should be held.
          * @return {@code this} instance.
          */
         public Builder setLockDirectory(final File lockDirectory) {
             this.lockDirectory = newFileOrigin(lockDirectory != null ? lockDirectory : FileUtils.getTempDirectory());
             return this;
         }
 
         /**
          * Sets the directory in which the lock file should be held.
          *
          * @param lockDirectory the directory in which the lock file should be held.
          * @return {@code this} instance.
          */
         public Builder setLockDirectory(final String lockDirectory) {
             this.lockDirectory = newFileOrigin(lockDirectory != null ? lockDirectory : FileUtils.getTempDirectoryPath());
             return this;
         }
 
     }
 
     /** The extension for the lock file. */
     private static final String LCK = ".lck";
 
     // Cannot extend ProxyWriter, as requires writer to be
     // known when super() is called
 
     /**
      * Constructs a new {@link Builder}.
      *
      * @return a new {@link Builder}.
      * @since 2.12.0
      */
     public static Builder builder() {
         return new Builder();
     }
 
     /** The writer to decorate. */
     private final Writer out;
 
     /** The lock file. */
     private final File lockFile;
 
     /**
      * Constructs a LockableFileWriter. If the file exists, it is overwritten.
      *
      * @param file the file to write to, not null
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final File file) throws IOException {
         this(file, false, null);
     }
 
     /**
      * Constructs a LockableFileWriter.
      *
      * @param file   the file to write to, not null
      * @param append true if content should be appended, false to overwrite
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final File file, final boolean append) throws IOException {
         this(file, append, null);
     }
 
     /**
      * Constructs a LockableFileWriter.
      * <p>
      * The new instance uses the virtual machine's {@link Charset#defaultCharset() default charset}.
      * </p>
      *
      * @param file    the file to write to, not null
      * @param append  true if content should be appended, false to overwrite
      * @param lockDir the directory in which the lock file should be held
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @deprecated Use {@link #LockableFileWriter(File, Charset, boolean, String)} instead
      */
     @Deprecated
     public LockableFileWriter(final File file, final boolean append, final String lockDir) throws IOException {
         this(file, Charset.defaultCharset(), append, lockDir);
     }
 
     /**
      * Constructs a LockableFileWriter with a file encoding.
      *
      * @param file    the file to write to, not null
      * @param charset the charset to use, null means platform default
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @since 2.3
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final File file, final Charset charset) throws IOException {
         this(file, charset, false, null);
     }
 
     /**
      * Constructs a LockableFileWriter with a file encoding.
      *
      * @param file    the file to write to, not null
      * @param charset the name of the requested charset, null means platform default
      * @param append  true if content should be appended, false to overwrite
      * @param lockDir the directory in which the lock file should be held
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @since 2.3
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final File file, final Charset charset, final boolean append, final String lockDir) throws IOException {
         // init file to create/append
         final File absFile = Objects.requireNonNull(file, "file").getAbsoluteFile();
         if (absFile.getParentFile() != null) {
             FileUtils.forceMkdir(absFile.getParentFile());
         }
         if (absFile.isDirectory()) {
             throw new IOException("File specified is a directory");
         }
 
         // init lock file
         final File lockDirFile = new File(lockDir != null ? lockDir : FileUtils.getTempDirectoryPath());
         FileUtils.forceMkdir(lockDirFile);
         testLockDir(lockDirFile);
         lockFile = new File(lockDirFile, absFile.getName() + LCK);
 
         // check if locked
         createLock();
 
         // init wrapped writer
         out = initWriter(absFile, charset, append);
     }
 
     /**
      * Constructs a LockableFileWriter with a file encoding.
      *
      * @param file        the file to write to, not null
      * @param charsetName the name of the requested charset, null means platform default
      * @throws NullPointerException                         if the file is null
      * @throws IOException                                  in case of an I/O error
      * @throws java.nio.charset.UnsupportedCharsetException thrown instead of {@link UnsupportedEncodingException} in version 2.2 if the encoding is not
      *                                                      supported.
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final File file, final String charsetName) throws IOException {
         this(file, charsetName, false, null);
     }
 
     /**
      * Constructs a LockableFileWriter with a file encoding.
      *
      * @param file        the file to write to, not null
      * @param charsetName the encoding to use, null means platform default
      * @param append      true if content should be appended, false to overwrite
      * @param lockDir     the directory in which the lock file should be held
      * @throws NullPointerException                         if the file is null
      * @throws IOException                                  in case of an I/O error
      * @throws java.nio.charset.UnsupportedCharsetException thrown instead of {@link UnsupportedEncodingException} in version 2.2 if the encoding is not
      *                                                      supported.
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final File file, final String charsetName, final boolean append, final String lockDir) throws IOException {
         this(file, Charsets.toCharset(charsetName), append, lockDir);
     }
 
     /**
      * Constructs a LockableFileWriter. If the file exists, it is overwritten.
      *
      * @param fileName the file to write to, not null
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final String fileName) throws IOException {
         this(fileName, false, null);
     }
 
     /**
      * Constructs a LockableFileWriter.
      *
      * @param fileName file to write to, not null
      * @param append   true if content should be appended, false to overwrite
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final String fileName, final boolean append) throws IOException {
         this(fileName, append, null);
     }
 
     /**
      * Constructs a LockableFileWriter.
      *
      * @param fileName the file to write to, not null
      * @param append   true if content should be appended, false to overwrite
      * @param lockDir  the directory in which the lock file should be held
      * @throws NullPointerException if the file is null
      * @throws IOException          in case of an I/O error
      * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
      */
     @Deprecated
     public LockableFileWriter(final String fileName, final boolean append, final String lockDir) throws IOException {
         this(new File(fileName), append, lockDir);
     }
 
     /**
      * Closes the file writer and deletes the lock file.
      *
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void close() throws IOException {
         try {
             out.close();
         } finally {
             FileUtils.delete(lockFile);
         }
     }
 
     /**
      * Creates the lock file.
      *
      * @throws IOException if we cannot create the file
      */
     private void createLock() throws IOException {
         synchronized (LockableFileWriter.class) {
             if (!lockFile.createNewFile()) {
                 throw new IOException("Can't write file, lock " + lockFile.getAbsolutePath() + " exists");
             }
             lockFile.deleteOnExit();
         }
     }
 
     /**
      * Flushes the stream.
      *
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void flush() throws IOException {
         out.flush();
     }
 
     /**
      * Initializes the wrapped file writer. Ensure that a cleanup occurs if the writer creation fails.
      *
      * @param file    the file to be accessed
      * @param charset the charset to use
      * @param append  true to append
      * @return The initialized writer
      * @throws IOException if an error occurs
      */
     private Writer initWriter(final File file, final Charset charset, final boolean append) throws IOException {
         final boolean fileExistedAlready = file.exists();
         try {
             return new OutputStreamWriter(new FileOutputStream(file.getAbsolutePath(), append), Charsets.toCharset(charset));
 
         } catch (final IOException | RuntimeException ex) {
             FileUtils.deleteQuietly(lockFile);
             if (!fileExistedAlready) {
                 FileUtils.deleteQuietly(file);
             }
             throw ex;
         }
     }
 
     /**
      * Tests that we can write to the lock directory.
      *
      * @param lockDir the File representing the lock directory
      * @throws IOException if we cannot write to the lock directory
      * @throws IOException if we cannot find the lock file
      */
     private void testLockDir(final File lockDir) throws IOException {
         if (!lockDir.exists()) {
             throw new IOException("Could not find lockDir: " + lockDir.getAbsolutePath());
         }
         if (!lockDir.canWrite()) {
             throw new IOException("Could not write to lockDir: " + lockDir.getAbsolutePath());
         }
     }
 
     /**
      * Writes the characters from an array.
      *
      * @param cbuf the characters to write
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void write(final char[] cbuf) throws IOException {
         out.write(cbuf);
     }
 
     /**
      * Writes the specified characters from an array.
      *
      * @param cbuf the characters to write
      * @param off  The start offset
      * @param len  The number of characters to write
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void write(final char[] cbuf, final int off, final int len) throws IOException {
         out.write(cbuf, off, len);
     }
 
     /**
      * Writes a character.
      *
      * @param c the character to write
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void write(final int c) throws IOException {
         out.write(c);
     }
 
     /**
      * Writes the characters from a string.
      *
      * @param str the string to write
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void write(final String str) throws IOException {
         out.write(str);
     }
 
     /**
      * Writes the specified characters from a string.
      *
      * @param str the string to write
      * @param off The start offset
      * @param len The number of characters to write
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void write(final String str, final int off, final int len) throws IOException {
         out.write(str, off, len);
     }
 
 }