%%%%%%%%%%%%%%%%%%%%%%%%% Header
:- op(800, fx, (def_object)).
:- op(800, fx, (end_def)).
:- op(401, xfx, (::)).
:- op(600, xfx, (isa)).
%%%%%%%%%%%%%%%%%%%%%%%%% OBJECT.op
'OBJECT'(defines_property(A), B) :-
	defines_prop(B, A).
'OBJECT'(parent(A), B) :-
	B isa A.
%%%%%%%%%%%%%%%%%%%%%%%%% shape.op

% point(x, y) isa object
point(xval(A), B, A, C).
point(yval(A), B, C, A).
point(move(A, B, point(C, D)), E, F, G) :-
	plus(F, A, C),
	plus(G, B, D).

% rectangle(origin, xlength, ylength) isa OBJECT
rectangle(origin(A), B, A, C, D).
rectangle(xlength(A), B, C, A, D).
rectangle(ylength(A), B, C, D, A).
rectangle(move(A, B, rectangle(C, D, E)), F, G, D, E) :-
	G :: move(A, B, C).
rectangle(perimeter(A), B, C, D, E) :-
	A is 2 * (D + E).
rectangle(area(A), B, C, D, E) :-
	A is D * E.
rectangle(rotate(rectangle(A, B, C)), D, E, C, B) :-
	plus(F, C, B),
	plus(G, B, C),
	H is G / 2,
	I is F / 2,
	E :: move(H, I, A).
rectangle(intersection(A, rectangle(point(B, C), D, E)), F, G, H, I) :-
	A :: origin(J),
	J :: xval(K),
	J :: yval(L),
	G :: xval(M),
	G :: yval(N),
	maximum(M, K, B),
	maximum(N, L, C),
	A :: xlength(O),
	A :: ylength(P),
	plus(K, O, Q),
	plus(L, P, R),
	plus(M, H, S),
	plus(N, I, T),
	minimum(S, Q, U),
	minimum(T, R, V),
	plus(B, W, U),
	plus(C, X, V),
	(if W >= 0, X >= 0 then
		D = W,
		E = X
	else
		D = 0,
		E = 0
	).

% square(origin, length) isa rectangle(origin, length, length)
square(perimeter(A), B, C, D) :-
	A is 4 * D.
square(rotate(square(A, B)), C, A, B).
maximum(A, B, C) :-
	(if A > B then
		C = A
	else
		C = B
	).
minimum(A, B, C) :-
	(if A =< B then
		C = A
	else
		C = B
	).


point(A, B) isa object.
rectangle(A, B, C) isa 'OBJECT'.
square(A, B) isa rectangle(A, B, B).

object('OBJECT').
object(point(A, B)).
object(rectangle(A, B, C)).
object(square(A, B)).

defines_prop('OBJECT', defines_property(A)).
defines_prop('OBJECT', parent(A)).
defines_prop(point(A, B), xval(C)).
defines_prop(point(A, B), yval(C)).
defines_prop(point(A, B), move(C, D, E)).
defines_prop(rectangle(A, B, C), origin(D)).
defines_prop(rectangle(A, B, C), xlength(D)).
defines_prop(rectangle(A, B, C), ylength(D)).
defines_prop(rectangle(A, B, C), move(D, E, F)).
defines_prop(rectangle(A, B, C), perimeter(D)).
defines_prop(rectangle(A, B, C), area(D)).
defines_prop(rectangle(A, B, C), rotate(D)).
defines_prop(rectangle(A, B, C), intersection(D, E)).
defines_prop(square(A, B), perimeter(C)).
defines_prop(square(A, B), rotate(C)).

call_object('OBJECT', defines_property(A), B) :-
	'OBJECT'(defines_property(A), B).
call_object('OBJECT', parent(A), B) :-
	'OBJECT'(parent(A), B).
call_object(point(A, B), xval(C), D) :-
	point(xval(C), D, A, B).
call_object(point(A, B), yval(C), D) :-
	point(yval(C), D, A, B).
call_object(point(A, B), move(C, D, E), F) :-
	point(move(C, D, E), F, A, B).
call_object(rectangle(A, B, C), origin(D), E) :-
	rectangle(origin(D), E, A, B, C).
call_object(rectangle(A, B, C), xlength(D), E) :-
	rectangle(xlength(D), E, A, B, C).
call_object(rectangle(A, B, C), ylength(D), E) :-
	rectangle(ylength(D), E, A, B, C).
call_object(rectangle(A, B, C), move(D, E, F), G) :-
	rectangle(move(D, E, F), G, A, B, C).
call_object(rectangle(A, B, C), perimeter(D), E) :-
	rectangle(perimeter(D), E, A, B, C).
call_object(rectangle(A, B, C), area(D), E) :-
	rectangle(area(D), E, A, B, C).
call_object(rectangle(A, B, C), rotate(D), E) :-
	rectangle(rotate(D), E, A, B, C).
call_object(rectangle(A, B, C), intersection(D, E), F) :-
	rectangle(intersection(D, E), F, A, B, C).
call_object(square(A, B), perimeter(C), D) :-
	square(perimeter(C), D, A, B).
call_object(square(A, B), rotate(C), D) :-
	square(rotate(C), D, A, B).