using System;

namespace HeuristicLab.Problems.ProgramSynthesis.Push.Problem {
  using System.Collections.Generic;
  using System.Linq;
  using Common;
  using Configuration;
  using Core;
  using Encodings.IntegerVectorEncoding;
  using Expressions;

  using HeuristicLab.BenchmarkSuite;
  using HeuristicLab.Data;
  using Instances;
  using Interpreter;
  using Optimization;
  using Parameters;
  using Persistence.Default.CompositeSerializers.Storable;
  using Stack;

  [StorableClass]
  [Creatable(CreatableAttribute.Categories.GeneticProgrammingProblems, Priority = 180)]
  [Item("Push Problem", "")]
  public class PushProblem : SingleObjectiveBasicProblem<IntegerVectorEncoding>, IProblemInstanceConsumer<IBenchmarkSuiteDataDescriptor> {
    [Storable]
    private readonly PushConfiguration config;
    private PushInterpreterPool pool;

    public PushProblem() {
      config = new PushConfiguration();
      pool = new PushInterpreterPool(config);

      InitEvents();
      InitParameters();
      Instructions = config;
    }

    [StorableConstructor]
    public PushProblem(bool deserializing)
      : base(deserializing) {
    }

    public PushProblem(PushProblem original, Cloner cloner)
      : base(original, cloner) {
      config = cloner.Clone(original.config);
      pool = new PushInterpreterPool(config);

      Instructions = config;

      this.InitEvents();
    }

    [StorableHook(HookType.AfterDeserialization)]
    // ReSharper disable once UnusedMember.Local
    private void AfterDeserialization() {
      pool = new PushInterpreterPool(config);
      Instructions = config;

      InitEvents();
    }

    private void InitEvents() {
      config.EnabledExpressionsChanged += EnabledExpressionsChanged;
    }

    private void EnabledExpressionsChanged(object sender, EnabledExpressionsChangedEventArgs e) {
      this.Encoding.Bounds[0, 1] = config.EnabledExpressions.Count - 1;
      this.Encoding.BoundsParameter.Value[0, 1] = config.EnabledExpressions.Count - 1;
    }

    #region Parameters

    private const string EvalPushLimitParameterName = "EvalPushLimit";
    private const string EvalPushLimitParameterDescription = "This is the maximum allowed number of \"executions\" in a single top-level call to the interpreter. The execution of a single Push instruction counts as one execution, as does the processing of a single literal, as does the descent into one layer of parentheses (that is, the processing of the \"(\" counts as one execution).";
    private const string MaxProgramLengthParameterName = "MaxProgramLength";
    private const string MaxProgramLengthParameterDescription = "This is the maximum size of an item on the CODE stack, expressed as a number of points. A point is an instruction, a literal, or a pair of parentheses.";
    private const string TopLevelPushCodeParameterName = "TopLevelPushCode";
    private const string TopLevelPushCodeParameterDescription = "When TRUE (which is the default), code passed to the top level of the interpreter will be pushed onto the CODE stack prior to execution.";
    private const string TopLevelPopCodeParameterName = "TopLevelPopCode";
    private const string TopLevelPopCodeParameterDescription = "When TRUE, the CODE stack will be popped at the end of top level calls to the interpreter. The default is FALSE.";
    private const string InstructionsParameterName = "Instructions";
    private const string InstructionsParameterDescription = "Enables/Disables Instructions";
    private const string DataParameterName = "Data";
    private const string DataParameterDescription = "Program Synthesis";
    private const string MinRandomIntegerParameterName = "MinRandomInteger";
    private const string MinRandomIntegerParameterDescription = "The minimum INTEGER that will be produced as an ephemeral random INTEGER constant or from a call to INTEGER.RAND.";
    private const string MaxRandomIntegerParameterName = "MaxRandomInteger";
    private const string MaxRandomIntegerParameterDescription = "The maximum INTEGER that will be produced as an ephemeral random INTEGER constant or from a call to INTEGER.RAND.";
    private const string MinRandomFloatParameterName = "MinRandomFloat";
    private const string MinRandomFloatParameterDescription = "The minimum FLOAT that will be produced as an ephemeral random FLOAT constant or from a call to FLOAT.RAND.";
    private const string MaxRandomFloatParameterName = "MaxRandomFloat";
    private const string MaxRandomFloatParameterDescription = "The maximum FLOAT that will be produced as an ephemeral random FLOAT constant or from a call to FLOAT.RAND.";
    private const string NewErcNameProbabilityParameterName = "NewErcNameProbability";
    private const string NewErcNameProbabilityParameterDescription = "The probability that the selection of the ephemeral random NAME constant for inclusion in randomly generated code will produce a new name.";
    private const string ErcProbabilityParameterName = "ErcProbability";
    private const string ErcProbabilityParameterDescription = "The probability that the selection of a epheral random literal constant for inclusion in randomly generated code will produce a new literal.";
    private const string MaxPointsInRandomInstructionParameterName = "MaxPointsInRandomInstruction";
    private const string MaxPointsInRandomInstructionParameterDescription = "MaxPointsInRandomInstruction";
    private const string DataBoundsParameterName = "DataBounds";

    private void InitParameters() {
      var bounds = new IntMatrix(1, 3, new[] { "Training Start", "Training End | Test Start", "Test End" });
      bounds.ItemChanged += (s, e) => {
        if (this.DataDescriptor == null)
          return;

        var max = this.DataDescriptor.OriginalTestCount + this.DataDescriptor.OriginalTrainingCount - 1;
        bounds[0, 0] = Math.Min(Math.Max(bounds[0, 0], 0), max);
        bounds[0, 2] = Math.Max(Math.Min(bounds[0, 2], max), 0);
        bounds[0, 1] = Math.Min(Math.Max(bounds[0, 0], bounds[0, 1]), bounds[0, 2]);
      };

      Parameters.Add(new FixedValueParameter<IntMatrix>(
        DataBoundsParameterName,
        bounds));

      Parameters.Add(new FixedValueParameter<IntValue>(
        EvalPushLimitParameterName,
        EvalPushLimitParameterDescription,
        new IntValue(config.EvalPushLimit)));

      Parameters.Add(new FixedValueParameter<IntValue>(
        MaxProgramLengthParameterName,
        MaxProgramLengthParameterDescription,
        new IntValue(config.MaxPointsInProgram)));

      Parameters.Add(new FixedValueParameter<BoolValue>(
        TopLevelPushCodeParameterName,
        TopLevelPushCodeParameterDescription,
        new BoolValue(config.TopLevelPushCode)) { Hidden = true });

      Parameters.Add(new FixedValueParameter<BoolValue>(
        TopLevelPopCodeParameterName,
        TopLevelPopCodeParameterDescription,
        new BoolValue(config.TopLevelPopCode)) { Hidden = true });

      Parameters.Add(new ValueParameter<IEnabledExpressionsConfiguration>(
        InstructionsParameterName,
        InstructionsParameterDescription));

      Parameters.Add(new FixedValueParameter<IntValue>(
        MinRandomIntegerParameterName,
        MinRandomIntegerParameterDescription,
        new IntValue(config.MinRandomInteger)) { Hidden = true });

      Parameters.Add(new FixedValueParameter<IntValue>(
        MaxRandomIntegerParameterName,
        MaxRandomIntegerParameterDescription,
        new IntValue(config.MaxRandomInteger)) { Hidden = true });

      Parameters.Add(new FixedValueParameter<DoubleValue>(
        MinRandomFloatParameterName,
        MinRandomFloatParameterDescription,
        new DoubleValue(config.MinRandomFloat)) { Hidden = true });

      Parameters.Add(new FixedValueParameter<DoubleValue>(
        MaxRandomFloatParameterName,
        MaxRandomFloatParameterDescription,
        new DoubleValue(config.MaxRandomFloat)) { Hidden = true });

      Parameters.Add(new FixedValueParameter<PercentValue>(
        NewErcNameProbabilityParameterName,
        NewErcNameProbabilityParameterDescription,
        new PercentValue(config.NewErcNameProbability)) { Hidden = true });

      Parameters.Add(new FixedValueParameter<PercentValue>(
        ErcProbabilityParameterName,
        ErcProbabilityParameterDescription,
        new PercentValue(config.ErcProbability)) { Hidden = true });

      Parameters.Add(new FixedValueParameter<IntValue>(
        MaxPointsInRandomInstructionParameterName,
        MaxPointsInRandomInstructionParameterDescription,
        new IntValue(config.MaxPointsInRandomExpression)) { Hidden = true });

      Parameters.Add(new ValueParameter<IBenchmarkSuiteDataDescriptor>(DataParameterName, DataParameterDescription));

      Encoding.Bounds[0, 0] = 0;
      Encoding.Bounds[0, 1] = config.EnabledExpressions.Count - 1;
      Encoding.Length = config.MaxPointsInProgram;
    }

    public IValueParameter<IntMatrix> DataBoundsParameter
    {
      get { return (IValueParameter<IntMatrix>)Parameters[DataBoundsParameterName]; }
    }

    public IntMatrix DataBounds
    {
      get { return DataBoundsParameter.Value; }
      set { DataBoundsParameter.Value = value; }
    }


    public IValueParameter<IEnabledExpressionsConfiguration> InstructionsParameter
    {
      get { return (IValueParameter<IEnabledExpressionsConfiguration>)Parameters[InstructionsParameterName]; }
    }

    public IEnabledExpressionsConfiguration Instructions
    {
      get { return InstructionsParameter.Value; }
      set { InstructionsParameter.Value = value; }
    }

    public IValueParameter<IBenchmarkSuiteDataDescriptor> DataParameter
    {
      get { return (IValueParameter<IBenchmarkSuiteDataDescriptor>)Parameters[DataParameterName]; }
    }

    public IBenchmarkSuiteDataDescriptor DataDescriptor
    {
      get { return DataParameter.Value; }
      set { DataParameter.Value = value; }
    }

    public IValueParameter<IntValue> EvalPushLimitParameter
    {
      get { return (IValueParameter<IntValue>)this.Parameters[EvalPushLimitParameterName]; }
    }

    public int EvalPushLimit
    {
      get { return config.EvalPushLimit; }
      set
      {
        this.EvalPushLimitParameter.Value.Value = value;
        config.EvalPushLimit = value;
      }
    }

    public IValueParameter<IntValue> MaxProgramLengthParameter
    {
      get { return (IValueParameter<IntValue>)this.Parameters[MaxProgramLengthParameterName]; }
    }

    public int MaxProgramLength
    {
      get { return config.MaxPointsInProgram; }
      set
      {
        this.MaxProgramLengthParameter.Value.Value = value;
        this.Encoding.LengthParameter.Value.Value = value;
        config.MaxPointsInProgram = value;
      }
    }

    public IValueParameter<BoolValue> TopLevelPushParameter
    {
      get { return (IValueParameter<BoolValue>)this.Parameters[TopLevelPushCodeParameterName]; }
    }

    public bool TopLevelPushCode
    {
      get { return config.TopLevelPushCode; }
      set
      {
        this.TopLevelPushParameter.Value.Value = value;
        config.TopLevelPushCode = value;
      }
    }

    public IValueParameter<BoolValue> TopLevelPopParameter
    {
      get { return (IValueParameter<BoolValue>)this.Parameters[TopLevelPopCodeParameterName]; }
    }

    public bool TopLevelPopCode
    {
      get { return config.TopLevelPopCode; }
      set
      {
        this.TopLevelPushParameter.Value.Value = value;
        config.TopLevelPopCode = value;
      }
    }

    public IValueParameter<IntValue> MinRandomIntegerParameter
    {
      get { return (IValueParameter<IntValue>)this.Parameters[MinRandomIntegerParameterName]; }
    }

    public int MinRandomInteger
    {
      get { return config.MinRandomInteger; }
      set
      {
        this.MinRandomIntegerParameter.Value.Value = value;
        config.MinRandomInteger = value;
      }
    }

    public IValueParameter<IntValue> MaxRandomIntegerParameter
    {
      get { return (IValueParameter<IntValue>)this.Parameters[MaxRandomIntegerParameterName]; }
    }

    public int MaxRandomInteger
    {
      get { return config.MaxRandomInteger; }
      set
      {
        this.MaxRandomIntegerParameter.Value.Value = value;
        config.MaxRandomInteger = value;
      }
    }

    public IValueParameter<DoubleValue> MinRandomFloatParameter
    {
      get { return (IValueParameter<DoubleValue>)this.Parameters[MinRandomFloatParameterName]; }
    }

    public double MinRandomFloat
    {
      get { return config.MinRandomFloat; }
      set
      {
        this.MinRandomFloatParameter.Value.Value = value;
        config.MinRandomFloat = value;
      }
    }

    public IValueParameter<DoubleValue> MaxRandomFloatParameter
    {
      get { return (IValueParameter<DoubleValue>)this.Parameters[MaxRandomFloatParameterName]; }
    }

    public double MaxRandomFloat
    {
      get { return config.MaxRandomFloat; }
      set
      {
        this.MaxRandomFloatParameter.Value.Value = value;
        config.MaxRandomFloat = value;
      }
    }

    public IValueParameter<PercentValue> NewErcNameProbabilityParameter
    {
      get { return (IValueParameter<PercentValue>)this.Parameters[NewErcNameProbabilityParameterName]; }
    }

    public double NewErcNameProbability
    {
      get { return config.NewErcNameProbability; }
      set
      {
        this.NewErcNameProbabilityParameter.Value.Value = value;
        config.NewErcNameProbability = value;
      }
    }

    public IValueParameter<PercentValue> ErcProbabilityParameter
    {
      get { return (IValueParameter<PercentValue>)this.Parameters[ErcProbabilityParameterName]; }
    }

    public double ErcProbability
    {
      get { return config.ErcProbability; }
      set
      {
        this.ErcProbabilityParameter.Value.Value = value;
        config.ErcProbability = value;
      }
    }

    public IValueParameter<IntValue> MaxPointsInRandomInstructionParameter
    {
      get { return (IValueParameter<IntValue>)Parameters[MaxPointsInRandomInstructionParameterName]; }
    }

    public int MaxPointsInRandomInstruction
    {
      get { return config.MaxPointsInRandomExpression; }
      set
      {
        this.MaxPointsInRandomInstructionParameter.Value.Value = value;
        config.MaxPointsInRandomExpression = value;
      }
    }

    #endregion

    public override bool Maximization { get { return false; } }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new PushProblem(this, cloner);
    }

    public override void Analyze(Individual[] individuals, double[] qualities, ResultCollection results, IRandom random) {
      const string bestSolutionResultName = "Best Solution";
      var bestQuality = Maximization ? qualities.Max() : qualities.Min();
      var bestIdx = Array.IndexOf(qualities, bestQuality);
      var bestIndividual = individuals[bestIdx];
      var solution = new PushSolution(bestIndividual.IntegerVector(), bestQuality, DataDescriptor, random, config);

      if (!results.ContainsKey(bestSolutionResultName)) {
        results.Add(new Result(bestSolutionResultName, solution));
      } else if (((PushSolution)results[bestSolutionResultName].Value).Quality < qualities[bestIdx]) {
        results[bestSolutionResultName].Value = solution;
      }
    }

    public override double Evaluate(Individual individual, IRandom random) {

      var program = individual.PushProgram(config.EnabledExpressions as IReadOnlyList<string>);
      var expandExpression = new ExecExpandExpression(program);
      var results = new List<double>();

      using (var interpreter = pool.GetInstance(random)) {
        for (var i = DataBounds[0, 0]; i < DataBounds[0, 1]; i++) {
          var example = this.DataDescriptor.Examples[i];

          interpreter.BooleanStack.Push(example.InputBoolean);
          interpreter.IntegerStack.Push(example.InputInt);
          interpreter.FloatStack.Push(example.InputFloat);

          interpreter.Run(expandExpression);

          var diff = GetDiff(example.OutputInt, interpreter.IntegerStack, this.DataDescriptor.WorstResult, LongDiffer) +
                     GetDiff(example.OutputFloat, interpreter.FloatStack, this.DataDescriptor.WorstResult, DoubleDiffer) +
                     GetDiff(example.OutputBoolean, interpreter.BooleanStack, this.DataDescriptor.WorstResult, BooleanDiffer);

          results.Add(diff);
          interpreter.Clear();
        }
      }

      return results.Count == 0 ? 0d : results.Average();
    }

    private static double DoubleDiffer(double a, double b) {
      var result = a - b;

      return result == double.MinValue ? double.MaxValue : Math.Abs(result);
    }

    private static double LongDiffer(long a, long b) {
      var result = a - b;

      return result == long.MinValue ? long.MaxValue : Math.Abs(result);
    }

    private static double BooleanDiffer(bool a, bool b) {
      return a && b ? 0 : a || b ? 1 : 2;
    }

    private static double GetDiff<T>(IReadOnlyList<T> estimated, IStack<T> resultStack, double worstResult, Func<T, T, double> differ)
      where T : IComparable {

      var count = Math.Min(estimated.Count, resultStack.Count);
      var result = resultStack.Peek(count);
      var comparableLength = Math.Min(estimated.Count, result.Length);
      var diff = 0d;

      for (var i = 0; i < comparableLength; i++) {
        diff += Math.Min(differ(estimated[i], result[0]), worstResult);
      }

      if (estimated.Count > result.Length) {
        diff += worstResult * (estimated.Count - comparableLength);
      }

      return diff;
    }

    public void Load(IBenchmarkSuiteDataDescriptor descriptor) {
      this.DataDescriptor = descriptor;
      BestKnownQuality = descriptor.BestResult;

      DataBounds[0, 0] = 0;
      DataBounds[0, 2] = this.DataDescriptor.OriginalTrainingCount + this.DataDescriptor.OriginalTestCount;
      DataBounds[0, 1] = this.DataDescriptor.OriginalTrainingCount;
    }
  }
}