Bollinger Band ZigZag Indicator 4 for Amibroker (AFL)

_SECTION_BEGIN("Bollinger Band ZigZag Indicator");
function ParamOptimize( description, defaultVal, minv, maxv, step )
    { 
    return Optimize(description, Param(description,defaultVal, minv, maxv, step ), minv, maxv, step ); 
    }

BlankBars = 10; // Set to the number set in preferences

Buy = Sell = Short = Cover = Pos = 0;
Periods = ParamOptimize( "Periods", 3, 3, 30, 1 );
Width = ParamOptimize( "Width", 1, 0, 5, 0.1 );
BBTOp = BBandTop( H, Periods, Width ); // Note H is used instead of the tradional C
BBBot = BBandBot( L, Periods, Width ); // Note L is used instead of the tradional C

Plot( BBTop, "BBTop", colorBlue, styleLine );
Plot( BBBOt, "BBBot", colorBlue, styleLine );
Plot( C, "", 1, 128 );

BI = BarIndex();
start = Status( "firstvisiblebarindex" ) - BI[0] - BlankBars;
end     = Status( "lastvisiblebarindex" ) - BI[0] - BlankBars;
LBI = LastValue( BarIndex() );

for ( b = LBI; b > Periods; b-- )
{
    if ( L[b] <= BBBot[b] AND pos <= 0 )
    {
        pos = 1;
        Buy[b] = True;
        BuyPrice[b] = BBBot[b];
    }
    else
        if ( H[b] >= BBTop[b] AND Pos >= 0 )
        {
            Pos = -1;
            Sell[b] = True;
            SellPrice[b] = BBTop[b];
        }
}

Short = Sell;
ShortPrice = SellPrice;

Cover = Buy;
CoverPrice = BuyPrice;

Eq = Equity( 1 );

if ( ParamToggle( "Equity", "HIDE|SHOW", 0 ) )
    Plot( Eq, "", colorYellow, 1 | styleOwnScale );

ShowTriangles = ParamToggle( "Arrows", "HIDE|SHOW", 1 );

if ( showTriangles )
{
    PlotShapes( IIf( Buy,     shapeSmallUpTriangle, shapeNone ), 5, 0, BuyPrice, 0 );
    PlotShapes( IIf( Sell,    shapeHollowDownTriangle, shapeNone ), 4, 0, SellPrice, 0 );
    PlotShapes( IIf( Cover, shapeHollowUpTriangle, shapeNone ), 5, 0, CoverPrice, 0 );
    PlotShapes( IIf( Short, shapeSmallDownTriangle, shapeNone ), 4, 0, ShortPrice, 0 );
}

if ( ParamToggle( "Trade Lines", "HIDE|SHOW", 0 ) )
{
    Sig = Buy OR Short;
    signum = Cum( Sig );
    y0 = 0;
    y1 = C[0];
    TPrice = C;
    Shortcolor = LongColor = colorWhite;

    for ( b = start ;b < end ;b++ )
    {
        if ( Sig[b] )
        {
            x0 = y0;
            x1 = y1;
            y0 = b;

            if ( Buy[b] )
            {
                y1 = BuyPrice[b];
                Color = Shortcolor;
            }
            else
                if ( Short[b] )
                {
                    y1 = ShortPrice[b];
                    Color = Longcolor;
                }

            if( SigNum[b] > 1 ) Plot( LineArray( x0, x1, y0, y1 ), "", Color, 1 | styleThick );
        }
    }
}
_SECTION_END();