/* 

  Wordle solver in Picat.

  This is a smaller version of Wordle solver than wordle.pi
  just including the solver, not all the other experiments.

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

*/

main => go.

go ?=>

  wordle("...n.",["","","","",""],"slat"),
  % ->  [crone,brine,crony,briny,prone,corny,borne,prune,drone,phone,brink,phony,bound,pound,grind,frond,found,bring,drink,being,whine,fiend,chunk,whiny,prong,mound,horny,urine,round,drunk,irony,doing,wound,hound,opine,wring,rhino,downy,wrong,wrung,ebony,ovine,dying,young,owing,eying,vying,eking,penne,penny,bunny,funny,going,ninny,ozone,icing]

  % wordle(".r.n.",["","","","",""],"slatcoe"),
  % -> [briny,brink,grind,bring,drink,drunk,wring,wrung]
  
  % wordle("...st",["s","","","",""],"flancre"),
  % -> [moist,hoist,ghost,midst,joist,joust,boost,twist]
  
  % wordle(".r.n.",["","","","",""],"slatcoe"),
  % -> [briny,brink,grind,bring,drink,drunk,wring,wrung]
  
  % wordle(".r.n.",["","","","",""],"slatcoebiy"),
  % -> [drunk,wrung]
  
  % wordle(".run.",["","","","",""],"slatcoebiydk"),
  % ->  [wrung]

  % wordle(".l...",["","","a","","t"],"sn"),
  % -> [alter,ultra,altar]

  % wordle(".....",["","","","",""],""),
  % -> All words...
  
  nl.
go => true.


%
%   wordle(Words,CorrectPos,CorrectChar,NotInWord)
%    - Words: the wordlist/candidates
%    - CorrectPos: correct character in correct position,
%      Example: n is in position 4 and t is in position 5: "...nt": 
%    - CorrectChar: correct character but in wrong position.
%      Example: a is not in position 1, l is not in position 2: ["a","l","","",""]
%    - NotInWord: characters not in word.
%      Example: s, a, and t are not in the word: "sat"
%
wordle(CorrectPos, CorrectChar, NotInWord) =>
  N = 5,
  % File = "unixdict.txt", % 3161 5 letter words. Is this the smallest word list?
  File = "wordle_small.txt", % 2314 words
  % File = "wordle_large.txt", % 12971 words
  % File = "eng_dict.txt", % 9336 5 letter words
  % File = "words_lower.txt", % 21830 English 5 letter words 

  Words = [W : W in read_file_lines(File), length(W) == N], 
  NumWords = Words.len,
  println(numWordsInDict=NumWords),

  wordle(Words, CorrectPos, CorrectChar, NotInWord,[],Candidates),
  println(candidates=Candidates),
  println(len=Candidates.len),
  (Candidates != [] -> println(suggestion=Candidates.first()) ; true),
  
  nl.

%
% The main engine:
% Loop through all words and check if they are in the scope.
% 
wordle([], _CorrectPos, _CorrectChar, _NotInWord,AllWords,Sorted) :-
  sort_candidates(AllWords,Sorted).
wordle([Word|Words], CorrectPos, CorrectChar, NotInWord, AllWords0,AllWords) :-
   ( (correct_pos(Word,CorrectPos),
      correct_char(Word,Word,CorrectChar),
      not_in_word(Word,NotInWord)) ->
       AllWords1 = AllWords0 ++ [Word],
       wordle(Words, CorrectPos, CorrectChar, NotInWord, AllWords1,AllWords)
    ;
     wordle(Words, CorrectPos, CorrectChar, NotInWord, AllWords0,AllWords)
   ).

%
% Correct position.
%
% Ensure that all chars != "." are in correct position.
% 
correct_pos([],[]).
correct_pos([C|Cs],[C2|CorrectPos]) :-
  (C == C2 ; C2 == '.'),
  correct_pos(Cs,CorrectPos).

%
% Correct char.
% Ensure that the character is in the word, but not
% in the given position.
% 
correct_char(_,_,[]).
correct_char(Word,[W|WordRest],[CC|CorrectChars]) :-
  correct_char_(Word,W,CC), % check each character in CorrectChars
  correct_char(Word,WordRest,CorrectChars).

%
% Helper function for correct_char/2.
% Check each character in CorrectChar against each
% character in the candidate word.
%
correct_char_(_,_,[]).
correct_char_(Word,W,[C|CorrectChars]) :-
  W != C,
  membchk(C,Word),
  correct_char_(Word,W,CorrectChars).

%
% Characters not in word.
% Ensure that the given chararacter are not in the
% candidate word.
% 
not_in_word(_Word,[]).
not_in_word(Word,[C|Cs]) :-
  not membchk(C,Word),
  not_in_word(Word,Cs).

%
% Sort the candidates.
%
sort_candidates(Candidates,Sorted) =>
  % The probability order for each position in the word.
  % Reversed and with missing chars.
  % See wordle.pi (go2/0) for the method to get this.
  Alphas = ["zyjkquinovhewlrmdgfaptbcsx",
            "zqfkgxvbsdymcwptnhulieroaj",
            "qjhzkxfwyvcbpmgdstlnrueoia",
            "xyzbwhfvpkmdguotcrilasnejq",
            "uzxbiwfcsgmpoakdnhlrtyejqv"
  ],
  score_words(Candidates,Alphas,[],Scores),
  Sorted = [W : [_S=W] in Scores.sort_down].

%
% Score all words
% 
score_words([],_Alpha,Scores,Scores).
score_words([Word|Words],Alphas,Scores0,[[Score=Word]|Scores]) :-
  % We prefer words with distinct characters
  Score1 = cond(Word.len==Word.remove_dups.len,100,0),
  score_word(Word,Alphas,Score1,Score),
  score_words(Words,Alphas,Scores0,Scores).

% Score each character in a word
score_word([],_Alpha,Score,Score).
score_word([C|Cs],[Alpha|Alphas],Score0,Score) :-
   nth(N,Alpha,C), % find the position of this character
   S = N / 2,
   Score1 = Score0 + S,
   score_word(Cs,Alphas,Score1,Score).

% Print an empty board
empty() =>
  println("wordle(\".....\",[\"\",\"\",\"\",\"\",\"\"],\"\")").