#region Apache License 2.0
/*
Nuclex .NET Framework
Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs

Licensed 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.
*/
#endregion // Apache License 2.0

using System;
using System.Collections;
using System.Collections.Generic;

using NUnit.Framework;

namespace Nuclex.Support.Collections {

  /// <summary>Unit Test for the double ended queue</summary>
  [TestFixture]
  internal class DequeTest {

    /// <summary>Verifies that the AddLast() method of the deque is working</summary>
    [Test]
    public void TestAddLast() {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 0; item < 48; ++item) {
        intDeque.AddLast(item);
      }

      for(int item = 0; item < 48; ++item) {
        Assert.AreEqual(item, intDeque[item]);
      }
    }

    /// <summary>Verifies that the AddFirst() method of the deque is working</summary>
    [Test]
    public void TestAddFirst() {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 0; item < 48; ++item) {
        intDeque.AddFirst(item);
      }

      for(int item = 0; item < 48; ++item) {
        Assert.AreEqual(47 - item, intDeque[item]);
      }
    }

    /// <summary>
    ///   Verifies that the RemoveFirst() method of the deque is working
    /// </summary>
    [Test]
    public void TestRemoveFirst() {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 0; item < 48; ++item) {
        intDeque.AddLast(item);
      }

      for(int item = 0; item < 48; ++item) {
        Assert.AreEqual(item, intDeque.First);
        Assert.AreEqual(48 - item, intDeque.Count);
        intDeque.RemoveFirst();
      }
    }

    /// <summary>
    ///   Verifies that the RemoveLast() method of the deque is working
    /// </summary>
    [Test]
    public void TestRemoveLast() {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 0; item < 48; ++item) {
        intDeque.AddLast(item);
      }

      for(int item = 0; item < 48; ++item) {
        Assert.AreEqual(47 - item, intDeque.Last);
        Assert.AreEqual(48 - item, intDeque.Count);
        intDeque.RemoveLast();
      }
    }

    /// <summary>Verifies that the Insert() method works in all cases</summary>
    /// <remarks>
    ///   We have several different cases here that will be tested. The deque can
    ///   shift items to the left or right (depending on which end is closer to
    ///   the insertion point) and the insertion point may fall in an only partially
    ///   occupied block, requiring elaborate index calculations
    /// </remarks>
    [Test]
    public void TestInsert() {
      for(int testedIndex = 0; testedIndex <= 96; ++testedIndex) {
        Deque<int> intDeque = createDeque(96);

        intDeque.Insert(testedIndex, 12345);

        Assert.AreEqual(97, intDeque.Count);

        for(int index = 0; index < testedIndex; ++index) {
          Assert.AreEqual(index, intDeque[index]);
        }
        Assert.AreEqual(12345, intDeque[testedIndex]);
        for(int index = testedIndex + 1; index < 97; ++index) {
          Assert.AreEqual(index - 1, intDeque[index]);
        }
      }
    }

    /// <summary>
    ///   Verifies that the Insert() method works in all cases when the deque doesn't
    ///   start at a block boundary
    /// </summary>
    [Test]
    public void TestInsertNonNormalized() {
      for(int testedIndex = 0; testedIndex <= 96; ++testedIndex) {
        Deque<int> intDeque = createNonNormalizedDeque(96);

        intDeque.Insert(testedIndex, 12345);

        Assert.AreEqual(97, intDeque.Count);

        for(int index = 0; index < testedIndex; ++index) {
          Assert.AreEqual(index, intDeque[index]);
        }
        Assert.AreEqual(12345, intDeque[testedIndex]);
        for(int index = testedIndex + 1; index < 97; ++index) {
          Assert.AreEqual(index - 1, intDeque[index]);
        }
      }
    }

    /// <summary>Verifies the the RemoveAt() method works in all cases</summary>
    [Test]
    public void TestRemoveAt() {
      for(int testedIndex = 0; testedIndex < 96; ++testedIndex) {
        Deque<int> intDeque = new Deque<int>(16);
        for(int item = 0; item < 96; ++item) {
          intDeque.AddLast(item);
        }

        intDeque.RemoveAt(testedIndex);

        Assert.AreEqual(95, intDeque.Count);

        for(int index = 0; index < testedIndex; ++index) {
          Assert.AreEqual(index, intDeque[index]);
        }
        for(int index = testedIndex; index < 95; ++index) {
          Assert.AreEqual(index + 1, intDeque[index]);
        }
      }
    }

    /// <summary>
    ///   Verifies the the RemoveAt() method works in all cases when the deque doesn't
    ///   start at a block boundary
    /// </summary>
    [Test]
    public void TestRemoveAtNonNormalized() {
      for(int testedIndex = 0; testedIndex < 96; ++testedIndex) {
        Deque<int> intDeque = new Deque<int>(16);
        for(int item = 4; item < 96; ++item) {
          intDeque.AddLast(item);
        }
        intDeque.AddFirst(3);
        intDeque.AddFirst(2);
        intDeque.AddFirst(1);
        intDeque.AddFirst(0);

        intDeque.RemoveAt(testedIndex);

        Assert.AreEqual(95, intDeque.Count);

        for(int index = 0; index < testedIndex; ++index) {
          Assert.AreEqual(index, intDeque[index]);
        }
        for(int index = testedIndex; index < 95; ++index) {
          Assert.AreEqual(index + 1, intDeque[index]);
        }
      }
    }

    /// <summary>
    ///   Tests whether the RemoveAt() method keeps the state of the deque intact when
    ///   it has to remove a block from the left end of the deque
    /// </summary>
    [Test]
    public void TestRemoveAtEmptiesLeftBlock() {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 1; item <= 16; ++item) {
        intDeque.AddLast(item);
      }
      intDeque.AddFirst(0);
      intDeque.RemoveAt(3);

      Assert.AreEqual(16, intDeque.Count);

      for(int index = 0; index < 3; ++index) {
        Assert.AreEqual(index, intDeque[index]);
      }
      for(int index = 3; index < 16; ++index) {
        Assert.AreEqual(index + 1, intDeque[index]);
      }
    }

    /// <summary>
    ///   Tests whether the RemoveAt() method keeps the state of the deque intact when
    ///   it has to remove a block from the right end of the deque
    /// </summary>
    [Test]
    public void TestRemoveAtEmptiesRightBlock() {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 0; item <= 16; ++item) {
        intDeque.AddLast(item);
      }
      intDeque.RemoveAt(13);

      Assert.AreEqual(16, intDeque.Count);

      for(int index = 0; index < 13; ++index) {
        Assert.AreEqual(index, intDeque[index]);
      }
      for(int index = 13; index < 16; ++index) {
        Assert.AreEqual(index + 1, intDeque[index]);
      }
    }

    /// <summary>
    ///   Validates that an exception is thrown if the 'First' property is accessed
    ///   in an empty deque
    /// </summary>
    [Test]
    public void TestThrowOnAccessFirstInEmptyDeque() {
      Deque<int> intDeque = new Deque<int>();
      Assert.Throws<InvalidOperationException>(
        delegate() { Console.WriteLine(intDeque.First); }
      );
    }

    /// <summary>
    ///   Validates that an exception is thrown if the 'Last' property is accessed
    ///   in an empty deque
    /// </summary>
    [Test]
    public void TestThrowOnAccessLastInEmptyDeque() {
      Deque<int> intDeque = new Deque<int>();
      Assert.Throws<InvalidOperationException>(
        delegate() { Console.WriteLine(intDeque.Last); }
      );
    }

    /// <summary>
    ///   Validates that an exception is thrown if the first item is attempted to be 
    ///   removed from an empty deque
    /// </summary>
    [Test]
    public void TestThrowOnRemoveFirstFromEmptyDeque() {
      Deque<int> intDeque = new Deque<int>();
      Assert.Throws<InvalidOperationException>(
        delegate() { intDeque.RemoveFirst(); }
      );
    }

    /// <summary>
    ///   Validates that an exception is thrown if the last item is attempted to be 
    ///   removed from an empty deque
    /// </summary>
    [Test]
    public void TestThrowOnRemoveLastFromEmptyDeque() {
      Deque<int> intDeque = new Deque<int>();
      Assert.Throws<InvalidOperationException>(
        delegate() { intDeque.RemoveLast(); }
      );
    }

    /// <summary>
    ///   Verifies that items can be assigned by their index
    /// </summary>
    [Test]
    public void TestIndexAssignment() {
      Deque<int> intDeque = createDeque(32);
      intDeque[16] = 12345;
      intDeque[17] = 54321;

      for(int index = 0; index < 16; ++index) {
        intDeque.RemoveFirst();
      }

      Assert.AreEqual(12345, intDeque.First);
      intDeque.RemoveFirst();
      Assert.AreEqual(54321, intDeque.First);
    }

    /// <summary>
    ///   Verifies that an exception is thrown if an invalid index is accessed
    /// </summary>
    [Test]
    public void TestThrowOnInvalidIndex() {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 0; item < 32; ++item) {
        intDeque.AddLast(item);
      }

      Assert.Throws<ArgumentOutOfRangeException>(
        delegate() { Console.WriteLine(intDeque[32]); }
      );
    }

    /// <summary>Tests the IndexOf() method</summary>
    [Test, TestCase(0), TestCase(16), TestCase(32), TestCase(48)]
    public void TestIndexOf(int count) {
      Deque<int> intDeque = new Deque<int>(16);
      for(int item = 0; item < count; ++item) {
        intDeque.AddLast(item);
      }

      for(int item = 0; item < count; ++item) {
        Assert.AreEqual(item, intDeque.IndexOf(item));
      }
      Assert.AreEqual(-1, intDeque.IndexOf(count));
    }

    /// <summary>
    ///   Tests the IndexOf() method with the deque not starting at a block boundary
    /// </summary>
    [Test, TestCase(0), TestCase(16), TestCase(32), TestCase(48)]
    public void TestIndexOfNonNormalized(int count) {
      Deque<int> intDeque = createNonNormalizedDeque(count);

      for(int item = 0; item < count; ++item) {
        Assert.AreEqual(item, intDeque.IndexOf(item));
      }
      Assert.AreEqual(-1, intDeque.IndexOf(count));
    }

    /// <summary>Verifies that the deque's enumerator works</summary>
    [Test]
    public void TestEnumerator() {
      Deque<int> intDeque = createNonNormalizedDeque(40);

      for(int testRun = 0; testRun < 2; ++testRun) {
        using(IEnumerator<int> enumerator = intDeque.GetEnumerator()) {
          for(int index = 0; index < intDeque.Count; ++index) {
            Assert.IsTrue(enumerator.MoveNext());
            Assert.AreEqual(index, enumerator.Current);
          }

          Assert.IsFalse(enumerator.MoveNext());

          enumerator.Reset();
        }
      }
    }

    /// <summary>Verifies that the deque's enumerator works</summary>
    [Test]
    public void TestObjectEnumerator() {
      Deque<int> intDeque = createNonNormalizedDeque(40);

      for(int testRun = 0; testRun < 2; ++testRun) {
        IEnumerator enumerator = ((IEnumerable)intDeque).GetEnumerator();
        for(int index = 0; index < intDeque.Count; ++index) {
          Assert.IsTrue(enumerator.MoveNext());
          Assert.AreEqual(index, enumerator.Current);
        }

        Assert.IsFalse(enumerator.MoveNext());

        enumerator.Reset();
      }
    }

    /// <summary>
    ///   Verifies that an exception is thrown if the enumerator is accessed in
    ///   an invalid position
    /// </summary>
    [Test]
    public void TestThrowOnInvalidEnumeratorPosition() {
      Deque<int> intDeque = createNonNormalizedDeque(40);

      using(IEnumerator<int> enumerator = intDeque.GetEnumerator()) {
        Assert.Throws<InvalidOperationException>(
          delegate() { Console.WriteLine(enumerator.Current); }
        );

        while(enumerator.MoveNext()) { }

        Assert.Throws<InvalidOperationException>(
          delegate() { Console.WriteLine(enumerator.Current); }
        );
      }
    }

    /// <summary>Tests whether a small deque can be cleared</summary>
    [Test]
    public void TestClearSmallDeque() {
      Deque<int> intDeque = createDeque(12);
      intDeque.Clear();
      Assert.AreEqual(0, intDeque.Count);
    }

    /// <summary>Tests whether a large deque can be cleared</summary>
    [Test]
    public void TestClearLargeDeque() {
      Deque<int> intDeque = createDeque(40);
      intDeque.Clear();
      Assert.AreEqual(0, intDeque.Count);
    }

    /// <summary>Verifies that the non-typesafe Add() method is working</summary>
    [Test]
    public void TestAddObject() {
      Deque<int> intDeque = new Deque<int>();
      Assert.AreEqual(0, ((IList)intDeque).Add(123));
      Assert.AreEqual(1, intDeque.Count);
    }

    /// <summary>
    ///   Tests whether an exception is thrown if the non-typesafe Add() method is
    ///   used to add an incompatible object into the deque
    /// </summary>
    [Test]
    public void TestThrowOnAddIncompatibleObject() {
      Deque<int> intDeque = new Deque<int>();
      Assert.Throws<ArgumentException>(
        delegate() { ((IList)intDeque).Add("Hello World"); }
      );
    }

    /// <summary>Verifies that the Add() method is working</summary>
    [Test]
    public void TestAdd() {
      Deque<int> intDeque = new Deque<int>();
      ((IList<int>)intDeque).Add(123);
      Assert.AreEqual(1, intDeque.Count);
    }

    /// <summary>Tests whether the Contains() method is working</summary>
    [Test]
    public void TestContains() {
      Deque<int> intDeque = createDeque(16);
      Assert.IsTrue(intDeque.Contains(14));
      Assert.IsFalse(intDeque.Contains(16));
    }

    /// <summary>Tests the non-typesafe Contains() method</summary>
    [Test]
    public void TestContainsObject() {
      Deque<int> intDeque = createDeque(16);
      Assert.IsTrue(((IList)intDeque).Contains(14));
      Assert.IsFalse(((IList)intDeque).Contains(16));
      Assert.IsFalse(((IList)intDeque).Contains("Hello World"));
    }

    /// <summary>Tests the non-typesafe Contains() method</summary>
    [Test]
    public void TestIndexOfObject() {
      Deque<int> intDeque = createDeque(16);
      Assert.AreEqual(14, ((IList)intDeque).IndexOf(14));
      Assert.AreEqual(-1, ((IList)intDeque).IndexOf(16));
      Assert.AreEqual(-1, ((IList)intDeque).IndexOf("Hello World"));
    }

    /// <summary>Tests wether the non-typesafe Insert() method is working</summary>
    [Test]
    public void TestInsertObject() {
      for(int testedIndex = 0; testedIndex <= 96; ++testedIndex) {
        Deque<int> intDeque = createDeque(96);

        ((IList)intDeque).Insert(testedIndex, 12345);

        Assert.AreEqual(97, intDeque.Count);

        for(int index = 0; index < testedIndex; ++index) {
          Assert.AreEqual(index, intDeque[index]);
        }
        Assert.AreEqual(12345, intDeque[testedIndex]);
        for(int index = testedIndex + 1; index < 97; ++index) {
          Assert.AreEqual(index - 1, intDeque[index]);
        }
      }
    }

    /// <summary>
    ///   Verifies that an exception is thrown if an incompatible object is inserted
    ///   into the deque
    /// </summary>
    [Test]
    public void TestThrowOnInsertIncompatibleObject() {
      Deque<int> intDeque = createDeque(12);
      Assert.Throws<ArgumentException>(
        delegate() { ((IList)intDeque).Insert(8, "Hello World"); }
      );
    }

    /// <summary>Validates that the IsFixedObject property is set to false</summary>
    [Test]
    public void TestIsFixedObject() {
      Deque<int> intDeque = new Deque<int>();
      Assert.IsFalse(((IList)intDeque).IsFixedSize);
    }

    /// <summary>Validates that the IsSynchronized property is set to false</summary>
    [Test]
    public void TestIsSynchronized() {
      Deque<int> intDeque = new Deque<int>();
      Assert.IsFalse(((IList)intDeque).IsSynchronized);
    }

    /// <summary>
    ///   Verifies that items can be assigned by their index using the non-typesafe
    ///   IList interface
    /// </summary>
    [Test]
    public void TestObjectIndexAssignment() {
      Deque<int> intDeque = createDeque(32);

      ((IList)intDeque)[16] = 12345;
      ((IList)intDeque)[17] = 54321;

      Assert.AreEqual(12345, ((IList)intDeque)[16]);
      Assert.AreEqual(54321, ((IList)intDeque)[17]);
    }

    /// <summary>
    ///   Tests whether an exception is thrown if an incompatible object is assigned
    ///   to the deque
    /// </summary>
    [Test]
    public void TestIncompatibleObjectIndexAssignment() {
      Deque<int> intDeque = createDeque(2);
      Assert.Throws<ArgumentException>(
        delegate() { ((IList)intDeque)[0] = "Hello World"; }
      );
    }

    /// <summary>Verifies that the Remove() method is working correctly</summary>
    [Test]
    public void TestRemove() {
      Deque<int> intDeque = createDeque(16);
      Assert.AreEqual(16, intDeque.Count);
      Assert.IsTrue(intDeque.Remove(13));
      Assert.IsFalse(intDeque.Remove(13));
      Assert.AreEqual(15, intDeque.Count);
    }

    /// <summary>Tests the non-typesafe remove method</summary>
    [Test]
    public void TestRemoveObject() {
      Deque<int> intDeque = createDeque(10);
      Assert.IsTrue(intDeque.Contains(8));
      Assert.AreEqual(10, intDeque.Count);
      ((IList)intDeque).Remove(8);
      Assert.IsFalse(intDeque.Contains(8));
      Assert.AreEqual(9, intDeque.Count);
    }

    /// <summary>
    ///   Tests the non-typesafe remove method used to remove an incompatible object
    /// </summary>
    [Test]
    public void TestRemoveIncompatibleObject() {
      Deque<int> intDeque = createDeque(10);
      ((IList)intDeque).Remove("Hello World"); // should simply do nothing
      Assert.AreEqual(10, intDeque.Count);
    }

    /// <summary>
    ///   Verifies that the IsSynchronized property and the SyncRoot property are working
    /// </summary>
    [Test]
    public void TestSynchronization() {
      Deque<int> intDeque = new Deque<int>();

      if(!(intDeque as ICollection).IsSynchronized) {
        lock((intDeque as ICollection).SyncRoot) {
          Assert.AreEqual(0, intDeque.Count);
        }
      }
    }

    /// <summary>
    ///   Validates that the IsReadOnly property of the deque returns false
    /// </summary>
    [Test]
    public void TestIsReadOnly() {
      Deque<int> intDeque = new Deque<int>();
      Assert.IsFalse(((IList)intDeque).IsReadOnly);
      Assert.IsFalse(((ICollection<int>)intDeque).IsReadOnly);
    }

    /// <summary>Tests the non-typesafe CopyTo() method</summary>
    [Test]
    public void TestCopyToObjectArray() {
      Deque<int> intDeque = createNonNormalizedDeque(40);

      int[] array = new int[40];
      ((ICollection)intDeque).CopyTo(array, 0);

      Assert.AreEqual(intDeque, array);
    }

    /// <summary>Tests the CopyTo() method</summary>
    [Test]
    public void TestCopyToArray() {
      Deque<int> intDeque = createDeque(12);
      intDeque.RemoveFirst();
      intDeque.RemoveFirst();

      int[] array = new int[14];
      intDeque.CopyTo(array, 4);

      Assert.AreEqual(
        new int[] { 0, 0, 0, 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 },
        array
      );
    }

    /// <summary>
    ///   Verifies that the non-typesafe CopyTo() method throws an exception if
    ///   the array is of an incompatible type
    /// </summary>
    [Test]
    public void TestThrowOnCopyToIncompatibleObjectArray() {
      Deque<int> intDeque = createDeque(4);

      short[] array = new short[4];
      Assert.Throws<ArgumentException>(
        delegate() { ((ICollection)intDeque).CopyTo(array, 4); }
      );
    }

    /// <summary>
    ///   Verifies that the CopyTo() method throws an exception if the target array
    ///   is too small
    /// </summary>
    [Test]
    public void TestThrowOnCopyToTooSmallArray() {
      Deque<int> intDeque = createDeque(8);
      Assert.Throws<ArgumentException>(
        delegate() { intDeque.CopyTo(new int[7], 0); }
      );
    }
    
#if DEBUG
    /// <summary>
    ///   Tests whether the deque enumerator detects when it runs out of sync
    /// </summary>
    [Test]
    public void TestInvalidatedEnumeratorDetection() {
      Deque<int> intDeque = createDeque(8);
      using(IEnumerator<int> enumerator = intDeque.GetEnumerator()) {
        Assert.IsTrue(enumerator.MoveNext());
        intDeque.AddFirst(12345);
        Assert.Throws<InvalidOperationException>(
          delegate() { enumerator.MoveNext(); }
        );
      }      
    }
#endif

    /// <summary>
    ///   Creates a deque whose first element does not coincide with a block boundary
    /// </summary>
    /// <param name="count">Number of items the deque will be filled with</param>
    /// <returns>The newly created deque</returns>
    private static Deque<int> createNonNormalizedDeque(int count) {
      Deque<int> intDeque = new Deque<int>(16);

      for(int item = 4; item < count; ++item) {
        intDeque.AddLast(item);
      }
      if(count > 3) { intDeque.AddFirst(3); }
      if(count > 2) { intDeque.AddFirst(2); }
      if(count > 1) { intDeque.AddFirst(1); }
      if(count > 0) { intDeque.AddFirst(0); }

      return intDeque;
    }

    /// <summary>Creates a deque filled with the specified number of items
    /// </summary>
    /// <param name="count">Number of items the deque will be filled with</param>
    /// <returns>The newly created deque</returns>
    private static Deque<int> createDeque(int count) {
      Deque<int> intDeque = new Deque<int>(16);

      for(int item = 0; item < count; ++item) {
        intDeque.AddLast(item);
      }

      return intDeque;
    }

  }

} // namespace Nuclex.Support.Collections