:- use_module(library(rdf)).
:- use_module(library(rdf_db)).

:-	rdf_register_ns(daml,'http://www.daml.org/2001/03/daml+oil#').
:-	rdf_register_ns(foaf,'http://xmlns.com/foaf/0.1/').
:-	rdf_register_ns(space,'http://frot.org/space/0.1/').
:-      rdf_register_ns(geo,'http://www.w3.org/2003/01/geo/wgs84_pos/').
:-	rdf_register_ns(dc,'http://purl.org/dc/1.0/').
:-      rdf_register_ns(bot,'http://frot.org/bot/bot#').
:-      rdf_register_ns('near','http://frot.org/space/near').

london:- rdf_load('/home/jo/london.rdf').
tube:- rdf_load('/home/jo/spacenamespace/prolog_tube.rdf').

connects(X,Y,S1,S2):-
    spaces(X,Y,S1,S2),
    rdf(S1,space:connects,S2).

connects_subject(X,Y):-
    rdf(X,space:connects,literal(Y)).

connect(X,Y,A,B):-
    spaces(X,Y,S1,S2),
    rdf_assert(S1,space:connects,literal(S2)),
    reify(S1,space:connects,literal(S2),A),
    rdf_assert(S2,space:connects,literal(S1)),
    reify(S2,space:connects,literal(S1),B).

space(X,Y) :- rdf(Y,space:name,literal(X)).

path(X,Y,P,[Y|P]):- X \== Y,connects(X,Y,S,S2).

path(X,Z,P,Path):-
    X \== Z,
    connects(X,Y,S1,S2),
    Y \== Z,
    \+ member(Y,P),
    path(Y,Z,[Y|P],Path).

% bigger(X,nil).
% bigger(X,[Y,A]):- geq(X,Y),bigger(X,A).
% geq(X,Y) :- X >= Y.
% exists(X).

tubeline(Name,L) :-
    tubeline(Name,X,L),
    reify(X,space:connects,literal(L),A).

do_tube :-
    tubeline(X,Y).

tubeline(Name,X,L) :-
    tube(Name,X),
    connects_subject(X,L).

tube(Name,Y):-
    rdf(Y,space:name,literal(Name)),
    rdf(Y,space:type,literal('Tube Line')).

list(X,Stn,List) :-
    connects(X,Stn,Id1,Id2),
    append(List,[Id1,Id2],List),
    list(X,Stn,List).

spaces(X,Y,S1,S2) :- 
    space(X,S1),
    space(Y,S2),
    not(X==Y).
 
route(X,Y,Path):- 
    X \== Y,
    append([X],[],R),
    path(X,Y,R,N),
    reverse(N,Path).

is_near(X,Y,Z):-
    space(Y,S1),
    space(Z,S2),
    rdf_assert(S1,X,S2).

near(X,Y,Z):-
    spaces(Y,Z,S1,S2),
    rdf(S1,X,literal(S2)).

create_space(X) :-
    gensym(X,Y),
    rdf_assert(Y,space:name,literal(X)).

reify(X,Y,Z,N) :-
    gensym(X,N),
    rdf_assert(N,rdf:subject,X),
    rdf_assert(N,rdf:predicate,Y),
    rdf_assert(N,rdf:object,Z).

reified(X,Y) :-
    append([],rdf(X,rdf:subject,A),[Al]),
    append(A1,rdf(X,rdf:predicate,B),[Bl]),
    append(B1,rdf(X,rdf:subject,A),[Y]).
    
    
:- create_space('t1').
:- create_space('t2').
:- create_space('t3').
:- create_space('t4').
:- connect('t1','t2',A,B).
:- connect('t3','t2',A,B).
:- connect('t3','t4',A,B).

:- trace(path/4).
:- trace(member/2).