/* 

  Substitution cipher (Rosetta code) in Picat.

  http://rosettacode.org/wiki/Substitution_cipher
  """
  
  """

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

*/

% import v3_utils.
% import util.
% import cp.


main => go.

go ?=>
  S = "The quick brown fox jumped over the lazy dog",
  cypher(S,E),
  println(E),

  cypher(D, E),
  println(D),

  S == D,
  println(ok),
  
  nl.
go => true.

% {{trans|Prolog)
cypher(O, S) :-
  nonvar(O),
  var(S),
  sub_chars(O,S).
cypher(O, S) :-
  nonvar(S),
  var(O),
  sub_chars(O,S).

base("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz ").
subs("VsciBjedgrzyHalvXZKtUPumGfIwJxqOCFRApnDhQWob LkESYMTN").
 
sub_chars(Original,Subbed) :-
  base(Base),
  subs(Subs),
  maplist($sub_char(Base,Subs),Original,Subbed).

sub_char([Co|_],[Cs|_],Co,Cs) :- !.
sub_char([_|To],[_|Ts], Co, Cs) :- sub_char(To,Ts,Co,Cs).

maplist(Goal, List1, List2) :-
    maplist_(List1, List2, Goal).

maplist_([], X, _) :- X = []. 
maplist_([Elem1|Tail1],
         [Elem2|Tail2],
         Goal) :-
    call(Goal, Elem1, Elem2),
    maplist_(Tail1, Tail2, Goal).


% Using maps
% Using the same base/1 and subs/1 as above
go2 =>
  S = "The quick brown fox jumped over the lazy dog!!!",
  E = encrypt(S),
  println(E),
  D = decrypt(E),
  println(D),

  % checking
  D == S,
  println(ok),
  nl.

encrypt(L) = [EncryptMap.get(C,C) : C in L] =>
  base(Base),
  subs(Subs),
  EncryptMap = new_map([B=S : {B,S} in zip(Base,Subs)]).

decrypt(L) = [DecryptMap.get(C,C) : C in L] =>
  base(Base),
  subs(Subs),
  DecryptMap = new_map([S=B : {B,S} in zip(Base,Subs)]).