% w9_1.pl
% Farmer - wolf - goat - cabbage
program:-
nl,write("All stages of the passage:"),nl,nl,
write("Alek | Bolek | Czarek | Darek | Bagaz | Lodka"),nl,
write("--------------------------------------------------"),
write("--------------------------------------------------"),
passage(position(east,east,east,east,east,boat_left_side),position(west,west,west,west,west,_)),
nl,write("End of all solutions."),nl.

passage(SI,SF):-
nl,
write("position(east, east, east, east, east, boat_left_side)"),
crossing_allowed(SI,SF,[SI],Stages,boat_left_side),nl,nl,
%write(Stages),nl,nl,
%write_crossing_allowed(Stages),
%write(" west | west | west | west | west | west "),
write(" All were safely brought across the river :)"),nl.
passage(_,_).



crossing_allowed(SF,SF,Stages,Stages,_):- !.
crossing_allowed(position(A,B,C,D,L,Boat),SF,Acc,Stages, Location_before):-
	crossing(position(A,B,C,D,L,Boat),position(A1,B1,C1,D1,L1,Boat1),Location_before),
	not(member(position(A1,B1,C1,D1,L1,Boat1),Acc)),nl,
	write(position(A1,B1,C1,D1,L1,Boat1)),
	change_boat_location(Location_before,Location_after),
	crossing_allowed(position(A1,B1,C1,D1,L1,Boat1),SF,[position(A1,B1,C1,D1,L1,Boat1)|Acc],Stages, Location_after).


% all possible crossings
% z lewej na prawo samotnie

crossing(position(X,B,C,D,L,_),position(Y,B,C,D,L,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Alek is crossing alone


crossing(position(A,X,C,D,L,_),position(A,Y,C,D,L,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Bolek is crossing alone


crossing(position(A,B,X,D,L,_),position(A,B,Y,D,L,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Czarek is crossing alone


crossing(position(A,B,C,X,L,_),position(A,B,C,Y,L,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Darek is crossing alone

% z prawej na lewo samotnie

crossing(position(X,B,C,D,L,_),position(Y,B,C,D,L,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Alek is crossing alone


crossing(position(A,X,C,D,L,_),position(A,Y,C,D,L,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Bolek is crossing alone


crossing(position(A,B,X,D,L,_),position(A,B,Y,D,L,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Czarek is crossing alone


crossing(position(A,B,C,X,L,_),position(A,B,C,Y,L,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Darek is crossing alone


% z lewej na prawo niesamotnie

crossing(position(A,X,C,D,X,_),position(A,Y,C,D,Y,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

crossing(position(A,B,X,D,X,_),position(A,B,Y,D,Y,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

crossing(position(A,B,C,X,X,_),position(A,B,C,Y,Y,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

crossing(position(A,B,X,X,L,_),position(A,B,Y,Y,L,boat_right_side),boat_left_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

% z prawej na lewo niesamotnie

crossing(position(A,X,C,D,X,_),position(A,Y,C,D,Y,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

crossing(position(A,B,X,D,X,_),position(A,B,Y,D,Y,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

crossing(position(A,B,C,X,X,_),position(A,B,C,Y,Y,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

crossing(position(A,B,X,X,L,_),position(A,B,Y,Y,L,boat_left_side),boat_right_side):-
	opposite_shores(X,Y). % the Alek is crossing alone

%WSZYSTKIE MOZLIWOSC WYLICZONE



/*
crossing(position(X,X,G,C),position(Y,Y,G,C)):-
	opposite_shores(X,Y). % the farmer is crossing with the wolf

crossing(position(X,W,X,C),position(Y,W,Y,C)):-
	opposite_shores(X,Y). % the farmer is crossing with the goat

crossing(position(X,W,G,X),position(Y,W,G,Y)):-
	opposite_shores(X,Y). % the farmer is crossing with the cabbage*/

/*
dangerous(position(Y,X,X,_)):-
opposite_shores(Y,X). % the wolf can eat the goat
dangerous( position(Y,_,X,X) ):-
opposite_shores(Y,X). % the goat can eat the cabbage*/

opposite_shores(east,west).
opposite_shores(west,east).

change_boat_location(boat_right_side,boat_left_side).
change_boat_location(boat_left_side,boat_right_side).



%writing the consecutive stages
write_crossing_allowed([_]):- !.
write_crossing_allowed([H1,H2|T]):-
	write_crossing_allowed([H2|T]),
	write_crossing(H2,H1).

write_crossing(position(A,B,C,D,L,Boat),position(A,B,C,D,L,Boat)):-!,
	write_all(A,B,C,D,L, Boat).

write_crossing(position(X,X,G,C),position(Y,Y,G,C)):-!,
	write_all(X,Y,X,G,C," The farmer takes the wolf from the ").

write_crossing(position(X,W,X,C),position(Y,W,Y,C)):-!,
	write_all(X,Y,W,X,C," The farmer takes the goat from the ").

write_crossing(position(X,W,G,X),position(Y,W,G,Y)):-!,
	write_all(X,Y,W,G,X," The farmer takes the cabbage from the ").

write_all(A,B,C,D,L,Boat):-
write(" "),write(A),write(" | "),write(B),write(" | "),write(C),write(" | "), write(D),write(L),write(B),nl.