// ****************************************************************

// Copyright 2008, Charlie Poole

// This is free software licensed under the NUnit license. You may

// obtain a copy of the license at http://nunit.org.

// ****************************************************************



using System;

using System.Collections;

#if NET_2_0

using System.Collections.Generic;

#endif

using System.Reflection;

using System.Text;

using NUnit.Core.Extensibility;



namespace NUnit.Core.Builders

{

	public class PairwiseStrategy : CombiningStrategy

	{

		internal class FleaRand

		{

			private const int FleaRandSize = 256;



			private uint b;

			private uint c;

			private uint d;

			private uint z;



			private uint[] m = new uint[FleaRandSize];

			private uint[] r = new uint[FleaRandSize];



			private uint q;



			public FleaRand(uint seed)

			{

				this.b = seed;

				this.c = seed;

				this.d = seed;

				this.z = seed;



				for (int i = 0; i < this.m.Length; i++)

				{

					this.m[i] = seed;

				}



				for (int i = 0; i < 10; i++)

				{

					this.Batch();

				}



				this.q = 0;

			}



			public uint Next()

			{

				if (this.q == 0)

				{

					this.Batch();

					this.q = (uint)this.r.Length - 1;

				}

				else

				{

					this.q--;

				}



				return this.r[this.q];

			}



			private void Batch()

			{

				uint a;

				uint b = this.b;

				uint c = this.c + (++this.z);

				uint d = this.d;



				for (int i = 0; i < this.r.Length; i++)

				{

					a = this.m[b % this.m.Length];

					this.m[b % this.m.Length] = d;

					d = (c << 19) + (c >> 13) + b;

					c = b ^ this.m[i];

					b = a + d;

					this.r[i] = c;

				}



				this.b = b;

				this.c = c;

				this.d = d;

			}

		}



		internal class FeatureInfo

		{

			public const string Names = "abcdefghijklmnopqrstuvwxyz";



			public readonly int Dimension;

			public readonly int Feature;



			public FeatureInfo(int dimension, int feature)

			{

				this.Dimension = dimension;

				this.Feature = feature;

			}



#if DEBUG

			public override string ToString()

			{

				return (this.Dimension + 1).ToString() + FeatureInfo.Names[this.Feature];

			}

#endif

		}



		internal class Tuple

		{

			private readonly ArrayList features = new ArrayList();



			public int Count

			{

				get

				{

					return this.features.Count;

				}

			}



			public FeatureInfo this[int index]

			{

				get

				{

					return (FeatureInfo)this.features[index];

				}

			}



			public void Add(FeatureInfo feature)

			{

				this.features.Add(feature);

			}



#if DEBUG

			public override string ToString()

			{

				StringBuilder sb = new StringBuilder();



				sb.Append('(');



				for (int i = 0; i < this.features.Count; i++)

				{

					if (i > 0)

					{

						sb.Append(' ');

					}



					sb.Append(this.features[i].ToString());

				}



				sb.Append(')');



				return sb.ToString();

			}

#endif

		}



		internal class TupleCollection

		{

			private readonly ArrayList tuples = new ArrayList();



			public int Count

			{

				get

				{

					return this.tuples.Count;

				}

			}



			public Tuple this[int index]

			{

				get

				{

					return (Tuple)this.tuples[index];

				}

			}



			public void Add(Tuple tuple)

			{

				this.tuples.Add(tuple);

			}



			public void RemoveAt(int index)

			{

				this.tuples.RemoveAt(index);

			}

		}



		internal class TestCase

		{

			public readonly int[] Features;



			public TestCase(int numberOfDimensions)

			{

				this.Features = new int[numberOfDimensions];

			}



			public bool IsTupleCovered(Tuple tuple)

			{

				for (int i = 0; i < tuple.Count; i++)

				{

					if (this.Features[tuple[i].Dimension] != tuple[i].Feature)

					{

						return false;

					}

				}



				return true;

			}



#if DEBUG

			public override string ToString()

			{

				StringBuilder sb = new StringBuilder();



				for (int i = 0; i < this.Features.Length; i++)

				{

					if (i > 0)

					{

						sb.Append(' ');

					}



					sb.Append(i + 1);

					sb.Append(FeatureInfo.Names[this.Features[i]]);

				}



				return sb.ToString();

			}

#endif

		}



		internal class TestCaseCollection : IEnumerable

		{

			private readonly ArrayList testCases = new ArrayList();



			public void Add(TestCase testCase)

			{

				this.testCases.Add(testCase);

			}



			public IEnumerator GetEnumerator()

			{

				return this.testCases.GetEnumerator();

			}



			public bool IsTupleCovered(Tuple tuple)

			{

				foreach (TestCase testCase in this.testCases)

				{

					if (testCase.IsTupleCovered(tuple))

					{

						return true;

					}

				}



				return false;

			}

		}



		internal class PairwiseTestCaseGenerator

		{

			private const int MaxTupleLength = 2;



			private readonly FleaRand random = new FleaRand(0);



			private readonly int[] dimensions;



			private readonly TupleCollection[][] uncoveredTuples;



			private readonly int[][] currentTupleLength;



			private readonly TestCaseCollection testCases = new TestCaseCollection();



			public PairwiseTestCaseGenerator(int[] dimensions)

			{

				this.dimensions = dimensions;



				this.uncoveredTuples = new TupleCollection[this.dimensions.Length][];



				for (int d = 0; d < this.uncoveredTuples.Length; d++)

				{

					this.uncoveredTuples[d] = new TupleCollection[this.dimensions[d]];



					for (int f = 0; f < this.dimensions[d]; f++)

					{

						this.uncoveredTuples[d][f] = new TupleCollection();

					}

				}



				this.currentTupleLength = new int[this.dimensions.Length][];



				for (int d = 0; d < this.dimensions.Length; d++)

				{

					this.currentTupleLength[d] = new int[this.dimensions[d]];

				}

			}



			public IEnumerable GetTestCases()

			{

				this.CreateTestCases();



				this.SelfTest();



				return this.testCases;

			}



			private void CreateTestCases()

			{

				while (true)

				{

					this.ExtendTupleSet();



					Tuple tuple = this.FindTupleToCover();



					if (tuple == null)

					{

						return;

					}



					TestCase testCase = this.FindGoodTestCase(tuple);



					this.RemoveTuplesCoveredBy(testCase);



					this.testCases.Add(testCase);

				}

			}



			private void ExtendTupleSet()

			{

				for (int d = 0; d < this.dimensions.Length; d++)

				{

					for (int f = 0; f < this.dimensions[d]; f++)

					{

						this.ExtendTupleSet(d, f);

					}

				}

			}



			private void ExtendTupleSet(int dimension, int feature)

			{

				// If tuples for [dimension][feature] already exists, it's no needs to add more tuples.

				if (this.uncoveredTuples[dimension][feature].Count > 0)

				{

					return;

				}



				// If maximum tuple length for [dimension][feature] is reached, it's no needs to add more tuples.

				if (this.currentTupleLength[dimension][feature] == MaxTupleLength)

				{

					return;

				}



				this.currentTupleLength[dimension][feature]++;



				int tupleLength = this.currentTupleLength[dimension][feature];



				if (tupleLength == 1)

				{

					Tuple tuple = new Tuple();



					tuple.Add(new FeatureInfo(dimension, feature));



					if (this.testCases.IsTupleCovered(tuple))

					{

						return;

					}



					this.uncoveredTuples[dimension][feature].Add(tuple);

				}

				else

				{

					for (int d = 0; d < this.dimensions.Length; d++)

					{

						for (int f = 0; f < this.dimensions[d]; f++)

						{

							Tuple tuple = new Tuple();

							tuple.Add(new FeatureInfo(d, f));



							if (tuple[0].Dimension == dimension)

							{

								continue;

							}



							tuple.Add(new FeatureInfo(dimension, feature));



							if (this.testCases.IsTupleCovered(tuple))

							{

								continue;

							}



							this.uncoveredTuples[dimension][feature].Add(tuple);

						}

					}

				}

			}



			private Tuple FindTupleToCover()

			{

				int tupleLength = MaxTupleLength;

				int tupleCount = 0;

				Tuple tuple = null;



				for (int d = 0; d < this.dimensions.Length; d++)

				{

					for (int f = 0; f < this.dimensions[d]; f++)

					{

						if (this.currentTupleLength[d][f] < tupleLength)

						{

							tupleLength = this.currentTupleLength[d][f];

							tupleCount = this.uncoveredTuples[d][f].Count;

							tuple = this.uncoveredTuples[d][f][0];

						}

						else

						{

							if (this.currentTupleLength[d][f] == tupleLength && this.uncoveredTuples[d][f].Count > tupleCount)

							{

								tupleCount = this.uncoveredTuples[d][f].Count;

								tuple = this.uncoveredTuples[d][f][0];

							}

						}

					}

				}



				return tuple;

			}



			private TestCase FindGoodTestCase(Tuple tuple)

			{

				TestCase bestTest = null;

				int bestCoverage = -1;



				for (int i = 0; i < 5; i++)

				{

					TestCase test = new TestCase(this.dimensions.Length);



					int coverage = this.CreateTestCase(tuple, test);



					if (coverage > bestCoverage)

					{

						bestTest = test;

						bestCoverage = coverage;

					}

				}



				return bestTest;

			}



			private int CreateTestCase(Tuple tuple, TestCase test)

			{

				// Create a random test case...

				for (int i = 0; i < test.Features.Length; i++)

				{

					test.Features[i] = (int)(this.random.Next() % this.dimensions[i]);

				}



				// ...and inject the tuple into it!

				for (int i = 0; i < tuple.Count; i++)

				{

					test.Features[tuple[i].Dimension] = tuple[i].Feature;

				}



				return this.MaximizeCoverage(test, tuple);

			}



			private int MaximizeCoverage(TestCase test, Tuple tuple)

			{

				int[] dimensionOrder = this.GetMutableDimensions(tuple);



				while (true)

				{

					bool progress = false;

					int totalCoverage = 1;



					// Scramble dimensions.

					for (int i = dimensionOrder.Length; i > 1; i--)

					{

						int j = (int)(this.random.Next() % i);

						int t = dimensionOrder[i - 1];

						dimensionOrder[i - 1] = dimensionOrder[j];

						dimensionOrder[j] = t;

					}



					// For each dimension that can be modified...

					for (int i = 0; i < dimensionOrder.Length; i++)

					{

						int d = dimensionOrder[i];



						ArrayList bestFeatures = new ArrayList();



						int bestCoverage = this.CountTuplesCovered(test, d, test.Features[d]);



						int bestTupleLength = this.currentTupleLength[d][test.Features[d]];



						// For each feature that can be modified, check if it can extend coverage.

						for (int f = 0; f < this.dimensions[d]; f++)

						{

							test.Features[d] = f;



							int coverage = this.CountTuplesCovered(test, d, f);



							if (this.currentTupleLength[d][f] < bestTupleLength)

							{

								progress = true;

								bestTupleLength = this.currentTupleLength[d][f];

								bestCoverage = coverage;

								bestFeatures.Clear();

								bestFeatures.Add(f);

							}

							else

							{

								if (this.currentTupleLength[d][f] == bestTupleLength && coverage >= bestCoverage)

								{

									if (coverage > bestCoverage)

									{

										progress = true;

										bestCoverage = coverage;

										bestFeatures.Clear();

									}



									bestFeatures.Add(f);

								}

							}

						}



						if (bestFeatures.Count == 1)

						{

							test.Features[d] = (int)bestFeatures[0];

						}

						else

						{

							test.Features[d] = (int)bestFeatures[(int)(this.random.Next() % bestFeatures.Count)];

						}



						totalCoverage += bestCoverage;

					}



					if (!progress)

					{

						return totalCoverage;

					}

				}

			}



			private int[] GetMutableDimensions(Tuple tuple)

			{

				bool[] immutableDimensions = new bool[this.dimensions.Length];



				for (int i = 0; i < tuple.Count; i++)

				{

					immutableDimensions[tuple[i].Dimension] = true;

				}



				ArrayList mutableDimensions = new ArrayList();



				for (int i = 0; i < this.dimensions.Length; i++)

				{

					if (!immutableDimensions[i])

					{

						mutableDimensions.Add(i);

					}

				}



				return (int[])mutableDimensions.ToArray(typeof(int));

			}



			private int CountTuplesCovered(TestCase test, int dimension, int feature)

			{

				int tuplesCovered = 0;



				TupleCollection tuples = this.uncoveredTuples[dimension][feature];



				for (int i = 0; i < tuples.Count; i++)

				{

					if (test.IsTupleCovered(tuples[i]))

					{

						tuplesCovered++;

					}

				}



				return tuplesCovered;

			}



			private void RemoveTuplesCoveredBy(TestCase testCase)

			{

				for (int d = 0; d < this.uncoveredTuples.Length; d++)

				{

					for (int f = 0; f < this.uncoveredTuples[d].Length; f++)

					{

						TupleCollection tuples = this.uncoveredTuples[d][f];



						for (int i = tuples.Count - 1; i >= 0; i--)

						{

							if (testCase.IsTupleCovered(tuples[i]))

							{

								tuples.RemoveAt(i);

							}

						}

					}

				}

			}



			private void SelfTest()

			{

				for (int d1 = 0; d1 < this.dimensions.Length - 1; d1++)

				{

					for (int d2 = d1 + 1; d2 < this.dimensions.Length; d2++)

					{

						for (int f1 = 0; f1 < this.dimensions[d1]; f1++)

						{

							for (int f2 = 0; f2 < this.dimensions[d2]; f2++)

							{

								Tuple tuple = new Tuple();

								tuple.Add(new FeatureInfo(d1, f1));

								tuple.Add(new FeatureInfo(d2, f2));



								if (!this.testCases.IsTupleCovered(tuple))

								{

									throw new ApplicationException("PairwiseStrategy self-test failed : Not all pairs are covered!");

								}

							}

						}

					}

				}

			}

		}



		public PairwiseStrategy(IEnumerable[] sources) : base(sources) { }



		public override IEnumerable GetTestCases()

		{

			ArrayList[] valueSet = CreateValueSet();

			int[] dimensions = CreateDimensions(valueSet);



			IEnumerable pairwiseTestCases = new PairwiseTestCaseGenerator(dimensions).GetTestCases();



#if NET_2_0

            List<ParameterSet> testCases = new List<ParameterSet>();

#else

            ArrayList testCases = new ArrayList();

#endif



			foreach (TestCase pairwiseTestCase in pairwiseTestCases)

			{

				object[] testData = new object[pairwiseTestCase.Features.Length];



				for (int i = 0; i < pairwiseTestCase.Features.Length; i++)

				{

					testData[i] = valueSet[i][pairwiseTestCase.Features[i]];

				}



                ParameterSet testCase = new ParameterSet();

                testCase.Arguments = testData;



				testCases.Add(testCase);

			}



			return testCases;

		}



		private ArrayList[] CreateValueSet()

		{

			ArrayList[] valueSet = new ArrayList[Sources.Length];



			for (int i = 0; i < valueSet.Length; i++)

			{

				ArrayList values = new ArrayList();



				foreach (object value in Sources[i])

				{

					values.Add(value);

				}



				valueSet[i] = values;

			}



			return valueSet;

		}



		private int[] CreateDimensions(ArrayList[] valueSet)

		{

			int[] dimensions = new int[valueSet.Length];



			for (int i = 0; i < valueSet.Length; i++)

			{

				dimensions[i] = valueSet[i].Count;

			}



			return dimensions;

		}

	}

}