#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2012 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Operators;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Operators.MPISupport.BinaryTransport;
using System.Collections.Generic;
using MPI;
using System;

namespace HeuristicLab.Operators.MPISupport {
  [Item("MPISolutionsCreator", "An operator which creates new solutions in parallel using MPI.")]
  [StorableClass]
  public sealed class MPISolutionsCreator : SingleSuccessorOperator {
    public ValueLookupParameter<IntValue> NumberOfSolutionsParameter {
      get { return (ValueLookupParameter<IntValue>)Parameters["NumberOfSolutions"]; }
    }
    public ValueLookupParameter<IOperator> SolutionCreatorParameter {
      get { return (ValueLookupParameter<IOperator>)Parameters["SolutionCreator"]; }
    }
    public ValueLookupParameter<IOperator> EvaluatorParameter {
      get { return (ValueLookupParameter<IOperator>)Parameters["Evaluator"]; }
    }
    public ValueLookupParameter<BoolValue> ParallelParameter {
      get { return (ValueLookupParameter<BoolValue>)Parameters["Parallel"]; }
    }
    private ScopeParameter CurrentScopeParameter {
      get { return (ScopeParameter)Parameters["CurrentScope"]; }
    }
    public IScope CurrentScope {
      get { return CurrentScopeParameter.ActualValue; }
    }
    public IntValue NumberOfSolutions {
      get { return NumberOfSolutionsParameter.Value; }
      set { NumberOfSolutionsParameter.Value = value; }
    }

    [StorableConstructor]
    private MPISolutionsCreator(bool deserializing) : base(deserializing) { }
    private MPISolutionsCreator(MPISolutionsCreator original, Cloner cloner) : base(original, cloner) { }
    public MPISolutionsCreator()
      : base() {
      Parameters.Add(new ValueLookupParameter<IntValue>("NumberOfSolutions", "The number of solutions that should be created."));
      Parameters.Add(new ValueLookupParameter<IOperator>("SolutionCreator", "The operator which is used to create new solutions."));
      Parameters.Add(new ValueLookupParameter<IOperator>("Evaluator", "The operator which is used to evaluate new solutions. This operator is executed in parallel, if an engine is used which supports parallelization."));
      Parameters.Add(new ValueLookupParameter<BoolValue>("Parallel", "True if the operator should be applied in parallel on all sub-scopes, otherwise false.", new BoolValue(true)));
      Parameters.Add(new ScopeParameter("CurrentScope", "The current scope to which the new solutions are added as sub-scopes."));
    }
    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() {
      if (!Parameters.ContainsKey("Parallel")) Parameters.Add(new ValueLookupParameter<BoolValue>("Parallel", "True if the operator should be applied in parallel on all sub-scopes, otherwise false.", new BoolValue(true))); // backwards compatibility
    }

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

    public override IOperation Apply() {
      int scopeCount = NumberOfSolutionsParameter.ActualValue.Value;
      IOperator creator = SolutionCreatorParameter.ActualValue;
      IOperator evaluator = EvaluatorParameter.ActualValue;
      bool parallel = ParallelParameter.ActualValue.Value;

      int current = CurrentScope.SubScopes.Count;
      for (int i = 0; i < scopeCount; i++)
        CurrentScope.SubScopes.Add(new Scope((current + i).ToString()));
      ScopeList scopes = CurrentScope.SubScopes;

      OperationCollection next = new OperationCollection();
      if (MPI.Communicator.world != null && MPI.Communicator.world.Size > 2) {
        int rank = MPI.Communicator.world.Rank;
        int size = MPI.Communicator.world.Size - 1;

        int count = scopes.Count / size;
        int start = count * (rank - 1);
        int end = (rank == size ? scopes.Count : start + count);

        List<Request> requests = new List<Request>();
        IScope parent = new Scope();

        for (int i = start; i < end; i++) {
          if (creator != null) {
            IAtomicOperation op = ExecutionContext.CreateOperation(creator, scopes[i]);
            MPIHelper.Execute(op);
          }

          if (evaluator != null) {
            IAtomicOperation op = ExecutionContext.CreateOperation(evaluator, scopes[i]);
            MPIHelper.Execute(op);
          }

          //SEND results to other clients
          parent.SubScopes.Add(MPIHelper.ShallowCopy(scopes[i]));
        }

        for (int dest = 1; dest <= size; dest++) {
          if (dest != rank) {
            var result = new MPIBinaryTransportWrapper(parent);
            requests.Add(MPI.Communicator.world.ImmediateSend<MPIBinaryTransportWrapper>(result, dest, 0));
          }
        }

        IExecutionContext globalScope = ExecutionContext;
        while (globalScope.Parent != null) {
          globalScope = globalScope.Parent;
        }

        //RECEIVE results from other clients
        for (int source = 1; source <= size; source++) {
          if (source != rank) {
            var result = MPI.Communicator.world.Receive<MPIBinaryTransportWrapper>(source, 0).GetInnerItem(globalScope) as IScope;

            int offset = count * (source - 1);
            for (int scopeIndex = 0; scopeIndex < result.SubScopes.Count; scopeIndex++) {
              scopes[scopeIndex + offset] = result.SubScopes[scopeIndex];
            }
          }
        }

        foreach (Request request in requests) {
          request.Wait();
        }
      } else {
        OperationCollection creation = new OperationCollection();
        OperationCollection evaluation = new OperationCollection() { Parallel = parallel };
        for (int i = 0; i < scopeCount; i++) {
          if (creator != null) creation.Add(ExecutionContext.CreateOperation(creator, CurrentScope.SubScopes[current + i]));
          if (evaluator != null) evaluation.Add(ExecutionContext.CreateOperation(evaluator, CurrentScope.SubScopes[current + i]));
        }

        next.Add(creation);
        next.Add(evaluation);
      }
      next.Add(base.Apply());
      return next;
    }
  }
}