defer_g

-module(defer_g).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([defer/2, start_defer/2, add_defer/3]).
-export_type([defer_context/0]).

-opaque defer_context() :: {defer_context, list(fun(() -> nil))}.

-spec defer(fun(() -> any()), fun(() -> HFC)) -> HFC.
defer(Defer_func, Rest) ->
    Result = Rest(),
    Defer_func(),
    Result.

-spec new_context() -> defer_context().
new_context() ->
    {defer_context, []}.

-spec append_to_context(defer_context(), fun(() -> nil)) -> defer_context().
append_to_context(Context, New_defer_func) ->
    {defer_context, Previous} = Context,
    {defer_context, [New_defer_func | Previous]}.

-spec run_defers(list(fun(() -> nil))) -> nil.
run_defers(Defers) ->
    case Defers of
        [] ->
            nil;

        [One] ->
            One();

        [One@1 | Rest] ->
            run_defers(Rest),
            One@1()
    end.

-spec start_defer(
    fun(() -> nil),
    fun((defer_context()) -> {defer_context(), HFG})
) -> HFG.
start_defer(Defer_func, Rest) ->
    Context = begin
        _pipe = new_context(),
        append_to_context(_pipe, Defer_func)
    end,
    {{defer_context, Defers}, Result} = Rest(Context),
    run_defers(Defers),
    Result.

-spec add_defer(
    defer_context(),
    fun(() -> nil),
    fun((defer_context()) -> {defer_context(), HFH})
) -> {defer_context(), HFH}.
add_defer(Context, Defer_func, First) ->
    Context@1 = append_to_context(Context, Defer_func),
    First(Context@1).