openfeature

-module(openfeature@evaluation_context).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([empty/0, get_attribute/2, get_all_attributes/1, merge/2]).
-export_type([evaluation_context/0]).

-type evaluation_context() :: {evaluation_context,
        gleam@option:option(binary()),
        gleam@dict:dict(binary(), gleam@dynamic:dynamic_())}.

-spec empty() -> evaluation_context().
empty() ->
    {evaluation_context, none, gleam@dict:new()}.

-spec get_attribute(evaluation_context(), binary()) -> {ok,
        gleam@dynamic:dynamic_()} |
    {error, nil}.
get_attribute(Evaluation_context, Key) ->
    gleam@dict:get(erlang:element(3, Evaluation_context), Key).

-spec get_all_attributes(evaluation_context()) -> list({binary(),
    gleam@dynamic:dynamic_()}).
get_all_attributes(Evaluation_context) ->
    maps:to_list(erlang:element(3, Evaluation_context)).

-spec merge(evaluation_context(), evaluation_context()) -> evaluation_context().
merge(Initial_context, Overriding_context) ->
    Targeting_key = case erlang:element(2, Overriding_context) of
        none ->
            erlang:element(2, Initial_context);

        {some, _} ->
            erlang:element(2, Overriding_context)
    end,
    Attributes = gleam@dict:combine(
        erlang:element(3, Initial_context),
        erlang:element(3, Overriding_context),
        fun(_, Overriding) -> Overriding end
    ),
    {evaluation_context, Targeting_key, Attributes}.