content: /*
   * 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.asterix.translator;
  
  import java.io.PrintWriter;
  import java.io.StringWriter;
  
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.prettyprint.AlgebricksAppendable;
  
  public class SessionOutput {
      private final SessionConfig config;
  
      // Output path for primary execution.
      private final PrintWriter out;
      private StringWriter buffer;
      private PrintWriter bufferedOut;
  
      private final SessionOutput.ResultDecorator preResultDecorator;
      private final SessionOutput.ResultDecorator postResultDecorator;
      private SessionOutput.ResultAppender handleAppender;
      private final SessionOutput.ResultAppender statusAppender;
  
      public SessionOutput(PrintWriter out) {
          this(null, out);
      }
  
      public SessionOutput(SessionConfig config, PrintWriter out) {
          this(config, out, null, null, null, null);
      }
  
      public SessionOutput(SessionConfig config, PrintWriter out, ResultDecorator preResultDecorator,
              ResultDecorator postResultDecorator, ResultAppender handleAppender, ResultAppender statusAppender) {
          this.config = config;
          this.out = out;
          this.preResultDecorator = preResultDecorator;
          this.postResultDecorator = postResultDecorator;
          this.handleAppender = handleAppender;
          this.statusAppender = statusAppender;
      }
  
      /**
       * Retrieve the PrintWriter to produce output to.
       */
      public PrintWriter out() {
          return this.bufferedOut != null ? this.bufferedOut : this.out;
      }
  
      public void setHandleAppender(SessionOutput.ResultAppender handleAppender) {
          this.handleAppender = handleAppender;
      }
  
      /**
       * buffer the data provided to the PrintWriter returned by out() to be able to set the status of the response
       * message when it can be determined. This is a no-op, if data is already buffered.
       */
      public void hold() {
          if (this.bufferedOut == null) {
              this.buffer = new StringWriter();
              this.bufferedOut = new PrintWriter(this.buffer);
          }
      }
  
      /**
       * release the data that was buffered by calling hold() and remove the buffer from the pipeline.
       * This is a no-op, if data is not buffered.
       */
      public void release() {
          if (this.bufferedOut != null) {
              this.bufferedOut.flush();
              this.out.write(buffer.toString());
              this.bufferedOut = null;
              this.buffer = null;
          }
      }
  
      public AlgebricksAppendable resultPrefix(AlgebricksAppendable app) throws AlgebricksException {
          return this.preResultDecorator != null ? this.preResultDecorator.append(app) : app;
      }
  
      public AlgebricksAppendable resultPostfix(AlgebricksAppendable app) throws AlgebricksException {
          return this.postResultDecorator != null ? this.postResultDecorator.append(app) : app;
      }
  
      public AlgebricksAppendable appendHandle(AlgebricksAppendable app, String handle) throws AlgebricksException {
          return this.handleAppender != null ? this.handleAppender.append(app, handle) : app;
      }
  
      public AlgebricksAppendable appendStatus(AlgebricksAppendable app, String status) throws AlgebricksException {
          return this.statusAppender != null ? this.statusAppender.append(app, status) : app;
      }
  
      public SessionConfig config() {
          return config;
      }
  
      @FunctionalInterface
      public interface ResultDecorator {
          AlgebricksAppendable append(AlgebricksAppendable app) throws AlgebricksException;
      }
  
      @FunctionalInterface
      public interface ResultAppender {
          AlgebricksAppendable append(AlgebricksAppendable app, String str) throws AlgebricksException;
      }
  }
  