/* 

  Eliza in Picat.

  ' Analogy program.

  This Picat version is based on the Prolog code from
  Leon S. Sterling: "The Art of Prolog", 2nd edition,
  page 273ff

  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


% import util.
% import cp.


main => go.


/*
  Here is a sample dialog,
  from The Art of Prolog, figure 14.6, page 273.
  (Don't forget the trailing ".")

  
   Picat> cl(eliza), eliza
   [i, am, unhappy].
   How long have you been unhappy ?
   [six, months, can, you, help, me].
   What makes you think I help you ?
   [you, make, me, think, of, my, father, and, my, brother].
   Please you tell me more about father
   [I, like, teasing, father].
   Does anyone else in your family like teasing father ?
   [no, only, me].
   Please go on .
   [bye].
   [Goodbye. I hope I have helped you]


*/

go => 
  eliza,
  nl.


go2 => 
  eliza([i, am, unhappy]),
  nl.


eliza ?=> 
   Input = read_term(), eliza(Input).
eliza([bye]) ?=>
   println(['Goodbye. I hope I have helped you']).

eliza(Input) =>
   pattern(Stimulus,Response),
   match(Stimulus,Table,Input),
   match(Response,Table,Output),
   reply(Output),
   Input1 = read_term(),
   eliza(Input1).

reply(HT) ?=> 
   HT=[Head|Tail],
   print(Head), print(' '), 
   reply(Tail).
reply([]) => nl.

pattern(Stimulus,Response) ?=> 
    Stimulus = [i,am,1],
    Response = ['How',long,have,you,been,1,?].
pattern(Stimulus, Response) ?=> 
    Stimulus = [1,you,2,me],
    Response = ['What',makes,you,think,'I',2,you,?].
pattern(Stimulus, Response) ?=> 
    Stimulus = [i,like,1],
    Response = ['Does',anyone,else,in,your,family,like,1,?].
pattern(Stimulus, Response) ?=> 
    Stimulus = [i,feel,1],
    Response = ['Do',you,often,feel,that,way,?].
pattern(Stimulus, Response) ?=> 
    Stimulus = [1,X,2],
    Response = ['Please',you,tell,me,more,about,X],
    important(X).
pattern(Stimulus, Response) => 
    Stimulus = [1],
    Response = ['Please',go,on,'.'].

index(-)
important(father).
important(mother).
important(sister).
important(brother).
important(son).
important(daughter).

match(NPattern,Table,Target) ?=>
   NPattern = [N|Pattern],
   integer(N),
   lookup1(N,Table,LeftTarget),
   append(LeftTarget,RightTarget,Target),
   match(Pattern,Table,RightTarget).
match(WordPattern,Table,WordTarget) ?=>
   WordPattern = [Word|Pattern],
   WordTarget = [Word|Target],
   atom(Word),
   match(Pattern,Table,Target).
match([],_Table,Target) => Target = [].


lookup1(X,XV,V) ?=>
   XV = [(X,V)|_XVs].
lookup1(X,XV,V) => 
   XV = [(X1,_V1)|XVs],
   X != X1, 
   lookup1(X,XVs,V).