eq = C;

yr = Year();
mo = Month();

YearChange = yr != Ref( yr, -1 );
MonChange = mo != Ref( mo, -1 );

FirstYr = 0;
LastYr = 0;

startbar = 0;

////////////////////////////
// SKIP non-trading bars
////////////////////////////
for( i = 0; i < BarCount; i++ )
{
  if( eq[ i ] )
  {
    startbar = i;
    break;
  } 
}

////////////////////////////
// collect yearly / monthly changes in equity
// into dynamic variables
////////////////////////////

LastYrValue = eq[ startbar  ];
LastMoValue = eq[ startbar  ];

MaxYrProfit = MinYrProfit = 0;
MaxMoProfit = MinMoProfit = 0;

for( i = startbar + 1; i < BarCount; i++ )
{
  if( YearChange[ i ] || i == BarCount - 1 )
  {
    Chg = 100 * ( -1 + eq[ i ] / LastYrValue );
    VarSet("ChgYear"+ yr[ i - 1 ], Chg );

    MaxYrProfit = Max( MaxYrProfit, Chg );
    MinYrProfit = Min( MinYrProfit, Chg );

    if( FirstYr == 0 ) FirstYr = yr[ i - 1 ];
    LastYr = yr[ i ];

    LastYrValue = eq[ i ];
  }

  if( MonChange [ i ] || i == BarCount - 1 )
  {
    mon = mo[ i - 1 ];

    Chg = 100 * ( -1 + eq[ i ] / LastMoValue );

    VarSet("ChgMon" + yr[ i - 1 ] + "-" + mon, Chg );
    VarSet("SumChgMon"+ mon, Chg + Nz( VarGet("SumChgMon"+ mon ) ) );
    VarSet("SumMon" + mon, 1 + Nz( VarGet("SumMon"+ mon ) ) );
 
    MaxMoProfit = Max( MaxMoProfit, Chg );
    MinMoProfit = Min( MinMoProfit, Chg );

    LastMoValue = eq[ i ];
  }
}

/////////////////////////////////////////////////
// Drawing code & helper functions
////////////////////////////////////////////////

GfxSetOverlayMode( 2 );

CellHeight = (Status("pxheight")-1)/(LastYr - FirstYr + 3 ); 
CellWidth = (Status("pxwidth")-1)/14; 
GfxSelectFont( "Tahoma", 8.5 ); 

GfxSetBkMode( 1 );

function PrintInCell( string, row, Col ) 
{
 Color =  ColorRGB( IIf( row == 0 || col == 0 || col == 13, 220, 255 ), 255, IIf( row % 2, 255, 220 ) );
 GfxSelectSolidBrush( Color   );
 GfxRectangle( Col * CellWidth, 
                    row * CellHeight, (Col + 1 ) * CellWidth + 1, 
                    (row + 1 ) * CellHeight  + 1); 
 GfxDrawText( string, Col * CellWidth + 1, 
                    row * CellHeight + 1, 
                    (Col + 1 ) * CellWidth, (row + 1 ) * CellHeight, 32+5 ); 
} 

YOffset = 25;
XOffset = 15;

function DrawBar( text, bar, numbars, y, Miny, Maxy )
{
 BarWidth = (Status("pxwidth") - 4 * XOffset )/( numbars + 1 ); 
 BarHeight = Status("pxheight") - 2 * YOffset;
 relpos = ( y - Miny ) / (Maxy - Miny );

 xp = XOffset + ( bar + 0.5 ) * BarWidth;
 yp = YOffset + BarHeight * ( 1 - relpos );
 xe = XOffset + ( bar + 1 ) * BarWidth;
 ye = YOffset + BarHeight * ( 1 - ( -miny )/( maxy - miny ) );
  
 if( y > 0 )
 {
 GfxGradientRect( xp, yp, 
                  xe , ye,
                  ColorHSB( 70, 255 * relpos, 255 ), ColorHSB( 70, 20, 255 ) ); 
 }
 else
 {
 GfxGradientRect( xp, ye, 
                  xe , yp,
                  ColorHSB( 0, 20, 255 ), ColorHSB( 0, 255 * ( 1 - relpos ), 255 ) ); 
 }
 GfxTextOut( text, xp, ye );
 GfxTextOut( StrFormat("%.2f", y ), xp, yp );
}    

function DrawLevels( Miny, Maxy )
{
  range = Maxy - Miny;

  grid = 100;
  if( range < 10 ) grid = 1;
  else 
  if( range < 20 ) grid = 2;
  else 
  if( range < 50 ) grid = 5;
  else 
  if( range < 100 ) grid = 10;
  else 
  if( range < 200 ) grid = 20;
  else 
  if( range < 500 ) grid = 50;

  _TRACE("grid = "+grid +" range "+range );
  
  width = Status("pxwidth") - 4 * XOffset;
  height = Status("pxheight") - 2 * YOffset;

  GfxSelectPen( colorBlack, 1, 2 );
  for( y = grid * ceil( Miny / grid ); y <= grid * floor( Maxy / grid ); y += grid )
  {
    yp =  YOffset + Height * ( 1 -  ( y - Miny ) / (Maxy - Miny ) );

    GfxMoveTo( XOffset, yp );
    GfxLineTo( XOffset + width , yp );
    GfxTextOut( ""+ y, XOffset + 2 + width, yp );
  }

  GfxSelectPen( colorBlack, 1, 0 );
  GfxMoveTo( XOffset, YOffset );
  GfxLineTo( XOffset + width, YOffset );
  GfxLineTo( XOffset + width, YOffset + Height );
  GfxLineTo( XOffset , YOffset + Height );
  GfxLineTo( XOffset , YOffset );
}

MonthNames = "Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec";

function DisplayProfitTable( )
{
 Header = "Year,"+MonthNames+",Yr%";
 for( Col = 0; (Colname = StrExtract( Header, Col ) ) != ""; Col++ )
 {
  PrintInCell( ColName, 0, Col );
 }

 Row = 1;
 for( y = FirstYr; y <= LastYr; y++ )
 {
  PrintInCell( StrFormat("%g", y ), Row, 0 ); 
  PrintInCell( StrFormat("%.1f%%", VarGet("ChgYear" + y ) ), Row, 13 ); 
  for( m = 1; m <= 12; m++ )
  { 
   Chg = VarGet("ChgMon" + y + "-" + m);
   if( Chg ) 
     PrintInCell( StrFormat("%.1f%%", Chg ), Row, m );
   else
     PrintInCell( "N/A", Row, m );
  }
  Row++;
 } 

 PrintInCell("Avg", Row, 0 );
 for( m = 1; m <= 12; m++ )
 { 
   PrintInCell( StrFormat("%.1f%%",  Nz( VarGet("SumChgMon" + m)/VarGet("SumMon" + m ) ) ), Row, m );
 }

}

function DisplayYearlyProfits()
{
 Bar = 0;
 for( y = FirstYr; y <= LastYr; y++ )
 {
   Chg = VarGet("ChgYear" + y );
   DrawBar( ""+y, Bar++, ( LastYr - FirstYr + 1 ), Chg, MinYrProfit, MaxYrProfit );
 }
 GfxTextOut("Yearly % Profit chart", 10, 10 );

 DrawLevels( MinYrProfit, MaxYrProfit ); 
}

function DisplayMonthlyProfits()
{
 Bar = 0;
 
 MinAvgProf = MaxAvgProf = 0;
 for( y = 1; y <= 12; y++ )
 {
   Chg = VarGet("SumChgMon" + y ) / VarGet("SumMon" + y );
   MinAvgProf = Min( MinAvgProf, Chg );
   MaxAvgProf = Max( MaxAvgProf, Chg );
 }

 for( y = 1; y <= 12; y++ )
 {
   Chg = VarGet("SumChgMon" + y ) / VarGet("SumMon" + y );
   DrawBar( StrExtract(MonthNames, y-1 ), Bar++, 13, Chg, MinAvgProf , MaxAvgProf );
 }
 GfxTextOut("Avg. Monthly % Profit chart", 10, 10 );

 DrawLevels( MinAvgProf , MaxAvgProf ); 
}

///////////////////////////
// This function checks if currently selected symbol
// is portfolio equity
//////////////////////////
function CheckSymbol()
{
 if( Name() != "~~~EQUITY" )
 {
  GfxSelectFont( "Tahoma", 20 ); 
  GfxSetBkMode( 2 );
  GfxTextOut("For accurate results switch to ~~~EQUITY symbol", 10, 10 );
 }
}

////////////////////////////
// Main program - chart type switch
////////////////////////////
type = ParamList("Chart Type", "Profit Table|Yearly Profits|Avg. Monthly Profits", 0 );

switch( type )
{
 case "Profit Table": 
         DisplayProfitTable();  
         break;
 case "Yearly Profits": 
         DisplayYearlyProfits();
         break;
 case "Avg. Monthly Profits": 
         DisplayMonthlyProfits();
         break;
}

CheckSymbol();