(* Copyright (C) 2022--2023  Petter A. Urkedal <paurkedal@gmail.com>
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version, with the LGPL-3.0 Linking Exception.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * and the LGPL-3.0 Linking Exception along with this library.  If not, see
 * <http://www.gnu.org/licenses/> and <https://spdx.org>, respectively.
 *)

(** Prerequisities for connecting to databases using Lwt

    This module contains most of the prerequisite types and modules.  Functions
    to establish database connections are provided by the [caqti-lwt.unix] and
    [caqti-mirage] libraries.  Pool instances are also found there due to
    additional OS dependencies. *)

(* A custom stream implementation instantiated for Lwt.  This is similar to
 * {!Lwt_seq}, except with error handling. *)
module Stream : Caqti_stream_sig.S with type 'a fiber := 'a Lwt.t

(* This should ideally be {!Lwt_switch}, but we need a way to cancel cleanup
 * jobs in order to avoid a memory leaks for long-lived pools. *)
module Switch : Caqti_switch_sig.S with type 'a fiber := 'a Lwt.t

(**/**)
(* For private use by caqti-lwt.unix and caqti-mirage. *)
module System_core : sig
  include Caqti_platform.System_sig.CORE
    with type 'a Fiber.t = 'a Lwt.t
     and module Stream = Stream
     and type Switch.t = Switch.t
     and type stdenv := unit
end
(**/**)

module type CONNECTION = Caqti_connection_sig.S
  with type 'a fiber := 'a Lwt.t
   and type ('a, 'e) stream := ('a, 'e) Stream.t

type connection = (module CONNECTION)

val or_fail : ('a, [< Caqti_error.t]) result -> 'a Lwt.t
(** Converts an error to an Lwt future failed with a {!Caqti_error.Exn}
    exception holding the error. *)