/*
    * 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.collections4;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.OutputStream;
  import java.io.Serializable;
  import java.nio.file.Files;
  import java.nio.file.Paths;
  
  import org.junit.jupiter.api.Test;
  
  /**
   * Tests {@link Object}.
   * <p>
   * To use, simply extend this class, and implement
   * the {@link #makeObject()} method.
   * <p>
   * If your {@link Object} fails one of these tests by design,
   * you may still use this base set of cases.  Simply override the
   * test case (method) your {@link Object} fails.
   */
  public abstract class AbstractObjectTest extends BulkTest {
  
      /** Current major release for Collections */
      public static final int COLLECTIONS_MAJOR_VERSION = 4;
  
      protected String getCanonicalEmptyCollectionName(final Object object) {
          final StringBuilder retval = new StringBuilder();
          retval.append(TEST_DATA_PATH);
          String colName = object.getClass().getName();
          colName = colName.substring(colName.lastIndexOf(".") + 1);
          retval.append(colName);
          retval.append(".emptyCollection.version");
          retval.append(getCompatibilityVersion());
          retval.append(".obj");
          return retval.toString();
      }
  
      protected String getCanonicalFullCollectionName(final Object object) {
          final StringBuilder retval = new StringBuilder();
          retval.append(TEST_DATA_PATH);
          String colName = object.getClass().getName();
          colName = colName.substring(colName.lastIndexOf(".") + 1);
          retval.append(colName);
          retval.append(".fullCollection.version");
          retval.append(getCompatibilityVersion());
          retval.append(".obj");
          return retval.toString();
      }
  
      // protected implementation
      /**
       * Gets the version of Collections that this object tries to
       * maintain serialization compatibility with. Defaults to 4, due to
       * the package change to collections4 introduced in version 4.
       *
       * This constant makes it possible for TestMap (and other subclasses,
       * if necessary) to automatically check SCM for a versionX copy of a
       * Serialized object, so we can make sure that compatibility is maintained.
       * See, for example, TestMap.getCanonicalFullMapName(Map map).
       * Subclasses can override this variable, indicating compatibility
       * with earlier Collections versions.
       *
       * @return The version, or {@code null} if this object shouldn't be
       * tested for compatibility with previous versions.
       */
      public String getCompatibilityVersion() {
          return "4";
      }
  
      /**
       * Returns true to indicate that the collection supports equals() comparisons.
       * This implementation returns true;
      */
     public boolean isEqualsCheckable() {
         return true;
     }
 
     /**
      * Is serialization testing supported.
      * Default is true.
      */
     public boolean isTestSerialization() {
         return true;
     }
 
     /**
      * Implement this method to return the object to test.
      *
      * @return the object to test
      */
     public abstract Object makeObject();
 
     /**
      * Read a Serialized or Externalized Object from bytes.
      * Useful for verifying serialization in memory.
      *
      * @param b byte array containing a serialized Object
      * @return Object contained in the bytes
      * @throws IOException
      * @throws ClassNotFoundException
      */
     protected Object readExternalFormFromBytes(final byte[] b) throws IOException, ClassNotFoundException {
         final ByteArrayInputStream stream = new ByteArrayInputStream(b);
         return readExternalFormFromStream(stream);
     }
 
     /**
      * Reads a Serialized or Externalized Object from disk.
      * Useful for creating compatibility tests between
      * different SCM versions of the same class
      *
      * @param path path to the serialized Object
      * @return the Object at the given path
      * @throws IOException
      * @throws ClassNotFoundException
      */
     protected Object readExternalFormFromDisk(final String path) throws IOException, ClassNotFoundException {
         try (InputStream stream = Files.newInputStream(Paths.get(path))) {
             return readExternalFormFromStream(stream);
         }
     }
 
     // private implementation
     private Object readExternalFormFromStream(final InputStream stream) throws IOException, ClassNotFoundException {
         final ObjectInputStream oStream = new ObjectInputStream(stream);
         return oStream.readObject();
     }
 
     protected Object serializeDeserialize(final Object obj) throws Exception {
         final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
         final ObjectOutputStream out = new ObjectOutputStream(buffer);
         out.writeObject(obj);
         out.close();
 
         final ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(buffer.toByteArray()));
         final Object dest = in.readObject();
         in.close();
 
         return dest;
     }
 
     protected boolean skipSerializedCanonicalTests() {
         return Boolean.getBoolean("org.apache.commons.collections:with-clover");
     }
 
     /**
      * Override this method if a subclass is testing an object
      * that cannot serialize an "empty" Collection.
      * (for example Comparators have no contents)
      *
      * @return true
      */
     public boolean supportsEmptyCollections() {
         return true;
     }
 
     /**
      * Override this method if a subclass is testing an object
      * that cannot serialize a "full" Collection.
      * (for example Comparators have no contents)
      *
      * @return true
      */
     public boolean supportsFullCollections() {
         return true;
     }
 
     /**
      * Tests serialization by comparing against a previously stored version in SCM.
      * If the test object is serializable, confirm that a canonical form exists.
      */
     @Test
     public void testCanonicalEmptyCollectionExists() {
         if (supportsEmptyCollections() && isTestSerialization() && !skipSerializedCanonicalTests()) {
             final Object object = makeObject();
             if (object instanceof Serializable) {
                 final String name = getCanonicalEmptyCollectionName(object);
                 assertTrue(
                         new File(name).exists(),
                         "Canonical empty collection (" + name + ") is not in SCM");
             }
         }
     }
 
     /**
      * Tests serialization by comparing against a previously stored version in SCM.
      * If the test object is serializable, confirm that a canonical form exists.
      */
     @Test
     public void testCanonicalFullCollectionExists() {
         if (supportsFullCollections() && isTestSerialization() && !skipSerializedCanonicalTests()) {
             final Object object = makeObject();
             if (object instanceof Serializable) {
                 final String name = getCanonicalFullCollectionName(object);
                 assertTrue(
                         new File(name).exists(),
                         "Canonical full collection (" + name + ") is not in SCM");
             }
         }
     }
 
     @Test
     public void testEqualsNull() {
         final Object obj = makeObject();
         assertFalse(obj.equals(null)); // make sure this doesn't throw NPE either
     }
 
     @Test
     public void testObjectEqualsSelf() {
         final Object obj = makeObject();
         assertEquals(obj, obj, "A Object should equal itself");
     }
 
     @Test
     public void testObjectHashCodeEqualsContract() {
         final Object obj1 = makeObject();
         if (obj1.equals(obj1)) {
             assertEquals(
                     obj1.hashCode(), obj1.hashCode(),
                     "[1] When two objects are equal, their hashCodes should be also.");
         }
         final Object obj2 = makeObject();
         if (obj1.equals(obj2)) {
             assertEquals(
                     obj1.hashCode(), obj2.hashCode(),
                     "[2] When two objects are equal, their hashCodes should be also.");
             assertEquals(obj2, obj1, "When obj1.equals(obj2) is true, then obj2.equals(obj1) should also be true");
         }
     }
 
     @Test
     public void testObjectHashCodeEqualsSelfHashCode() {
         final Object obj = makeObject();
         assertEquals(obj.hashCode(), obj.hashCode(), "hashCode should be repeatable");
     }
 
     @Test
     public void testSerializeDeserializeThenCompare() throws Exception {
         final Object obj = makeObject();
         if (obj instanceof Serializable && isTestSerialization()) {
             final Object dest = serializeDeserialize(obj);
             if (isEqualsCheckable()) {
                 assertEquals(obj, dest, "obj != deserialize(serialize(obj))");
             }
         }
     }
 
     /**
      * Sanity check method, makes sure that any Serializable
      * class can be serialized and de-serialized in memory,
      * using the handy makeObject() method
      *
      * @throws IOException
      * @throws ClassNotFoundException
      */
     @Test
     public void testSimpleSerialization() throws Exception {
         final Object o = makeObject();
         if (o instanceof Serializable && isTestSerialization()) {
             final byte[] object = writeExternalFormToBytes((Serializable) o);
             readExternalFormFromBytes(object);
         }
     }
 
     /**
      * Converts a Serializable or Externalizable object to
      * bytes.  Useful for in-memory tests of serialization
      *
      * @param o Object to convert to bytes
      * @return serialized form of the Object
      * @throws IOException
      */
     protected byte[] writeExternalFormToBytes(final Serializable o) throws IOException {
         final ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
         writeExternalFormToStream(o, byteStream);
         return byteStream.toByteArray();
     }
 
     /**
      * Writes a Serializable or Externalizable object as
      * a file at the given path.  NOT USEFUL as part
      * of a unit test; this is just a utility method
      * for creating disk-based objects in SCM that can become
      * the basis for compatibility tests using
      * readExternalFormFromDisk(String path)
      *
      * @param o Object to serialize
      * @param path path to write the serialized Object
      * @throws IOException
      */
     protected void writeExternalFormToDisk(final Serializable o, final String path) throws IOException {
         try (FileOutputStream fileStream = new FileOutputStream(path)) {
             writeExternalFormToStream(o, fileStream);
         }
     }
 
     private void writeExternalFormToStream(final Serializable o, final OutputStream stream) throws IOException {
         final ObjectOutputStream oStream = new ObjectOutputStream(stream);
         oStream.writeObject(o);
     }
 
 }