strata_postgres

-module(strata_postgres).

-behaviour(strata_driver).

-export([up/1, down/1, list/1, add/3, delete/2, last/1, exec/2]).

-spec exec(any(), iodata()) -> ok | {error, any()}.
exec(_Conn, Query) ->
    case pgo:query(Query, []) of
        {error, _Err} = E ->
            E;
        #{rows := _} ->
            ok
    end.

-spec up(any()) -> ok | {error, any()}.
up(_Conn) ->
    case pgo:query([<<"CREATE TABLE IF NOT EXISTS __strata_migrations ( ">>,
                    <<"  id SERIAL PRIMARY KEY, ">>,
                    <<"  name TEXT NOT NULL, ">>,
                    <<"  timestamp INTEGER NOT NULL ">>,
                    <<")">>],
                   [])
    of
        {error, _Err} = E ->
            E;
        #{rows := _} ->
            ok
    end.

-spec down(any()) -> ok | {error, any()}.
down(_Conn) ->
    case pgo:query(<<"DROP TABLE IF EXISTS __strata_migrations">>, []) of
        {error, _Err} = E ->
            E;
        #{rows := _} ->
            ok
    end.

-spec list(any()) -> {ok, list()} | {error, any()}.
list(_Conn) ->
    case
        pgo:query(<<"SELECT id, name, timestamp FROM __strata_migrations ORDER BY timestamp ASC">>,
                  [])
    of
        {error, _Err} = E ->
            E;
        #{rows := Rows} ->
            {ok, format_rows(Rows)}
    end.

-spec format_rows(list()) -> list().
format_rows(Rows) ->
    lists:map(fun format_row/1, Rows).

-spec format_row({integer(), binary(), integer()} | any()) ->
                    {integer(), module(), integer()} | {error, invalid_row}.
format_row({Id, Name, Timestamp}) ->
    {Id, binary_to_atom(Name), Timestamp};
format_row(_) ->
    {error, invalid_row}.

-spec add(any(), binary(), integer()) -> ok | {error, any()}.
add(_Conn, Name, Timestamp) ->
    case pgo:query(<<"INSERT INTO __strata_migrations (name, timestamp) VALUES ($1, $2)">>,
                   [Name, Timestamp])
    of
        {error, _Err} = E ->
            E;
        #{rows := _} ->
            ok
    end.

-spec last(any()) -> {error, any()} | {ok, {integer(), module(), integer()}}.
last(_Conn) ->
    case
        pgo:query(<<"SELECT id, name, timestamp FROM __strata_migrations ORDER BY timestamp DESC LIMIT 1">>,
                  [])
    of
        {error, _Err} = E ->
            E;
        #{rows := [{Id, Name, Timestamp}]} ->
            {ok, {Id, binary_to_atom(Name), Timestamp}}
    end.

-spec delete(any(), integer()) -> ok | {error, any()}.
delete(_Conn, Id) ->
    case pgo:query(<<"DELETE FROM __strata_migrations WHERE id = $1">>, [Id]) of
        {error, _Err} = E ->
            E;
        #{rows := _} ->
            ok
    end.