/**
    * 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.rdf.api;
  
  import java.util.Arrays;
  import java.util.Optional;
  import java.util.stream.Stream;
  
  class DummyDataset implements Dataset {
      
      boolean streamCalled = false;
      boolean filteredStreamCalled;
      
      @Override
      public void add(final Quad Quad) {
          if (! contains(Quad)) {
              throw new IllegalStateException("DummyDataset can't be modified");
          }
      }
      
      @Override
      public void add(final BlankNodeOrIRI graphName, final BlankNodeOrIRI subject, final IRI predicate, final RDFTerm object) {
          if (! contains(Optional.ofNullable(graphName), subject, predicate, object)) { 
              throw new IllegalStateException("DummyDataset can't be modified");
          }
      }
      
      @Override
      public boolean contains(final Quad Quad) {
          return Quad.equals(new DummyQuad());
      }
      
      @Override
      public boolean contains(final Optional<BlankNodeOrIRI> graphName, final BlankNodeOrIRI subject, final IRI predicate, final RDFTerm object) {        
          return (graphName == null || ! graphName.isPresent()) &&
                  (subject == null || subject.equals(new DummyIRI(1))) && 
                  (predicate == null || predicate.equals(new DummyIRI(2))) && 
                  (object == null || object.equals(new DummyIRI(3)));
      }
      @Override
      public void remove(final Quad Quad) {
          if (contains(Quad)) {
              throw new IllegalStateException("DummyDataset can't be modified");
          }
      }
      @Override
      public void remove(final Optional<BlankNodeOrIRI> graphName, final BlankNodeOrIRI subject, final IRI predicate, final RDFTerm object) {
          if (contains(graphName, subject, predicate, object)) {
              throw new IllegalStateException("DummyDataset can't be modified");
          }
      }
      @Override
      public void clear() {
          throw new IllegalStateException("DummyDataset can't be modified");
      }
      @Override
      public long size() {
          return 1;
      }
      @Override
      public Stream<? extends Quad> stream() {
          streamCalled = true;
          return Arrays.asList(new DummyQuad()).stream();
      }
  
      @Override
      public Stream<? extends Quad> stream(final Optional<BlankNodeOrIRI> graphName, final BlankNodeOrIRI subject, final IRI predicate,
              final RDFTerm object) {
          filteredStreamCalled = true;
          if (contains(graphName, subject, predicate, object)) { 
              return Stream.of(new DummyQuad());
          } else {
              return Stream.empty();
          }
      }
  
      @Override
      public Graph getGraph() {
          return new DummyGraph();
      }
  
      @Override
      public Optional<Graph> getGraph(final BlankNodeOrIRI graphName) {
          if (graphName == null) { 
             return Optional.of(getGraph());
         } else {
             return Optional.empty();
         }
     }
 
     @Override
     public Stream<BlankNodeOrIRI> getGraphNames() {
         return Stream.empty();
     }
 }