-module(glint).
-compile(no_auto_import).

-export([new/0, add_command/4, execute/2, run/2]).
-export_type([command_input/0, command/0]).

-type command_input() :: {command_input,
                          list(binary()),
                          gleam@map:map_(binary(), glint@flag:flag_value())}.

-opaque command() :: {command,
                      gleam@option:option(fun((command_input()) -> nil)),
                      gleam@map:map_(binary(), command()),
                      gleam@map:map_(binary(), glint@flag:flag_value())}.

-spec new() -> command().
new() ->
    {command, none, gleam@map:new(), gleam@map:new()}.

-spec add_command(
    command(),
    list(binary()),
    fun((command_input()) -> nil),
    list(glint@flag:flag())
) -> command().
add_command(Root, Path, F, Flags) ->
    case Path of
        [] ->
            erlang:setelement(
                4,
                erlang:setelement(2, Root, {some, F}),
                glint@flag:build_map(Flags)
            );

        [X | Xs] ->
            Update_subcommand = fun(Node) -> case Node of
                    none ->
                        add_command(
                            {command, none, gleam@map:new(), gleam@map:new()},
                            Xs,
                            F,
                            Flags
                        );

                    {some, Node@1} ->
                        add_command(Node@1, Xs, F, Flags)
                end end,
            erlang:setelement(
                3,
                Root,
                gleam@map:update(erlang:element(3, Root), X, Update_subcommand)
            )
    end.

-spec execute_root(command(), list(binary())) -> {ok, nil} |
    {error, snag:snag()}.
execute_root(Cmd, Args) ->
    case erlang:element(2, Cmd) of
        {some, F} ->
            {ok, F({command_input, Args, erlang:element(4, Cmd)})};

        none ->
            {error,
             begin
                 _pipe = snag:new(<<"command not found"/utf8>>),
                 snag:layer(_pipe, <<"failed to run command"/utf8>>)
             end}
    end.

-spec execute(command(), list(binary())) -> {ok, nil} | {error, snag:snag()}.
execute(Cmd, Args) ->
    case Args of
        [] ->
            execute_root(Cmd, []);

        [Arg | Rest] ->
            case gleam@string:starts_with(Arg, <<"-"/utf8>>) of
                true ->
                    case begin
                        _pipe = glint@flag:update_flags(
                            erlang:element(4, Cmd),
                            gleam@string:drop_left(Arg, 1)
                        ),
                        snag:context(_pipe, <<"failed to run command"/utf8>>)
                    end of
                        {error, _try} -> {error, _try};
                        {ok, New_flags} ->
                            execute(erlang:setelement(4, Cmd, New_flags), Rest)
                    end;

                false ->
                    case gleam@map:get(erlang:element(3, Cmd), Arg) of
                        {ok, Cmd@1} ->
                            execute(Cmd@1, Rest);

                        {error, _@1} ->
                            execute_root(Cmd, Args)
                    end
            end
    end.

-spec run(command(), list(binary())) -> nil.
run(Cmd, Args) ->
    case execute(Cmd, Args) of
        {ok, nil} ->
            nil;

        {error, Err} ->
            _pipe = Err,
            _pipe@1 = snag:pretty_print(_pipe),
            gleam@io:println(_pipe@1)
    end.