/* Gann Swing chart v4 */
/* Last modified 24 Feb 2001 */
/* AFL implementation by */
/* (C)2001 Tomasz Janeczko  */
/* one and two - bar reversal version */

/* Change this to 1 for two-bar mode */
twobarmode = 0;

outsidebar = outside();
insidebar = H <= Ref( H, -1 ) AND L >= Ref( L, -1 ); // built-in inside() works
with < > instead of <= >=

upbar = H > Ref( H, -1 ) AND L >= Ref( L, -1 );
downbar = L < Ref( L, -1 ) AND H <= Ref( H, -1 );

upbar2 = upbar OR ( outsidebar AND ref( downbar, 1 ) ) ;
downbar2 = downbar OR ( outsidebar and ref( upbar, 1 ) );

Poi =  outsidebar AND ref( insidebar, 1 );
Poo =  outsidebar AND ref( outsidebar, 1 );
Pooi = Poo AND ref( insidebar, 2 );
Poio = Poi AND ref( outsidebar, 2 );
Poii =  Poi AND ref( insidebar, 2 );
Pooo = Poo AND ref( outsidebar, 2 );
Poooi = Pooo AND ref( insidebar, 3 );
Pooio = Pooi AND ref( outsidebar, 3 );
Poioo = Poio AND ref( outsidebar, 3 );

upbar3 = upbar2 OR ( Poi AND ref( downbar, 2 ) );
downbar3 = downbar2 OR ( Poi AND ref( upbar, 2 ) );
 
upbar4 = upbar3 OR ( Poo  AND ref( upbar, 2 ) );
downbar4 = downbar3 OR ( Poo  AND ref( downbar, 2 ) );

upbar5 = upbar4 OR  ( Pooi AND ref( upbar, 3 ) );
downbar5 = downbar4 OR  ( Pooi  AND ref( downbar, 3 ) );

upbar6 = upbar5 OR  ( Poio AND ref( upbar, 3 ) );
downbar6 = downbar5 OR  ( Poio  AND ref( downbar, 3 ) );

upbar7 = upbar6 OR  ( Poii AND ref( downbar, 3 ) );
downbar7 = downbar6 OR  ( Poii  AND ref( upbar, 3 ) );

upbar8 = upbar7 OR  ( Pooo AND ref( downbar, 3 ) );
downbar8 = downbar7 OR  ( Pooo AND ref( upbar, 3 ) );

upbar9 = upbar8 OR  ( Poooi AND ref( downbar, 4 ) );
downbar9 = downbar8 OR  (Poooi  AND ref( upbar, 4 ) );

upbar10 = upbar9 OR  ( Pooio AND ref( downbar, 4 ) );
downbar10 = downbar9 OR  (  Pooio AND ref( upbar, 4 ) );

upbar11 = upbar10 OR  (  Poioo AND ref( downbar, 4 ) );
downbar11 = downbar10 OR  ( Poioo  AND ref( upbar, 4 ) );

fupbar = upbar11;
fdownbar = downbar11;
 
// Two-bar mode handling
fupbar = IIF( twobarmode, fupbar AND ref( fupbar, 1 ), fupbar );
fdownbar = IIF( twobarmode, fdownbar AND ref( fdownbar, 1 ), fdownbar );

/* Barcount since most recent up and down swings */
Us = BarsSince( fupbar  ); 
Ds = BarsSince( fdownbar ) ;

Sd1 =IIf( Us==0, 1,  IIf( Ds==0, -1, 0) );

Sd2 = IIf( Sd1 == 1,  IIf( Ref( BarsSince(Sd1==1), -1) > Ref( BarsSince( Sd1 ==
-1), -1), 1, 0), 
          IIf( Sd1 == -1,  IIf( Ref( BarsSince(Sd1==1),-1) < Ref( BarsSince( Sd1
== -1),-1), -1, 0),  0 ) ); 

g0 =  ValueWhen( Sd2, Sd2 ); /* sample and hold non-zero values */

/* shift back one bar, add one dummy swing at the end and shift forward */
/* to ensure proper handling of the last swing */
lastbar = Cum(1) == LastValue( cum(1) );
swinglevel = IIF( g0 == -1, HighestSince( Sd2 == 1, H ), LowestSince( Sd2 == -1,
L ) );
swinglevel = IIF( lastbar, IIF( g0 == -1, LowestSince( Sd2 == -1, L ),
HighestSince( Sd2 == 1, H )), Ref( swinglevel, 1 ) );

/* Gann Swing chart drawn here */
graph1 =  Ref( ValueWhen( Ref( Sd2 != 0, 1 ) or lastbar, swinglevel ,  0 ), -1
);
graph1style = 512+1024;
graphxspace = 5;

/* Colourized price bars drawn here */
/* graph0 = close; */
/* graph0style = 128; */
/* barcolor =  IIF( outsidebar, 1, IIF( downbar, 4, IIF( upbar, 5, 0 ) ) ); */
/* graph0barcolor = ValueWhen( barcolor != 0, barcolor ); */