% am reprezentat un nod ca o pereche între caracter și lista de noduri
% copii; rădăcina are literalul gol pe prima poziție
% am reprezentat un cuvânt ca o listă de literali

emptyTrie(('', [])).


% vezi mai multe comentarii în implementarea în Haskell

% varianta A

canBeFollowedBy(Letter, (_, Children)) :-
    findall(Char, member((Char, _), Children), Chars),
    member(Letter, Chars).

getSubtreeFor(Letter, (_, Children), Child) :-
    member(Child, Children),
    Child = (Letter, _).

addWord([], Node, Node).
addWord([C|Word], Node, Result) :-
    canBeFollowedBy(C, Node), !,
    Node = (NodeChar, Children),
    findall(Child, (member(Child, Children), Child = (A, _), A \= C), List1),
    getSubtreeFor(C, Node, Selected),
    addWord(Word, Selected, SelectedResult),
    List = [SelectedResult | List1],
    Result = (NodeChar, List).
addWord([C|Word], (Char, Children), Result) :-
    addWord(Word, (C, []), NewNode),
    Result = (Char, [NewNode|Children]).


% varianta B

countWords((_, []), 1) :- !.
countWords((_, Children), Count) :-
    findall(C, (member(Child, Children), countWords(Child, C)), Counts),
    sum_list(Counts, Count).

printWords(('', Children), Result) :- !,
    findall(Print, (member(Child, Children), printWords(Child, Print)), Prints),
    append(Prints, Result).
printWords((Char, []), [[Char]]) :- !.
printWords((Char, Children), Result) :-
    findall(Print, (member(Child, Children), printWords(Child, Print)), Prints),
    append(Prints, OneList),
    findall(Word, (member(W, OneList), Word = [Char|W]), Result).

predict([], Node, Result) :- !, printWords(Node, Result).
predict(Prefix, ('', Children), Result) :- !,
    member(Child, Children),
    predict(Prefix, Child, Result).
predict([Char|Rest], (Char, Children), Result) :-
    findall(Res,
           (   member(Child, Children),
               predict(Rest, Child, Predictions),
               findall(Word, (member(W, Predictions), Word = [Char|W]), Res)
           ),
            Results),
    append(Results, Result).





% altele

addWords([], Trie) :- emptyTrie(Trie).
addWords([Word|Words], Trie) :- addWords(Words, Trie1), addWord(Word, Trie1, Trie).

%  addWords([[m,i,c,a], [m,i,n,a], [m,a,m,a], [m,e,l,c], [m,i,c,i]],
% Trie),