:- dynamic ct/3.
:- multifile ct/3.

ct(removeService(D,E,'Down','Standby'), (
	serviceN(D,'Down'),
	not(
		serviceN(S,'Standby'),
		D \= S,
		backupRelation(_,D,S)
	)
),(
	delete(serviceN(D,'Down')),
	add(emptyN(E))
)).

ct(initializeEmptyNode(E), (
	not(emptyN(E))
),(
	add(emptyN(E))
)).
%ct(initializeEmptyNode(A), (
%	not(initNode(A),emptyNode(E))
%),(
%	add(emptyNode(E)),
%	add(initNode(A))
%)).


ct(powerOnService(E,A,'Up'), ( 
	emptyN(E)
),(
	add(serviceN(A,'Up')),
	delete(emptyN(E))
)).

%open_world_cts([
%	powerOnService,removeService,initializeEmptyNode
%]).

ct(registerService(S,'Active','Up'), (
    serviceN(S,'Up')
),(
    replace(serviceN(S,'Up'),serviceN(S,'Active'))
)).

ct(unregisterService(S,'Active','Up'), (
    serviceN(S,'Active'),
    not(
    	serviceN(S2,_),
    	S2 \= S,
    	backupRelation(_b,S,S2)
    )
),(
	replace(serviceN(S,'Active'),serviceN(S,'Up'))
)).

ct(standbyService(A,U,Rb,'Active','Standby','Up'), (
	serviceN(A,'Active'),
	serviceN(U,'Up'),
	A \= U,
	not( backupRelation(Rb,A,U) )

),(
	replace(serviceN(S,'Up'),serviceN(S,'Standby')),
	add(backupRelation(Rb,A,U))
)).

ct(detachService(A,S,Rb,'Active','Standby','Up'), (
	serviceN(A,'Active'),
	serviceN(S,'Standby'),
	A \= S,
	backupRelation(Rb,A,S)
),(
	delete(backupRelation(Rb,A,S)),
	replace(serviceN(S,'Standby'),serviceN(S,'Up'))
)).

ct(failoverService(D,S,Rb,'Down','Standby'), (
	serviceN(D,'Down'),
	serviceN(S,'Standby'),
	D \= S,
	backupRelation(Rb,D,S)
),(
	delete(backupRelation(Rb,D,S)),
	replace(serviceN(S,'Standby'),serviceN(S,'Active'))
)).