/*
    * 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.any23.extractor;
  
  import org.apache.any23.source.MemCopyFactory;
  import org.apache.any23.source.StringDocumentSource;
  import org.apache.any23.writer.TripleHandler;
  import org.apache.any23.writer.TripleHandlerException;
  import org.apache.any23.writer.TurtleWriter;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * A reporter for example input and output of an extractor. Example
   * input is part of every extractor's metadata; example output is
   * obtained by running the extractor on its own example input. This
   * is useful as a documentation device.
   *
   * @author Richard Cyganiak (richard@cyganiak.de)
   */
  public class ExampleInputOutput {
  
      private final ExtractorFactory<?> factory;
  
      public ExampleInputOutput(String extractorName) {
          this(ExtractorRegistryImpl.getInstance().getFactory(extractorName));
      }
  
      public ExampleInputOutput(ExtractorFactory<?> factory) {
          this.factory = factory;
      }
  
      public String getExampleInput() throws IOException {
          if (factory.getExampleInput() == null) {
              return null;
          }
          if (isBlindExtractor()) {
              return null;
          }
          InputStream in = factory.createExtractor().getClass().getResourceAsStream(
                  factory.getExampleInput());
          if (in == null) {
              throw new IllegalArgumentException(
                      "Example input resource not found for extractor " +
                              factory.getExtractorName() + ": " +
                              factory.getExampleInput());
          }
          return new String(MemCopyFactory.toByteArray(in), "utf-8");
      }
  
      public String getExampleURI() {
          if (factory.getExampleInput() == null) {
              return null;
          }
          if (isBlindExtractor()) {
              return factory.getExampleInput();    // Should be a URI.
          }
          return "http://example.com/";
      }
  
      public String getExampleOutput() throws IOException, ExtractionException {
          if (factory.getExampleInput() == null) {
              return null;
          }
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          TripleHandler writer = new TurtleWriter(out);
          new SingleDocumentExtraction(
                  new StringDocumentSource(getExampleInput(), getExampleURI()),
                  factory,
                  writer).run();
          try {
              writer.close();
          } catch (TripleHandlerException e) {
              throw new ExtractionException("Error while closing the triple handler", e);
          }
          return out.toString("utf-8");
      }
  
      private boolean isBlindExtractor() {
          return factory.createExtractor() instanceof Extractor.BlindExtractor;
      }
  
 }