package require Tk
package require nx::trait

 ##############################################################################
 # Trait ListUtils
 #
 # Some list utilities, not part of a package we can require here.
 ##############################################################################

 nx::Trait create ::nx::trait::listUtils {

   :protected method lpick {list} {
     # return a random entry from a given list
     lindex $list [expr {int(rand()*[llength $list])}]
   }
   :protected method lremove {listName what} {
     # remove a list element referenced by the elements value
     :upvar $listName list
     set pos  [lsearch $list $what]
     set list [lreplace $list $pos $pos]
   }
 }

 ##############################################################################
 # Class Horse
 #
 # This class defines the logic, how and where a single horse and
 # jockey are drawn. The painting of the horse happens just at startup
 # time, later the horses are moved via their tags.
 ##############################################################################

 nx::Class create Horse {
   :property name:required      ;# name is the external name of the horse
   :property tag:required       ;# tag is an internal id
   :property canvas:required    ;# the canvas, on which the horse is drawn
   :property n:integer,required ;# the position on the canvas

   :require trait nx::trait::callback
   :require trait nx::trait::listUtils

   :method draw {x y} {
     set hide [:lpick {black brown white gray brown3 brown4}]
     set c1 [:lpick {red yellow blue purple pink green}]
     set c2 [:lpick {red yellow blue purple pink green}]
     ${:canvas} create oval 0 -1 18 4 -fill $hide -outline $hide -tag ${:tag}
     ${:canvas} create line 1 12 3 0 5 12 -fill $hide -tag ${:tag} -width 2
     ${:canvas} create line 15 12 17 0 19 12 -fill $hide -tag ${:tag} -width 2
     ${:canvas} create line 16 0 20 -7 24 -5 -fill $hide -tag ${:tag} -width 3
     # Jockey:
     ${:canvas} create line 9 4 11 1 7 -1 -fill $c1 -width 2 -tag ${:tag}
     ${:canvas} create line 7 -2 10 -6 15 -3 -fill $c2 -width 2 -tag ${:tag}
     ${:canvas} create oval 9 -7 12 -10 -fill orange -outline orange -tag ${:tag}
     ${:canvas} move ${:tag} $x $y
   }

   :method init {} {
     set w [entry ${:canvas}.e${:n} -textvar [:bindvar name] -width 7 -bg green3]
     ${:canvas} create window 5 [expr {${:n}*30+5}] -window $w -anchor nw
     :draw 70 [expr {${:n}*30+14}]
   }
 }

 ##############################################################################
 # Class HorseGame
 #
 # Defines the main canvas of the Game and contains the logic of
 # starting, resetting etc.
 ##############################################################################

 nx::Class create HorseGame {
   :property {bg1 green4}   ;# background color of the canvas
   :property {bg2 green3}   ;# background color of the result label
   :property {width 750}    ;# width of the canvas
   :property {height 330}   ;# height of the canvas
   :property {horses}       ;# a list of horse names participating in the game

   :require trait nx::trait::callback
   :require trait nx::trait::listUtils

   :method init {} {
     #
     # create the canvas
     #
     set :canvas [canvas .c -bg ${:bg1} -width ${:width} -height ${:height}]
     pack ${:canvas}
     #
     # create the Horses
     #
     set n 0
     foreach name ${:horses} {
       set h [::Horse create horse$n -name $name -canvas ${:canvas} -n $n -tag horse$n]
       lappend :tags horse$n
       incr n
     }

     # finish line
     set w [expr {${:width} - 20}]
     ${:canvas} create line $w 0 $w ${:height} -fill white -tag finish

     # start button
     button ${:canvas}.button -text Start -pady 0 -width 0 \
         -command [:callback start ${:tags}]
     ${:canvas} create window 5 [expr {$n*30}] -window ${:canvas}.button -anchor nw

     # label for the results
     label ${:canvas}.winners -textvar [:bindvar winners] -bg ${:bg2} -width 80
     ${:canvas} create window 70 [expr {$n*30}] -window ${:canvas}.winners -anchor nw
   }

   :public method start {running} {
     #
     # When the "Start" button is pressed, we turn this button into a
     # "Reset" button and the horse race starts. We stop, when more
     # than two horses pass the finish line.
     #
     ${:canvas}.button config -text Reset -command [:callback reset]
     set :winners {}
     set finish [expr {[lindex [${:canvas} bbox finish] 2]+10}]
     while {[llength ${:winners}]<3} {
       set this [:lpick $running]
       ${:canvas} move $this [:lpick {0 1 2 3}] 0
       update
       if {[lindex [${:canvas} bbox $this] 2] > $finish} {
         lappend :winners [expr {[llength ${:winners}]+1}]:[$this cget -name]
         :lremove running $this
       }
     }
   }

   :public method reset {} {
     #
     # When the "Reset" button is pressed, we switch back to the start
     # configuration, the horses come back to the start.
     #
     ${:canvas}.button config -text Start -command [:callback start ${:tags}]
     foreach tag ${:tags} {
       set x [lindex [${:canvas} bbox $tag] 0]
       ${:canvas} move $tag [expr {70-$x}] 0
     }
   }
 }

 #
 # everything is defined, create the game
 #
 bind . <space> {exec wish $argv0 &; exit}
 HorseGame new -horses {Blaise NX Animal Ada Alan XOTcl Grace itcl John Linus}