-module(storch).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([migrate/2]).
-export_type([migration/0]).

-type migration() :: {migration, integer(), binary()}.

-spec migrate(list(migration()), sqlight:connection()) -> {ok, nil} |
    {error, sqlight:error()}.
migrate(Migrations, Connection) ->
    Transaction = (gleam@result:'try'(
        sqlight:exec(<<"begin transaction;"/utf8>>, Connection),
        fun(_) ->
            gleam@result:'try'(
                sqlight:exec(
                    <<"create table if not exists storch_migrations (id integer, applied integer);"/utf8>>,
                    Connection
                ),
                fun(_) ->
                    Migrations_decoder = gleam@dynamic:tuple2(
                        fun gleam@dynamic:int/1,
                        fun sqlight:decode_bool/1
                    ),
                    Applications = gleam@list:try_each(
                        Migrations,
                        fun(Migration) ->
                            gleam@result:'try'(
                                sqlight:'query'(
                                    <<"select id, applied from storch_migrations where id = ?;"/utf8>>,
                                    Connection,
                                    [sqlight:int(erlang:element(2, Migration))],
                                    Migrations_decoder
                                ),
                                fun(Migrated) ->
                                    Already_applied = case Migrated of
                                        [] ->
                                            false;

                                        [{_, Applied}] ->
                                            Applied;

                                        _ ->
                                            erlang:error(#{gleam_error => panic,
                                                    message => <<"Multiple migrations with the same id in the storch migrations table"/utf8>>,
                                                    module => <<"storch"/utf8>>,
                                                    function => <<"migrate"/utf8>>,
                                                    line => 44})
                                    end,
                                    gleam@bool:guard(
                                        Already_applied,
                                        {ok, nil},
                                        fun() ->
                                            gleam@result:'try'(
                                                sqlight:exec(
                                                    erlang:element(3, Migration),
                                                    Connection
                                                ),
                                                fun(_) ->
                                                    gleam@result:'try'(
                                                        sqlight:'query'(
                                                            <<"insert into storch_migrations (id, applied) values (?,?) returning *;"/utf8>>,
                                                            Connection,
                                                            [sqlight:int(
                                                                    erlang:element(
                                                                        2,
                                                                        Migration
                                                                    )
                                                                ),
                                                                sqlight:bool(
                                                                    true
                                                                )],
                                                            Migrations_decoder
                                                        ),
                                                        fun(_) -> {ok, nil} end
                                                    )
                                                end
                                            )
                                        end
                                    )
                                end
                            )
                        end
                    ),
                    gleam@result:'try'(
                        Applications,
                        fun(_) ->
                            gleam@result:'try'(
                                sqlight:exec(<<"commit;"/utf8>>, Connection),
                                fun(_) -> {ok, nil} end
                            )
                        end
                    )
                end
            )
        end
    )),
    case Transaction of
        {ok, _} ->
            {ok, nil};

        {error, Err} ->
            gleam@io:println(<<"error running migration"/utf8>>),
            gleam@io:debug(Err),
            gleam@io:println(<<"rolling back"/utf8>>),
            _ = sqlight:exec(<<"rollback;"/utf8>>, Connection),
            {error, Err}
    end.