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-module(shr_roll).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-export
(
[
percentage/0,
between/2,
percentage_with_luck/2
]
).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec calculate_costs (boolean(), 0..100, 0..100) -> integer().
calculate_costs (true, Roll, Chance) when (Chance > 50) ->
% Succeeded, was likely to succeed.
% Only pay what was used.
max(0, (Roll - Chance));
calculate_costs (true, _Roll, Chance) when (Chance =< 50) ->
% Succeeded, was unlikely to succeed.
% Pay a lot!
(Chance - 55);
calculate_costs (false, _Roll, Chance) when (Chance > 50) ->
% Failure due to bad roll.
% Was likely to succeed, you get a lot!
(Chance - 45);
calculate_costs (_, _, _) ->
% Failure on unlikely roll. Not costs.
0.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec between (non_neg_integer(), non_neg_integer()) -> non_neg_integer().
between (Min, Max) ->
Diff = (Max - Min),
(Min + (rand:uniform(Diff + 1) - 1)).
-spec percentage () -> 0..100.
percentage () ->
between(0, 100).
-spec percentage_with_luck
(
non_neg_integer(),
integer()
)
-> {0..100, boolean(), integer(), integer()}.
percentage_with_luck (Chance, Luck) ->
Roll = percentage(),
ModedChance = max(0, min((Chance + Luck), 100)),
ModedRoll = max(0, min((Roll - Luck), 100)),
IsSuccess = (Roll =< ModedChance),
BadLuckBonus =
case (Luck < 0) of
true -> 1;
false -> 0
end,
{
ModedRoll,
IsSuccess,
(BadLuckBonus + calculate_costs(IsSuccess, Roll, Chance)),
calculate_costs((not IsSuccess), (100 - Roll), (100 - ModedChance))
}.
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