MQLArticles/RM/LoteSizeCalc.mqh

<EFBFBD><EFBFBD>//+------------------------------------------------------------------+
//|                                                 LoteSizeCalc.mqh |
//|                                  Copyright 2025, Niquel Mendoza. |
//|                     https://www.mql5.com/es/users/nique_372/news |
//+------------------------------------------------------------------+
#property copyright "Copyright 2025, Niquel Mendoza."
#property link      "https://www.mql5.com/es/users/nique_372/news"
#property strict

#ifndef MQLARTICLES_RM_LOTSIZECALC_MQH
#define MQLARTICLES_RM_LOTSIZECALC_MQH

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
#include <Trade/Trade.mqh>
#include "RM_Defines.mqh"
#include "..\\Utils\\Basic.mqh"

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
typedef double (*PriceCalculatorFunc)(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits);

namespace GetLoteFunctions
{
//+------------------------------------------------------------------+
inline double PriceCal_CalcMarketPrice(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits)
 {
  return price;
 }

//+------------------------------------------------------------------+
inline double PriceCal_CalcBuyLimitPrice(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits)
 {
  return NormalizeDouble(price - deviation * point_value, digits);
 }

//+------------------------------------------------------------------+
inline double PriceCal_CalcSellLimitPrice(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits)
 {
  return NormalizeDouble(price + deviation * point_value, digits);
 }

//+------------------------------------------------------------------+
inline double PriceCal_CalcBuyStopPrice(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits)
 {
  return NormalizeDouble(price + deviation * point_value, digits);
 }

//+------------------------------------------------------------------+
inline double PriceCal_CalcSellStopPrice(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits)
 {
  return NormalizeDouble(price - deviation * point_value, digits);
 }

//+------------------------------------------------------------------+
inline double PriceCal_CalcBuyStopLimitPrice(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits)
 {
  return NormalizeDouble(price + deviation * point_value - stop_limit * point_value, digits);
 }

//+------------------------------------------------------------------+
inline double PriceCal_CalcSellStopLimitPrice(double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits)
 {
  return NormalizeDouble(price - deviation * point_value + stop_limit * point_value, digits);
 }
}
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
class CGetLote : public CLoggerBase
 {
private:
  string             symbol;
  double             volumeStep;
  double             minLote;
  double             maxLote;
  double             volume_limit;
  double             point_value;
  int8_t             digits;
  double             ganancia_por_tick_real;

public:
                     CGetLote(string _symbol);
  //--- Update
  void               Update();

  //--- Symbol
  void               SetSymbol(string new_value);
  inline string      GetSymbol() const { return symbol;  }

  //---
  inline double      MinVolume() const { return minLote; }
  inline double      MaxVolume() const { return maxLote; }

  //--- General functions
  // Calcula el stop loss ideal en puntos, basandose en el riesgo de operacion y en un lote especificado
  // Calculates the ideal stop loss in points, based on the transaction risk and a specified lot
  long               CalculateSLWithLot(const ENUM_ORDER_TYPE type, double risk_per_operation, double entry_price, double lot, ulong deviation, ulong stop_limit);

  // Calcula el stop loss ideal en puntos, basandose en el riesgo de operacion, ademas devuelve el lote ideal
  // Calculates the ideal stop loss in points, based on the operation risk, and also returns the ideal lot
  long               CalculateSL(const ENUM_ORDER_TYPE type, double risk_per_operation, double entry_price, double &chosen_lot, ulong deviation, ulong stop_limit);

  // Calcula el lote en base al riesgo por operacion y el stop loss en puntos
  // Calculate the lot based on the risk per operation and the stop loss in points
  double             GetLoteByRiskPerOperationAndSL(double glot, double max_risk_per_operation, double &new_risk_per_operation, long StopLoss);

  // Obtiene el lote maximo que se puede ejecutar
  // Get the maximum batch that can be executed
  double             GetMaxLote(ENUM_ORDER_TYPE type, double entry_price, ulong deviation, ulong stop_limit);

  // Obtiene el lote maximo que se puede comprar por el riesgo por operacion en USD (no %, osea un riesgo ya calculado)
  // Gets the maximum lot that can be purchased for the risk per operation in USD (not %, i.e. a risk already calculated)
  double             GetLoteByRiskPerOperation(ENUM_ORDER_TYPE type, double risk_per_operation, double entry_price, ulong deviation, ulong stop_limit);
 };
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
CGetLote::CGetLote(string _symbol)
 {
  this.symbol = _symbol;
  Update();
 }

//+---------------------------------------------------------------------+
//| Determine the optimal lot size based on risk and current conditions |
//+---------------------------------------------------------------------+
double CGetLote::GetLoteByRiskPerOperationAndSL(double glot, double max_risk_per_operation, double &new_risk_per_operation, long StopLoss)
 {
  new_risk_per_operation = 0.0;
  double nlot = 0.00;

//---
  if(glot <= 0)
   {
    LogError(StringFormat("Lote maximo invalido: %.2f", glot), FUNCION_ACTUAL);
    return 0.00;
   }

  if(StopLoss <= 0)
   {
    LogError(StringFormat("Stop Loss distance is less than or equal to zero, now correct the stoploss distance: %d", StopLoss), FUNCION_ACTUAL);
    return nlot;
   }

  if(max_risk_per_operation <= 0)
   {
    LogError(StringFormat("El riesgo maximo por operacion %.2f es invalido", max_risk_per_operation), FUNCION_ACTUAL);
    return nlot;
   }

//---
  long spread = SymbolInfoInteger(symbol, SYMBOL_SPREAD);
  double rpo = glot * (ganancia_por_tick_real * (spread + 1 + StopLoss));

  if(rpo > max_risk_per_operation)
   {
    double new_lot = (max_risk_per_operation / rpo) * glot;
    new_lot  = RoundToStep(new_lot, volumeStep);
    new_risk_per_operation =  new_lot * (ganancia_por_tick_real * (spread + 1 + StopLoss));
    nlot =  new_lot;
   }
  else
   {
    new_risk_per_operation = rpo;
    nlot = glot;
   }

//---
  if(nlot > maxLote)
    nlot = maxLote;

  LogInfo(StringFormat("Risk per operation(%.2f) = %.2f * ( %f * ( %i + 1 + %i)))", new_risk_per_operation, nlot, ganancia_por_tick_real, spread, StopLoss), FUNCION_ACTUAL);

//---
  if(nlot <= 0.00)
    LogWarning(StringFormat("The lot %.2f is invalid, the risk %.2f increases or the sl %d decreases", nlot, max_risk_per_operation, StopLoss), FUNCION_ACTUAL);
  else
    LogInfo(StringFormat("For the stop loss %i in points and risk per operation: %.2f, the ideal lot is: %.2f", StopLoss, max_risk_per_operation, nlot), FUNCION_ACTUAL);

  return nlot;
 }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
long CGetLote::CalculateSLWithLot(const ENUM_ORDER_TYPE type, double risk_per_operation, double entry_price, double lot, ulong deviation, ulong stop_limit)
 {
//--- Check lot
  if(lot <= 0)
   {
    LogError(StringFormat("No se pudo calcular lote valido para el riesgo especificado = %.2f", risk_per_operation), FUNCION_ACTUAL);
    return 0;
   }

//--- Calculamos el stop loss en base al riesgo por operacion y al lote
  const long spread = (long)SymbolInfoInteger(symbol, SYMBOL_SPREAD);
  const double result = (risk_per_operation / (lot * ganancia_por_tick_real)) - spread - 1;
  const long ideal_sl = long(MathRound(result));

//--- Check SL
  if(ideal_sl <= 0)
   {
    LogError(StringFormat("Stop loss %i invalid, please increase the risk per trade %.2f", ideal_sl, risk_per_operation), FUNCION_ACTUAL);
    return 0;
   }
  return ideal_sl;
 }

//+-----------------------------------------------------------------------+
//| Calculate the stop loss distance in points based on risk and lot size |
//+-----------------------------------------------------------------------+
long CGetLote::CalculateSL(const ENUM_ORDER_TYPE type, double risk_per_operation, double entry_price, double &chosen_lot, ulong deviation, ulong stop_limit)
 {
  chosen_lot = GetLoteByRiskPerOperation(type, risk_per_operation, entry_price, deviation, stop_limit);

  if(chosen_lot <= 0)
   {
    LogError(StringFormat("No se pudo calcular lote valido para el riesgo especificado = %.2f", risk_per_operation), FUNCION_ACTUAL);
    return 0;
   }

  long spread = (long)SymbolInfoInteger(symbol, SYMBOL_SPREAD);
  double result = (risk_per_operation / (chosen_lot * ganancia_por_tick_real)) - spread - 1;
  long ideal_sl = long(MathRound(result));

  if(ideal_sl <= 0)
   {
    LogError(StringFormat("Stop loss %i invalid, please increase the risk per trade %.2f", ideal_sl, risk_per_operation), FUNCION_ACTUAL);
    return 0;
   }
  return ideal_sl;
 }


//+--------------------------------------------------------------------+
//| Function to obtain the ideal lot based on your risk per operation  |
//+--------------------------------------------------------------------+
// risk_per_operation in USD, not %
double CGetLote::GetLoteByRiskPerOperation(ENUM_ORDER_TYPE type, double risk_per_operation, double entry_price, ulong deviation, ulong stop_limit)
 {
  double price = OrderTypeToPriceCalculator[type](entry_price, deviation, stop_limit, point_value, digits);
  double margin_free = AccountInfoDouble(ACCOUNT_MARGIN_FREE);

//---
  if(margin_free <= 0.00)
   {
    LogError(StringFormat("Free margin of %+.2f is invalid, you cannot open trades right now", margin_free), FUNCION_ACTUAL);
    return 0.0;
   }

//---
  double margin = EMPTY_VALUE;
  const static double VOLUME = 1.0;

  ResetLastError();
  if(!OrderCalcMargin(MarketOrderToOrderType[type], symbol, VOLUME, price, margin))
   {
    LogError(StringFormat("OrderCalcMargin() failed. Error = %d", GetLastError()), FUNCION_ACTUAL);
    return 0.0;
   }

//---
  if(risk_per_operation >=  margin_free)
    risk_per_operation = margin_free;

//---
  double result = MathFloor((risk_per_operation / margin) / volumeStep) * volumeStep;

  if(result < minLote)
   {
    LogWarning(StringFormat("The lot %.2f is invalid, the risk %.2f increases", result, risk_per_operation), FUNCION_ACTUAL);
    return result;
   }

  if(result >= maxLote)
    return maxLote;

  if(result >= volume_limit && volume_limit > 0.00)
    return volume_limit;

//---
  LogInfo(StringFormat("The ideal lot for %.2f risk per trade is %.2f lots, margin for 1 lote: %.2f", risk_per_operation, result, margin), FUNCION_ACTUAL);
  return result;
 }

//+------------------------------------------------------------------+
double CGetLote::GetMaxLote(ENUM_ORDER_TYPE type, double entry_price, ulong deviation, ulong stop_limit)
 {
//double price, ulong deviation, ulong stop_limit, double point_value, int8_t digits
  double price = OrderTypeToPriceCalculator[type](entry_price, deviation, stop_limit, point_value, digits);
  double margin_free = AccountInfoDouble(ACCOUNT_MARGIN_FREE);

//---
  if(margin_free <= 0.00)
   {
    LogError(StringFormat("Free margin of %+.2f is invalid, you cannot open trades right now", margin_free), FUNCION_ACTUAL);
    return 0.0;
   }

//---
  double margin = EMPTY_VALUE;
  const static double VOLUME = 1.0;

  ResetLastError();
  if(!OrderCalcMargin(MarketOrderToOrderType[type], symbol, VOLUME, price, margin))
   {
    LogError(StringFormat("OrderCalcMargin() failed. Error = %d", GetLastError()), FUNCION_ACTUAL);
    return 0.0;
   }

//---
  double result = MathFloor((margin_free / margin) / volumeStep) * volumeStep;

//---
  if(result < minLote)
    return 0.0;

  if(result >= maxLote)
    return maxLote;

  if(result >= volume_limit && volume_limit > 0.00)
    return volume_limit;

//---
  LogInfo(StringFormat("Lote maximo = %.2f >> precio = %.*f >> margen(1) = %.2f", result, digits, entry_price, margin), FUNCION_ACTUAL);
  return result;
 }

//+------------------------------------------------------------------+
void CGetLote::Update(void)
 {
  this.volumeStep = SymbolInfoDouble(symbol, SYMBOL_VOLUME_STEP);
  this.minLote = SymbolInfoDouble(symbol, SYMBOL_VOLUME_MIN);
  this.maxLote = SymbolInfoDouble(symbol, SYMBOL_VOLUME_MAX);
  this.volume_limit = SymbolInfoDouble(symbol, SYMBOL_VOLUME_LIMIT);
  this.digits = (int8_t)SymbolInfoInteger(symbol, SYMBOL_DIGITS);
  this.point_value = SymbolInfoDouble(symbol, SYMBOL_POINT);

//---
  ENUM_SYMBOL_CALC_MODE calc_mode = (ENUM_SYMBOL_CALC_MODE)SymbolInfoInteger(symbol, SYMBOL_TRADE_CALC_MODE);;

  switch(calc_mode)
   {
    case SYMBOL_CALC_MODE_FOREX:
    case SYMBOL_CALC_MODE_FOREX_NO_LEVERAGE:
      this.ganancia_por_tick_real = SymbolInfoDouble(symbol, SYMBOL_TRADE_TICK_VALUE);
      break;

    case SYMBOL_CALC_MODE_CFD:
    case SYMBOL_CALC_MODE_CFDINDEX:
    case SYMBOL_CALC_MODE_CFDLEVERAGE:
      this.ganancia_por_tick_real = SymbolInfoDouble(symbol, SYMBOL_TRADE_CONTRACT_SIZE) * SymbolInfoDouble(symbol, SYMBOL_TRADE_TICK_SIZE);
      break;

    default:
      this.ganancia_por_tick_real = SymbolInfoDouble(symbol, SYMBOL_TRADE_CONTRACT_SIZE) * SymbolInfoDouble(symbol, SYMBOL_TRADE_TICK_SIZE);
      break;
   }
 }

//+------------------------------------------------------------------+
void CGetLote::SetSymbol(string new_value)
 {
  this.symbol = new_value;
  Update();
 }
/*
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_BUY = 0
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_SELL = 1
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_BUY_LIMIT = 2
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_SELL_LIMIT = 3
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_BUY_STOP = 4
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_SELL_STOP = 5
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_BUY_STOP_LIMIT = 6
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_SELL_STOP_LIMIT = 7
2025.08.06 16:50:41.989 GetID (XAUUSD,M1) ORDER_TYPE_CLOSE_BY = 8
*/

const ENUM_ORDER_TYPE MarketOrderToOrderType[9] =
 {
  ORDER_TYPE_BUY,
  ORDER_TYPE_SELL,
  ORDER_TYPE_BUY,
  ORDER_TYPE_SELL,
  ORDER_TYPE_BUY,
  ORDER_TYPE_SELL,
  ORDER_TYPE_BUY,
  ORDER_TYPE_SELL,
  WRONG_VALUE
 };

const PriceCalculatorFunc OrderTypeToPriceCalculator[9] =
 {
  GetLoteFunctions::PriceCal_CalcMarketPrice,
  GetLoteFunctions::PriceCal_CalcMarketPrice,
  GetLoteFunctions::PriceCal_CalcBuyLimitPrice,
  GetLoteFunctions::PriceCal_CalcSellLimitPrice,
  GetLoteFunctions::PriceCal_CalcBuyStopPrice,
  GetLoteFunctions::PriceCal_CalcSellStopPrice,
  GetLoteFunctions::PriceCal_CalcBuyStopLimitPrice,
  GetLoteFunctions::PriceCal_CalcSellStopLimitPrice,
  GetLoteFunctions::PriceCal_CalcMarketPrice
 };
//+------------------------------------------------------------------+
#endif // MQLARTICLES_RM_LOTSIZECALC_MQH
//+------------------------------------------------------------------+