MACD Calculation

main:-
    create_candle_list,
    list_ema(12).

create_candle_list:-
    open("candlestick-data.txt", read, Str),
    read_file(Str,Lines),
    close(Str).

read_file(Stream,[]) :-
    at_end_of_stream(Stream).

read_file(Stream,[X|L]) :-
    \+ at_end_of_stream(Stream),
    read(Stream,X),
    assert(X),
    read_file(Stream,L).


% This rule lists all the candles.
list_candles:-
    candle(W, X, Y, Z),
    write('candle('),
    write(W), write(', '),
    write(X), write(', '),
    write(Y), write(', '),
    write(Z), write(')'),
    nl, fail.


% This rule lists the exponential moving averages.

list_ema(P):-
    retract(period(X)),
    write(2),
    fail.
list_ema(P):-                                           % set the initial period to 0
    asserta(period(0)),
    write(2),
    fail.
list_ema(P):-                                           % reset current sma and period pointer values and ema multiplier
    write(2),
    retract(curr_ema(Z)),
    asserta(curr_ema(0)),
    retract(curr_period_ptr(Y)),
    asserta(curr_period_ptr(0)),
    retract(ema_multiplier(X)),
    fail.
list_ema(P):-                                           % remove every ema listed so far
    write(2),
    retract(curr_ema_list(Y)),
    asserta(curr_ema_list(0)),
    fail.
list_ema(P):-
    write(2),
    Denom is P + 1,
    M is 2 / Denom,
    asserta(ema_multiplier(M)),
    fail.
list_ema(P):-                                           % calculate the ema values
    write(2),
    candle(W, X, Close, Z),
    calculate_sub_ema(Close),
    fail.
list_ema(P):-                                           % display the ema values
    curr_ema_list(X), write(X), nl,
    fail.

ema(P):-
    retract(period(X)),
    fail.
ema(P):-                                            % set the initial period to 0
    asserta(period(0)),
    fail.
ema(P):-                                            % reset current sma and period pointer values and ema multiplier
    retract(curr_ema(Z)),
    asserta(curr_ema(0)),
    retract(curr_period_ptr(Y)),
    asserta(curr_period_ptr(0)),
    retract(ema_multiplier(X)),
    fail.
ema(P):-                                            % remove every ema listed so far
    retract(curr_ema_list(Y)),
    asserta(curr_ema_list(0)),
    fail.
ema(P):-
    Denom is P + 1,
    M is 2 / Denom,
    asserta(ema_multiplier(M)),
    fail.
ema(P):-                                            % calculate the ema values
    candle(W, X, Close, Z),
    calculate_sub_ema(Close),
    fail.
ema(P):-                                            % display the ema values
    curr_ema_list(X),
    X = 0,
    retract(curr_ema_list(0)),
    fail.
ema(P):-                                            % display the ema values
    curr_ema_list(X),
    write(X), nl,
    fail.

calculate_sub_ema(Close):-      % initialize things
    curr_ema_list(Prev_Close),
    ema_multiplier(M),
    Prev_M is 1 - M,
    Prev_Weight is Prev_Close * Prev_M,
    Curr_Weight is Close * M,
    Curr_EMA is Prev_Weight + Curr_Weight,
    asserta(curr_ema_list(Curr_EMA)),
    !.

curr_candle([]).
curr_candle_list([]).
curr_sma(0).
curr_sma_list([]).
curr_ema(0).
curr_ema_list([]).
curr_period_ptr(0).
max_period(0).