telega

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

-export([set_webhook/1, is_webhook_path/2, is_secret_token_valid/2, reply/2, add_handler/2, handle_update/2, new/4]).
-export_type([config/0, bot/0, handler/0, context/0, command/0, command_context/0]).

-opaque config() :: {config,
        binary(),
        binary(),
        binary(),
        gleam@option:option(binary()),
        binary()}.

-type bot() :: {bot, config(), list(handler())}.

-type handler() :: {handle_all, fun((context()) -> {ok, nil} | {error, nil})} |
    {handle_command,
        fun((command_context()) -> {ok, nil} | {error, nil}),
        binary()} |
    {handle_commands,
        fun((command_context()) -> {ok, nil} | {error, nil}),
        list(binary())} |
    {handle_text, fun((context()) -> {ok, nil} | {error, nil})}.

-type context() :: {context, telega@message:message(), bot()}.

-type command() :: {command, binary(), binary(), gleam@option:option(binary())}.

-type command_context() :: {command_context,
        telega@message:message(),
        bot(),
        command()}.

-spec set_webhook(bot()) -> {ok, boolean()} | {error, binary()}.
set_webhook(Bot) ->
    Webhook_url = <<<<(erlang:element(3, erlang:element(2, Bot)))/binary,
            "/"/utf8>>/binary,
        (erlang:element(4, erlang:element(2, Bot)))/binary>>,
    gleam@result:'try'(
        telega@api:set_webhook(
            erlang:element(2, erlang:element(2, Bot)),
            Webhook_url,
            erlang:element(6, erlang:element(2, Bot)),
            erlang:element(5, erlang:element(2, Bot))
        ),
        fun(Response) -> case erlang:element(2, Response) of
                200 ->
                    {ok, true};

                _ ->
                    {error, <<"Failed to set webhook"/utf8>>}
            end end
    ).

-spec is_webhook_path(bot(), binary()) -> boolean().
is_webhook_path(Bot, Path) ->
    erlang:element(4, erlang:element(2, Bot)) =:= Path.

-spec is_secret_token_valid(bot(), binary()) -> boolean().
is_secret_token_valid(Bot, Token) ->
    case erlang:element(5, erlang:element(2, Bot)) of
        {some, Secret} ->
            Secret =:= Token;

        none ->
            true
    end.

-spec reply(context(), binary()) -> {ok, telega@message:message()} |
    {error, nil}.
reply(Ctx, Text) ->
    Chat_id = erlang:element(
        2,
        erlang:element(8, erlang:element(3, erlang:element(2, Ctx)))
    ),
    _pipe = telega@api:send_message(
        Chat_id,
        Text,
        erlang:element(2, erlang:element(2, erlang:element(3, Ctx))),
        erlang:element(6, erlang:element(2, erlang:element(3, Ctx)))
    ),
    _pipe@1 = gleam@result:map(_pipe, fun(_) -> erlang:element(2, Ctx) end),
    gleam@result:nil_error(_pipe@1).

-spec add_handler(bot(), handler()) -> bot().
add_handler(Bot, Handler) ->
    erlang:setelement(3, Bot, [Handler | erlang:element(3, Bot)]).

-spec extract_command(telega@message:message()) -> command().
extract_command(Message) ->
    case erlang:element(17, erlang:element(3, Message)) of
        none ->
            {command, <<""/utf8>>, <<""/utf8>>, none};

        {some, Text} ->
            case gleam@string:split(Text, <<" "/utf8>>) of
                [Command | Payload] ->
                    {command, Text, Command, case Payload of
                            [] ->
                                none;

                            [Payload@1 | _] ->
                                {some, Payload@1}
                        end};

                _ ->
                    {command, Text, <<""/utf8>>, none}
            end
    end.

-spec do_handle_update(bot(), telega@message:message(), list(handler())) -> nil.
do_handle_update(Bot, Message, Handlers) ->
    case Handlers of
        [Handler | Rest] ->
            Handle_result = case {Handler, erlang:element(2, Message)} of
                {{handle_all, Handle}, _} ->
                    Handle({context, Message, Bot});

                {{handle_text, Handle@1}, text_message} ->
                    Handle@1({context, Message, Bot});

                {{handle_command, Handle@2, Command}, command_message} ->
                    Message_command = extract_command(Message),
                    case erlang:element(3, Message_command) =:= Command of
                        true ->
                            Handle@2(
                                {command_context, Message, Bot, Message_command}
                            );

                        false ->
                            {ok, nil}
                    end;

                {{handle_commands, Handle@3, Commands}, command_message} ->
                    Message_command@1 = extract_command(Message),
                    case gleam@list:contains(
                        Commands,
                        erlang:element(3, Message_command@1)
                    ) of
                        true ->
                            Handle@3(
                                {command_context,
                                    Message,
                                    Bot,
                                    Message_command@1}
                            );

                        false ->
                            {ok, nil}
                    end;

                {_, _} ->
                    {ok, nil}
            end,
            case Handle_result of
                {ok, _} ->
                    do_handle_update(Bot, Message, Rest);

                {error, _} ->
                    telega@log:error(<<"Failed to handle message"/utf8>>),
                    nil
            end;

        _ ->
            nil
    end.

-spec handle_update(bot(), telega@message:message()) -> nil.
handle_update(Bot, Message) ->
    do_handle_update(Bot, Message, erlang:element(3, Bot)).

-spec new(binary(), binary(), binary(), gleam@option:option(binary())) -> bot().
new(Token, Server_url, Webhook_path, Secret_token) ->
    {bot,
        {config,
            Token,
            Server_url,
            Webhook_path,
            Secret_token,
            <<"https://api.telegram.org/bot"/utf8>>},
        []}.