% Assess whether the user is of low income.
low_income(X) :- X =< 20000.
% Are they old enough to remember Margaret Thatcher? Assuming the user
% had to be at least 5 years old in 1990 - ie the year of their birth
% was 1985 or earlier.
remembersThatcher(X) :- X =< 1985.
% Count the number of hits in a list.
%
hits([], SearchList, 0). % If there are no search terms there can be no hits.
hits([Head|Tail], SearchList, Sum) :-
	member(Head, SearchList),
	hits(Tail, SearchList, Temp),
	Sum is Temp + 1.
hits([Head|Tail], SearchList, Sum) :-
	\+ member(Head, SearchList),
	hits(Tail, SearchList, Sum).

education(graduate).
education(none).

gender(male). gender(m). gender(female). gender(f).

toryLike(['nimbyIssues']).
toryHate(['europe']).

 % Special Case, poor people who remember Margaret Thatcher will never vote Tory.
neverVotesTory(AnualIncome, YearOfBirth) :-
	low_income(AnualIncome), remembersThatcher(YearOfBirth).
% Establish a 'base level' based on socio-economic background.
tory(_,_,_,_,_,_,0).
tory(YearOfBirth, AnualIncome, MyEducation, graduate, Gender, [], [], Confidence) :-
	education(MyEducation),
	gender(Gender),
	\+ neverVotesTory(AnualIncome, YearOfBirth),
	Confidence is 1.
tory(YearOfBirth, AnualIncome, MyEducation, FathersEducation, male, [], [], Confidence) :-
	education(MyEducation), education(FathersEducation),
	\+ neverVotesTory(AnualIncome, YearOfBirth),
	Confidence is 1 rdiv 2.

% Multiply the Confidence value by 1 / the number of hated likes and
% liked hates.
tory(YearOfBirth, AnualIncome, MyEducation, FathersEducation, Gender, Likes, Dislikes, Confidence) :-
	education(MyEducation), education(FathersEducation),
	toryLike(ToryLike), toryHate(ToryHate),
	hits(ToryLike, Dislikes, Temp1), hits(ToryHate, Likes, Temp2),
	Temp3 is Temp2 + Temp1 + 1,!,
	tory(YearOfBirth, AnualIncome, MyEducation, FathersEducation, Gender, [], [], Temp),
	Confidence is Temp rdiv Temp3,
	writeln(MyEducation).