/* Dinner party prolog file */

table([seat(0,_),seat(1,_),seat(2,_),seat(3,_),seat(4,_),seat(5,_),seat(6,_), seat(7,_)]).

dinner(Table) :- table(Table),
        member(seat(0, mrsDavis), Table),
        member(seat(SeatMRDAVIS, mrDavis), Table),
        member(seat(SeatMRBLAKE, mrBlake), Table),
        member(seat(SeatMRSBLAKE, mrsBlake), Table),
        member(seat(SeatMRASTOR, mrAstor), Table),
        member(seat(SeatMRSASTOR, mrsAstor), Table),
        member(seat(SeatMRCRANE, mrCrane), Table),
        member(seat(SeatMRSCRANE, mrsCrane), Table),

        member(seat(1, LDavis), Table),
        member(seat(7, RDavis), Table),

        leftPerson(SeatMRSASTOR,SeatMRBLAKE),
        accrossFrom(SeatMRSCRANE, SeatMRBLAKE),

        seatCounter(P,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, N),

        married(LDavis, RDavis), N =:= 1.

rightPerson(X,Y) :- Y is ((X+7) mod 8).
leftPerson(X,Y)  :- Y is ((X+1) mod 8).
accrossFrom(X,Y) :- X is ((Y+4) mod 8).


seatCounter(P,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, N) :-
        upCount(0,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C0),
        upCount(1,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C1),
        upCount(2,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C2),
        upCount(3,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C3),
        upCount(4,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C4),
        upCount(5,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C5),
        upCount(6,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C6),
        upCount(7,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, C7),

        N is (C0+C1+C2+C3+C4+C5+C6+C7).

upCount(P,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, V) :- betweenMen(P,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE), V is 1.
upCount(P,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE, V) :- not(betweenMen(P,SeatMRDAVIS,SeatMRBLAKE,SeatMRASTOR,SeatMRCRANE)), V is 0.

betweenMen(P, MD,MB,MA,MC) :-
        isBetween(P, MA, MB);
        isBetween(P, MA, MC);
        isBetween(P, MA, MD);

        isBetween(P, MB, MC);
        isBetween(P, MB, MD);

        isBetween(P, MC, MD).

isBetween(A,X,Y) :- rightPerson(X,A), leftPerson(Y,A).
isBetween(A,X,Y) :- rightPerson(Y,A), leftPerson(X,A).

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