/**
    * 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 static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertTrue;
  import static org.junit.Assert.fail;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.stream.Stream;
  
  import org.junit.Assume;
  import org.junit.Before;
  import org.junit.Test;
  
  /**
   * Test Graph implementation
   * <p>
   * To add to your implementation's tests, create a subclass with a name ending
   * in <code>Test</code> and provide {@link #createFactory()} which minimally
   * must support {@link RDF#createGraph()} and {@link RDF#createIRI(String)}, but
   * ideally support all operations.
   * <p>
   * This test uses try-with-resources blocks for calls to {@link Graph#stream()}
   * and {@link Graph#iterate()}.
   * 
   * @see Graph
   * @see RDF
   */
  public abstract class AbstractGraphTest {
  
      protected RDF factory;
      protected Graph graph;
      protected IRI alice;
      protected IRI bob;
      protected IRI name;
      protected IRI knows;
      protected IRI member;
      protected BlankNode bnode1;
      protected BlankNode bnode2;
      protected Literal aliceName;
      protected Literal bobName;
      protected Literal secretClubName;
      protected Literal companyName;
      protected Triple bobNameTriple;
  
      /**
       * 
       * This method must be overridden by the implementing test to provide a
       * factory for the test to create {@link Graph}, {@link IRI} etc.
       * 
       * @return {@link RDF} instance to be tested.
       */
      protected abstract RDF createFactory();
  
      @Before
      public void createGraphAndAdd() {
          factory = createFactory();
          graph = factory.createGraph();
          assertEquals(0, graph.size());
  
          alice = factory.createIRI("http://example.com/alice");
          bob = factory.createIRI("http://example.com/bob");
          name = factory.createIRI("http://xmlns.com/foaf/0.1/name");
          knows = factory.createIRI("http://xmlns.com/foaf/0.1/knows");
          member = factory.createIRI("http://xmlns.com/foaf/0.1/member");
          try {
              bnode1 = factory.createBlankNode("org1");
              bnode2 = factory.createBlankNode("org2");
          } catch (final UnsupportedOperationException ex) {
              // leave as null
          }
  
          try {
              secretClubName = factory.createLiteral("The Secret Club");
              companyName = factory.createLiteral("A company");
             aliceName = factory.createLiteral("Alice");
             bobName = factory.createLiteral("Bob", "en-US");
         } catch (final UnsupportedOperationException ex) {
             // leave as null
         }
 
         if (aliceName != null) {
             graph.add(alice, name, aliceName);
         }
         graph.add(alice, knows, bob);
 
         if (bnode1 != null) {
             graph.add(alice, member, bnode1);
         }
 
         if (bobName != null) {
             try {
                 bobNameTriple = factory.createTriple(bob, name, bobName);
             } catch (final UnsupportedOperationException ex) {
                 // leave as null
             }
             if (bobNameTriple != null) {
                 graph.add(bobNameTriple);
             }
         }
         if (bnode1 != null) {
             graph.add(factory.createTriple(bob, member, bnode1));
             graph.add(factory.createTriple(bob, member, bnode2));
             if (secretClubName != null) {
                 graph.add(bnode1, name, secretClubName);
                 graph.add(bnode2, name, companyName);
             }
         }
     }
 
     @Test
     public void size() throws Exception {
         assertTrue(graph.size() > 0);
         Assume.assumeNotNull(bnode1, bnode2, aliceName, bobName, secretClubName, companyName, bobNameTriple);
         // Can only reliably predict size if we could create all triples
         assertEquals(8, graph.size());
     }
 
     @Test
     public void iterate() throws Exception {
 
         Assume.assumeTrue(graph.size() > 0);
 
         final List<Triple> triples = new ArrayList<>();
         for (final Triple t : graph.iterate()) {
             triples.add(t);
         }
         assertEquals(graph.size(), triples.size());
         if (bobNameTriple != null) {
             assertTrue(triples.contains(bobNameTriple));
         }
 
         // aborted iteration
         final Iterable<Triple> iterate = graph.iterate();
         final Iterator<Triple> it = iterate.iterator();
 
         assertTrue(it.hasNext());
         it.next();
         closeIterable(iterate);
 
         // second iteration - should start from fresh and
         // get the same count
         long count = 0;
         final Iterable<Triple> iterable = graph.iterate();
         for (@SuppressWarnings("unused") final
         Triple t : iterable) {
             count++;
         }
         assertEquals(graph.size(), count);
     }
 
     /**
      * Special triple closing for RDF4J.
      */
     private void closeIterable(final Iterable<Triple> iterate) throws Exception {
         if (iterate instanceof AutoCloseable) {
             ((AutoCloseable) iterate).close();
         }
     }
 
     @Test
     public void iterateFilter() throws Exception {
         final List<RDFTerm> friends = new ArrayList<>();
         final IRI alice = factory.createIRI("http://example.com/alice");
         final IRI knows = factory.createIRI("http://xmlns.com/foaf/0.1/knows");
         for (final Triple t : graph.iterate(alice, knows, null)) {
             friends.add(t.getObject());
         }
         assertEquals(1, friends.size());
         assertEquals(bob, friends.get(0));
 
         // .. can we iterate over zero hits?
         final Iterable<Triple> iterate = graph.iterate(bob, knows, alice);
         for (final Triple unexpected : iterate) {
             fail("Unexpected triple " + unexpected);
         }
         // closeIterable(iterate);
     }
 
     @Test
     public void contains() throws Exception {
         assertFalse(graph.contains(bob, knows, alice)); // or so he claims..
 
         assertTrue(graph.contains(alice, knows, bob));
 
         try (Stream<? extends Triple> stream = graph.stream()) {
             final Optional<? extends Triple> first = stream.skip(4).findFirst();
             Assume.assumeTrue(first.isPresent());
             final Triple existingTriple = first.get();
             assertTrue(graph.contains(existingTriple));
         }
 
         final Triple nonExistingTriple = factory.createTriple(bob, knows, alice);
         assertFalse(graph.contains(nonExistingTriple));
 
         Triple triple = null;
         try {
             triple = factory.createTriple(alice, knows, bob);
         } catch (final UnsupportedOperationException ex) {
         }
         if (triple != null) {
             // FIXME: Should not this always be true?
             // assertTrue(graph.contains(triple));
         }
     }
 
     @Test
     public void remove() throws Exception {
         final long fullSize = graph.size();
         graph.remove(alice, knows, bob);
         final long shrunkSize = graph.size();
         assertEquals(1, fullSize - shrunkSize);
 
         graph.remove(alice, knows, bob);
         assertEquals(shrunkSize, graph.size()); // unchanged
 
         graph.add(alice, knows, bob);
         graph.add(alice, knows, bob);
         graph.add(alice, knows, bob);
         // Undetermined size at this point -- but at least it
         // should be bigger
         assertTrue(graph.size() > shrunkSize);
 
         // and after a single remove they should all be gone
         graph.remove(alice, knows, bob);
         assertEquals(shrunkSize, graph.size());
 
         Triple otherTriple;
         try (Stream<? extends Triple> stream = graph.stream()) {
             final Optional<? extends Triple> anyTriple = stream.findAny();
             Assume.assumeTrue(anyTriple.isPresent());
             otherTriple = anyTriple.get();
         }
 
         graph.remove(otherTriple);
         assertEquals(shrunkSize - 1, graph.size());
         graph.remove(otherTriple);
         assertEquals(shrunkSize - 1, graph.size()); // no change
 
         // for some reason in rdf4j this causes duplicates!
         graph.add(otherTriple);
         // graph.stream().forEach(System.out::println);
         // should have increased
         assertTrue(graph.size() >= shrunkSize);
     }
 
     @Test
     public void clear() throws Exception {
         graph.clear();
         assertFalse(graph.contains(alice, knows, bob));
         assertEquals(0, graph.size());
         graph.clear(); // no-op
         assertEquals(0, graph.size());
     }
 
     @Test
     public void getTriples() throws Exception {
         long tripleCount;
         try (Stream<? extends Triple> stream = graph.stream()) {
             tripleCount = stream.count();
         }
         assertTrue(tripleCount > 0);
 
         try (Stream<? extends Triple> stream = graph.stream()) {
             assertTrue(stream.allMatch(t -> graph.contains(t)));
         }
 
         // Check exact count
         Assume.assumeNotNull(bnode1, bnode2, aliceName, bobName, secretClubName, companyName, bobNameTriple);
         assertEquals(8, tripleCount);
     }
 
     @Test
     public void getTriplesQuery() throws Exception {
 
         try (Stream<? extends Triple> stream = graph.stream(alice, null, null)) {
             final long aliceCount = stream.count();
             assertTrue(aliceCount > 0);
             Assume.assumeNotNull(aliceName);
             assertEquals(3, aliceCount);
         }
 
         Assume.assumeNotNull(bnode1, bnode2, bobName, companyName, secretClubName);
         try (Stream<? extends Triple> stream = graph.stream(null, name, null)) {
             assertEquals(4, stream.count());
         }
         Assume.assumeNotNull(bnode1);
         try (Stream<? extends Triple> stream = graph.stream(null, member, null)) {
             assertEquals(3, stream.count());
         }
     }
 
     @Test
     public void addBlankNodesFromMultipleGraphs() {
 
         try {
             // Create two separate Graph instances
             final Graph g1 = createGraph1();
             final Graph g2 = createGraph2();
 
             // and add them to a new Graph g3
             final Graph g3 = factory.createGraph();
             addAllTriples(g1, g3);
             addAllTriples(g2, g3);
 
             // Let's make a map to find all those blank nodes after insertion
             // (The Graph implementation is not currently required to
             // keep supporting those BlankNodes with contains() - see
             // COMMONSRDF-15)
 
             final Map<String, BlankNodeOrIRI> whoIsWho = new ConcurrentHashMap<>();
             // ConcurrentHashMap as we will try parallel forEach below,
             // which should not give inconsistent results (it does with a
             // HashMap!)
 
             // look up BlankNodes by name
             final IRI name = factory.createIRI("http://xmlns.com/foaf/0.1/name");
             try (Stream<? extends Triple> stream = g3.stream(null, name, null)) {
                 stream.parallel().forEach(t -> whoIsWho.put(t.getObject().ntriplesString(), t.getSubject()));
             }
 
             assertEquals(4, whoIsWho.size());
             // and contains 4 unique values
             assertEquals(4, new HashSet<>(whoIsWho.values()).size());
 
             final BlankNodeOrIRI b1Alice = whoIsWho.get("\"Alice\"");
             assertNotNull(b1Alice);
             final BlankNodeOrIRI b2Bob = whoIsWho.get("\"Bob\"");
             assertNotNull(b2Bob);
             final BlankNodeOrIRI b1Charlie = whoIsWho.get("\"Charlie\"");
             assertNotNull(b1Charlie);
             final BlankNodeOrIRI b2Dave = whoIsWho.get("\"Dave\"");
             assertNotNull(b2Dave);
 
             // All blank nodes should differ
             notEquals(b1Alice, b2Bob);
             notEquals(b1Alice, b1Charlie);
             notEquals(b1Alice, b2Dave);
             notEquals(b2Bob, b1Charlie);
             notEquals(b2Bob, b2Dave);
             notEquals(b1Charlie, b2Dave);
 
             // And we should be able to query with them again
             // as we got them back from g3
             final IRI hasChild = factory.createIRI("http://example.com/hasChild");
             assertTrue(g3.contains(b1Alice, hasChild, b2Bob));
             assertTrue(g3.contains(b2Dave, hasChild, b1Charlie));
             // But not
             assertFalse(g3.contains(b1Alice, hasChild, b1Alice));
             assertFalse(g3.contains(b1Alice, hasChild, b1Charlie));
             assertFalse(g3.contains(b1Alice, hasChild, b2Dave));
             // nor
             assertFalse(g3.contains(b2Dave, hasChild, b1Alice));
             assertFalse(g3.contains(b2Dave, hasChild, b1Alice));
 
             // and these don't have any children (as far as we know)
             assertFalse(g3.contains(b2Bob, hasChild, null));
             assertFalse(g3.contains(b1Charlie, hasChild, null));
         } catch (final UnsupportedOperationException ex) {
             Assume.assumeNoException(ex);
         }
     }
 
     private void notEquals(final BlankNodeOrIRI node1, final BlankNodeOrIRI node2) {
         assertFalse(node1.equals(node2));
         // in which case we should be able to assume
         // (as they are in the same graph)
         assertFalse(node1.ntriplesString().equals(node2.ntriplesString()));
     }
 
     /**
      * Add all triples from the source to the target.
      * <p>
      * The triples may be copied in any order. No special conversion or
      * adaptation of {@link BlankNode}s are performed.
      *
      * @param source
      *            Source Graph to copy triples from
      * @param target
      *            Target Graph where triples will be added
      */
     private void addAllTriples(final Graph source, final Graph target) {
 
         // unordered() as we don't need to preserve triple order
         // sequential() as we don't (currently) require target Graph to be
         // thread-safe
 
         try (Stream<? extends Triple> stream = source.stream()) {
             stream.unordered().sequential().forEach(t -> target.add(t));
         }
     }
 
     /**
      * Make a new graph with two BlankNodes - each with a different
      * uniqueReference
      */
     private Graph createGraph1() {
         final RDF factory1 = createFactory();
 
         final IRI name = factory1.createIRI("http://xmlns.com/foaf/0.1/name");
         final Graph g1 = factory1.createGraph();
         final BlankNode b1 = createOwnBlankNode("b1", "0240eaaa-d33e-4fc0-a4f1-169d6ced3680");
         g1.add(b1, name, factory1.createLiteral("Alice"));
 
         final BlankNode b2 = createOwnBlankNode("b2", "9de7db45-0ce7-4b0f-a1ce-c9680ffcfd9f");
         g1.add(b2, name, factory1.createLiteral("Bob"));
 
         final IRI hasChild = factory1.createIRI("http://example.com/hasChild");
         g1.add(b1, hasChild, b2);
 
         return g1;
     }
 
     /**
      * Create a different implementation of BlankNode to be tested with
      * graph.add(a,b,c); (the implementation may or may not then choose to
      * translate such to its own instances)
      * 
      * @param name
      * @return
      */
     private BlankNode createOwnBlankNode(final String name, final String uuid) {
         return new BlankNode() {
             @Override
             public String ntriplesString() {
                 return "_: " + name;
             }
 
             @Override
             public String uniqueReference() {
                 return uuid;
             }
 
             @Override
             public int hashCode() {
                 return uuid.hashCode();
             }
 
             @Override
             public boolean equals(final Object obj) {
                 if (!(obj instanceof BlankNode)) {
                     return false;
                 }
                 final BlankNode other = (BlankNode) obj;
                 return uuid.equals(other.uniqueReference());
             }
         };
     }
 
     private Graph createGraph2() {
         final RDF factory2 = createFactory();
         final IRI name = factory2.createIRI("http://xmlns.com/foaf/0.1/name");
 
         final Graph g2 = factory2.createGraph();
 
         final BlankNode b1 = createOwnBlankNode("b1", "bc8d3e45-a08f-421d-85b3-c25b373abf87");
         g2.add(b1, name, factory2.createLiteral("Charlie"));
 
         final BlankNode b2 = createOwnBlankNode("b2", "2209097a-5078-4b03-801a-6a2d2f50d739");
         g2.add(b2, name, factory2.createLiteral("Dave"));
 
         final IRI hasChild = factory2.createIRI("http://example.com/hasChild");
         // NOTE: Opposite direction of loadGraph1
         g2.add(b2, hasChild, b1);
         return g2;
     }
 
     /**
      * An attempt to use the Java 8 streams to look up a more complicated query.
      * <p>
      * FYI, the equivalent SPARQL version (untested):
      * 
      * <pre>
      *     SELECT ?orgName WHERE {
      *             ?org foaf:name ?orgName .
      *             ?alice foaf:member ?org .
      *             ?bob foaf:member ?org .
      *             ?alice foaf:knows ?bob .
      *           FILTER NOT EXIST { ?bob foaf:knows ?alice }
      *    }
      * </pre>
      *
      * @throws Exception If test fails
      */
     @Test
     public void whyJavaStreamsMightNotTakeOverFromSparql() throws Exception {
         Assume.assumeNotNull(bnode1, bnode2, secretClubName);
         // Find a secret organizations
         try (Stream<? extends Triple> stream = graph.stream(null, knows, null)) {
             assertEquals("\"The Secret Club\"",
                     // Find One-way "knows"
                     stream.filter(t -> !graph.contains((BlankNodeOrIRI) t.getObject(), knows, t.getSubject()))
                             .map(knowsTriple -> {
                                 try (Stream<? extends Triple> memberOf = graph
                                         // and those they know, what are they
                                         // member of?
                                         .stream((BlankNodeOrIRI) knowsTriple.getObject(), member, null)) {
                                     return memberOf
                                             // keep those which first-guy is a
                                             // member of
                                             .filter(memberTriple -> graph.contains(knowsTriple.getSubject(), member,
                                                     // First hit is good enough
                                                     memberTriple.getObject()))
                                             .findFirst().get().getObject();
                                 }
                             })
                             // then look up the name of that org
                             .map(org -> {
                                 try (Stream<? extends Triple> orgName = graph.stream((BlankNodeOrIRI) org, name,
                                         null)) {
                                     return orgName.findFirst().get().getObject().ntriplesString();
                                 }
                             }).findFirst().get());
         }
     }
 }