%% @doc Add ticket.source field and index on error_hash.
%% No-op if `ticket` table is absent (e.g. migration_engine unit tests).
-module('20260716230000_ticket_source_and_hash_index').

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

-include("records.hrl").

up() ->
  case ticket_table_exists() of
    false ->
      ok;
    true ->
      ensure_source_field(),
      ensure_error_hash_index(),
      ok
  end.

down() ->
  case ticket_table_exists() of
    false ->
      ok;
    true ->
      case catch mnesia:del_table_index(ticket, error_hash) of
        {atomic, ok} -> ok;
        {aborted, {no_exists, _}} -> ok;
        {aborted, {no_exists, _, _}} -> ok;
        _ -> ok
      end
  end.

ticket_table_exists() ->
  try lists:member(ticket, mnesia:system_info(tables))
  catch
    _:_ -> false
  end.

ensure_source_field() ->
  Attrs = mnesia:table_info(ticket, attributes),
  case lists:member(source, Attrs) of
    true ->
      ok;
    false ->
      Fun = fun(Rec) ->
        case tuple_size(Rec) of
          14 ->
            %% ticket + 13 fields (pre-source)
            list_to_tuple(tuple_to_list(Rec) ++ [<<"backend">>]);
          _ ->
            Rec
        end
      end,
      case mnesia:transform_table(ticket, Fun, record_info(fields, ticket)) of
        {atomic, ok} -> ok;
        {aborted, Reason} -> error({transform_ticket_failed, Reason})
      end
  end.

ensure_error_hash_index() ->
  Indexes = mnesia:table_info(ticket, index),
  HasIndex = lists:any(fun
    (error_hash) -> true;
    (N) when is_integer(N) -> N =:= #ticket.error_hash;
    (_) -> false
  end, Indexes),
  case HasIndex of
    true ->
      ok;
    false ->
      case mnesia:add_table_index(ticket, error_hash) of
        {atomic, ok} -> ok;
        {aborted, {already_exists, _}} -> ok;
        {aborted, {already_exists, _, _}} -> ok;
        {aborted, Reason} -> error({add_index_failed, Reason})
      end
  end.