using HeuristicLab.Operators;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using HeuristicLab.Common;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Parameters;
using HeuristicLab.Optimization;
using HeuristicLab.PluginInfrastructure;
using HeuristicLab.Analysis;

namespace HeuristicLab.Algorithms.SimulatedAnnealing
{
    [Item("RandomWalkReheatingOperator", "Performs a randomwalk with the lenght of n after x consecutive solutions were rejected.")]
    [StorableClass]
    public class RandomWalkReheatingOperator : SingleSuccessorOperator, IReheatingOperator
    {
        #region Strings
        private const string AnnealingOperatorName = "AnnealingOperator";
        private const string LowerTemperatureName = "LowerTemperature";
        private const string IterationsName = "Iterations";
        private const string TemperatureStartIndexName = "TemperatureStartIndex";
        private const string StartTemperatureName = "StartTemperature";
        private const string EndTemperatureName = "EndTemperature";
        private const string TemperatureName = "Temperature";
        private const string MaximumIterationsName = "MaximumIterations";
        private const string CurrentRandomWalkStepName = "CurrentRandomWalkStep";
        private const string RandomWalkLengthName = "RandomWalkLength";
        private const string ThresholdName = "Threshold";
        private const string IsAcceptedName = "IsAccepted";
        private const string ConsecutiveRejectedSolutionsCountName = "ConsecutiveRejectedSolutions";
        private const string LastAcceptedQualityName = "LastAcceptedQuality";
        private const string MoveQualityName = "MoveQuality";
        private const string CoolingName = "Cooling";


        #endregion

        #region Parameters
        public ILookupParameter<DoubleValue> TemperatureParameter
        {
            get { return (ILookupParameter<DoubleValue>)Parameters[TemperatureName]; }
        }
        public ILookupParameter<DoubleValue> LowerTemperatureParameter
        {
            get { return (ILookupParameter<DoubleValue>)Parameters[LowerTemperatureName]; }
        }
        public ILookupParameter<DoubleValue> StartTemperatureParameter
        {
            get { return (ILookupParameter<DoubleValue>)Parameters[StartTemperatureName]; }
        }
        public ILookupParameter<DoubleValue> EndTemperatureParameter
        {
            get { return (ILookupParameter<DoubleValue>)Parameters[EndTemperatureName]; }
        }
        public ILookupParameter<IntValue> TemperatureStartIndexParameter
        {
            get { return (ILookupParameter<IntValue>)Parameters[TemperatureStartIndexName]; }
        }
        public ILookupParameter<IntValue> IterationsParameter
        {
            get { return (ILookupParameter<IntValue>)Parameters[IterationsName]; }
        }
        public ILookupParameter<IOperator> AnnealingOperatorParameter
        {
            get { return (ILookupParameter<IOperator>)Parameters[AnnealingOperatorName]; }
        }
        public ILookupParameter<IntValue> MaximumIterationsParameter
        {
            get { return (ILookupParameter<IntValue>)Parameters[MaximumIterationsName]; }
        }
        private ValueParameter<IntValue> ThresholdParameter
        {
            get { return (ValueParameter<IntValue>)Parameters[ThresholdName]; }
        }
        private ValueParameter<IntValue> RandomWalkLengthParameter
        {
            get { return (ValueParameter<IntValue>)Parameters[RandomWalkLengthName]; }
        }
        public ILookupParameter<BoolValue> IsAcceptedParameter
        {
            get { return (ILookupParameter<BoolValue>)Parameters[IsAcceptedName]; }
        }
        public ILookupParameter<IntValue> ConsecutiveRejectedSolutionsCountParameter
        {
            get { return (ILookupParameter<IntValue>)Parameters[ConsecutiveRejectedSolutionsCountName]; }
        }
        public ILookupParameter<IntValue> RandomWalkLengthNameParameter
        {
            get { return (ILookupParameter<IntValue>)Parameters[RandomWalkLengthName]; }
        }
        public ILookupParameter<IntValue> CurrentRandomWalkStepParameter
        {
            get { return (ILookupParameter<IntValue>)Parameters[CurrentRandomWalkStepName]; }
        }
        public ILookupParameter<BoolValue> CoolingParameter
        {
            get { return (ILookupParameter<BoolValue>)Parameters[CoolingName]; }
        }
        public ILookupParameter<DoubleValue> MoveQualityParameter
        {
            get { return (ILookupParameter<DoubleValue>)Parameters[MoveQualityName]; }
        }
        public ILookupParameter<DoubleValue> LastAcceptedQualityParameter
        {
            get { return (ILookupParameter<DoubleValue>)Parameters[LastAcceptedQualityName]; }
        }

        #endregion

        public RandomWalkReheatingOperator() : base()
        {
            #region Create parameters
            Parameters.Add(new LookupParameter<DoubleValue>(TemperatureName, "The current temperature."));
            Parameters.Add(new LookupParameter<DoubleValue>(LowerTemperatureName, "The lower bound of the temperature."));
            Parameters.Add(new LookupParameter<IntValue>(IterationsName, "The number of iterations."));
            Parameters.Add(new LookupParameter<IOperator>(AnnealingOperatorName, "The operator that cools the temperature."));
            Parameters.Add(new LookupParameter<IntValue>(TemperatureStartIndexName, "The index where the annealing or heating was last changed."));
            Parameters.Add(new LookupParameter<DoubleValue>(StartTemperatureName, "The temperature from which cooling or reheating should occur."));
            Parameters.Add(new LookupParameter<DoubleValue>(EndTemperatureName, "The temperature to which should be cooled or heated."));
            Parameters.Add(new LookupParameter<IntValue>(MaximumIterationsName, "The maximum number of iterations which should be processed."));
            Parameters.Add(new LookupParameter<BoolValue>(IsAcceptedName, "Whether the move was accepted or not."));
            Parameters.Add(new LookupParameter<IntValue>(ConsecutiveRejectedSolutionsCountName, "Amount of consecutive rejected solutions."));
            Parameters.Add(new ValueParameter<IntValue>(ThresholdName, "How many consecutive rejected solutions must occur to trigger a reheat.", new IntValue(10000)));
            Parameters.Add(new ValueParameter<IntValue>(RandomWalkLengthName, "Amount of randomly accepted moves upon reheat.", new IntValue(1)));
            Parameters.Add(new LookupParameter<IntValue>(CurrentRandomWalkStepName, "Current random walk step."));
            Parameters.Add(new LookupParameter<DoubleValue>(MoveQualityName, "The value which represents the quality of a move."));
            Parameters.Add(new LookupParameter<BoolValue>(CoolingName, "True when the temperature should be cooled, false otherwise."));
            Parameters.Add(new LookupParameter<DoubleValue>(LastAcceptedQualityName, "Quality of last accepted solution."));
            #endregion

            Parameterize();
        }

        [StorableConstructor]
        protected RandomWalkReheatingOperator(bool deserializing) : base(deserializing) { }
        protected RandomWalkReheatingOperator(RandomWalkReheatingOperator original, Cloner cloner) : base(original, cloner) { }


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

        public void Parameterize()
        {
        }

        public override IOperation Apply()
        {
            var cooling = CoolingParameter.ActualValue.Value;
            var quality = MoveQualityParameter.ActualValue;
            var lastAcceptedQuality = LastAcceptedQualityParameter.ActualValue;
            var isAccepted = IsAcceptedParameter.ActualValue.Value;
            var consecutiveRejectedSolutionsCount = ConsecutiveRejectedSolutionsCountParameter.ActualValue;

            if (cooling)
            {
                // add acceptance value to consecutive rejected solutions count
                // if quality hasnt changed, we might be stuck on a plateau
                if (!isAccepted || quality.Value.Equals(lastAcceptedQuality.Value))
                {
                    consecutiveRejectedSolutionsCount.Value++;
                }
                else
                {
                    consecutiveRejectedSolutionsCount.Value = 0;
                }

                // check if we are trapped in a local optimum
                if (consecutiveRejectedSolutionsCount.Value >= ThresholdParameter.Value.Value)
                {
                    cooling = false;
                    consecutiveRejectedSolutionsCount.Value = 0;
                }
            }


            if (!cooling)
            {
                // random walk finished, start cooling again
                if (RandomWalkLengthParameter.Value.Value <= CurrentRandomWalkStepParameter.ActualValue.Value)
                {
                    cooling = true;
                    CurrentRandomWalkStepParameter.ActualValue.Value = 0;
                }
                else
                {
                    CurrentRandomWalkStepParameter.ActualValue.Value++;
                }
            }

            if (isAccepted)
            {
                LastAcceptedQualityParameter.ActualValue.Value = quality.Value;
            }

            CoolingParameter.ActualValue.Value = cooling;
            return cooling ? Cool() : Heat();
        }

        private IOperation Heat()
        {
            TemperatureParameter.ActualValue.Value = Double.PositiveInfinity;
            return base.Apply();
        }

        private IOperation Cool()
        {
            return new OperationCollection {
                    ExecutionContext.CreateOperation(AnnealingOperatorParameter.ActualValue),
                    base.Apply()
                };
        }
    }
}