%% @doc Create calendar_follow table and indexes if missing.
-module('20260720210000_calendar_follow').

-export([up/0, down/0]).

-include("records.hrl").

up() ->
  ensure_table(calendar_follow, record_info(fields, calendar_follow)),
  ensure_index(calendar_follow, calendar_id),
  ensure_index(calendar_follow, user_id),
  ok.

down() ->
  _ = mnesia:delete_table(calendar_follow),
  ok.

ensure_table(Table, Attrs) ->
  case lists:member(Table, mnesia:system_info(tables)) of
    true ->
      ok;
    false ->
      case mnesia:create_table(Table, [{disc_copies, [node()]}, {attributes, Attrs}]) of
        {atomic, ok} -> ok;
        {aborted, {already_exists, Table}} -> ok;
        {aborted, Reason} -> error({create_table_failed, Table, Reason})
      end
  end.

ensure_index(Table, Attr) ->
  case mnesia:add_table_index(Table, Attr) of
    {atomic, ok} -> ok;
    {aborted, {already_exists, Table, _Pos}} -> ok;
    {aborted, {already_exists, Table, Attr}} -> ok;
    {aborted, {already_exists, _}} -> ok;
    {aborted, Reason} -> error({add_index_failed, Table, Attr, Reason})
  end.