content: /*
   * Copyright 2016 Google 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.
   */
  
  package com.google.googlejavaformat.java.filer;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import com.google.common.io.CharSink;
  import com.google.common.io.CharSource;
  import com.google.googlejavaformat.java.Formatter;
  import com.google.googlejavaformat.java.FormatterException;
  import java.io.IOException;
  import java.io.Writer;
  import jdkx.annotation.processing.Messager;
  import jdkx.tools.Diagnostic;
  import jdkx.tools.ForwardingJavaFileObject;
  import jdkx.tools.JavaFileObject;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /** A {@link JavaFileObject} decorator which {@linkplain Formatter formats} source code. */
  final class FormattingJavaFileObject extends ForwardingJavaFileObject<JavaFileObject> {
    /** A rough estimate of the average file size: 80 chars per line, 500 lines. */
    private static final int DEFAULT_FILE_SIZE = 80 * 500;
  
    private final Formatter formatter;
    private final Messager messager;
  
    /**
     * Create a new {@link FormattingJavaFileObject}.
     *
     * @param delegate {@link JavaFileObject} to decorate
     * @param messager to log messages with.
     */
    FormattingJavaFileObject(
        JavaFileObject delegate, Formatter formatter, @Nullable Messager messager) {
      super(checkNotNull(delegate));
      this.formatter = checkNotNull(formatter);
      this.messager = messager;
    }
  
    @Override
    public Writer openWriter() throws IOException {
      final StringBuilder stringBuilder = new StringBuilder(DEFAULT_FILE_SIZE);
      return new Writer() {
        @Override
        public void write(char[] chars, int start, int end) throws IOException {
          stringBuilder.append(chars, start, end - start);
        }
  
        @Override
        public void write(String string) throws IOException {
          stringBuilder.append(string);
        }
  
        @Override
        public void flush() throws IOException {}
  
        @Override
        public void close() throws IOException {
          try {
            formatter.formatSource(
                CharSource.wrap(stringBuilder),
                new CharSink() {
                  @Override
                  public Writer openStream() throws IOException {
                    return fileObject.openWriter();
                  }
                });
          } catch (FormatterException e) {
            // An exception will happen when the code being formatted has an error. It's better to
            // log the exception and emit unformatted code so the developer can view the code which
            // caused a problem.
            try (Writer writer = fileObject.openWriter()) {
              writer.append(stringBuilder.toString());
            }
            if (messager != null) {
              messager.printMessage(Diagnostic.Kind.NOTE, "Error formatting " + getName());
            }
          }
        }
      };
    }
  }
  