\ sticks.fs
\ After "23 Matches" in Ahl, _Basic Computer Games_
\ Ahl attributes the original to Bob Albrecht

cr .( Reading sticks.fs ... )

\ Random number generator
include random.fs

\ Rules of the game
: rules ( -- )
cr ." Sticks"
cr
cr ." The game starts with 23 sticks. "
    ." By turns, you and Forth take"
cr ." from 1 to 3 sticks. "
    ." Whoever takes the last stick loses."
cr
cr ." You take sticks by entering: n STICKS"
cr ." where n is 1, 2, or 3"
cr ;

\ Display sticks
: .sticks ( n -- ) 0 ?do ." |" loop ;

\ Report remaining sticks
: left ( sticks taken -- left ) - dup cr .sticks space dup . ." left." ;

\ The fates of Forth
: you-win ( sticks -- ) drop ." You win! " ;

: forth-wins ( sticks -- ) ." Forth took " 1- . cr ." 1 left - sorry!" ;

: 4-play ( sticks -- sticks left ) ." Forth took " 3 choose 1+ dup . left ;

\ My esteemed opponent
: computer ( sticks -- left| )
   cr
   dup 1 = if you-win else
   dup 5 < if forth-wins else
         4-play
      then then ;

\ First play
: coin ( 23 -- n )
   2 choose
   cr ." A coin has been flipped: "
   if ." Heads, Forth is first." computer
   else ." Tails, you start."
   then ;

\ Confine n between min and max
: clamp ( n min max -- n ) rot min max ;

\ May take between 1 and 3 sticks, leaving at least 1
: legal ( sticks try -- sticks taken ) over 1- 3 min 1 swap clamp ;

\ My play
: programmer ( sticks try -- left ) legal left ;

\ 1 Round
: sticks ( sticks try -- left| ) programmer computer ;

\ Alias for STICKS
: stick ( sticks try -- left| ) sticks ;

: game ( -- ) rules 23 dup cr .sticks randomize coin ;

cr .( Ready. To play, enter: GAME)