%%%%%%%%%%%%%%%%%%%%
%
% Policies for registration
%
%%%%%%%%%%%%%%%%%%%%

% early registration phase
initiates(startEarlyRegistration,open(earlyRegistration),T).
terminates(closeEarlyRegistration,open(earlyRegistration),T).
initiates(startRegularRegistration,open(regularRegistration),T).
terminates(closeRegularRegistration,open(regularRegistration),T).


% permit registration during early and late registration phase
permit(Participant,register(Participant)):-
     sysTime(T),
     holdsAt(open(earlyRegistration),T).
permit(Participant,register(Participant)):-
     sysTime(T),
     holdsAt(open(regularRegistration),T).     
     
% registration axioms for registered participants
initiates(register(Participant),registered(Participant),T).
terminates(cancel(Participant),registered(Participant),T).


% registration fee policy
% compute fee depending on the registration phase 
% and possible discounts

fee(earlyRegistration,currency_Dollar:500).
fee(regularRegistration,currency_Dollar:600).

computeFee(Participant,Fee):-
  sysTime(T),
  computeFee(Participant,Fee,T).
computeFee(Participant,Fee,T):-   
   holdsAt(open(RegistrationPhase),T),
   fee(RegistrationPhase,BasicFee),
   %discount(Participant,Discount),
   Fee = BasicFee.
   %Fee = BasicFee - (BasicFee * Discount).
%Could be further extended, e.g. with extra fee for
% overlengthed papers such as 50$ extra for each 
% additional page above the maximum papge size
% (not enforced in RuleML-2007)   
   
% TODO: Implement discount rules for sponsors and collaboration partners
% Sponsoring rules will be implemented in the personal profile of the Publicity Chair    
   
% a participant is obliged to pay the registration fee
% when he has registered and not payed yet
% and not canceled the registration
oblige(Participant,pay(Fee)):-
   happens(register(Participant),T),
   not(happens(pay(Participant,Fee),T2)), %no payment 
   sysTime(CurrentTime),
   % still registered and not canceled
   holdsAt(registered(Participant),CurrentTime),
   computeFee(Participant,Fee,T).
   
 % a participant is permitted to attend if he has payed the fee
permit(Participant,attend):-
    happens(pay(Participant,Fee),T).        
    
    

open(earlyRegistration):-
       sysTime(T),
       holdsAt(open(earlyRegistration),T).           
dates(earlyRegistration,Start,End):-
       happens(startEarlyRegistration,Start),
       happens(closeEarlyRegistration,End). 
open(regularRegistration):-
       sysTime(T),
       holdsAt(open(regularRegistration),T).           
dates(regularRegistration,Start,End):-
       happens(startRegularRegistration,Start),
       happens(closeRegularRegistration,End). 
          
%%%%%%%%%%%%%%%%%%
%
% Test assertions 
%%%%%%%%%%%%%%%%%%

happens(startEarlyRegistration, datetime(2007,6,15,0,0,0)).
happens(closeEarlyRegistration, datetime(2007,8,15,0,0,0)).     
happens(startRegularRegistration, datetime(2007,8,16,0,0,0)).
happens(closeRegularRegistration, datetime(2007,9,26,0,0,0)).

happens(register("Adrian Paschke"), datetime(2007,7,13,0,0,0)).

%:-solve(holdsAt(open(earlyRegistration),datetime(2007,8,15,0,0,0))).
%:-solve(holdsAt(open(regularRegistration),datetime(2007,8,17,0,0,0))).
%:-solve(permit("Adrian Paschke",register(Participant))).
%:-solve(holdsAt(registered(Participant),datetime(2007,7,15,0,0,0))).
%:-solve(computeFee("Adrian Paschke",Fee)).
%:-solve(oblige("Adrian Paschke",Action)).