-module(x_version_4).

-import(util_record, [insert_version/2,
                      update_version/2,
                      insert_field/3,
                      update_field/3,
                      remove_field/2,
                      update_record/3]).

-include_lib("eunit/include/eunit.hrl").

-compile(export_all).


% -record(x, {field_a                :: string()}).

% -record(x, {version = {version, 1} :: {version, integer()},
%             field_a                :: string()}).

% -record(x, {version = {version, 2} :: {version, integer()},
%             field_a                :: string(),
%             field_b                :: string()}).

% -record(x, {version = {version, 3} :: {version, integer()},
%             field_b                :: string()}).

-record(x, {version = {version, 4} :: {version, integer()},
             field_b                :: atom()}).


-spec update_x(not_versioned | integer(), tuple()) -> #x{}.
update_x(not_versioned, X) ->
    update_x(1, insert_version(1, X));
update_x(1, X) ->
    update_x(2, update_version(2, insert_field(3, "default_field_b", X)));
update_x(2, X) ->
    update_x(3, update_version(3, remove_field(2, X)));
update_x(3, X) ->
    update_x(4, update_version(4, update_field(2, fun list_to_atom/1, X)));
update_x(4, X) ->
    X.

-spec update_x(tuple()) -> #x{}.
update_x(X) ->
    update_record(x, fun update_x/2, X).


update_x_not_versioned_test() ->
    ?assertEqual(#x{version = {version, 4},
                    field_b = default_field_b},
                 update_x({x, "field_a"})).

update_x_version_1_test() ->
    ?assertEqual(#x{version = {version, 4},
                    field_b = default_field_b},
                 update_x({x, {version, 1}, "field_a"})).

update_x_version_2_test() ->
    ?assertEqual(#x{version = {version, 4},
                    field_b = field_b},
                 update_x({x, {version, 2}, "field_a", "field_b"})).

update_x_version_3_test() ->
    ?assertEqual(#x{version = {version, 4},
                    field_b = field_b},
                 update_x({x, {version, 3}, "field_b"})).

update_x_version_4_test() ->
    ?assertEqual(#x{version = {version, 4},
                    field_b = field_b},
                 update_x({x, {version, 4}, field_b})).