gleam_stats

-module(gleam_stats@distributions@uniform).
-compile(no_auto_import).

-export([uniform_mean/2, uniform_variance/2, uniform_pdf/3, uniform_cdf/3, uniform_random/4]).

-spec check_uniform_parameters(float(), float()) -> {ok, boolean()} |
    {error, binary()}.
check_uniform_parameters(A, B) ->
    case A =< B of
        false ->
            _pipe = <<"Invalid input arugment: a > b. Valid input is a <= b."/utf8>>,
            {error, _pipe};

        true ->
            _pipe@1 = true,
            {ok, _pipe@1}
    end.

-spec uniform_mean(float(), float()) -> {ok, float()} | {error, binary()}.
uniform_mean(A, B) ->
    case check_uniform_parameters(A, B) of
        {error, String} ->
            _pipe = String,
            {error, _pipe};

        _@1 ->
            _pipe@1 = (A + B) / 2.0,
            {ok, _pipe@1}
    end.

-spec uniform_variance(float(), float()) -> {ok, float()} | {error, binary()}.
uniform_variance(A, B) ->
    case check_uniform_parameters(A, B) of
        {error, String} ->
            _pipe = String,
            {error, _pipe};

        _@1 ->
            {ok, V@1} = case gleam_stats@math:pow(B - A, 2.0) of
                {ok, V} -> {ok, V};
                _try ->
                    erlang:error(#{gleam_error => assert,
                                   message => <<"Assertion pattern match failed"/utf8>>,
                                   value => _try,
                                   module => <<"gleam_stats/distributions/uniform"/utf8>>,
                                   function => <<"uniform_variance"/utf8>>,
                                   line => 84})
            end,
            _pipe@1 = V@1 / 12.0,
            {ok, _pipe@1}
    end.

-spec uniform_pdf(float(), float(), float()) -> {ok, float()} |
    {error, binary()}.
uniform_pdf(X, A, B) ->
    do_uniform_pdf(X, A, B).

-spec do_uniform_pdf(float(), float(), float()) -> {ok, float()} |
    {error, binary()}.
do_uniform_pdf(X, A, B) ->
    case check_uniform_parameters(A, B) of
        {error, String} ->
            _pipe = String,
            {error, _pipe};

        _@1 ->
            case (X >= A) andalso (X =< B) of
                true ->
                    _pipe@1 = case (B - A) of
                        0.0 -> 0.0;
                        Gleam@denominator -> 1.0 / Gleam@denominator
                    end,
                    {ok, _pipe@1};

                false ->
                    _pipe@2 = 0.0,
                    {ok, _pipe@2}
            end
    end.

-spec uniform_cdf(float(), float(), float()) -> {ok, float()} |
    {error, binary()}.
uniform_cdf(X, A, B) ->
    do_uniform_cdf(X, A, B).

-spec do_uniform_cdf(float(), float(), float()) -> {ok, float()} |
    {error, binary()}.
do_uniform_cdf(X, A, B) ->
    case check_uniform_parameters(A, B) of
        {error, String} ->
            _pipe = String,
            {error, _pipe};

        _@1 ->
            case X < A of
                true ->
                    _pipe@1 = 0.0,
                    {ok, _pipe@1};

                false ->
                    case (X >= A) andalso (X =< B) of
                        true ->
                            _pipe@2 = case (B - A) of
                                0.0 -> 0.0;
                                Gleam@denominator -> (X - A) / Gleam@denominator
                            end,
                            {ok, _pipe@2};

                        false ->
                            case X > B of
                                _@2 ->
                                    _pipe@3 = 1.0,
                                    {ok, _pipe@3}
                            end
                    end
            end
    end.

-spec uniform_random(
    gleam@iterator:iterator(integer()),
    float(),
    float(),
    integer()
) -> {ok, {list(float()), gleam@iterator:iterator(integer())}} |
    {error, binary()}.
uniform_random(Stream, A, B, M) ->
    do_uniform_random(Stream, A, B, M).

-spec do_uniform_random(
    gleam@iterator:iterator(integer()),
    float(),
    float(),
    integer()
) -> {ok, {list(float()), gleam@iterator:iterator(integer())}} |
    {error, binary()}.
do_uniform_random(Stream, A, B, M) ->
    case check_uniform_parameters(A, B) of
        {error, String} ->
            _pipe = String,
            {error, _pipe};

        _@1 ->
            case M > 0 of
                false ->
                    {error,
                     <<"Invalid input arugment: m < 0. Valid input is m > 0."/utf8>>};

                true ->
                    {ok, Out@1} = case gleam_stats@generators:take_randints(
                        Stream,
                        M
                    ) of
                        {ok, Out} -> {ok, Out};
                        _try ->
                            erlang:error(#{gleam_error => assert,
                                           message => <<"Assertion pattern match failed"/utf8>>,
                                           value => _try,
                                           module => <<"gleam_stats/distributions/uniform"/utf8>>,
                                           function => <<"do_uniform_random"/utf8>>,
                                           line => 314})
                    end,
                    Numbers = begin
                        _pipe@1 = gleam@pair:first(Out@1),
                        gleam@list:map(
                            _pipe@1,
                            fun(X) ->
                                A
                                + (case gleam@int:to_float(4294967295) of
                                    0.0 -> 0.0;
                                    Gleam@denominator -> (gleam@int:to_float(X)
                                    * (B
                                    - A))
                                    / Gleam@denominator
                                end)
                            end
                        )
                    end,
                    _pipe@2 = {Numbers, gleam@pair:second(Out@1)},
                    {ok, _pipe@2}
            end
    end.