///////////////////////////////////////////////////////
// 
// SaherElm IT Center XRange Indicator
// ---------------------------------------------
// saherelm implementation of above indicator ...
//
// Maintainer:
// ------------
// Hadi Khazaee Asl (hadi_khazaee_asl@yahoo.com)
// 
//////////////////////////////////////////////////////
//
// Global Properties ...
#property copyright "Copyright 2023, SaherElm IT Center"
#property link "https://saherelm.ir"
#property version "1.00"
#property description "SaherElm XRange Indicator"
#property strict

//
// START Inputs ...
//
input int marketLength = 14;
//
// END Inputs ...
//

//
// START Global Definitions: Variables, Properties and etc ...
//
#property indicator_chart_window

//
#property indicator_buffers 3

//
#property indicator_plots 3

//
// Start Define Indicator Buffer Styles ...
//
//
// Highest High Buffer ...
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrGreen
#property indicator_style1  STYLE_DOT
#property indicator_width1  1

//
// Lowest Low Buffer ...
#property indicator_type2   DRAW_LINE
#property indicator_color2  clrRed
#property indicator_style2  STYLE_DOT
#property indicator_width2  1

//
// Middle Buffer ...
#property indicator_type3   DRAW_LINE
#property indicator_color3  clrYellow
#property indicator_style3  STYLE_DASH
#property indicator_width3  1
//
// End Define Indicator Buffer Styles ...
//

//
// Buffers ...
//
#define highestHighBufferIndex 0
#define lowestLowBufferIndex 1
#define middleBufferIndex 2

//
double highestHighBuffer[];
double lowestLowBuffer[];
double middleBuffer[];

//
datetime startTime;
//
// END Global Definitions: Variables, Properties and etc ...
//

//
// Start Event Handlers ...
// 
//
// Initialization ...
int OnInit() {
    //
    // Initialize what we want ...
    if (
        marketLength <= 0
    ) {
        return INIT_PARAMETERS_INCORRECT;    
    }
    
    //
    string hhLbl = StringConcatenate(
        "XR HH(", marketLength, ")"
    );
    SetIndexBuffer(highestHighBufferIndex, highestHighBuffer);
    SetIndexLabel(highestHighBufferIndex, hhLbl);
    
    //
    string llLbl = StringConcatenate(
        "XR LL(", marketLength, ")"
    );
    SetIndexBuffer(lowestLowBufferIndex, lowestLowBuffer);
    SetIndexLabel(lowestLowBufferIndex, llLbl);
    
    //
    string midLbl = StringConcatenate(
        "XR Mid(", marketLength, ")"
    );
    SetIndexBuffer(middleBufferIndex, middleBuffer);
    SetIndexLabel(middleBufferIndex, midLbl);

    //
    return INIT_SUCCEEDED;
}

//
// Calculating what we want ...
int OnCalculate(const int rates_total,
                const int 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 int &spread[]
) {
    //
    // this counts Available Bars ...
    int limit;

    //
    // because in some cases we may have more than one input for 
    // calculation and we must prevent any calculation
    // untill we pass the biggest input length, here we get max Input length
    // and then wait until pass it ...
    int maxLength = MathMax(0, marketLength);

    //
    // input variable, we return 0 means nothing passed ...
    if (rates_total < maxLength) {
      return 0;
    }
   
    //
    // found which candles calculated before ...
    limit = (prev_calculated == 0) ? rates_total - maxLength - 1 : rates_total - prev_calculated + 1;

    //
    // this is the main loop of calculations, for each bar index ...
    for (int i = limit - 1; i >= 0; i--) {
        //
        // Start Calculation here ...
        // i is bar_index ... 
        
        //
        // Calculations ...
        CalculateBuffers(i);
    }

    //
    return rates_total;
}
//
// END Event Handlers ...
// 

//
// START Functions ...
//
//
// Calculations ...
void CalculateBuffers(
    const int &bar_index
) {
    //
    // Retrieve Bar Time ...
    datetime barTime = iTime(
            _Symbol,
            _Period,
            bar_index
        );

    //
    if (startTime == 0) {
        //
        startTime = barTime;
        SetIndicatorBuffersNone(bar_index);
        return;
    }

    //
    int startBarIndex = iBarShift(
        _Symbol,
        _Period,
        startTime
    );

    //
    int startDistance = startBarIndex - bar_index;
    if (startDistance < marketLength) {
        //
        SetIndicatorBuffersNone(bar_index);
        return;
    }

    //
    // Highest High ...
    int hhIdx = iHighest(
        _Symbol,
        _Period,
        MODE_HIGH,
        marketLength,
        bar_index
    );
    double hh = iHigh(
        _Symbol,
        _Period,
        hhIdx
    );
    highestHighBuffer[bar_index] = hh;

    //
    // Lowest Low ...
    int llIdx = iLowest(
        _Symbol,
        _Period,
        MODE_LOW,
        marketLength,
        bar_index
    );
    double ll = iLow(
        _Symbol,
        _Period,
        llIdx
    );
    lowestLowBuffer[bar_index] = ll;

    //
    // Middle Buffer ...
    double mid = (hh + ll) / 2;
    middleBuffer[bar_index] = mid;

    //
    // Reset Start Time ...
    startTime = 0;
}

//
void SetIndicatorBuffersNone(
    const int bar_index
) {
    //
    int lastBarIndex = bar_index + 1;

    //
    double lastHighestHigh;
    double lastLowestLow;
    
    //
    // Highest High ...
    if (ArraySize(highestHighBuffer) > lastBarIndex) {
        lastHighestHigh = highestHighBuffer[lastBarIndex];
    } else {
        lastHighestHigh = 0;
    }

    //
    // Lowest Low ...
    if (ArraySize(lowestLowBuffer) > lastBarIndex) {
        lastLowestLow = lowestLowBuffer[lastBarIndex];
    } else {
        lastLowestLow = 0;
    }

    //
    highestHighBuffer[bar_index] = lastHighestHigh;
    lowestLowBuffer[bar_index] = lastLowestLow;

    //
    double mid = (lastHighestHigh + lastLowestLow) / 2;
    middleBuffer[bar_index] = mid;
}
//
// END Functions ...
//