-module(migrant@lib).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function]).

-export([get_or_make_migration/3, validate_direction/2]).

-spec get_or_make_migration(
    binary(),
    gleam@dict:dict(binary(), migrant@types:migration()),
    fun((migrant@types:migration()) -> {ok,
            {binary(), migrant@types:migration()}} |
        {error, migrant@types:error()})
) -> {ok, {binary(), migrant@types:migration()}} |
    {error, migrant@types:error()}.
get_or_make_migration(Name, Migrations, Next) ->
    case gleam@dict:get(Migrations, Name) of
        {ok, Migration} ->
            Next(Migration);

        {error, _} ->
            Next({migration, none, none})
    end.

-spec validate_direction(
    binary(),
    fun((binary()) -> {ok, {binary(), migrant@types:migration()}} |
        {error, migrant@types:error()})
) -> {ok, {binary(), migrant@types:migration()}} |
    {error, migrant@types:error()}.
validate_direction(Direction, Next) ->
    case Direction of
        <<"up"/utf8>> ->
            Next(<<"up"/utf8>>);

        <<"down"/utf8>> ->
            Next(<<"down"/utf8>>);

        _ ->
            {error, {filename_error, <<"Expected `up` or `down`"/utf8>>}}
    end.