-module(gleam_synapses@model@net_elems@activation).
-compile(no_auto_import).

-export([math_exp/1, math_log/1, math_tanh/1, restricted_input/2, restricted_output/2, sigmoid/0, identity/0, tanh/0, leaky_re_lu/0, serialized/1, deserialized/1, json_encoded/1, json_decoder/0, generator/0]).
-export_type([activation/0]).

-type activation() :: {activation,
                       binary(),
                       fun((float()) -> float()),
                       fun((float()) -> float()),
                       fun((float()) -> float()),
                       {float(), float()}}.

-spec math_exp(float()) -> float().
math_exp(A) ->
    math:exp(A).

-spec math_log(float()) -> float().
math_log(A) ->
    math:log(A).

-spec math_tanh(float()) -> float().
math_tanh(A) ->
    math:tanh(A).

-spec restricted_input(activation(), float()) -> float().
restricted_input(Activation, X) ->
    {Min, Max} = erlang:element(6, Activation),
    gleam@float:clamp(X, Min, Max).

-spec restricted_output(activation(), float()) -> float().
restricted_output(Activation, Y) ->
    {Min, Max} = erlang:element(6, Activation),
    gleam@float:clamp(
        Y,
        (erlang:element(3, Activation))(Min),
        (erlang:element(3, Activation))(Max)
    ).

-spec min_abs_float(boolean()) -> float().
min_abs_float(Is_positive) ->
    X = 1.7976931348623157 * gleam@float:power(10.0, 308.0),
    case Is_positive of
        true ->
            X;

        false ->
            0.0 - X
    end.

-spec sigmoid_f(float()) -> float().
sigmoid_f(X) ->
    case (1.0 + math:exp(0.0 - X)) of
        0.0 -> 0.0;
        Gleam@denominator -> 1.0 / Gleam@denominator
    end.

-spec sigmoid() -> activation().
sigmoid() ->
    {activation,
     <<"sigmoid"/utf8>>,
     fun sigmoid_f/1,
     fun(D) -> sigmoid_f(D) * (1.0 - sigmoid_f(D)) end,
     fun(Y) -> math:log(case (1.0 - Y) of
                 0.0 -> 0.0;
                 Gleam@denominator -> Y / Gleam@denominator
             end) end,
     {-700.0, 20.0}}.

-spec identity() -> activation().
identity() ->
    {activation,
     <<"identity"/utf8>>,
     fun(X) -> X end,
     fun(_) -> 1.0 end,
     fun(Y) -> Y end,
     {min_abs_float(false), min_abs_float(true)}}.

-spec tanh() -> activation().
tanh() ->
    {activation,
     <<"tanh"/utf8>>,
     fun math:tanh/1,
     fun(D) -> 1.0 - (math:tanh(D) * math:tanh(D)) end,
     fun(Y) -> 0.5 * math:log(case (1.0 - Y) of
                 0.0 -> 0.0;
                 Gleam@denominator -> (1.0 + Y) / Gleam@denominator
             end) end,
     {-10.0, 10.0}}.

-spec leaky_re_lu() -> activation().
leaky_re_lu() ->
    {activation, <<"leakyReLU"/utf8>>, fun(X) -> case X < 0.0 of
             true ->
                 0.01 * X;

             false ->
                 X
         end end, fun(D) -> case D < 0.0 of
             true ->
                 0.01;

             false ->
                 1.0
         end end, fun(Y) -> case Y < 0.0 of
             true ->
                 Y / 0.01;

             false ->
                 Y
         end end, {min_abs_float(false), min_abs_float(true)}}.

-spec serialized(activation()) -> binary().
serialized(Activation) ->
    erlang:element(2, Activation).

-spec deserialized(binary()) -> activation().
deserialized(Activation_serialised) ->
    case Activation_serialised of
        <<"sigmoid"/utf8>> ->
            sigmoid();

        <<"identity"/utf8>> ->
            identity();

        <<"tanh"/utf8>> ->
            tanh();

        <<"leakyReLU"/utf8>> ->
            leaky_re_lu()
    end.

-spec json_encoded(binary()) -> gleam_synapses@model@edited_jsone:json_value().
json_encoded(Activation_serialised) ->
    gleam_synapses@model@edited_jsone:string(Activation_serialised).

-spec json_decoder() -> decode:decoder(binary()).
json_decoder() ->
    decode:string().

-spec generator() -> minigen:generator(activation()).
generator() ->
    minigen:always(sigmoid()).