//+------------------------------------------------------------------+
//|       Article-22469-Candlestick-Alphabetical-Encoding-System.mq5 |
//|                                  Copyright 2023, MetaQuotes Ltd. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property script_show_inputs
#property strict

input int lookback = 500;

//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- indicator buffers mapping
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int32_t rates_total,
                const int32_t prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int32_t &spread[])
  {
//--- set arrays as series
   ArraySetAsSeries(time, true);
   static datetime lastTime;
   int Lmt = (prev_calculated == 0) ?
             MathMin(rates_total - 3, lookback - 3) : 3;
   if(lastTime == time[0])
      return 0;
   lastTime = time[0];
   for(int i = Lmt; i >= 0; i--)
     {
      CheckBullishPattern(i);
      CheckBearishPattern(i);
     }
//--- return value of prev_calculated for next call
   return(rates_total);
  }

//+------------------------------------------------------------------+
//|  Candle Type labeling function                                   |
//+------------------------------------------------------------------+
string CandleType(int shift)
  {
//--- Get price data for the specified candle
   double open = iOpen(NULL, 0, shift);   // Price Open
   double close = iClose(NULL, 0, shift); // Price Close
   double high = iHigh(NULL, 0, shift);   // Price High
   double low = iLow(NULL, 0, shift);     // Price Low
   
//--- Calculate candle components
   double body = MathAbs(close - open);
   double upperWick = high - MathMax(open, close);
   double lowerWick = MathMin(open, close) - low;
   
//--- Handle bullish candles
   if(close > open)
     {
      if(body > 1.5 * upperWick && body > 1.5 * lowerWick)     // long, short, marubozu
         return "A";
      if(2 * body < upperWick && 2 * body < lowerWick)         // spinning top
         return "G";
      if(lowerWick > 2.5 * body && lowerWick > 2 * upperWick)  // pinbar
         return "H";
      if(upperWick > 2.5 * body && upperWick > 2 * lowerWick)  // inverted pinbar
         return "E";
     }
//--- Handle bearish candles
   else
      if(close < open)
        {
         if(body > 1.5 * upperWick && body > 1.5 * lowerWick)
            return "a";
         if(2 * body < upperWick && 2 * body < lowerWick)
            return "g";
         if(lowerWick > 2.5 * body && lowerWick > 2 * upperWick)
            return "h";
         if(upperWick > 2.5 * body && upperWick > 2 * lowerWick)
            return "e";
        }
      else
         if(close == open)
            return "D"; // doji
//--- Return empty string if no conditions met
   return "";
  }

//+------------------------------------------------------------------+
//| Check for bullish two-candle patterns and print if found         |
//+------------------------------------------------------------------+
void CheckBullishPattern(int shift)
  {
   string candle2 = CandleType(shift + 1);   // older candle
   string candle1 = CandleType(shift);       // newer candle
   string pattern = candle2 + candle1;
//--- Bullish patterns (uppercase pairs)
   if(pattern == "AH" || pattern == "AE" || pattern == "AG" ||
      pattern == "HA" || pattern == "HE" || pattern == "HG" ||
      pattern == "EA" || pattern == "EH" || pattern == "EG" ||
      pattern == "GA" || pattern == "GH" || pattern == "GE")
     {
      Print("Bullish pattern detected: ", pattern);
      Alert("Bullish pattern detected: ", pattern);
     }
  }

//+------------------------------------------------------------------+
//| Check for bearish two-candle patterns and print if found         |
//+------------------------------------------------------------------+
void CheckBearishPattern(int shift)
  {
   string candle2 = CandleType(shift + 1);
   string candle1 = CandleType(shift);
   string pattern = candle2 + candle1;
//--- Bearish patterns (lowercase pairs)
   if(pattern == "ah" || pattern == "ae" || pattern == "ag" ||
      pattern == "ha" || pattern == "he" || pattern == "hg" ||
      pattern == "ea" || pattern == "eh" || pattern == "eg" ||
      pattern == "ga" || pattern == "gh" || pattern == "ge")
     {
      Print("Bearish pattern detected: ", pattern);
      Alert("Bearish pattern detected: ", pattern);
     }
  }
//+------------------------------------------------------------------+