//+------------------------------------------------------------------+
//| NeuronBase.mqh                                                    |
//|                                                                   |
//| CNeuronBase - the pure-MQL5 dense neuron: init, forward,          |
//| gradients, activation, persistence.                               |
//|                                                                   |
//| Included from AI\Network.mqh AFTER every class declaration -      |
//| bodies only, no declarations. Relocation is behaviour-neutral by  |
//| construction: nothing here is reachable until Network.mqh ends.   |
//+------------------------------------------------------------------+
#ifndef WARRIOR_AI_IMPL_NEURONBASE_MQH
#define WARRIOR_AI_IMPL_NEURONBASE_MQH
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
double CNeuronBase::alpha = momentum;     // momentum
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
CNeuronBase::CNeuronBase(void)  :
   outputVal(1),
   gradient(0),
   activation(TANH),
   t(1),
   optimization(SGD)
  {
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
CNeuronBase::~CNeuronBase(void)
  {
   if(CheckPointer(Connections) != POINTER_INVALID)
      delete Connections;
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
bool CNeuronBase::Init(uint numOutputs, uint myIndex, ENUM_OPTIMIZATION optimization_type, double weighScale = -1.0)
  {
   if(CheckPointer(Connections) == POINTER_INVALID)
     {
      Connections = new CArrayCon();
      if(CheckPointer(Connections) == POINTER_INVALID)
         return false;
     }
//---
   if(!Connections.Reserve(fmax(numOutputs, 1)))
     {
      Print(__FUNCTION__ + ": Connections.Reserve failed (allocation failure?) - neuron would silently end up with 0 connections");
      return false;
     }
   for(uint c = 0; c < numOutputs; c++)
     {
      if(!Connections.CreateElementScaled(c, weighScale))
         return false;
      Connections.IncreaseTotal();
     }
//---
   m_myIndex = myIndex;
   optimization = optimization_type;
   return true;
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
bool CNeuronBase::feedForward(CObject *&SourceObject)
  {
   bool result = false;
//---
   if(CheckPointer(SourceObject) == POINTER_INVALID)
      return result;
//---
   CLayer *temp_l;
   CNeuronPool *temp_n;
   switch(SourceObject.Type())
     {
      case defLayer:
         temp_l = SourceObject;
         result = feedForward(temp_l);
         break;
      case defNeuronConv:
      case defNeuronPool:
      case defNeuronLSTM:
         temp_n = SourceObject;
         result = feedForward(temp_n.getOutputLayer());
         break;
     }
//---
   return result;
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
bool CNeuronBase::updateInputWeights(CObject *SourceObject)
  {
   bool result = false;
//---
   if(CheckPointer(SourceObject) == POINTER_INVALID)
      return result;
//---
   CLayer *temp_l;
   CNeuronPool *temp_n;
   switch(SourceObject.Type())
     {
      case defLayer:
         temp_l = SourceObject;
         result = updateInputWeights(temp_l);
         break;
      case defNeuronConv:
      case defNeuronPool:
      case defNeuronLSTM:
         temp_n = SourceObject;
         temp_l = temp_n.getOutputLayer();
         result = updateInputWeights(temp_l);
         break;
     }
//---
   return result;
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
bool CNeuronBase::calcHiddenGradients(CObject *&TargetObject)
  {
   bool result = false;
//---
   if(CheckPointer(TargetObject) == POINTER_INVALID)
      return result;
//---
   CLayer *temp_l;
   CNeuronPool *temp_n;
   switch(TargetObject.Type())
     {
      case defLayer:
         temp_l = TargetObject;
         result = calcHiddenGradients(temp_l);
         break;
      case defNeuronConv:
      case defNeuronPool:
      case defNeuronLSTM:
         switch(Type())
           {
            case defNeuron:
               temp_n = TargetObject;
               result = temp_n.calcInputGradients(GetPointer(this), m_myIndex);
               break;
            case defNeuronLSTM:
               temp_n = TargetObject;
               temp_l = getOutputLayer();
               if(!temp_n.calcInputGradients(temp_l))
                 {
                  result = false;
                  break;
                 }
               result = calcHiddenGradients(temp_l);
               break;
            default:
               temp_l =getOutputLayer();
               temp_n = TargetObject;
               result = temp_n.calcInputGradients(temp_l);
               break;
           }
         break;
     }
//---
   return result;
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
bool CNeuronBase::Save(int file_handle)
  {
   if(file_handle == INVALID_HANDLE)
      return false;
   if(FileWriteInteger(file_handle, Type()) < INT_VALUE)
      return false;
//---
   if(FileWriteInteger(file_handle, (int)activation, INT_VALUE) < INT_VALUE)
      return false;
//---
   if(FileWriteInteger(file_handle, (int)optimization, INT_VALUE) < INT_VALUE)
      return false;
//---
   if(FileWriteInteger(file_handle, t, INT_VALUE) < INT_VALUE)
      return false;
//---
   return Connections.Save(file_handle);
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
double CNeuronBase::activationFunction(double x)
  {
   switch(activation)
     {
      case NONE:
         return(x);
         break;
      case TANH:
         return TanhFunction(x);
         break;
      case SIGMOID:
         return SigmoidFunction(x);
         break;
      case PRELU:
         // fixed 0.01 slope, matches CNeuronConv::activationFunction's `param` default -
         // this case was previously missing here, so any generic Dense (defNeuron) layer
         // given PRELU silently fell through to the `return x` below (pure linear identity,
         // no nonlinearity at all) instead of leaky-ReLU.
         return(x >= 0 ? x : 0.01 * x);
         break;
     }
//---
   return x;
  }
//+------------------------------------------------------------------+
//|                                                                   |
//+------------------------------------------------------------------+
double CNeuronBase::activationFunctionDerivative(double x)
  {
   switch(activation)
     {
      case NONE:
         return(1);
         break;
      case TANH:
         return TanhFunctionDerivative(x);
         break;
      case SIGMOID:
         return SigmoidFunctionDerivative(x);
         break;
      case PRELU:
         // See activationFunction() above - was previously missing here too, defaulting
         // to a derivative of 1 (which happens to be right for x>=0, but wrong for x<0,
         // where it must be the 0.01 leak slope, not 1).
         return(x >= 0 ? 1.0 : 0.01);
         break;
     }
//---
   return 1;
  }
#endif