:-use_module(library(rdf_db)).

nt(S,P,O) :-
	rdf_db(C),
	nt(S,P,O,C).
nt(S,P,O,C) :-
	rdf(S,P,O,C),
	ntriple(S,P,O,Result, _),
	write_ln(hi),
	checklist(write, Result), write_ln('').

ntriple(S,P,O)-->
	bracketed_uri(S), bracketed_uri(P), bracketed_uri(O), ['.']. 

bracketed_uri(Uri) -->
	['<', Uri, '> '].
qname(this) -->
	[this].
qname(literal(L)) -->
      !,['"',L,'"'].
qname(Uri) -->
	{rdf_db:ns(Prefix, Ns),
	 atom_concat(Ns, Lname, Uri), 
	 concat_atom([Prefix,':',Lname], Qname)},
	[Qname].
qname(Uri) -->
	{atom_concat(anon_, Var,Uri)},
	['_:_', Var].
qname(Uri) -->
	[Uri].
n3_context(Context) -->
	{findall([S,P,O], rdf(S,P,O,Context), Triples)},
	n3_statements(Triples).
n3_statements([]) --> [].
n3_statements([[S, 'http://www.w3.org/2000/10/swap/log#implies',O]|Triples]) -->
	['{'], n3_context(S), ['} \n\t'], 
	qname('http://www.w3.org/2000/10/swap/log#implies'),
	[' {'], n3_context(O), ['}.\n\n'],
	n3_statements(Triples).

n3_statements([[S,P,O]|Triples]) -->
	{Triples=[] -> Line_end = []; Line_end = ['\n']},
       	qname(S),[' '], qname(P), [' '], qname(O), ['.'], Line_end,
	n3_statements(Triples).

n3_statement(S,P,O, Indent, Line_end) -->
	Indent, qname(S),[' '], qname(P), [' '], qname(O), ['.'], Line_end.

n3_anon(Triples) -->
	['['],n3_anon_clauses(Triples), ['].\n'].
n3_anon_clauses([[_,P,O]|[]]) -->
	qname(P), [' '], qname(O).
n3_anon_clauses([[_,P,O]|Triples]) -->
	qname(P), [' '], qname(O), [';\n'],
	n3_anon_clauses(Triples).

n3(S,P,O) :-
	rdf_db(C),
	n3(S,P,O,C).

n3(S,P,O,C) :-
	rdf(S,P,O,C),
	n3(S,P,O,C,Result, _).

/*n3(Ant, 'http://www.w3.org/2000/10/swap/log#implies', Cons, C) -->
	{rdf(S1, P1, S
n3(S,P,O,C) -->
	{P = }
	ntriple(S,P,O).*/

%formula(In_context) -->
	

all_triples(Rdf_db, Triple_list) :-
	findall([S,P,O], rdf(S,P,O,Rdf_db), Triple_list).

prefixes(Prefix_list) :-
	setof([Prefix, Uri], rdf_db:ns(Prefix, Uri), Prefix_list).
prefix_block -->
	{prefixes(Prefix_list)},
	prefix_list(Prefix_list).
prefix_list([]) -->
	[].

prefix_list([[Prefix, Uri] | Prefix_list]) -->
	{Prefix = 'default_' -> Pre = ''; Pre = Prefix},
	['@prefix ', Pre, ': '], bracketed_uri(Uri),['.\n'],
	prefix_list(Prefix_list).


%same_S_P(S,P,[[S,P,O]|Init],[[S,P,O]|Result]) :-
%	same_S_P(S,P, Init, Result).
%same_S_P(S,P,[],[]).	

%same_S(S, [[S,P,O]|Init],[[S,P,O]|Result]) :-
%	same_S(S,Init, Result).
%same_S(S, [S, _, _],[S,_,_]).
same_S_prefix(List,Result) :-
	[[S|_]|_] = List,
	same_S_prefix_1(S, List, Result).
same_S_prefix_1(S, [H|T], Result) :-
	[S|_] = H ->
	   (same_S_prefix_1(S, T, R),
	    Result = [H|R]);
	   Result=[].
same_SP_prefix(List, Result) :-
	[[S, P , _]|_] = List,
	same_SP_prefix_1(S,P,List, Result).
same_SP_prefix_1(S,P, [H|T], Result) :-
	[S, P| _] = H ->
	   (same_SP_prefix_1(S,P,T,R),
	    Result=[H|R]);
	   Result=[].
%prefix_of_S([SList, Result).