#!/usr/bin/wish

proc jump {} {
    global n_blank ans cur_focus cur_show
    if {"[.e{$cur_show} cget -state]" != "disabled"} {
	.l{$cur_show} configure -text ""
    }

    set r [expr int(rand()*$n_blank)]
    for {set i 0} {$i < $n_blank} {incr i} {
	set cur_focus [expr ($i+$r) % $n_blank]
	if { "[.e{$cur_focus} cget -state]" != "disabled" } break
    }
    if { $i >= $n_blank } {
	puts "congratulations!"
	exit
    }
    focus .e{$cur_focus}

    set r [expr int(rand()*$n_blank)]
    for {set i 0} {$i < $n_blank} {incr i} {
	set cur_show [expr ($i+$r) % $n_blank]
	if { "[.e{$cur_show} cget -state]" != "disabled" } break
    }
    .l{$cur_show} configure -text [lindex $ans $cur_show]
    after 2000 jump
}

proc check {i} {
    global ans
    if {[.e{$i} get] != [lindex $ans $i]} return
    .l{$i} configure -bg red -text [lindex $ans $i]
    .e{$i} configure -bg red -state disabled
}

set n_digit 4
set n_blank 5
set ans {}
for {set i 0} {$i < $n_blank} {incr i} {
    entry .e{$i} -width $n_digit -takefocus 0
    label .l{$i} -width $n_digit -bd 2 -relief ridge
    grid .e{$i} .l{$i}
    bind .e{$i} <KeyRelease> "check $i"
    lappend ans [expr int(rand()*pow(10,$n_digit))]
}

set cur_show 0
jump