-module(lustre).
-compile([no_auto_import, nowarn_unused_vars]).

-export([element/1, simple/3, application/3, start/2]).
-export_type([app/2, error/0]).

-opaque app(GNE, GNF) :: {app,
        {GNE, lustre@cmd:cmd(GNF)},
        fun((GNE, GNF) -> {GNE, lustre@cmd:cmd(GNF)}),
        fun((GNE) -> lustre@element:element(GNF))}.

-type error() :: element_not_found.

-spec element(lustre@element:element(GNM)) -> app(nil, GNM).
element(Element) ->
    Init = {nil, lustre@cmd:none()},
    Update = fun(_, _) -> {nil, lustre@cmd:none()} end,
    Render = fun(_) -> Element end,
    {app, Init, Update, Render}.

-spec simple(
    GNQ,
    fun((GNQ, GNR) -> GNQ),
    fun((GNQ) -> lustre@element:element(GNR))
) -> app(GNQ, GNR).
simple(Init, Update, Render) ->
    Init@1 = {Init, lustre@cmd:none()},
    Update@1 = fun(Model, Msg) -> {Update(Model, Msg), lustre@cmd:none()} end,
    {app, Init@1, Update@1, Render}.

-spec application(
    {GNV, lustre@cmd:cmd(GNW)},
    fun((GNV, GNW) -> {GNV, lustre@cmd:cmd(GNW)}),
    fun((GNV) -> lustre@element:element(GNW))
) -> app(GNV, GNW).
application(Init, Update, Render) ->
    {app, Init, Update, Render}.

-spec start(app(any(), GOF), binary()) -> {ok, fun((GOF) -> nil)} |
    {error, error()}.
start(App, Selector) ->
    _pipe = '.@ffi.mjs':mount(App, Selector),
    gleam@result:replace_error(_pipe, element_not_found).